Car pulling to the left and front end instability

[Monkibouy]

I've been dealing with an odd suspension issue for the past several months, hoping that the F8X hivemind might have some insight. My car has been pulling noticeably to the left to the point where I end up fully in the next lane over in ~5sec on straight, flat roads if I take my hands off the wheel at freeway speeds. You can see the wheel turn about 10-15deg to the left if you let the car "center" it. There is also a noticeable increase in steering effort when turning right instead of left that feels unnatural.

In addition, the front end of the car occasionally feels unstable and wants to wander, especially on a day like this AM when there was some light moisture on the ground. For example, I can feel DSC intervene on a relatively tame freeway interchange, this made me slow down to ~60mph vs the 80+mph I've easily been able to take it at before. Changing to MDM/DSC-off reduces the intervention but the odd feeling in the chassis and steering wheel remains. This behavior seems to be exacerbated over rough, undulating roads.

One other thing to note is that whatever is causing this issue has caused two monoballs on the driver's side to fail, one of them in less than ~1K miles (currently on my 3rd monoball ). In troubleshooting this, I have had two different alignment shops and my independent BMW shop look the car over but, according to them, the alignment is spot on and nothing in the suspension is loose/suspect/etc.. They all know that something is up with how it drives but it's being quite difficult to nail down whatever is causing this.

Here's what has been done so far:

• Driver's side monoball replaced (twice)
• Front LCAs, tie rods, and tension struts checked
• Reset EPS calibration via ISTA
• Reset ICM/EDC via ISTA
• Replaced rear tires (were ready for replacement anyway)
• Replaced front and rear sway bar end links (some pre-load was present on rear)
• Replaced driver's front wheel bearing/hub
• Swapped front tires
• Aligned (after initial mono ball and rear tire replacement); all subsequent checked have shown it to be "in spec"

As far as the car and suspension, the chassis has ~121K miles. Tension struts, LCAs, rear lower links (SPL traction/toe) and shocks/struts/mounts were replaced about a year/12K miles ago (running stock springs on Evolve Bilstein Damptronics). Coding wise, it has CS EDC and GTS steering/diff/MDM. Front tires have >4mm tread with similar wear between left and right, rears are effectively new. No errors present when scanning via ISTA and my latest alignment results (post-first monoball replacement) are below.

[6ixSpd]

Hmm at that point (after the various suspension part replacements) I’d check the front subframe and bolts.

[noemon]

I'm guessing the wheels and all suspension arms/wishbones have been inspected closely?

I would next swap the shocks with stock, especially since you lose the monoballs like that, first port of call for me would be to take them shocks out.

A broken shock internally does not always show up as EDC chassis error as the electric signal may still go through.

[Monkibouy]

Originally Posted by 6ixSpd

Hmm at that point (after the various suspension part replacements) I’d check the front subframe and bolts.

I haven't gone down that rabbit hole just yet, wouldn't that show up on an alignment rack?

Originally Posted by noemon

I'm guessing the wheels and all suspension arms/wishbones have been inspected closely?

I would next swap the shocks with stock, especially since you lose the monoballs like that, first port of call for me would be to take them shocks out.

A broken shock internally does not always show up as EDC chassis error as the electric signal may still go through.

Yeah, according to my indy and the alignment shop, every component in the suspension is tight, I'm unable to find any play either . That's an interesting thought on the strut though - I actually had a small leak in my first driver's side strut that was replaced under warranty back in August, though there wasn't any odd behavior like this to go with it. I do still have my (somewhat worn) OEM setup - outside of swapping directly, is there any way to reliably test this? Both sides on the front feel very tight (pressing down gives almost no movement).

[robert58]

Does the wheel bearing / brake disc get warmer on the left side?

[Monkibouy]

Originally Posted by robert58

Does the wheel bearing / brake disc get warmer on the left side?

I haven't measured temperatures but I don't see any difference in brake wear between sides. The bearing/hub was replaced on the driver's side and the new one did feel slightly smoother when comparing the two while they were off of the carrier but there was no apparent failure and the issue remains.

I think noemon might be on to something though - I noticed there is what seems like spring bind on the driver's side strut. I don't hear or feel any obvious signs of strut mount failure that I'm accustomed to when driving but, when that strut is unloaded, the mount doesn't move smoothly as compared to the passenger side. I'll tackle this part next and see if there is any improvement.

[Monkibouy]

Following up on this, the driver's side strut mount was replaced and the pulling/instability issues are GONE . Oddly enough, I couldn't feel any binding or obvious signs of wear in it while it was unloaded. All is not well, though, because I also discovered that the driver's side strut is leaking. Again . Starting the warranty process again with Evolve/Bilstein and heavily considering moving to a different setup. With the money I've spent on this kit + troubleshooting and removing/reinstalling (never mine the time investment...), I could have just started with 2 way adjustable JRZ/MCS or gone with a 3DM Ohlins R&T kit and even saved a bit of money. Live and learn, amirite?

** EDIT **

I spoke too soon - instability and pulling issues are still present but muted compared to before and I still get EDC intervention/pushing on relatively tame turns/interchanges. There's also an occasional pogo effect on the front end (left to right) that I'm noticing that wasn't as obvious beforehand with the other issues still present. Still working with the vendor to get the RMA processed.

[b_w.]

Get a set of MCs. Won't regret it.

[M3SQRD]

I 2nd it - get a set of MCS dampers and you’ll be set!

That sucks. You’ve had reoccurring leaking problems with the Evolve/Bilstein B6 dampers? Is it the driver’s side leaking again? How many miles before the first and second leak? It sounds like they’ve made the warranty/replacement process painful?

[Monkibouy]

That's correct, my original driver's front started leaking after ~3k miles and now my current one after ~8k miles. The warranty process with Evolve/Bilstein wasn't necessarily painful, just a bit time consuming (Evolve works as the middle man - they're great, no complaints about them) and of course there's the added labor to swap it out again. My primary frustration is in the apparent reliability of the part which prevents me from trusting the new one and the rest of the system.

Do you have a recommendation as to which MCS would be good for a primarily daily driven car? I do put a fair bit of miles on the car (~12k/yr, mostly freeway with some mixed quality roads, no real plans for HPDEs/track days) so something that doesn't require frequent rebuilds would be high on my list. I did daily a MK7 GTI on Ohlins R&T for ~40k and there was negligible degradation in ride quality/capability, if I can get that out of a set of MCS, I'd be down.

I'm also kicking around the idea of doing a CS retrofit; I already have the base springs and coding, I just need the dampers and rear sway bar. I know the valving would be inferior to MCS but it would be a step up from the base suspension and also OEM (a parts bin special, yes, but still OEM ). Retaining EDC isn't as important to me as when I decided to go the Damptronic route but it would be a small bonus.

[Track/S]

This has happened to me in other cars (non bmw), the solution was to calibrate steering wheel.

[M3SQRD]

Originally Posted by Monkibouy

That's correct, my original driver's front started leaking after ~3k miles and now my current one after ~8k miles. The warranty process with Evolve/Bilstein wasn't necessarily painful, just a bit time consuming (Evolve works as the middle man - they're great, no complaints about them) and of course there's the added labor to swap it out again. My primary frustration is in the apparent reliability of the part which prevents me from trusting the new one and the rest of the system.

Do you have a recommendation as to which MCS would be good for a primarily daily driven car? I do put a fair bit of miles on the car (~12k/yr, mostly freeway with some mixed quality roads, no real plans for HPDEs/track days) so something that doesn't require frequent rebuilds would be high on my list. I did daily a MK7 GTI on Ohlins R&T for ~40k and there was negligible degradation in ride quality/capability, if I can get that out of a set of MCS, I'd be down.

I'm also kicking around the idea of doing a CS retrofit; I already have the base springs and coding, I just need the dampers and rear sway bar. I know the valving would be inferior to MCS but it would be a step up from the base suspension and also OEM (a parts bin special, yes, but still OEM ). Retaining EDC isn't as important to me as when I decided to go the Damptronic route but it would be a small bonus.

Wow. Started leaking after only 3k miles and then 8k miles with the warrantied replacement damper. These two (known) failures definitely are not a good sign for long term reliability especially if Evolve’s statements about the delays getting the Evolve/Bilstein f8x and e92 M3 dampers to market were due to Bilstein having to redo their design verification and life-cycle testing. When they aren’t leaking, how’s the ride quality?

I was going to also suggest the Ohlins R&T as another viable option and, with no plans to track, it might be the better option. The only issue with the R&T f8x setup are the original spring rates were/are too high for the street. The F/R rates were 120/230 N/mm (685/1313 lbf/in). They revised the rates when the f87 kit was released to 90/190 N/mm (515/1087 lbf/in) which is still a little high for street-use only. I don’t know if Ohlins still offers this but at one point you could select your own rates at no additional cost. I’d recommend 80/140 N/mm (456/800 lbf/in), maybe a little softer rates. R&T have excellent longevity and I’d say 50k miles before first rebuild. I have a set on my r56 Mini and they’re still going strong after almost 1.5 decades.

For a MCS street setup, I’d strongly recommend a 2WR setup with increased suspension travel and a high-speed compression blow-off valve located in the remote reservoir. The reservoir nitrogen N2 pressure is adjustable in the reservoir from 100-275 psi but 100 psi is sufficient for use on the street. The lower reservoir pressure also improves ride quality but if you do decide to track the car I’d raise it to at least 250 psi. I’d use similar rates to the R&T 450-500 lbf/in front and 800-850 lbf/in rear. For pure street driving you should get at least 40k. I installed a set of 2WR with 500/800 lbf/in spring rates + 100 psi reservoir pressure on my wife’s f22 240ix and she absolutely loves it. Only negative is the cost which is ~2x the cost of R&T.

Getting a set of zcp or cs dampers, cs mixed sway bars and cs edc coding is another option that will have improved ride quality but I think the R&T and MCS setups will have superior ride quality and performance. CS upgrade is probably the best cost option.

[Monkibouy]

Originally Posted by Track/S

This has happened to me in other cars (non bmw), the solution was to calibrate steering wheel.

I ran through the ISTA steering calibration but didn't notice any difference, unfortunately.

Originally Posted by M3SQRD

Wow. Started leaking after only 3k miles and then 8k miles with the warrantied replacement damper. These two (known) failures definitely are not a good sign for long term reliability especially if Evolve’s statements about the delays getting the Evolve/Bilstein f8x and e92 M3 dampers to market were due to Bilstein having to redo their design verification and life-cycle testing. When they aren’t leaking, how’s the ride quality?

I was going to also suggest the Ohlins R&T as another viable option and, with no plans to track, it might be the better option. The only issue with the R&T f8x setup are the original spring rates were/are too high for the street. The F/R rates were 120/230 N/mm (685/1313 lbf/in). They revised the rates when the f87 kit was released to 90/190 N/mm (515/1087 lbf/in) which is still a little high for street-use only. I don’t know if Ohlins still offers this but at one point you could select your own rates at no additional cost. I’d recommend 80/140 N/mm (456/800 lbf/in), maybe a little softer rates. R&T have excellent longevity and I’d say 50k miles before first rebuild. I have a set on my r56 Mini and they’re still going strong after almost 1.5 decades.

For a MCS street setup, I’d strongly recommend a 2WR setup with increased suspension travel and a high-speed compression blow-off valve located in the remote reservoir. The reservoir nitrogen N2 pressure is adjustable in the reservoir from 100-275 psi but 100 psi is sufficient for use on the street. The lower reservoir pressure also improves ride quality but if you do decide to track the car I’d raise it to at least 250 psi. I’d use similar rates to the R&T 450-500 lbf/in front and 800-850 lbf/in rear. For pure street driving you should get at least 40k. I installed a set of 2WR with 500/800 lbf/in spring rates + 100 psi reservoir pressure on my wife’s f22 240ix and she absolutely loves it. Only negative is the cost which is ~2x the cost of R&T.

Getting a set of zcp or cs dampers, cs mixed sway bars and cs edc coding is another option that will have improved ride quality but I think the R&T and MCS setups will have superior ride quality and performance. CS upgrade is probably the best cost option.

Awesome, appreciate the detail! Ride quality w/the Evolve/Bilstein is geared towards the stiffer side of the spectrum, great on smooth surfaces but can feel unsettled when they on rough or heavily undulating roads. Sport tends to feel the best on most roads as Comfort still has a similar initial jolt over bumps but takes longer to settle than Sport/Sport+. There's a small but noticeable increase in NVH over the stock setup, overall it feels more stable with less roll/brake dive but with commensurate ride quality degradation over stock. I find it livable but my wife is not a huge fan.

Granted it was on a different platform but I was a fan of the daily driveability and overall handling balance with my Ohlins R&Ts. If I decide to go that route, I would probably do either the 3DM Roadsport (70nm/160nm) or Turner Street Performance (70nm/140nm) kit with the softer spring rates. It would be ~40% premium over doing fresh ZCP/CS dampers but I feel the value is there, even if it means dealing with coding out EDC.

What are your thoughts on the MCS 1WNR? Those appear to be at a similar price point to the Ohlins kits and MCS gets rave reviews, are those too much of a compromise compared to the higher end kits?

[M3SQRD]

Originally Posted by Monkibouy

I ran through the ISTA steering calibration but didn't notice any difference, unfortunately.



Awesome, appreciate the detail! Ride quality w/the Evolve/Bilstein is geared towards the stiffer side of the spectrum, great on smooth surfaces but can feel unsettled when they on rough or heavily undulating roads. Sport tends to feel the best on most roads as Comfort still has a similar initial jolt over bumps but takes longer to settle than Sport/Sport+. There's a small but noticeable increase in NVH over the stock setup, overall it feels more stable with less roll/brake dive but with commensurate ride quality degradation over stock. I find it livable but my wife is not a huge fan.

Granted it was on a different platform but I was a fan of the daily driveability and overall handling balance with my Ohlins R&Ts. If I decide to go that route, I would probably do either the 3DM Roadsport (70nm/160nm) or Turner Street Performance (70nm/140nm) kit with the softer spring rates. It would be ~40% premium over doing fresh ZCP/CS dampers but I feel the value is there, even if it means dealing with coding out EDC.

What are your thoughts on the MCS 1WNR? Those appear to be at a similar price point to the Ohlins kits and MCS gets rave reviews, are those too much of a compromise compared to the higher end kits?

Evolve talks up their EB6 like it completely changes the Bilstein B6 version to have better ride quality and performance based on their comfort and sport+ tuning differences. Bilstein uses a high N2 gas pressure that causes the B6 to skip over decent sized bumps rather than absorbing them. Plus people tend to forget what EDC’s prime objective is - damp out disturbances as quickly as possible! It’s not designed to be more underdamped than a conventional damper. Your experience with them matches what I expected to hear from people that have tried the EB6.

Absolutely. The 3DM and Turner R&T street-biased kits are the way to go. I’d go with the 3DM version because you get one free revalve. I’m confident 3DM will allow you to alter (soften the rear) spring rates if you wanted lower rates. 913 lbf/in is still a little high for a street-only setup. I’m running MCS 2WR setups on my e92 M3 with 600/900 lbf/in and f82 with 700/1100 lbf/in and, although, they are street friendly you feel the high spring rate. IMO, the 500/800 on my wife’s car is a great setup for the street.

The MCS 1WNR is a great damper and I was supposed to get one of the first sets for my other e92 M3 but the release was delayed. I ended up getting the JRZ RS1 which is very similar to the 1WNR. Unlike the R&T, the 1WNR is only adjustable in rebound. R&T single adjuster controls both rebound and compression which gives you more control over your setup but nowhere near the freedom a 2-way damper with independently controlled rebound and compression damper can. The 1WNR with 400-500 lbf/in front and 700-800 lbf/in rear would be a great street setup. Rebuild interval will be similar to the 2WR so around 40k street miles. Unlike the 2WR, the gas pressure is fixed in the internal reservoir on the 1WNR. If I had to pick between these two, I’d go R&T for a street-only setup or the 1WNR for a dual street-track setup.

[Monkibouy]

Good stuff - again, appreciate all the info. Reaching out to 3DM to get more details on their kit and the possibility for changing up the rear springs.

[M3SQRD]

Originally Posted by Monkibouy

Good stuff - again, appreciate all the info. Reaching out to 3DM to get more details on their kit and the possibility for changing up the rear springs.

You’re welcome

Let me know which way you end up going and your selected spring rates.