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      11-04-2011, 05:53 AM   #23
eeghie
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Quote:
Originally Posted by rldzhao View Post
Do you have the raw data? Graphs are a little hard to read
+1, however with values on both axis, all the curves can be approximated and or scalled for comparisson.

Last edited by eeghie; 11-04-2011 at 06:00 AM.
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      11-04-2011, 07:21 PM   #24
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Quote:
Originally Posted by MDORPHN View Post
A well-known suspension tuner who tested the stock springs told me that the fronts are in the 220-240 range and the rears 540-550.

Neil
That makes sense. Almost equal wheel frequencies front and rear. It's a bit stiffer in the front than I had used for calculations. I'm still not getting compression damping nearly that stiff, though... I found someone who would know for sure, though:

These guys are very local to me. Nice to see someone that puts in the effort to understand the issues- I probably need to go check them out.
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      11-05-2011, 06:10 AM   #25
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WOW please take detailed pics throughout the process!!! Awesome work, awesome car.... with the right tweaks these cars will be giant killers.
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      11-14-2011, 03:33 PM   #26
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Just got some JRZ RS dampers!

Just picked up some very slightly used JRZ RS dampers from a fellow with a E92 M3!

Anyone have a good idea about how low a spring rate I can run with these?

Since the 1M is lighter than the M3 and my car is dual use (daily driver and track), I'm thinking about about something low -- like 350#/600#.

Will this work or would the JRZs be happier with something stiffer?

Neil
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      11-14-2011, 03:48 PM   #27
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so u r the guy who bought that setup.

have u spoken to JC on this? he suggested the same dampers for me (NASA time trials) but he didnt get into spring rates etc.
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      11-14-2011, 03:51 PM   #28
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Quote:
Originally Posted by MDORPHN View Post
Just picked up some very slightly used JRZ RS dampers from a fellow with a E92 M3!

Anyone have a good idea about how low a spring rate I can run with these?

Since the 1M is lighter than the M3 and my car is dual use (daily driver and track), I'm thinking about about something low -- like 350#/600#.

Will this work or would the JRZs be happier with something stiffer?

Neil
Score.

Did you get shock dynos with them? If not, any idea when they were last charged and rebuilt?

JRZs, probably including the RS, are race dampers with very low friction seals for low hysteresis. Due to this they will typically leak and need rebuild on a semi-regular basis- I've done mine a couple times. First thing I'd do is find a shock dyno and see what you're working with- if they need rebuild that can be done at the same time. From there you can calculate what spring rate range they are designed to deal with.

JRZs can be built up an various configurations and filled with various viscosity oils- knowing where they came from originally could also give you an idea of how they were set up.
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      11-14-2011, 03:53 PM   #29
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Quote:
Originally Posted by Franklin Joseph View Post
so u r the guy who bought that setup.

have u spoken to JC on this? he suggested the same dampers for me (NASA time trials) but he didnt get into spring rates etc.
Yes, I've spoken to James. He thinks that 350#/600# may be just a bit low, and I've since spoken to a fellow at JRZ USA who said 350#-400# is as low as I should go.

So.... I'm now thinking about going with some 392#/672# Swift springs.

Neil
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      11-14-2011, 04:00 PM   #30
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any more pics OP??
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      11-14-2011, 04:21 PM   #31
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Quote:
Originally Posted by MDORPHN View Post
Yes, I've spoken to James. He thinks that 350#/600# may be just a bit low, and I've since spoken to a fellow at JRZ USA who said 350#-400# is as low as I should go.

So.... I'm now thinking about going with some 392#/672# Swift springs.

Neil
keep me posted on what you end up with. are you going with a diff. camber plate? (thought you had one custom made for stock springs)
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      11-14-2011, 04:34 PM   #32
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Anyone used Ground Control camber plates?
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      11-14-2011, 09:57 PM   #33
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Quote:
Originally Posted by Franklin Joseph View Post
keep me posted on what you end up with. are you going with a diff. camber plate? (thought you had one custom made for stock springs)
Yes, the Ground Control camber/caster plates I'm currently running are designed only for use with stock springs.

I'm planning to get some Vorshlag plates for use with the JRZ RS dampers and Swift springs.

I'll then probably look to sell the GC plates.

Neil
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      11-14-2011, 11:35 PM   #34
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Quote:
Originally Posted by MDORPHN View Post
Quote:
Originally Posted by Franklin Joseph View Post
keep me posted on what you end up with. are you going with a diff. camber plate? (thought you had one custom made for stock springs)
Yes, the Ground Control camber/caster plates I'm currently running are designed only for use with stock springs.

I'm planning to get some Vorshlag plates for use with the JRZ RS dampers and Swift springs.

I'll then probably look to sell the GC plates.

Neil

I am going to try and beat up terry some more to make Vorshlag plates for stock suspension, but in case he doesn't, put me down for first dibs on your GC plates.
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      11-14-2011, 11:42 PM   #35
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Quote:
Originally Posted by M3 Adjuster View Post
I am going to try and beat up terry some more to make Vorshlag plates for stock suspension, but in case he doesn't, put me down for first dibs on your GC plates.
Mark -

I'll be in touch when I take them off the car.

Neil
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      11-15-2011, 12:29 PM   #36
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I have a JRZ under my 1M it s really really awesome. Very very happy with it. The car is incredible with it. I will post up picture s and tell my experience with it later on. It the perfect compromise between road and track days.
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      11-15-2011, 12:39 PM   #37
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Quote:
Originally Posted by Advevo View Post
I have a JRZ under my 1M it s really really awesome. Very very happy with it. The car is incredible with it. I will post up picture s and tell my experience with it later on. It the perfect compromise between road and track days.
Terrific!

What spring rates are you running? Also what are the spring lengths?

Thanks.

Neil
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      11-15-2011, 01:22 PM   #38
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It s not the springs. Springs are from Eibach made to fit you can also use these springs on you're original dampers. You can order directly from eibach if you wish.

But it s not the springs which made the difference. It s the damper.

If the springs are to hard you loose to much comfort. This setup has better comfort then original dampers and can be adjusted to suit the track.

You can use original bmw top mounts so you don't have rattle problems.

Racing dampers with adjustable rebound and bump settings are nice if you use you're car only for tracks. This JRZ setup can be adjusted with 22 settings. From soft to hard. I tested it on road and track. Gives perfect comfort to drive to track. Then adjusted to hard and drive you're socks off on track. Perfect.

The JRZ wil be offered as a complete package for very good price.

Last edited by Advevo; 11-15-2011 at 01:27 PM.
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      11-15-2011, 03:15 PM   #39
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Quote:
Originally Posted by Advevo View Post
It s not the springs. Springs are from Eibach made to fit you can also use these springs on you're original dampers. You can order directly from eibach if you wish.

But it s not the springs which made the difference. It s the damper.

If the springs are to hard you loose to much comfort. This setup has better comfort then original dampers and can be adjusted to suit the track.

You can use original bmw top mounts so you don't have rattle problems.

Racing dampers with adjustable rebound and bump settings are nice if you use you're car only for tracks. This JRZ setup can be adjusted with 22 settings. From soft to hard. I tested it on road and track. Gives perfect comfort to drive to track. Then adjusted to hard and drive you're socks off on track. Perfect.

The JRZ wil be offered as a complete package for very good price.
I understand that, but I'm going with a "custom" approach and will be spec'ing the spring rates myself (my preference).

In any event, I remain interested in the spring rates and length on your set-up.

Neil
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      11-15-2011, 04:51 PM   #40
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Quote:
Originally Posted by Pete_vB View Post
Holy compression damping, Batman!

Where did these come from? I must say I'm pretty surprised- I'm not familiar with BMW's shock tuning, but it almost looks to me like rebound and compression are reversed!
You're right, they are switched, my bad. If I can, will try to correct original graphs
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      11-17-2011, 12:50 PM   #41
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Quote:
Originally Posted by eeghie View Post
You're right, they are switched, my bad. If I can, will try to correct original graphs
Thanks for that change, that looks more like it. I'm more used to seeing these with the graph axis reversed, but the numbers are closer to what I'm calculating. Still slightly different what I'd get with a .65 - .75 critical damping ratio, however, which either means my numbers are a little off, and/ or suggests BMW is using the shocks to tune corner entry and exit behavior.

It will be interesting to see what the aftermarket guys are dialing into their shocks if someone dynos those...
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      11-17-2011, 05:34 PM   #42
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Quote:
Originally Posted by Pete_vB View Post
Thanks for that change, that looks more like it. I'm more used to seeing these with the graph axis reversed, but the numbers are closer to what I'm calculating. Still slightly different what I'd get with a .65 - .75 critical damping ratio, however, which either means my numbers are a little off, and/ or suggests BMW is using the shocks to tune corner entry and exit behavior.

It will be interesting to see what the aftermarket guys are dialing into their shocks if someone dynos those...
What M/Mass [Kg] and Stock spring value [N/M] are you using?

How common is .65 - .75 critical (under critical !?) damping with sport suspension?

Also interested in aftermarket values of Moton, KW and JRZ for comparison.
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      11-23-2011, 04:12 AM   #43
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I like KW I had them on my M6 and M3 the ride is good and they lower the car perfectly. I'm also buying KWs for my 1M
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      12-10-2011, 10:13 AM   #44
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Quote:
Originally Posted by MDORPHN View Post
Yes, I've spoken to James. He thinks that 350#/600# may be just a bit low, and I've since spoken to a fellow at JRZ USA who said 350#-400# is as low as I should go.

So.... I'm now thinking about going with some 392#/672# Swift springs.

Neil

A 392/672 is going to work well. A slight stiffer rear spring may help give you a better flat ride control on the street but only if you setup the shocks accordingly. The ideal spring lengths are 8" front and 9" in the rear. As general rule, this allow spring to work in droop travel which will be very important for ride qaulity/control on the street. I tried just about every combo of springs over the last 3 years and this is the best one and the calculation matches as well.


Quote:
Originally Posted by Pete_vB View Post
So first, I am fairly convinced that rebound and compression are mis-labeled on those graphs. I ran some simulation numbers and came out with rebound higher than compression (which is the norm), so I wouldn't want to read to much into these before that can be double checked.

Second, I'm not surprised the rear is overall stiffer than the front. Assuming the 1M's motion ratios are identical to the M3s (purely an assumption on my part based on what I've read about the M3 and 1M sharing parts) then the rear motion ratio is something like .56 vs a front of .96. This means the rear shocks would need to be much stiffer at the shock itself to have identical values at the wheel. Quick rough simulation suggested rear shocks almost 3x stiffer than the fronts would be about right- these are less than 2x, suggesting they may be softening up the rear (likely both springs and shocks?) to help put power down. Seems to make sense.

Could you post the M3 values you have as well? Any way to double check bounce if and rebound are labeled right?
The rear suspension frequency is variable due to inclination of the spring and artificial spring rate increase due to the spring bending along a curved axis when using 60 mm race springs. The rear suspension frequency will increase about 0.2 – 0.4 Hz from what is calculated through the working range of the suspension. The rate of increase is fairly quick at some points in the stroke so spiking should be expected although not excessive.

As a reference I designed an articulating spring perch that sits between the helper and main spring to combat the spring bending along a curved axis. At full droop the device is tilted about 9 degrees. Having the helper springs on the bottom on the camber link goes along way at reducing stiffness cause by spring bending along a curved axis. The helper spring will translate up 5-7 mm during use.

Last edited by Orb; 02-14-2012 at 03:30 PM.
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