Coilovers and wheel clearance

[Pig Farmer]

Originally Posted by fe1rx

Is that picture taken with the wheel jacked off the ground or with the car sitting at ride height?

On the ground fully weighted.

[dcaron9999]

Phenomenal input guys. Thanks for all of this.

fe1rx, as usual, nice experimenting with your ride height!

Based on your picture, seems I would be better off with 40mm or even 35mm offset front wheels.

Assuming linear springs (rate stays the same during compression), and properlay matched bump stops supplied by the coilver vendor, is it better to have a stiffer 6" spring with very litlle preload, or a softer 7" spring preloaded by 1"?

[Kgolf31]

Originally Posted by Ginger_Extract

I wanted to throw my .02 in here as well. I am running TCK Singles, at a ride height about 1/4-1/2" higher than Kyle, at -3.1* camber. Because my spring perch is situated just a touch higher than his, I have additional inner clearance. I have approx 1/4" of clearance with my 17x8.5 ET40 w/ 255/40R17 RS3. RS3 ARE FAT in this size, and side walls are ballooned pretty well. I want to go wider, but it looks like the tire is the issue, I foresee no issues running a 17x9 on the car if the tires didn't balloon as much. Not sure if there would be a tangible gain going from 17x8.5 w/ 255 to a 17x9 w/ 245. Debating it.

There most certainly is.

You're strengthening the sidewall on a 245 tire by throwing it on a bigger wheel. This will incerase turn-in and response.

You also won't have a much bigger footprint if you do 255 on a 9"

[Ginger_Extract]

Originally Posted by Kgolf31

There most certainly is.

You're strengthening the sidewall on a 245 tire by throwing it on a bigger wheel. This will incerase turn-in and response.

You also won't have a much bigger footprint if you do 255 on a 9"

Are you saying this relative to a 245 on the same wheel, or versus my current 255/8.5" setup? I have spoken with a few locals on their thoughts, and by a large I have been told to go for the wider wheel and make the wheel fit, versus focusing on the tire size as the end all be all.

[Kgolf31]

Originally Posted by Ginger_Extract

Are you saying this relative to a 245 on the same wheel, or versus my current 255/8.5" setup? I have spoken with a few locals on their thoughts, and by a large I have been told to go for the wider wheel and make the wheel fit, versus focusing on the tire size as the end all be all.

Sorry, just caught this.

To answer your question, on both accounts.

A 245 tire on a 8.5" will have a larger contact patch on a 9" wheel.

Not nearly the same with a 255, since you're pinching it on a 8.5" the delta from going to a 9" wheel won't be great. However you'll stiffen the sidewall.


Stiffening the sidewall (especially on RS3s) is critical. You greatly increase response.

I'd rather run a 245 on a 9" wheel over a 8.5" anyday of the week. I may even prefer a 245 on a 9" wheel over a 255 actually.

Anyways, play around with this:

http://bndtechsource.ucoz.com/index/...alculator/0-20

[dcaron9999]

I'm struggling with the proper next suspension modification on my 2011 135i, hence bumping my own thread.

I had my mind set on KW CS coilovers but don't want to give up my wide tires (see my signature). This would mean replacing my KW CS springs with shorter 6" springs so that the top of my tires align under the spring perch. This is of course an expensive proposition.

Ideally I would like to stay as close as possible to my stock height, and get a good damper and spring combination that will perform very well on the track and be decent on the street. I want to reduce body lean in curves. I want to reduce low speed understeer. I want to dial back my front camber which is at - 3.2*...

Thinking about stiffer or stock springs (2011 135i has linear springs) that are close to stock height, and affordable matched dampers that are corrosion resistant. Might add an E93/M3 front sway bar to the mix, but do the dampers and springs first. I dont really need infinite damper or height adjustments.

I would rather have a damper/spring combo with longevity, performance, and low maintenance. Been looking at the Bilstein B12 Pro Kit or just the B8 dampers + my stock springs, which fits the bill nicely.

Would like to stick with "Ze German" options (KW, Bilstein, Eibach) to leverage good rebates I have on these though a local importer. The CAD-USD exchange rate is currently at its lowest Ive seen in a while ...

Will add adjustable solid rear toe arms to the mix as well...

Would like to hear your suggestions.

[3002 tii]

Originally Posted by dcaron9999

I'm struggling with the proper next suspension modification on my 2011 135i, hence bumping my own thread.

I had my mind set on KW CS coilovers but don't want to give up my wide tires (see my signature). This would mean replacing my KW CS springs with shorter 6" springs so that the top of my tires align under the spring perch. This is of course an expensive proposition.

Ideally I would like to stay as close as possible to my stock height, and get a good damper and spring combination that will perform very well on the track and be decent on the street. I want to reduce body lean in curves. I want to reduce low speed understeer. I want to dial back my front camber which is at - 3.2*...

Thinking about stiffer or stock springs (2011 135i has linear springs) that are close to stock height, and affordable matched dampers that are corrosion resistant. Might add an E93/M3 front sway bar to the mix, but do the dampers and springs first. I dont really need infinite damper or height adjustments.

I would rather have a damper/spring combo with longevity, performance, and low maintenance. Been looking at the Bilstein B12 Pro Kit or just the B8 dampers + my stock springs, which fits the bill nicely.

Would like to stick with "Ze German" options (KW, Bilstein, Eibach) to leverage good rebates I have on these though a local importer. The CAD-USD exchange rate is currently at its lowest Ive seen in a while ...

Will add adjustable solid rear toe arms to the mix as well...

Would like to hear your suggestions.

You should consider:

1a) Bilstein B8 + stock M-sport springs or
1b) Koni Sport + Dinan springs

combined with

2) Dinan camber plates & M3 arms

The difference obviously being the Dinan springs will offer a modest drop over your current stance. But this combination fits the bill in that it's budget "friendly" (especially if you sell your GC hybrid plates), maintains a stock-ish height and will provide decent amount of camber. 1a/2 should net you between -1.5 and -2.0 degrees of camber. 1b/2 should net you -2.5 to -3.0 of camber. You also get the added benefit of noise-free camber plates but downside being lack of adjustability.

I'm running BMW PS shocks + Dinan springs + Dinan camber + m3 arms and I got -2.7 of camber. I also have the m3 FSB and I must say the car handles noticeably better. I have not pushed the car to the limits so I can't comment if it'll equate into better lap times but I don't see why not when we all know the stock shocks were very under dampened to begin with.

FWIW the BMW PS Yellow springs would offer less drop over Dinan but since your car is track focused I wouldn't bother. I find Dinan's increase in stiffness to be pretty modest as it is, so the Yellow would be even less. May as well stick with M-sport at that point.

Here's a shot of my ride, you can see the drop is definitely there. Wheel gap looks *reduced* because I upsized my tires to 225 and 255. IIRC you're running 255 square so the wheel gap should be similar on your car if you go Dinan.





I don't think the B12 kit is bad by the way but I only exclude it this time since you seem to emphasize wanting to really stick near stock ride height.

[dcaron9999]

Originally Posted by 3002 tii

You should consider:

1a) Bilstein B8 + stock M-sport springs or
1b) Koni Sport + Dinan springs

combined with

2) Dinan camber plates & M3 arms

I have had the M3 FCA's and the GC camber plates for a while. The GC plates emit a slight rattle on certain bumps, on stock springs and dampers. Something that Ive somewhat learned to live with. Im thinking better dampers will help in this area, and prevent the wheels crashing into street ruts and potholes ...

Originally Posted by 3002 tii

The difference obviously being the Dinan springs will offer a modest drop over your current stance. But this combination fits the bill in that it's budget "friendly" (especially if you sell your GC hybrid plates), maintains a stock-ish height and will provide decent amount of camber. 1a/2 should net you between -1.5 and -2.0 degrees of camber. 1b/2 should net you -2.5 to -3.0 of camber. You also get the added benefit of noise-free camber plates but downside being lack of adjustability.

Thanks for this. Great info! Allways wondered what the cumulative M3 FCA's + Dinan fixed camber plates would equate to. I think I read that the Dinan plates would raise the car by half an inch, but if I opt for shorter aftermarket springs, the net-net will be limited to no drop.

Originally Posted by 3002 tii

I'm running BMW PS shocks + Dinan springs + Dinan camber + m3 arms and I got -2.7 of camber. I also have the m3 FSB and I must say the car handles noticeably better. I have not pushed the car to the limits so I can't comment if it'll equate into better lap times but I don't see why not when we all know the stock shocks were very under dampened to begin with..

Did you do the E92/M3 or E93/M3 FSB? Did you do them before, during, or after the dampers+shocks?

Originally Posted by 3002 tii

FWIW the BMW PS Yellow springs would offer less drop over Dinan but since your car is track focused I wouldn't bother. I find Dinan's increase in stiffness to be pretty modest as it is, so the Yellow would be even less. May as well stick with M-sport at that point.

Good point. If I go through the trouble of replacing springs, I want them to be noticeable firmer, and combined with matched dampers ...

Originally Posted by 3002 tii

Here's a shot of my ride, you can see the drop is definitely there. Wheel gap looks *reduced* because I upsized my tires to 225 and 255. IIRC you're running 255 square so the wheel gap should be similar on your car if you go Dinan.

Dayuumm ... your 135is is sweeeet! These pictures are stunning!

Originally Posted by 3002 tii

I don't think the B12 kit is bad by the way but I only exclude it this time since you seem to emphasize wanting to really stick near stock ride height.

I would accept a modest drop, but want to minimize my chances of the car scraping on the ground or bumps (which I get already on stock M suspension), and the possibility wider tires rubbing on top of the fender.

The solid adjustable toe arms are to prevent the flex, and resulting toe out during hard acceleration (shorter 3.46 final drive ratio with my Quaife LSD), stage 2 agressive tune, and sticky tires. Harold @ HPA recommends them ...

[Kgolf31]

Originally Posted by dcaron9999

I have had the M3 FCA's and the GC camber plates for a while. The GC plates emit a slight rattle on certain bumps, on stock springs and dampers. Something that Ive somewhat learned to live with. Im thinking better dampers will help in this area, and prevent the wheels crashing into street ruts and potholes ...


Thanks for this. Great info! Allways wondered what the cumulative M3 FCA's + Dinan fixed camber plates would equate to. I think I read that the Dinan plates would raise the car by half an inch, but if I opt for shorter aftermarket springs, the net-net will be limited to no drop.



Did you do the E92/M3 or E93/M3 FSB? Did you do them before, during, or after the dampers+shocks?


Good point. If I go through the trouble of replacing springs, I want them to be noticeable firmer, and combined with matched dampers ...


Dayuumm ... your 135is is sweeeet! These pictures are stunning!


I would accept a modest drop, but want to minimize my chances of the car scraping on the ground or bumps (which I get already on stock M suspension), and the possibility wider tires rubbing on top of the fender.

The solid adjustable toe arms are to prevent the flex, and resulting toe out during hard acceleration (shorter 3.46 final drive ratio with my Quaife LSD), stage 2 agressive tune, and sticky tires. Harold @ HPA recommends them ...

How are you scraping already?!

When I'm at my track setup (one turn from full bottom out) I never scraped everywhere. In fact my Z4M on stock suspension still has a lower clearance.

[3002 tii]

The increased stack height from fixed plates doesn't seem that big. Call me old but I can't imagine going any shorter than what I have now for daily driving. I get by fine without scraping as long as I'm careful on steep inclines.

I did the E93 fsb and that was before shocks and springs. Just on the stock suspension the change in handling from the bar was petty noticeable. Knowing this increases the spring rate is why I didn't go with anything too stiff. The Dinan springs and thicker bar is the orobably limit of my comfort level. Again, maybe I'm just getting old lol but if you have higher tolerance you could always throw Swift springs as a 3rd option (with Koni sport).

Thanks for the complements.

[dcaron9999]

Originally Posted by Kgolf31

How are you scraping already?!

When I'm at my track setup (one turn from full bottom out) I never scraped everywhere. In fact my Z4M on stock suspension still has a lower clearance.

Only in specific cases, speed bumps, ice ridge between a parking lot and the street, etc.
I'm sometimes surprised by this and not always driving in a preventive mode. To me, the 135i is close to the ground in stock form, so I'm not after lowering it further...

[Kgolf31]

Originally Posted by 3002 tii

The increased stack height from fixed plates doesn't seem that big. Call me old but I can't imagine going any shorter than what I have now for daily driving. I get by fine without scraping as long as I'm careful on steep inclines.

I did the E93 fsb and that was before shocks and springs. Just on the stock suspension the change in handling from the bar was petty noticeable. Knowing this increases the spring rate is why I didn't go with anything too stiff. The Dinan springs and thicker bar is the orobably limit of my comfort level. Again, maybe I'm just getting old lol but if you have higher tolerance you could always throw Swift springs as a 3rd option (with Koni sport).

Thanks for the complements.

The more and more I drive my car, the more I realize my car is extremely stiff.

So yea, don't go that route.

[3002 tii]

Originally Posted by Kgolf31

The more and more I drive my car, the more I realize my car is extremely stiff.

So yea, don't go that route.

Different chassis but I currently run 550f/650r with H&R fsb on the E86 and that's pretty stiff. Originally ran 450f/550r with stock fsb and that was tolerable on NJ roads.

[dcaron9999]

Using 3002tii's idea, I compiled the following list, for budget and low maintenance alternatives to coilovers ...

Affordable dampers...
1) Bilstein B8 or B12 bundle (B8 dampers and Eibach 148+456 lb/in springs)
2) BMW Performance Suspension dampers
3) Koni Sport

...combined with ...

Springs ...
a) stock M-sport (120+350lb/in F&R rates)
b) BMW Performance Suspension springs (160+420lb/in. Drop is 10mm compared to sport suspension)
c) Swift R-spec springs (201+503lb/in. Drop is 1")
d) Dinan springs
e) Cobb springs (148+457lb/in. Drop is 1.2")
f) Eibach springs (B12 bundle contains 148+456 lb/in springs)

Above can be combined with below, and implemented gradually ...

Other suspension related mods
* Dinan "fixed" camber plates, or adjustable camber plates (Vorshlag, Ground Control, etc)
* M3 front control arms
* M3 rear subframe bushings
* Stiffer Front Sway Bar (E92/M3, E93/M3, or aftermarket) - If upgraded springs+dampers still dont reduce car leaning/swaying when cornering...
* M3 rear guide rods - If you are still not happy with the rear end stability under full acceleration.
* Adjustable Toe arms (Rogue Engineering, Megan Racing, etc) - If your car is dropped, and you are struggling with toe and camber adjustments, and you are getting rear end toe out under full acceleration.

[dcaron9999]

Found a place locally where I could get good pricing on the Bilstein B8 or Koni Sport dampers for $75 more. I would match either dampers with Swift Spec-R springs.

According to my research, and collected feedback:

1. The Koni sports are adjustable, but will require frequent rebuilds. A guy I know at the track needed a rebuild after 12 months of track+street use.
   
2. The Bilstein are not adjustable, about as stiff as the Koni set for medium firm. They can last a lifetime without a rebuild. They are more resistant to corrosion.

I will be using as a dual duty setup with 70% track time and 30% street.

I was going to throw on an E93/M3 aFront Sway Bar at the same time, but decided to postpone until later, to fully appreciate and assess the individual changes in handling.

Which combo would you choose and why?

[Kgolf31]

Are you sure the shocks being rebuilt were Koni Sports and not a Race type shock? Higher end shocks DO need to be rebuilt. It's the nature of the beast but a Koni Sport should not...

[dcaron9999]

Originally Posted by Kgolf31

Are you sure the shocks being rebuilt were Koni Sports and not a Race type shock? Higher end shocks DO need to be rebuilt. It's the nature of the beast but a Koni Sport should not...

I have asked him, and will post more info.

His brother and him have track-prepped Toyota Echo's, but pretty darn fast on the track ...

Edit: Track buddy has confirmed that the Koni Yellows have started leaking after one year, for no apparent reason.

Also got this response from a suspension shop in Canada "I don’t sell Bilstien or Koni. I would recommend Bilstien over koni as they are monotube. Konis of late are also really bad at rusting on the chrome rod. I get a lot brought to me for service, I also cannot fix Koni, and cannot get parts. "

[dcaron9999]

Update: Settled on Bilstein B8 dampers and Swift R-Spec springs (201+503lb/in with drop of 1"), rear M3 guide rods, and Dinan Rear Shock Mounts.

Longest lasting dampers and stiffest springs out there, short of a coilover. More wheel clearance than a coilover setup.

I get to keep using my four 18x8.5 ET52 rear stock wheels and 255/35R18 tires.

Should be a step up from stock dampers and springs, which Ive been abusing at the track for two years.

More money left for for tracking events.

(Car is dual duty with ~70% track and ~30% street).

[3002 tii]

Originally Posted by dcaron9999

Update: Settled on Bilstein B8 dampers and Swift R-Spec springs (201+503lb/in with drop of 1"), and rear M3 guide rods.

Longest lasting dampers and stiffest springs out there, short of a coilover. More wheel clearance than a coilover setup.

I get to keep using my four 18x8.5 ET52 rear stock wheels and 255/35R18 tires.

Should be a step up from stock dampers and springs, which Ive been abusing at the track for two years.

More money left for for tracking events.

(Car is dual duty with ~70% track and ~30% street).

Sounds like a great combination, congrats!

[KRyn]

Wow, super happy I stumbled upon this thread. I have been contemplating how I could run a square set of 8.5" 264s with 255/35/18s on my car. I had noticed it mentioned in a few threads.

I managed to find a set of DA TC Kline coils with Swift front(450)/rear(700) springs as well as a set of HyperCo fronts. I also have a pair of Vorshlag camber plates, does anyone know how much camber I will be able to get out of these plates? I really want to attempt to squeeze a 255/35/18 upfront like some of you guys are doing. However, I feel that 3 degrees of negative camber is just to much to be running on the streets as my car is daily driven in the summer and sees auto-x duty almost every weekend. Do you think a minor fender roll would make up for running a little less camber?

Since I plan to run the style 264 rears (ET52) in the front would it be more beneficial to pick up a 12mm spacer or stick with a 10mm like it appears everyone else is doing?

[135]

Originally Posted by KRyn

Wow, super happy I stumbled upon this thread. I have been contemplating how I could run a square set of 8.5" 264s with 255/35/18s on my car. I had noticed it mentioned in a few threads.

I managed to find a set of DA TC Kline coils with Swift front(450)/rear(700) springs as well as a set of HyperCo fronts. I also have a pair of Vorshlag camber plates, does anyone know how much camber I will be able to get out of these plates? I really want to attempt to squeeze a 255/35/18 upfront like some of you guys are doing. However, I feel that 3 degrees of negative camber is just to much to be running on the streets as my car is daily driven in the summer and sees auto-x duty almost every weekend. Do you think a minor fender roll would make up for running a little less camber?

Since I plan to run the style 264 rears (ET52) in the front would it be more beneficial to pick up a 12mm spacer or stick with a 10mm like it appears everyone else is doing?

You should be able to get ~-3° with the Vorshlag camber plates if you set the adjustable caster to the minimum.
Why do you think -3° is too much for the street?

Even with -3° camber, you may also need to roll your fenders to fit 255/35/18 tyres - it's all dependent on the actual tyre you use as they all have different section widths and shoulder profiles - and the roll may need to be more than just minor.

If you just wanted to fit 245 tyres up front then 10mm spacers may be sufficient. But beware of some 10mm spacers as they have problems with fitment.

Since you want to fit 255 tyres up front, you should go with the 12mm spacers - but, again, that will really be dependent on your coilovers and where the lower spring perch sits relative to the tyre's sidewall, i.e. section, which is the widest part of your tyre (apart from the tyre's rim guard). You could even go as large as 15mm spacers but you will definitely require maximum camber as well as a guard roll & pull. And then you need to watch out for the bumper tab.

My best advice is to measure and then measure again, and when you're certain you've got the right measurements, measure it again. Although, this is more relevant if your getting custom offset wheels as you really only have one chance to get it right. At least with OE wheels, you could just try 10/12/15mm spacers.

[Kgolf31]

Originally Posted by KRyn

Wow, super happy I stumbled upon this thread. I have been contemplating how I could run a square set of 8.5" 264s with 255/35/18s on my car. I had noticed it mentioned in a few threads.

I managed to find a set of DA TC Kline coils with Swift front(450)/rear(700) springs as well as a set of HyperCo fronts. I also have a pair of Vorshlag camber plates, does anyone know how much camber I will be able to get out of these plates? I really want to attempt to squeeze a 255/35/18 upfront like some of you guys are doing. However, I feel that 3 degrees of negative camber is just to much to be running on the streets as my car is daily driven in the summer and sees auto-x duty almost every weekend. Do you think a minor fender roll would make up for running a little less camber?

Since I plan to run the style 264 rears (ET52) in the front would it be more beneficial to pick up a 12mm spacer or stick with a 10mm like it appears everyone else is doing?

I run -3.6* of camber up front all last year and had no issues.

Toe is your wear factor (mostly)