Alignment - toe gets knocked out of place easily

[kyippee]

I'm curious to hear others' experiences... does anybody else find their E9x M3 track car gets knocked out of proper alignment very quickly on track?

For example, I've been finding that toe gets messed up very quickly, sometimes even after just one session on track. It can be the front or rear, and it seems odd that I'm having this issue so frequently. It's enough of a change that holding the steering wheel straight does not drive it straight; I often have to point the steering wheel a bit to to the right to make it go straight.

My car has SPL arms up front and an SPL rear toe lockout kit in the rear. Recently replaced a lot of suspension bushings with Powerflex purple, solid rear subframe mount, and recently replaced trans+diff mounts too.

What are the starting points I should ask the shop to check? I'd like to solve this so I don't have to keep on aligning the car every single track day. They've already been marking screws/bolts during alignments and they don't seem to be coming loose. Things are just moving!

[Redd]

Definitely not normal unless you're hitting the kerbs pretty hard and pretty often. I have Dinan rear toe arms (similar to your SPL) and toe settings hardly move even during trackdays. Is your alignment guy tightening the bolts enough?

[kyippee]

Originally Posted by Redd

Definitely not normal unless you're hitting the kerbs pretty hard and pretty often. I have Dinan rear toe arms (similar to your SPL) and toe settings hardly move even during trackdays. Is your alignment guy tightening the bolts enough?

They should be tightening it enough! We even swapped the SPL hardware from TI screws to stainless steel. I've had alignments and work done at two different shops now, and the same issue persists.

I'm wondering out loud if there is something else going on. Could there be something else moving around, such as the rear subframe or some front subframe parts? I don't know the mechanical parts very well, but I assume the suspension arms connect to something (a subframe?) and thus that part may be something to check for bending.

[Redd]

Firstly, is your front or rear alignment moving, or both? If the rear toe is shifting, you'll definitely feel it. Especially if it goes toe out (not fun).

If you have rear solid subframe bushes then the subframe is solidly mounted to the chassis, it should not move. The front subframe bolt holes tolerances are very very small. Unlikely they will shift. If you have a bent subframe or arm, unlikely you will be able to get a good alignment in the first place.

Are u hitting the kerbs hard at track?

[Ximian]

Is front worse or rear? If you've marked the screws/bolts and they haven't moved, that's really odd.

Focusing on the rear -

The attached picture has the stock rear toe arm. The only way I can see losing alignment is if something is being deformed, which would explain the screws/bolts not moving, or another control arm is on its way out the door.

Is the wheel carrier (part all the control arms attach to with the wheel hub assembly) in good shape?

The trailing arm (black piece with holes in it) is designed to deform and if it is and getting worse, I can see it causing issues with alignment.

*not an expert, just spent too much time unnecessarily replacing control arms

[Tommysalami]

My rear alignment used to shift a bit, so I replaced the eccentric bolts. They can get weaker over time and not hold alignment as well. Solved the issue for me.

[M43S7RO]

How much are your specs moving? I think there is naturally gonna be some degree of variance.

[kyippee]

It's moving enough that I am annoyed that the car isn't driving straight, even after just 1 session on track. Noticeably holding the steering wheel off-center to drive straight and it's just awkward. I've been dealing with it and getting alignments after every track day, but it's starting to become tiring after a couple years of this!

I could take pictures of recent alignment sheets and post them if it helps

[dogbone]

I had an alignment done 6 weeks ago when I changed rear springs. Since then I had a dramatic off at Pueblo---easy 100 feet into the unknown.....I've also had a couple other dropped wheels and less dramatic dirt experiences since then. And I've been driving hard in TT competitions on slicks and A7.

I swapped rear springs again over the weekend and drove them Sunday. Went to get an alignment on Monday. The front alignment was still perfect. We didn't touch it. The rear toe was slightly off. Once I swap springs, I'm not surprised if things are off.

I have all stock control arms except for rear toe arms. My control arm bushings are all stock except for front tension arm bushings are Power Flex urethane.

I also run straps through my front rims when I tow.

I think the stock stuff holds up pretty well, but I have to say I was pretty surprised the front held up so well.

[kyippee]

The above from dogbone is why I suspect something is wrong with my car!

[kyippee]

Here's some examples- April and June alignment sheets. The colored with red outline image is the June alignment.

[//steve\\]

Didn't your car have a cracked shock tower or something?

[dparm]

I would give SPL a call. Talk to Turner over there and see what he thinks the weak point would be.

The problem you're seeing is that all of the upgraded components are more rigid, so now you've got play somewhere else.

[dogbone]

I'm not a super expert on this topic, but I've looked at my share of alignment readings. After looking at your alignment readings, it seems that toe is your main problem. Your toe seems to be drastically changing between alignment checks.

Your front toe is looking like quite different between the Final-April alignment and then the initial reading in June. You went from 0 front toe after the April alignment to 7/32 of toe-out on the right and 3/16 toe-in on the left. This is not ideal to say the least. I would give a hard look at whatever is controlling the toe.

Your rear toe moved around too, but less than the front. Left side moved 2/32 more towards toe in and the right side moved 1/32 towards toe out.

Not sure what's causing all your toe settings to wander, but that's where I would start.

The camber changes are pretty minor. Not sure what to make of the right caster change between April and June......

I'm curious that you said you have to hold the steering wheel to the right to make it go straight......Toe out on the right and toe in on the left, which is what the initial June reading shows would generally have you holding the steering wheel to the left to keep the car going straight.

fwiw, the tires that the car is aligned on can have an impact on this stuff. I had the car aligned a few months ago on tires that were already corded and I didn't realize it. When I swapped rims to better tires, I had to hold the steering wheel off-center to go straight. Had to revisit the alignment shop immediately.

[dparm]

There is no reason for the toe to change that drastically over short periods. Something is broken, bent, loose, etc. Take the car to a reputable race shop and have them look it over closely. I am sticking by what I said above -- check with SPL, they should know what the common weak points are.

[kyippee]

Yea we're going to diag more in-depth! Thank you for all the feedback thus far. So far, neither shop that has worked on the car over the years has spent much effort digging into this.

Now, I'm pushing to take a deeper look, rather than just looking at the most immediate items. (Most immediate being the points that are adjusted for alignment) basically "hey I'm convinced something upstream of the alignment adjustment points are broken, let's do a deep diag.

Hm. Good suggestion on asking SPL- will do that and curious to see what they might suggest looking at

[fsmtnbiker]

My guess is it's rear toe moving around. Make sure the lockouts are very tight. The subframe tends to get deformed around those slots and will allow stuff to slip. If the rear toe slips it will show the front toe is off too because of the thrust angle.

I would expect SPL toe arms to hold alignment pretty well, especially with solid subframe bushings. I doubt the front is changing unless there's a loose balljoint somewhere, as it is very hard to get front toe to change/move around. The front suspension is very simple in comparison and doesn't have very many places that things can slip/move. Don't bother looking at individual front toe, just total toe, when comparing alignments. Front individual toe is sensitive to the steering wheel being centered and the Hunter Machines totally ignore that to make the 'before' readings always look worse.

Also, GROSS at using 1/32's as a measurement unit.

One more note - the differences in the measurements down the sheet (wheelbase diff, SAI) tell me that either something is fatigued and moving around significantly in your car (unlikely) or they didn't get the alignment heads on securely and they moved during the initial compensation (likely.) Alignment machines are great tools but they are *extremely* sensitive to user error.

[roastbeef]

Check for subframe cracks up front. You've put that thing through the ringer.

[Tommysalami]

The rear alignment bolts require a lot of torque to stay in place. Over time, the bolts fatigue and stretch. As they fatigue, they don't hold the alignment as well, which could be causing your issues at the rear. It's a cheap place to start if you're gonna replace anything. I'd suggest replacing with ones from FCP, telling your alignment guy to give them extra ugga duggas, and then taking advantage of free replacements once in a while.

As for the front, like fsmtnbiker said, it may be down to the machine's initial reading and not any actual issue. Could also be tires. I've had ones that caused the car to pull, until I swapped them front and rear, and problem gone. Also were tire pressures even all around when the car is pulling? On track you're going to get different pressure rise at each corner as they heat up, and also as they cool back down.

[kyippee]

Interesting! Some stuff to look into.

fsmtnbiker good tips on rear end - I was just at the shop today with my Supra for brake fluid change before its first track day. They noted that they felt it was the rear end moving around more than the front.

The rear end has the SPL rear toe lockout kit and the ECS rear trailing arms. None of the other arms/major parts have been changed. (just bushings and mounts)

I don't know the parts well, but it seems like I still have some original parts with ~86k miles and many track days on them:
- Rear upper arms
- Controls arms? I need to look into what parts are outstanding

Would throwing money at it by buying this kit and having the shop swap them all be a good start? I don't know if there's overlap in parts with the existing SPL rear toe lockout kit, but it seems like some of those parts on my car haven't been replaced yet!
https://www.fcpeuro.com/products/bmw...xm310piecerear

On the topic of tires during alignment, I've been getting the car aligned on my street wheels/tires. Steering is similarly off (need to turn the wheel to drive straight) whether I drive the car with street or track wheels. The street tires were replaced just a few months ago with 560 TW Conti tires and are 36 cold psi all around.

Agreed on the rear ugga duggas - I asked for it

[Redd]

I don't think swapping out arms will solve your problem. If they're worn, they make noise. If they don't they shd be fine. I had stock arms with a lot of miles in them for a long time and had no issues.

I'm gonna throw out a dumb suggestion here - maybe put back your original rear toe arms and see if that helps?

[atopa2002]

Originally Posted by kyippee

Interesting! Some stuff to look into.

fsmtnbiker good tips on rear end - I was just at the shop today with my Supra for brake fluid change before its first track day. They noted that they felt it was the rear end moving around more than the front.

The rear end has the SPL rear toe lockout kit and the ECS rear trailing arms. None of the other arms/major parts have been changed. (just bushings and mounts)

I don't know the parts well, but it seems like I still have some original parts with ~86k miles and many track days on them:
- Rear upper arms
- Controls arms? I need to look into what parts are outstanding

Would throwing money at it by buying this kit and having the shop swap them all be a good start? I don't know if there's overlap in parts with the existing SPL rear toe lockout kit, but it seems like some of those parts on my car haven't been replaced yet!
https://www.fcpeuro.com/products/bmw...xm310piecerear

On the topic of tires during alignment, I've been getting the car aligned on my street wheels/tires. Steering is similarly off (need to turn the wheel to drive straight) whether I drive the car with street or track wheels. The street tires were replaced just a few months ago with 560 TW Conti tires and are 36 cold psi all around.

Agreed on the rear ugga duggas - I asked for it

https://www.ecstuning.com/b-genuine-...146888626~oeb/

This is what Fbike and tommysalami were talking about.