BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

Post Reply
 
Thread Tools Search this Thread
      04-29-2015, 07:40 PM   #155
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

DAMPING

With the suspension completely removed this winter, I took the opportunity to have the dampers dyno tested on a Roehrig 2VS shock dyno.

http://roehrigengineering.com/produc...actuators/2vs/

Not mine, unfortunately, so I had to pay for what I am about to reveal. As I had an OE rear shock on hand (for no reason than I hadn't gotten around to throwing it out, although it was still serviceable with about 90,000 km of use). The OEM shock provides an interesting comparison.

It is typical to test dampers at shaft speeds from 0 - 10 inches per second and to measure the damping force in lbs (+ve for compression and -ve for rebound). The front struts have 28 adjustment positions and the rear shocks have 32 adjustment positions, so both were tested at a sampling of the range, with more emphasis on the stiffer end.

The chassis (and the wheel) do not respond at the shaft speed, but at the shaft speed divided by the motion ratio. Similarly the damping force seen by the chassis (or wheel) is not the force at the damper shaft, but that force times the motion ratio. So rather than providing the raw data from the shock dyno, I have adjusted the forces and velocities by the motion ratio. This makes it possible to meaningfully compare the front damping to the rear.

FRONT STRUT

Name:  Front Wheel Damping.jpg
Views: 2127
Size:  109.4 KB

Several conclusions can be drawn from the above graph:

1) the Ohlins strut adjustments are effective from 1 (stiffest) to about 14 (mid adjustment), with any setting higher than 14 providing practically no change in damper characteristics. For reference, Ohlins recommends a setting of 10 as a starting point.
2) the Ohlins strut is a single-adjustable that primarily affects rebound damping but with a lesser effect on compression damping.

REAR SHOCK

Name:  Rear Wheel Damping.jpg
Views: 2229
Size:  110.1 KB

1) like the front strut, the rear adjustments are effective over about half the total adjustment range (about 1 to 15, 32 being maximum). Higher settings were omitted to avoid congesting the graph. Again Ohlins recommends 10 as a starting point.
2) the rear shock has similar damping curves to the front.
3) the OEM rear shock has less compression damping than the Ohlins shock at any setting of the Ohlins shock.
4) the OEM rear shock has less low-speed rebound damping than the Ohlins shock at any setting of the Ohlins shock (which probably explains some of the float experienced on the OE suspension).

FRONT AND REAR COMPARED

Name:  Ohlins Damping Extremes.jpg
Views: 2124
Size:  109.8 KB

1) the full-stiff settings on the Ohlins dampers are similar front and rear.
2) the full-soft setting on the Ohlins front strut is considerably softer in rebound than the full-soft setting on the Ohlins rear shock.

In my experience a setting of 10 works well both front and rear for street driving, even though my rear springs are twice as stiff as those that came with the Ohlins kit (which would suggest that a higher setting at the rear might be desirable).

The other benefit of having the dampers tested is that one can see how well each side is matched to the other, at the same damper setting. My dampers appear well matched, side to side.
Appreciate 5
      04-29-2015, 11:13 PM   #156
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

The Old "Nut and Bolt"

A "nut and bolt" inspection is a pre-track / pre-race / start of season tradition. The idea being to check that every fastener underneath your car is present, accounted for and properly torqued. The method can be anything from a cursory look, to a pull on everything critical with a wrench and whatever feels about right, to a check with a torque wrench on everything that can be reached with a torque wrench.

There is a better way. Once you have torqued a fastener to spec, mark it with Torque Seal . This is a lacquer paste that comes in a small tube that you apply to the junction of a fastener and a fitting. It dries to brittle state so that it will crack and fall off if there is any relative motion between the fastener and the fitting.

http://www.aircraftspruce.com/catalog/cspages/f900.php

If your torque seal is intact, all is good.

Name:  Torque Seal.jpg
Views: 1979
Size:  212.3 KB

On a big project, sometimes it is hard to know if you are installing something for good or just for now. It is easy to forget if you have actually torqued a fastener in such cases. Torque Seal applied after the torque wrench is a clear indication that the fastener has been torqued to spec.

We have all laughed at the guy who forgot to torque his wheel nuts and lost a wheel. There but for the grace of god go I. This is "human factors" at work, and it can strike the best of us given the right conditions. Driver's meetings are mandatory. What happens if you get interrupted in your wheel change by a driver's meeting. Are you sure you will remember to torque your wheels when you get back? One trick is to always put your torque wrench on the driver's seat when you start a wheel change. That way you can't drive off without seeing it as a reminder the job isn't quite done.

Other good habits:
- use a checklist and check it off AS YOU DO THE TASKS.
- never leave a job half-done without leaving the work in an obvious state (leave the fastener out rather than putting it in finger tight for example)
- when you restart a job, start back a couple of steps from where you left off
- make a REAL final inspection part of the job
- the right solution for a given task depends on the situation. How familiar are you with the task? How critical is it? Can it be completed without interruption? Will it be completed without interruption?

For involved tasks, I like a complete checklist showing all critical tasks, torque specs, manual references and wrench sizes. The job is not done until every box is initialled. Here are a couple of examples for the front and rear suspension installation. Sometimes the official torque value can't be found, but you can always make an educated guess and identify it as such. These lists aren't static - they should be revised with experience and new information.

Name:  Front Installation Checklist.jpg
Views: 2002
Size:  227.6 KB

Name:  Rear Installation Checklist.jpg
Views: 2062
Size:  236.4 KB
Appreciate 2
      04-30-2015, 09:31 AM   #157
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
When discussing the rear springs, you refer to the difference between kg/mm and N/mm and how it can impact the conversion to lbs/in. I'm not sure what units the Ohlins spring rates are measured in but the Swift Spring rates are, as per your example for the Z65-228-120, specified as both 12.0 kg/mm and 672 lbs/in according to the Swift Springs website. 12 kg/mm converts to 117.68 N/mm, which then converts to 671.97 lbs/in, but, in your example, you've used 120 N/mm and 684 lbs/in. Since you mentioned the differences between the units of measure, I thought you may have just rounded the N/mm measurement so, when I saw that you referenced 684 lbs/in in the associated spreadsheet calculation and graph, I was a little confused. Am I missing some minor or obvious detail?
I had that Swift data in front of me too. Strictly speaking they refer to "kgf" not "kg". A "kgf" (kilogram force) is not a normal metric unit, but in the same spirit as a "lb" (pound) is a unit of mass and a "lbf" (pound force, shorthand "pound" to confuse things) is a unit of force and is the force exerted by one lb when acted on by 1 g, a kgf is presumably the force exerted by one kg when acted on by 1 g.

In that scenario, the conversion from kgf/mm to lbf/in is kgf/mm x 2.2046 (lb/kg) x 25.4 (mm/in).

If you do the math 12 kgf/mm = 12 x 2.2046 x 25.4 = 672 lbf/in

That agrees with the Swift website data. The only problem is that it does not agree with my measured Swift spring rate data.

The correct metric unit of force is the Newton, which is the force acting on 1 kg when accelerated at 1 g.

1 Newton = 1 kg x 9.81 m/s^2 = 9.81 kg.m/s^2

Assuming "12 kgf/mm" really means "120 N/mm" we convert to lbf/in:

120 N/mm * 2.2046 lb/kg * 25.4 mm/in / (9.81 N/kg) = 685 lbf/in

That does agree closely with what I measured whenever I have measured Swift springs.

The "6.0 kg/mm" springs (stamped "60") should be 342 lbf/in if they are really 60 N/mm. I have measured between 344 lbf/in and 346 lbf/in. (3 springs).

The "12.0 kg/mm" springs (stamped "120") should be 685 lbf/in if they are really 120 N/mm. I have measured 684 lbf/in (1 spring).

By "measured", I mean I compressed the springs with a hydraulic cylinder and measured the resulting load with an electronic load cell. I measured the deflection with a caliper. I took readings every 10 mm (approx) and continued to a total compression of at least 100 mm. I plotted the results and used Excel to plot a linear regression line on the points from 20 mm to 100 mm. I rounded the slope of that line to 3 significant digits and that is the measured rate I am reporting.

It is too late to say "in short", but, in short the Swift catalog appears to be wrong (ie. produced by marketing not by engineering). I have to conclude from my testing that the Swift springs are manufactured in increments of 10 N/mm, not increments of 1 kgf/mm.

Incidentally, the Ohlins springs in the kit are 60 N/mm front = 342 lbf/in (I measured 344 lbf/in), and 70 N/mm rear = 400 lbf/in (I measured 399 lbf/in).
Thanks for that explanation. I do remember originally writing kgf/mm from the Swift website but then I saw your references to kg/mm and starting using copy/paste. In any case, it actually appears Swift Springs got more than one thing wrong. Like you said, the difference between marketing and engineering can lead to confusion and, in the absence of measuring equipment, such as what you have access to, this would lead everyone else to relying on the published marketing data.

Strangely, I had actually used the same logic that you've presented when I was trying to determine why the values you had were different and I calculated 342 lbf/in for your front springs (and 399 lbf/in for the 70 N/mm springs). When you wrote 345 "lb/in", I thought that was a keyboard typo, since 5 is above 2 on the keypad. Now I know that was intentional since that's what you measured it at. It also makes more sense why the Swift 70 N/mm springs are referred to as "400 lbs" springs.

So, based on your measurements, we should presume that the Swift data is actually supposed to refer to N/mm, which requires that their "kgf/mm" value be increased by a factor of 10 to represent the N/mm value and that their lbs/inch value is worthless and needs to be recalculated (and correctly referred to as lbf/in) from the newly determined N/mm value.
Similarly, their Maximum Load values refer to two different units of measure: kgf and lbs.
I think more weight (no pun intended) can be given to your summation since the springs are stamped in increments of 10, implying N/mm - unless Swift Springs were implying a decimal point, since they listed their spring rate as __.0 kgf/mm. Will we ever know?

Being a Japanese company, Swift Springs would have measured everything using metric units, possibly further evident by the ordering of metric and imperial values, so their "lbs/inch" and inch values were always going to be calculated rather than measured. Furthermore, there seems to be less of an understanding on their part as to what the equivalent imperial unit of measure is for a particular metric unit of measure - notwithstanding their complete misunderstanding of using the correct metric unit of measure, although, that may just be attributable to having been lost in translation.
Being a highly reputable spring manufacturer, I would have expected the same attention to detail as is evident in the manufacture of their springs and the quality that they are renown for.
I have seen other spring manufacturers that use metric units of measure listing their spring rates using N/mm - let's hope they are correct!


Well, that dissection was fun! On to even more fun an interesting things.
Appreciate 0
      04-30-2015, 09:34 AM   #158
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

I've taken a few weeks to absorb this, to go back to your previous posts, and to try and determine how your responses can help me to fill the gaps in my understanding, so I've documented my full thought process as well as my eventual realisations - at least it can provide a historical record for me and maybe answer some of the same questions others may have after reading this thread. If you'd like to respond, some of my latter comments may address some of the things I was originally having problems with comprehending so you may like to just reference those as being the correct interpretations. Hopefully it isn't too disjointed.


Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
The Static Spring Load was calculated at 3600 N (or 810 lbs), i.e. the Static Spring Compression (60mm) multiplied by the Ohlins Spring Rate (60 N/mm). You then used this 3600 N value in the spreadsheet calculation for the Ohlin springs. You then went on to use the same 3600 N value in the spreadsheet calculation for the Swift 65mm 7" 60 N/mm springs.

Since the Static Spring Load was originally calculated based on the compressed spring height of the Ohlins spring (i.e. 60mm), I thought the Static Spring Load would have to be recalculated for the Swift springs because, for example, the Swift spring at 178mm free length may only need to be compressed by 15mm, resulting in a 163mm static spring length at ride height. This 15mm compression would result in a Static Spring Load of 900 N/mm (157.61 lbs/in), which is far from the 3600 N/mm Static Spring Load used.

Also, I'm not sure whether the top mount height should factor into a comparative measurement, i.e. the 26mm difference in top mount height (70mm OE vs 44mm GC plates) could be considered against the Swift springs compressed height of 163mm (in my example) giving a comparative measurement of 137mm (178-15-26mm) against the 140mm OE Top Mount based measurement (200-60mm), meaning a relatively like-for-like comparison.
Again, I'm confused.

Why is the same Static Spring Load used for both springs?
Maybe another question is, why does the Swift 7" spring still need to be compressed by 60mm?
To clarify, the "static compression" is the total spring compression from its free length when the car is sitting statically (not moving) on the ground. That spring is supporting its corresponding corner weight, less the unsprung weight, but it is doing so with a motion ratio which increases the weight supported by the spring relative to the sprung weight supported by that wheel. The static compression includes whatever preload you put into the spring when you installed it - perhaps that is what you are missing in your thinking? Every 60 N/mm spring will have a static compression of 60 mm at a load of 3600 N, regardless of its original free length. The only exception would be if you preloaded the spring to more than 3600 N, in which case it wouldn't move any further until you exceeded that preload.
I am definitely not understanding something regarding how the static spring load is fixed at 3600 N. I can understand it being a product of a given static spring compression and spring rate but I don't understand how it can remain at 3600 N, particularly for different spring lengths - I thought that the static spring compression would have to differ from 60mm to maintain the same ride height with different top mount assemblies and even more so for different spring lengths.

While I don't have the hub mounting stands that you've constructed, I have remeasured my front springs correctly, while under normal vehicle load, with the wheels still mounted and the car sitting on the ground - I manoeuvred a tape measure into the wheel-well behind the wheel/tyre to sit flush with the spring. My measurements should be accurate to within 1mm. Below are those measurements:

General
178mm free spring length
70 N/mm spring rate (Swift Z60-178-70)
49mm top mount height (Vorshlag camber plates)
3mm spacer thickness (Swift thrust sheets x2)

Left
129mm static/compressed spring length
3430 N static spring load ((178-129)x70)
49mm static spring compression (178-129)
51.5mm exposed thread below the lower spring perch
328mm ride height (RHD car, no driver)

Right
134mm static/compressed spring length
3080 N static spring load ((178-134)x70)
44mm static spring compression (178-134)
50.0mm exposed thread below the lower spring perch
326mm ride height (RHD car, no driver)
For starters, even though it's comparing left and right, it's strange that a 5mm difference in static spring length results in only (i) a 1.5mm difference in the exposed thread below the lower spring perch and (ii) a 2mm difference in ride height. I would have thought that the difference would have been considerate of the 0.96 motion ratio and, therefore, equal to ~4.8mm.
That aside, the static spring load for each side differs and it also differs to your 3600 N value, which I thought there might be some correlation or relativeness even though it's comparing 70 N/mm and 60 N/mm spring rates.

You made a statement:
"Every 60 N/mm spring will have a static compression of 60 mm at a load of 3600 N". This makes me think that the static spring load is the known value from which others are calculated, which concurs with your spreadsheet calculations but it doesn't make sense to me considering the process that you used to initially determine that spring rate was dependent on the measurements for the free spring length, static/compressed spring length and spring rate, which implies the static spring load is the calculated value and, therefore, it should be recalculated for different height springs or springs that aren't compressed as much.

I can see how the conversion from static spring load to corner weight shows the relationship between the two and so 3600 N makes sense from that perspective, which means that force was required for that corner weight, which was a result of that ride height, which required that 60 N/mm spring to be compressed by 60mm to achieve that... but... I can't make the link between all that and how the static spring compression would still be 60mm when you changed from OE top mounts to GC plates that had different top mount heights or when changing spring lengths.

For the top mount change, I thought you would require 26mm less spring compression, which, for your 60 N/mm springs, would result in 1560 N less static spring load, that being 2040 N.

For the spring length change from 200mm to 178mm, I thought you would require 22mm less compression, which, for your 60 N/mm springs, would result in 1320 N less static spring load, that being 2280 N.

But then anything different to 3600 N static spring load would not result in the same corner weight.

This is what I mean... I understand most parts in isolation but not all in unison. The spreadsheet calculations make sense but I'm having trouble understanding the theory.

Speaking of the aforementioned spreadsheet, based on a 3600 N static spring load, I calculated what the values would be if the spring rate was changed from 60 N/mm to 70 N/mm (as is the case for my Swift springs) and it resulted in a static spring compression of 51mm (rounded down). For my springs, that have a free length of 178mm, this would result in a static spring length of 127mm, which is close to the 134mm (+4%) static spring length that I measured for my FR spring, which also has a 326mm ride height (without driver though), so I could see that the calculations roughly panned out but I was still stuck on why the 3600 N static spring load is fixed.

Lightbulb moment!
Now, I couldn't make sense of any of this until I realised that these linear springs are just obeying Hooke's Law, which states that "the restoring force F needed to extend or compress a spring by some distance X is proportional to that distance" and can be represented by
F = -kX
where F is the static spring load, k is a constant factor characteristic of the spring, i.e. it's spring rate, and X is the static spring compression.
This restoring force (i) returns the spring to equilibrium, i.e. its natural state, (ii) is in the opposite direction to the applied force that’s extending or compressing the spring, and (iii) is reflected by the negative sign on the right side of the equation.
Therefore, instead of solving for the restoring force, the equation can be changed to solve for the applied force, in which case, the restoring force would be negated resulting in the formula being
-F = -kX
or
F = kX

So, at least Hooke's Law helped me to understand the constant relationship between the static spring load, spring rate and static spring compression. I presume it also means that no single value needs to be considered fixed or known as they are all co-dependent and one value, e.g. static spring load, can initially be calculated from the other values and that calculated value can then later be used as the constant in the relationship since it will eventually be the other two values that will, or can, be variable.

By using various values in the spreadsheet, I can see that, if the spring characteristics remain the same and the top mount is changed from OE top mounts to GC plates, the ride height will remain the same if the lower spring perch location is changed by the same amount as the change in top mount height. But since that is outside the scope of the spring, Hooke's Law doesn't apply.

While writing this, I think I have made one further connection - based on your image below (as long as it is drawn to scale, which I believe it is considering your attention to detail), for a change in top mounts only, i.e. still using 200mm 60 N/mm springs, I now realise that, (i) the lower threaded portion of the strut assembly (where the lower spring perch is located) is in the same position, (ii) the different top mount assemblies slightly affected (perhaps by 10-12mm, something similar to the height of the top nut) the positioning of the shock in that assembly (there is a visible height different between the top of the strut top thread, and various other points of the upper shock, in the two drawings) resulting in less shock compression at static ride height and (iii) the additional height gained from the GC plates allowed the lower spring perch to be raised for increased tyre clearance.


As a result, the static spring length is still the same to achieve all this, which means the static spring load is also the same.
But there was a slight difference between the top portion of the two drawings, so the question still stands, although, the values are not to the same degree: how can the static spring length still be 60mm when there is a 10-12mm difference after changing to the GC plates? I thought you would require ~15mm less spring compression, which, for your 60 N/mm springs, would result in 900 N less static spring load, that being 2700 N.

Possibly, due to the above-mentioned decreased shock compression, the shock has more length/stroke available before bottoming out and the spring could potentially have less static compression, resulting in more length/stroke available before coil binding (although, since the lower spring perch location was also raised to maintain ride height, the spring's potential has been negated at the "expense" of increased tyre clearance).

Has there just been a repositioning of the spring in the vertical plane and, therefore, the static spring length doesn't change?

Perhaps it's because the ride height is based on the overall static strut length and it doesn't really matter what the component measurements are, as long as the relationship between, and the measurements for, free spring length, spring rate, static spring load, static spring compression and static spring length remain the same or relatively the same.
Appreciate 0
      04-30-2015, 09:36 AM   #159
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
I can imagine placing a 10mm spacer between the chassis' strut tower mounting point and the top of the camber plate would simply result in raising the vehicle - but by how much?
This effectively increases the strut length by 10 mm. The strut has a motion ratio relative to the wheel because of its angle relative to vertical. I figure it is about 0.95. Therefore a 10 mm spacer on top of the strut top mount will raise the car about 10/.95 = 10.5 mm.

Something I omitted in my original approach was recognition that the OE top mount compresses under load. I have posted elsewhere that under static load it compresses about 5 mm. So if you are measuring things on the bench hoping to figure out your new ride height, you need to take that into account.
A 10mm spacer above the camber plate is something that I considered quite some time ago but never got around to implementing, more so due to trying to determine the most appropriate front wheel offset for a 255/35/18 tyre with my suspension setup - a bit of a "chicken and egg" scenario. The relativeness to motion ratio was just for my curiosity because, in the grand scheme of things, 0.5mm either way isn't going to make too much difference, although, I do like to be exact, so at least it's good to confirm my thinking.

Just for reference, I have Vorshlag camber plates that have been set to its maximum camber of -3° - I've been hesitant to slot the towers for an additional -0.5° to -1.0° of camber.
Appreciate 0
      04-30-2015, 09:37 AM   #160
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
As a side note, some Moton coilovers (such as the ones I have) come with remote reservoirs, which are nitrogen charged at 175psi, and I've been advised that the reservoir pressure can be increased to preload the springs for better transitioning.
I don't think you have that description quite right. Gas pressure results in a lifting force that will raise your car. It is equal to, in your case, 175 psi times the cross sectional area of the piston rod. Raise the pressure and you will raise the car a little bit, which actually takes load off the springs.

To be clear, when I speak of preload, I mean how much the spring is compressed when the strut is fully extended. If you are using helper springs, the preload of your main spring is zero.
I'm 99% certain that was what I was told but your description regarding gas pressure and preload does seem logical so perhaps I misunderstood. The ability to adjust the pressure was more an option rather than something that I'm likely to do. There's a lot more for me to look at before I'd consider changing the pressure.


Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
With my Moton coilovers and Z60-178-70 60mm 7" (178mm) 392 lbs/in Swift springs (Usable/Maximum Stroke 96/115mm) set with a static spring length of 163mm (Effective Usable/Maximum Stroke 81/100), I don't experience any coil bind. Nor did I experience coil bind when the static spring length was as short as 138mm (Effective Usable/Maximum Stroke 56/75) - this was purely based on no evidence of binding on the spring coils.
Just to clarify - I would call 163 the preload length, not the static length.

The thing about a lot of preload is that as you unload the tire, as soon as the spring extends to its preloaded length the wheel suddenly picks up off the ground. This looks dramatic at the front of the car, but it results in a sudden weight transfer to the opposite wheel, which will cause an immediate understeer reaction. Ideally, you want your inside front tire to get very light at steady state limit cornering, but not come off the ground.
You are correct and this is where my initial confusion was regarding my measurements (or mis-measurements). The 163mm and the 138mm measurements are the spring preload lengths (for two different ride height setups), while the static spring length is 129mm/134mm (relative to the 163mm spring preload length measurement).

Since I mis-measured the static spring compression, I'll need to recalculate the measurements to determine whether a 5" or 6" spring will be more suitable and which, if any, helper spring will be required.
Although, even at ~130mm static spring length for the Z60-178-70 7" springs, I have not experienced, and there is no evidence of, coil bind.

Considering my previous measurements indicated a static spring length of 138-163mm, whereas it is actually 129mm/134mm, it points to shorter springs. The physical evidence also points to a shorter spring - it just doesn't seem right to have so much static spring compression.

My thoughts are that it would be better to have a main/helper spring configuration such that:
(i) the main spring is not pre-loaded and the helper spring is fully/mostly compressed at static ride height,
(ii) the helper spring extends/decompresses (up to its total free length) at full droop, and
(iii) the main spring compresses (without coil binding) during shock/damper compression.

Doesn't this make sense?


Isn't the spring preload length just the unladen spring length as a result of the lower spring perch location? And, therefore, isn't the issue of lifting the tyre not affected by the spring configuration or amount of preload? i.e. it won't make a difference whether a longer heavily pre-loaded spring is used or a shorter spring plus helper spring combination is used, or how much any of those springs are pre-loaded, the spring will reach its predetermined maximum allowable extended length anyway and it's going to lift the tyre no matter what?
Appreciate 0
      04-30-2015, 09:38 AM   #161
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
What I'm wondering initially, though, is whether the maximum usable stroke would be affected by the Helper spring. If you've considered this or have any formulae for determining this, it would be greatly appreciated if you could also attach them to this thread.
I follow your helper spring discussion but won't try to dissect it. Your calculations generally make sense.

Usable stroke is defined by the main spring and is reduced by preload. Because a helper spring lets you run zero preload on the main spring, a helper spring does not reduce usable stroke of that spring.

That said, if you are using a helper spring, that means you have selected a shorter free length main spring. By necessity, that main spring will have a shorter usable stroke than a longer spring (of the same design family) with the same rate.
Sorry, I didn't phrase my question very well. What I meant was, does the main spring's maximum useable stroke need to include the helper spring's FCH (presuming it is fully compressed) since the two springs are in series?
This would be so it could be compared to a non-helper spring setup and the calculations can be made for the formula, i.e. the static spring compression was 60mm in your car so, if it the spring configuration was changed to a shorter spring plus helper, which had an FCH of 19mm, then the static spring compression of the shorter spring would be 41mm, but we would still need to specify 60mm as the static spring compression.

So, wouldn't the useable stroke be additive (with the helper spring's FCH) in nature, understanding that the spring rate is not additive?

It seems like the helper spring length/FCH should factor in to some degree but I'm not sure how.
Appreciate 0
      04-30-2015, 09:41 AM   #162
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
Quote:
Originally Posted by 135 View Post
I know you've previously recommended against a higher spring rate but I thought those comments may have been based on the limitations of an Ohlins coilovers setup and, considering the absence of coil bind in a range of a scenarios with my Moton coilovers, I would be interested to hear your thoughts on the above options, especially regarding the 6" vs 5"+Helper decision?
Based on the undamped natural frequency of the car, I would not suggest a front spring stiffer than 70 N/mm. At that, your undamped natural ride frequency at the front is about 2 Hz (when tires are considered in the calculation), which is in the high range of normal for a sedan based race car. Suspecting that your car, like mine, does dual duty, that is really the upper limit of reasonable. If the car doesn't feel stiff enough at that, I suggest that something else is actually the problem. If it is roll stiffness, that should be addressed with bars not with springs.
From my reading, there are various opinions on what the undamped natural frequency of the car should be and there appears to be general consensus that a comfortable ride is around 1.0 Hz and a race car with downforce is around 3.5 Hz+. So what's in between? It depends on how you want to define the categories but you could have:
1.0-2.0 Hz - Sports cars (street)
2.0-2.5 Hz - Dual duty street/track cars
2.5-3.5 Hz - Race cars without downforce
The problem is that it is all subjective. What one person deems harsh may be acceptable to another - within reason.

While not exact measurements for my car, I have reused the same tyre rate (2200 lbf/in), front bushing rate (7 lbf/in) and rear bushing rate (23 lbf/in) that you quoted. In addition, I have decided to use a uniform 120 lbs for the front/rear unsprung mass, more so because my wheels and brakes are not OE and, while I am not currently in a position to measure the individual components, the lighter wheels and larger (and heavier?) BBK will most likely cancel each other out. Based on this, my current natural frequencies are:
Front 1.98 Hz ± 0.03 Hz
Rear 1.80 Hz ± 0.04 Hz
The quoted figures are left/right averages with the deviation indicating the spread from average for the left and right.
My preference is for the rear to be 10% less (or within a range or 0.2-0.3 Hz less) than the front, so the current figures are very close to being within those limits.
As per your suspicions, my car is dual duty, although I have made compromises on comfort to target a more track-oriented ride.

The Z60-152-100 (6") or Z60-127-100 (5"+Helper) Swift springs options that I was considering would put the front natural frequency at 2.29 Hz ± 0.05 Hz, which is not too extreme for the front but, without also increasing the rear spring rate, the difference between front and rear is ~0.5 Hz, which is more than target. The rear springs would need to be increased to 180-200 N/mm to get back within the desired 0.2-0.3 Hz range.

Following are the average front and rear natural frequencies (deviation, front ± 0.04 Hz, rear ± 0.05 Hz) for my car for the specified spring rates:

Front
N/mm ... Hz
80 ..... 2.09
90 ..... 2.19
100 .... 2.29

Rear
N/mm ... Hz
150 .... 1.85
160 .... 1.90
170 .... 1.95
180 .... 1.99
190 .... 2.03
200 .... 2.07


Based on my target front/rear differential, the following front/rear spring rate pairings could be used:
F 70, R 140 - current configuration
F 80, R 140-160
F 90, R 160-180
F 100, R 180-200

I was advised that my Moton dampers are valved to support spring rates up to 1100 lbf/in (~192 N/mm), although, I'm not sure if that was before or after the motion ratio was applied. To provide a safety buffer, this limit could be reduced by a token 100 lbf/in (~9%), resulting in 1000 lbf/in (~175 N/mm). If the damper valving was based on spring rate before the motion ratio was applied, then this would rule out the rear 180-200 N/mm spring rates and, therefore, the front 100 N/mm spring rate, which I was considering.

My decision would then revolve around whether I should maintain the existing spring rates or step them up. Based on spring rates and frequencies alone, I would most likely select
Front: 90 N/mm, 2.19 Hz
Rear: 180N/mm, 1.99 Hz
While the rear 180 N/mm (~1028 lbf/in) spring rate does extend into my self-imposed safety buffer, it is only by a small margin. The alternative would be to use a 170 N/mm (~971 lbf/in) 1.95 Hz rear spring rate.

Following all this, I would then need to go back and consider stroke to ensure coil-bind was still not going to be an issue.

Thank you for your responses, which made me pay more attention to the ride frequencies. I'd be happy to hear your thoughts.
Appreciate 0
      04-30-2015, 09:42 AM   #163
135
Captain
Australia
113
Rep
682
Posts

Drives: 135i
Join Date: Sep 2012
Location: Australia

iTrader: (4)

Quote:
Originally Posted by fe1rx View Post
This overestimates the ride natural frequency of the chassis, because it omits the tire deflection, which is about 0.41 inches assuming a tire rate of 2200 lb/in. Increasing static deflection to 2.85 in reduces the front natural frequency to 1.85 Hz.

...

This overestimates the ride natural frequency of the chassis, because it omits the tire deflection, which is about 0.37 inches assuming a tire rate of 2200 lb/in. Increasing static deflection to 2.88 in reduces the rear natural frequency to 1.84 Hz.
How did you calculate or approximate the tyre rate?
Appreciate 0
      04-30-2015, 12:49 PM   #164
chris82
Brigadier General
chris82's Avatar
United_States
825
Rep
3,856
Posts

Drives: 128i
Join Date: Aug 2012
Location: NY NY

iTrader: (8)

Garage List
2009 BMW 128i  [9.80]
Quote:
Originally Posted by fe1rx View Post
Several conclusions can be drawn from the above graph:

1) the Ohlins strut adjustments are effective from 1 (stiffest) to about 14 (mid adjustment), with any setting higher than 14 providing practically no change in damper characteristics. For reference, Ohlins recommends a setting of 10 as a starting point.
2) the Ohlins strut is a single-adjustable that primarily affects rebound damping but with a lesser effect on compression damping.

REAR SHOCK

Attachment 1201283

1) like the front strut, the rear adjustments are effective over about half the total adjustment range (about 1 to 15, 32 being maximum). Higher settings were omitted to avoid congesting the graph. Again Ohlins recommends 10 as a starting point.
HALF the adjustment range not making a difference? That's just terrible . . . I'd be pissed if I found this out on a product I spent over $2k for. I expect this from a company like BC Racing lol, not Ohlins
Appreciate 0
      04-30-2015, 02:02 PM   #165
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by chris82 View Post
HALF the adjustment range not making a difference? That's just terrible . . . I'd be pissed if I found this out on a product I spent over $2k for. I expect this from a company like BC Racing lol, not Ohlins
This doesn't really bother me. You really only need 10 settings, or, if you are a fan of "Spinal Tap", 11.

Seriously though, you know up front that if Ohlins recommends setting 10 for street use, nothing much higher (softer) than that matters. What does annoy me is that the guy testing my dampers didn't follow my instructions, which said test from 1 to 13 in increments of two. He covered the whole range in larger increments and counted clicks from full soft instead of full hard like I asked.
Appreciate 0
      04-30-2015, 02:04 PM   #166
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by 135 View Post
How did you calculate or approximate the tyre rate?
Tested ...

http://www.1addicts.com/forums/showp...5&postcount=17
Appreciate 0
      04-30-2015, 02:18 PM   #167
chris82
Brigadier General
chris82's Avatar
United_States
825
Rep
3,856
Posts

Drives: 128i
Join Date: Aug 2012
Location: NY NY

iTrader: (8)

Garage List
2009 BMW 128i  [9.80]
Quote:
Originally Posted by fe1rx View Post
This doesn't really bother me. You really only need 10 settings, or, if you are a fan of "Spinal Tap", 11.

Seriously though, you know up front that if Ohlins recommends setting 10 for street use, nothing much higher (softer) than that matters. What does annoy me is that the guy testing my dampers didn't follow my instructions, which said test from 1 to 13 in increments of two. He covered the whole range in larger increments and counted clicks from full soft instead of full hard like I asked.
It was probably Ohlins' marketing department that added the extra clicks in, 28 clicks sounds better than 14 clicks to some people, and some will buy them based on that, colors, etc. alone. I guess I'm just surprised that this stuff is going on at this level of the game.
Appreciate 0
      04-30-2015, 04:25 PM   #168
houtan
Colonel
houtan's Avatar
701
Rep
2,430
Posts

Drives: 2011 135i
Join Date: Jun 2013
Location: socal

iTrader: (17)

Garage List
2011 135i  [9.80]
fe1rx, I had a question regarding the ohlins torque sheet a few posts earlier. Per the ohlins sheet, the subframe side of the rear guide rod and upper arm are listed under the torque at ride height section. per your m3 rear arm analysis, both of these connections are ball jointed, which means they could be torqued at any height. just want to confirm this is the case or is it still better to torque the ball joints at ride height?

when I did my initial install, I torque the rear arms at ride height, but it would be much easier to torque them at full extension if I had to remove them for some reason.
Appreciate 0
      04-30-2015, 05:51 PM   #169
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by houtan View Post
fe1rx, I had a question regarding the ohlins torque sheet a few posts earlier. Per the ohlins sheet, the subframe side of the rear guide rod and upper arm are listed under the torque at ride height section. per your m3 rear arm analysis, both of these connections are ball jointed, which means they could be torqued at any height. just want to confirm this is the case or is it still better to torque the ball joints at ride height?

when I did my initial install, I torque the rear arms at ride height, but it would be much easier to torque them at full extension if I had to remove them for some reason.
You are right. This feature of the checklist is a remnant from when I still had the OE arms and I didn't change it the M3 arms. The ball joints can be torqued at any height.

The same argument can be made for the M3 front lateral link (wishbone), however I have noted that there is substantial play in the bolted connections (because BMW uses fully threaded bolts in shear joints for some mysterious reason). Particularly up front it is worth having some weight on the suspension to load that connection in the "more camber" direction when tightening the bolt.
Appreciate 0
      05-01-2015, 07:07 AM   #170
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by 135 View Post
From my reading, there are various opinions on what the undamped natural frequency of the car should be and there appears to be general consensus that a comfortable ride is around 1.0 Hz and a race car with downforce is around 3.5 Hz+. So what's in between? It depends on how you want to define the categories but you could have:
1.0-2.0 Hz - Sports cars (street)
2.0-2.5 Hz - Dual duty street/track cars
2.5-3.5 Hz - Race cars without downforce
The problem is that it is all subjective. What one person deems harsh may be acceptable to another - within reason.
These numbers are not consistent with what I have generally read, although I think I recall a Julian Edgar article that talked along these lines. These numbers are high, not typical.

If you want to explore the upper end of the envelope, it should be based on what actually works (i.e. based on testing) not just on math. My point in raising the subject of suspension ride frequencies is that it is a tool for seeing if you are in the right ballpark. Let's say you are bottoming out your front suspension. It is natural to think you need to go stiffer up front, but if your ride frequencies are "right", the problem is actually your ride height. The Ohlins kit as delivered is glaringly out of balance, with a rear ride frequency much lower than the front. I suspect this was a necessary concession to the soft rear subframe bushings.

Speaking of which, once you go really stiff, other compliances (tires, bushings, suspension arms, chassis) will defeat your attempt to get the ride frequencies you think you are getting. Race cars are caged, ball-jointed and reinforced to reduce these compliances.

I suggest finding someone who actually races a race-prepared 135i and find out what springs they are running. Whatever it is, you probably don't want to go that stiff for a dual duty car.

For a practical street driven car I would be skeptical of any car that does not permit at least 4" of total front wheel travel. The OE 135i doesn't have much more than that. It can't afford to lose much (in my opinion).
Appreciate 0
      05-01-2015, 12:13 PM   #171
KevinK2
New Member
2
Rep
5
Posts

Drives: 93 Rx7 FD
Join Date: Apr 2015
Location: Delaware

iTrader: (0)

First, regarding spring rate units, rather than rely on some vendor's table, I have always used 2 conversion factors to get to lb/in from the metric system:

1 N/mm = 5.71 lb/in
1 kg/mm = 56.00 lb/in

You can find these on "unit converion calculators" on the internet. It's been my practice to check unusual metric units or formulas before I use them. An example is the Puhn formula for sway bars. I derived it from beam formulas before using it. You also get a feel for the limitations.

Second, speaking of sway bars, it is somewhat academic to discuss coil spring travel limits, without considering sway bar stiffness, which often is the major contribution to weight transfer, and prevents the struts from seeing full travel when a wheel lifts on a corner. Ex:

Quote:
Originally Posted by fe1rx
The thing about a lot of preload is that as you unload the tire, as soon as the spring extends to its preloaded length the wheel suddenly picks up off the ground. This looks dramatic at the front of the car, but it results in a sudden weight transfer to the opposite wheel, which will cause an immediate understeer reaction. Ideally, you want your inside front tire to get very light at steady state limit cornering, but not come off the ground.
In most cases, with a car reasonably flat in a corner, sway bars limit extension of the inboard shocks, but as you said, once tire lift occurs, the front roll center becomes the outboard tire contact patch center, and front mass center rises as the lift increases, with all roll resistance now at the opposite end of the car. Shock travel limits and spring containment come into play when you "get air" over an abrupt drop in an uphill section of a long straight section of a high speed road course. The helper spring, or belt type limits, make sure a spring remains preloaded. I have talked to pro drivers that like some rate on the helper springs so they have a more comforable ride during an endurance race, with a small compromise in handling.

.
__________________
current cars, 04 Mazda6, 93 Rx7 FD
tracked cars, 68 Triumph GT6, 81 Porsche 924T, 93 Rx7

Last edited by KevinK2; 05-01-2015 at 06:07 PM..
Appreciate 1
      05-02-2015, 08:33 PM   #172
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by 02rsxpilot View Post
Please let us know your impressions of the RE-71Rs on track and on street! I'd be very inclined to give them a go if they are quieter on the street than the ZIIs have been.
RE-71Rs are a quiet tire. Remarkably so. To calibrate that statement against my sense of loud, ZIIs are loud when new and very loud when used. Nitto NT01s are very loud always.

I just finished one track day and they seem to have gotten perhaps a bit louder, but they still sound very civilized. Noise from road imperfections is not at all objectionable. Bridgestone has done an amazing job with the road manners of this tire. Who knows how they will age, but I think you will see these tires as an improvement over the ZIIs. One odd thing though, my commute to the track includes some grooved highway sections. In some of these sections the tires developed a strange rumble that had me stopping to check out if one was loosing pressure. That section of highway seems to be special though - I have experienced some winter tires (different vehicle) develop a directional uneasiness in the same area.

Dry grip is very good. Even at full tread depth they feel like an R-compound tires. This was a working day at the track for me and I was running street brake pads so I had limited opportunity to test them out and no opportunity to experiment with tire pressures. I used 36 psi cold. This is on 235/40R18 all around. Steering response is really direct and confidence inspiring. This was by no means a 10/10ths day though so I can't say how they will stand up to extended lapping in high temperatures.
Appreciate 2
      05-03-2015, 04:24 AM   #173
_Ryan_
Captain
No_Country
59
Rep
741
Posts

Drives: E87 130i
Join Date: Jan 2012
Location: Melbourne, AU

iTrader: (0)

Garage List
2005 BMW 130i  [5.24]
Quote:
Originally Posted by fe1rx View Post
RE-71Rs are a quiet tire. Remarkably so. To calibrate that statement against my sense of loud, ZIIs are loud when new and very loud when used. Nitto NT01s are very loud always.

I just finished one track day and they seem to have gotten perhaps a bit louder, but they still sound very civilized. Noise from road imperfections is not at all objectionable. Bridgestone has done an amazing job with the road manners of this tire. Who knows how they will age, but I think you will see these tires as an improvement over the ZIIs. One odd thing though, my commute to the track includes some grooved highway sections. In some of these sections the tires developed a strange rumble that had me stopping to check out if one was loosing pressure. That section of highway seems to be special though - I have experienced some winter tires (different vehicle) develop a directional uneasiness in the same area.

Dry grip is very good. Even at full tread depth they feel like an R-compound tires. This was a working day at the track for me and I was running street brake pads so I had limited opportunity to test them out and no opportunity to experiment with tire pressures. I used 36 psi cold. This is on 235/40R18 all around. Steering response is really direct and confidence inspiring. This was by no means a 10/10ths day though so I can't say how they will stand up to extended lapping in high temperatures.
Awesome. Thoughts on the 20mm rear bar?
Appreciate 0
      05-03-2015, 06:29 AM   #174
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by _Ryan_ View Post
Awesome. Thoughts on the 20mm rear bar?
I am very happy with the change. The car corners flatter, takes a set quicker, and handles transitions better. More important, I have definitely not gone too far aft in terms of roll stiffness distribution because the car is easy to drive with nannies off (my normal mode). With them on, intervention seems much more subtle (although I didn't fully explore this). My hypothesis is that the improved balance and perhaps by reducing the nasty transients due to excessive body roll may result in the DSC seeing less need to intervene. I will try a faster few laps with DSC on today to see if this is in fact the case.

The car seems to handle curbing a bit better than last year, but this is probably in part due to the fact that I am now making proper use of the front bump stops. One wheel bumps are not at all problematic, but this is not too surprising because the front total roll stiffness is still higher than the rear.

Before heading onto the track I made a few laps of a skid pad to make sure I wasn't going to be surprised. Limit cornering attitude is very controllable with throttle. The car is very easy to drive, which is what I found with last year's setup too. Clearly the car still understeers at the limit, or it wouldn't be easy to drive, but that characteristic is so mild as to be unobtrusive.

I will log some more laps today with the AIM Solo DL. I have some competition data from last year at the same track (on NT01s) so should be able to get a good comparison, although I am hobbled by OEM brake pads today. I will be able to see how much eDiff activity there is when pushing a bit harder by checking the data logs.
Appreciate 0
      05-03-2015, 08:20 AM   #175
_Ryan_
Captain
No_Country
59
Rep
741
Posts

Drives: E87 130i
Join Date: Jan 2012
Location: Melbourne, AU

iTrader: (0)

Garage List
2005 BMW 130i  [5.24]
Quote:
Originally Posted by fe1rx View Post
I am very happy with the change. The car corners flatter, takes a set quicker, and handles transitions better. More important, I have definitely not gone too far aft in terms of roll stiffness distribution because the car is easy to drive with nannies off (my normal mode). With them on, intervention seems much more subtle (although I didn't fully explore this). My hypothesis is that the improved balance and perhaps by reducing the nasty transients due to excessive body roll may result in the DSC seeing less need to intervene. I will try a faster few laps with DSC on today to see if this is in fact the case.

The car seems to handle curbing a bit better than last year, but this is probably in part due to the fact that I am now making proper use of the front bump stops. One wheel bumps are not at all problematic, but this is not too surprising because the front total roll stiffness is still higher than the rear.

Before heading onto the track I made a few laps of a skid pad to make sure I wasn't going to be surprised. Limit cornering attitude is very controllable with throttle. The car is very easy to drive, which is what I found with last year's setup too. Clearly the car still understeers at the limit, or it wouldn't be easy to drive, but that characteristic is so mild as to be unobtrusive.

I will log some more laps today with the AIM Solo DL. I have some competition data from last year at the same track (on NT01s) so should be able to get a good comparison, although I am hobbled by OEM brake pads today. I will be able to see how much eDiff activity there is when pushing a bit harder by checking the data logs.
Have fun! Looking forward to the data.
Appreciate 0
      05-03-2015, 09:59 PM   #176
fe1rx
Captain
1390
Rep
776
Posts

Drives: 135i, 328i, Cayman S
Join Date: Jan 2008
Location: Canada

iTrader: (3)

Quote:
Originally Posted by _Ryan_ View Post
Have fun! Looking forward to the data.
Unfortunately this is a bit of apples-to-oranges comparison as the track layouts differ a bit between runs. Here is a GPS trace of my fastest race lap (blue) from last year on this track, and my fastest practice lap (red) from today on the same track, less the carousel on the returning straight. Up to that deviation (turn 10) the data can be compared.

Name:  GPS Overlay.jpg
Views: 2206
Size:  45.8 KB

The data is displayed using the segments depicted below with the start line being at the top of the map and the track run clockwise.

Name:  Red Segments.jpg
Views: 2142
Size:  34.8 KB

Speed traces are comparable, with a bit better launch through the start line in the competition. The competition was run with the Cobb tune removed. Today was run at Stage 1 - Drive, which really doesn't make much difference. I run it primarily for the linear throttle. The blue run includes a downshift to 2nd in turn 4, but is run in 3rd in the red run.

Name:  Speed.jpg
Views: 2261
Size:  224.0 KB

The competition run (blue) was run with DTC 60/70 pads, which explains the higher in maximum braking g. Maximum lateral g are comparable between the NT01 R-compounds and the RE-71R Extreme Performance street tires.

Name:  g-g.jpg
Views: 2234
Size:  194.7 KB

Data logging is with an AIM Solo DL, collecting chassis data through the CAN Bus. I log a math channel I call E Diff Activity, which is the difference between left and right rear brake pressures. Any difference is due to intervention of the E Diff. Not unexpectedly the stiff rear bar does increase E Diff activity in slow corners. Rear brake pressures due to E Diff are in the order of 15 bar.

Name:  E-diff.jpg
Views: 2252
Size:  182.9 KB

A point of interest, given that the deceleration rates are comparable between the two laps: with OE pads, maximum brake pressures are typically about 20 bar higher than for the DTC pads under normal braking. This being because the track pads have more bite.

Last edited by fe1rx; 05-04-2015 at 08:17 PM.. Reason: Today's tune was Stage 1 - Drive, not Stage 1 - Sport
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 02:02 PM.




1addicts
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST