Advice on springs to pair with Bilstein dampers

[850tgul]

Hi All,

About to start attacking the spring/shocks on my '09 128. Car has 30k on it and currently sits on the OEM sports suspension.

I run Apex Arc-8 wheels, in a square setup, sized 18x8.5 ET45 w/ Hankook Ventus V12 235/40/18. Have never rubbed on this setup and am looking to avoid rubbing in the future. This car is my DD year round in New England and don’t want to slam it or start bottoming out with the horrendous roads we have here.

Having said that, the suspension in its current setup, is flat out unacceptable imo. I removed the run flats, installed the E93 front bar, and did the whiteline subframe inserts. These all helped but it’s still not there yet. Full M3 bushings are on my to do list but first I’m looking at the springs/dampers.

My original plan was to keep the OEM sport springs and just install the Bilstein B6/HD dampers. Certainly still open to this option but have some concerns....mainly there seems to be contradicting data on whether or not the Bilsteins, if done alone, slightly raise the ride height of the car. I would be doing the install myself and it would really suck if upon completion I discover that I have to re-do the whole thing with new springs because the car is at 4x4 level. Second, I don’t mind a stiffer ride (insert hacky joke here), so the addition of any aftermarket springs would further tighten up the ride beyond the OEM sport springs which is a plus. Third, I certainly like the look of a properly lowered car if it doesn’t adversely impact the car or my requirements.

From my research it seems like BMWP springs is the way to go. They would likely drop the car a minimal amount compared to my current setup and the rates would be higher than the sports springs. Thing is, those look to run $425+. I can pick up a used set of Eibachs for a whole lot less but am concerned with the drop and potential rake. Swift may also work well but at $325, I’m close enough to BMWP springs that I’d likely go that route.

Looking for advice from the suspension gurus or folks with a similar setup.

Would I rub with the Eibachs?

Also, with 30k miles on the odometer, are there any parts I shouldn’t re-use when I do the springs and/or dampers swap? Front upper mounts? Anything else?

Here are some pics of the current wheel gap and front strut clearance. Wheel gap is fairly even at all 4 corners. I can get 2 fingers between the top of each tire and the bottom of the fender lip. Not much strut clearance up front. Do I need some thin spacers for the thicker Bilstein up front?





Thx

[850tgul]

Should clarify that I have already decided to go with Bilstein B6/HD dampers. Went with these because they can be used with every spring from oem sport to Eibach, BMWP, or Swift. If I went with the B8/Sport dampers I'd have to use one of the lower springs. thx

[ShocknAwe]

HD/Swift on my car, great setup. Click on sig link for pictures. Keep in mind, my wheels are 19s.

[850tgul]

Originally Posted by ShocknAwe

HD/Swift on my car, great setup. Click on sig link for pictures. Keep in mind, my wheels are 19s.

Wow, your drop looks absolutely perfect.

So your wheels are 0.5" thinner than mine up front, 8.5 vs 8.0 but w/ the same offset. You have 19's w/235/35 vs. my 18s w/ 235/40 so probably minimal height difference there.
Do the upper and lower shock mounts and M3 control arms you have impact the drop at all?
I also sse you have some fender work done?

I take it if you only had the HD/Swift combo with your wheels you would be rubbing, correct?

[dcaron9999]

Running B8 dampers and Swift spec-R springs. Still able to fit same square 255/35R18 setup as I did with with my stock M sport dampers and springs.
The damper to wheel clearance is small but causes no rubbing issues.
I am using a 10 mm spacer in the front just as I did with stock suspension.

The wheels I use are four rear style 261 rims (18X8.5 ET52), M3 front control arms, BMS 10mm spacers in the front, and Ground Control Street camber plates. Tires are Dunlop Direzza ZII StarSpecs. Camber is set for - 3.0* to reduce understreering at the track and clear he fenders.

I ended up with almost 25mm rake due to camber plates stack height being thinner than BMW top hats. I had my camber plates modified and 22 mm spacer installed on top of them, and under shock towers. My 135i now sits nice and even and has a nice drop. Works really well at the track and on the street. Car sits about an inch lower, and is much flatter when cornering/braking/accelerating hard. Not too firm on the street.

A little follow-the-leader lapping to get the participants up to speed:


Having a few hot laps with a few instructors. A bit of dive during hard braking, even with the Swift Springs and B8 dampers:

[sympL128]

Square 18 x 8 with 225/40/18 (maybe 235s next time around), 45 offset on Swift springs with Koni Yellows. No issues, no rubbing, even drop with no rake. This is my DD and the ride quality is great, not too stiff.

[_Ryan_]

B8 damper, Spec R Swift springs could work, ask @dcaron9999 for his experience.

[dcaron9999]

Originally Posted by _Ryan_

B8 damper, Spec R Swift springs.

R U using camber plates? How's your rake?

[850tgul]

Originally Posted by sympL128

Square 18 x 8 with 225/40/18 (maybe 235s next time around), 45 offset on Swift springs with Koni Yellows. No issues, no rubbing, even drop with no rake. This is my DD and the ride quality is great, not too stiff.

Looks great. Any other suspension pieces? Camber plates, m3 control arms, spacers, etc?

[ShocknAwe]

Originally Posted by 850tgul

Wow, your drop looks absolutely perfect.

So your wheels are 0.5" thinner than mine up front, 8.5 vs 8.0 but w/ the same offset. You have 19's w/235/35 vs. my 18s w/ 235/40 so probably minimal height difference there.
Do the upper and lower shock mounts and M3 control arms you have impact the drop at all?
I also sse you have some fender work done?

I take it if you only had the HD/Swift combo with your wheels you would be rubbing, correct?

Shock mounts and control arms don't impact ride height. Yes, fenders have been rolled on all four corners.

[_Ryan_]

Originally Posted by dcaron9999

R U using camber plates? How's your rake?

If your user name wasn't so annoying I would have tagged you to comment.

[dtla1]

Originally Posted by dcaron9999

Running B8 dampers and Swift spec-R springs. Still able to fit same square 255/35R18 setup as I did with with my stock M sport dampers and springs.
The damper to wheel clearance is small but causes no rubbing issues.
I am using a 10 mm spacer in the front just as I did with stock suspension.

The wheels I use are four rear style 261 rims (18X8.5 ET52), M3 front control arms, BMS 10mm spacers in the front, and Ground Control Street camber plates. Tires are Dunlop Direzza ZII StarSpecs. Camber is set for - 3.0* to reduce understreering at the track and clear he fenders.

I also have B8 Dampers but Eibach Pro-Kit springs. I have M3 front control arms on order as well as the dinan fixed camber plates. From your experience, do you think this setup would clear with rear 261M wheels and a 10MM spacer on the front even without being able to get to the -3.0* of camber which you have?

Also, how is your tire wear?

[850tgul]

Decided there was enough good feedback here that I'm going with the Swift springs. Hoping I won't have to play with camber or roll my fenders with my wheels.
Is there any hardware I should absolutely replace when doing the spring/damper install? thx

[sympL128]

Originally Posted by 850tgul

Looks great. Any other suspension pieces? Camber plates, m3 control arms, spacers, etc?

Nope. I didn't want things to get too complicated or costly. Just did the research and pulled the trigger. That's why I went 225's to be on the safe side for clearance. May do more later but for now all is good.

[dcaron9999]

Originally Posted by dtla1

I also have B8 Dampers but Eibach Pro-Kit springs. I have M3 front control arms on order as well as the dinan fixed camber plates. From your experience, do you think this setup would clear with rear 261M wheels and a 10MM spacer on the front even without being able to get to the -3.0* of camber which you have?

Also, how is your tire wear?

You might able to reach about -2.x* with the above, and rake will not be as bad because of the thickness of the added thickness of Dinan fixed plates, sitting on top of your OE top hats. Clearance from the strut will be fine with 10mm spacers. You will have to be careful running as wide as Im doing, as your might rub on the outside fender liner, or "bumper to fender" tab.

You can try to get 8 mm hubcentric spacers (harder to get), or get your wheels slightly "lathed" down by 2mm (where they mate to the hub). By doing one of the other, you will move your wheel closer to the strut by another 2mm, and further from the fender.

What tire size were you planning in the front?

My tire wear is even and I rotate my tires (side to side), half way through their lifecycle (about 3-4 months). I visit the track almost every week from end of April to end of October. Camber alone will not accelerate the wear on your tires on the street. Excessive toe will do that though, and rolling onto the edges of under-inflated tires at the track, or insufficient camber at the track.


Here's a "clearance" picture of a rear 18x8.5 ET52 wheel, used in the front with 255/35R18 tires, 10 mm spacers, and stock BMW Strut. It is close but there is no rubbing, even with track useage. To my amazement, the Bilstein B8 damper offers a little more clearance.

[dcaron9999]

Originally Posted by sympL128

Nope. I didn't want things to get too complicated or costly. Just did the research and pulled the trigger. That's why I went 225's to be on the safe side for clearance. May do more later but for now all is good.

225/40R18 and 255/35R18 will be fine on stock 18x7.5 ET49 and 18x8.5 ET52 wheels, even with stock camber ( no control arms and no camber plates). This is the first setup I ran after ditching the RE-050 RunFlats.

[MightyMouseTech]

Originally Posted by dcaron9999

Ste Eustache. Nice.

Although, after 2 hours of racing in a torrential downpour, I was getting sick doing such short laps.

[dcaron9999]

Originally Posted by MightyMouseTech

Ste Eustache. Nice.

Although, after 2 hours of racing in a torrential downpour, I was getting sick doing such short laps.

LOL ... Definitely not the longest track in Quebec, but one of the oldest, with good pavement, and one banked turn a la Nascar style (woo-hoo). Autodrome St-Eustache and its lapping clubc (ASELC) have the best lapping school in the province (AISA).

The two other tracks in the Montreal vicinity are Mirabel - ICAR, which is twice the length, made out of a flat concrete surface (airport field). Then there's the mother of them all, Le Circuit Mt. Tremblant, which is three times the size of St-Eustache, on a hilly terrain, complete with blind corners, negative camber turns, and beautiful scenery...

[MightyMouseTech]

Originally Posted by dcaron9999

LOL ... Definitely not the longest track in Quebec, but one of the oldest. Also has the best lapping school in the province (AISA). The two other tracks in the Montreal vicinity are Mirabel - ICAR, which is twice the length, made out of a flat concrete surface (airport field). Then there's the mother of them all, Le Circuit Mt. Tremblant, which is three times the size, on a hilly terrain, complete with blind corners, negative camber turns, and beautiful scenery...

Yup, been to them all. Love Tremblant. Good luck racing there anymore these days. Damn Hilfiger dude.

[dcaron9999]

Originally Posted by MightyMouseTech

Yup, been to them all. Love Tremblant. Good luck racing there anymore these days. Damn Hilfiger dude.

Tremblant still has a couple of races there actually.

Tremblant just hosted the first event of the 2015 Micra Cup race series on May 23, 24.

A few lapping clubs visit the track during the week (Mon-Fri). The clubs I know are: Viper Club, BMWQC club, Audi NEC, Porsche PCA, VAG Motorsport Club, Virages Club.

But yeah, the track owner has a "hate" club going for him. He is said to be quite rude and excentric. He has a history of pissing off a few organizers ...

[dtla1]

Originally Posted by dcaron9999

You might able to reach about -2.x* with the above, and rake will not be as bad because of the thickness of the added thickness of Dinan fixed plates, sitting on top of your OE top hats. Clearance from the strut will be fine with 10mm spacers. You will have to be careful running as wide as Im doing, as your might rub on the outside fender liner, or "bumper to fender" tab.

You can try to get 8 mm hubcentric spacers (harder to get), or get your wheels slightly "lathed" down by 2mm (where they mate to the hub). By doing one of the other, you will move your wheel closer to the strut by another 2mm, and further from the fender.

What tire size were you planning in the front?

My tire wear is even and I rotate my tires (side to side), half way through their lifecycle (about 12 months). I visit the track almost every week from end of April to end of October. Camber alone will not accelerate the wear on your tires on the street. Excessive toe will do that though, and rolling onto the edges of under-inflated tires at the track, or insufficient camber at the track.

Thanks for all this knowledge my friend.

I currently have MPSS and like the grip of them, although I feel like the soft shoulders are a bit of an issue. My fronts are currently scrubbing quite a bit when I drive my local canyons, but this may be attributed to my current lack of -camber more than the tires, I shall see.

I was hoping to run 255/25/18 in the front, same as the rear so I could rotate and get a little bit more life out of my tires.

About the spacers, if necessary I'm sure i could buy a set of 10mm spacers and then just have a buddy of mine machine them down, or take them to the local machine shop and do it myself. I'll have to do a bit more reasearch but this sounds promising, at least until APEX decides to manufacture some 17" 1series wheels.

[850tgul]

Originally Posted by sympL128

Nope. I didn't want things to get too complicated or costly. Just did the research and pulled the trigger. That's why I went 225's to be on the safe side for clearance. May do more later but for now all is good.

Great to hear, thx. I feel like my Hankook V12s are a fairly slim 235 width tire, so my fingers are crossed.