Wandering at Highway Speeds

[Nanniepoo]

I've been noticing that my car wanders a bit at highway speeds. Oddly enough I notice it the most headed home from work, going west. Getting on the highway and decelerating for the ramp going south, nothing. Going east to work, not enough that it catches my attention. It's the same freeway so I imagine the road condition and type is the same going both ways. It started off as more of a jerky tramlining feel, which went away and now it just feels floaty, like I'm driving in windy conditions, enough that I feel like I need to pay extra attention. Definitely feels like it's from the front to me. Car brakes perfectly straight, tracks perfectly straight at sub highway speeds, and corners extremely well.

Nearly my entire suspension is new. RTABs about two years ago. Then front bearings, control arms and bushings, tie rods, sway bar and bushings/links, shocks/struts and hardware all around (same springs), new front calipers in February. I've put less than 2k miles on my car since then. Tire pressure was off for a bit, and did help, but not fix, the situation when I got everything inflated. 35 rear, 32 front. The tires are still fairly new, pretty sure I have less than 4k on them. I'll upload my alignment numbers after I post. It was done at a specialty shop that does a lot of BMW work, particularly E36.

It's not really at a point that I feel unsafe, but it's just annoying that I put so much money and time into the suspension work, and it feels awesome on highway ramps...but once I try to go straight I lose that planted feeling. I DD my car, but only live about 5 miles from work, and we usually take the wife's X5 on trips, so really my only experience with my car since the work is this one stretch of road. It did not feel particularly worse when I got up above 80.

I'm off work this Friday, and I'll hopefully be getting under my car to check things out. Really my only thought is something has loosened up. I have looked at it while it's on the ground and there's nothing obvious. I can move both front wheels side to side, but there's no movement at 12 and 6.



One thing that came up in my reading is steering rack. What are the symptoms of it going bad? There is a clicking when I turn my steering wheel that's been there since I got it 3 years ago and I do see evidence of a powering steering fluid leak. In general my steering feels great though.

Another thought is my front splash panel/underpanel is pretty well destroyed. Can that screw up the aerodynamics enough to cause this?

[Nanniepoo]

Alignment

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[JEC928]

I can't read the numbers on the alignment pic... but I hope that you did align it after doing all that refresh work.

The behavior you describe usually means shot bushings, but a bad steering rack will do that floaty-wandering too.

The intardwebz tell me that Z3M or E46 330i ZHP racks are the hot ticket.

[Nanniepoo]

Yes alignment was after all the work.

After alignment:
Front left toe: 0.18 deg
Front right: 0.15
Total: 0.31

Rear left: 0.17
Rear right: 0.17
Total: 0.34

With that amount of toe in I'm assuming my alignment isn't the issue

[Eric93se]

I wonder if you -3 caster and +3 on the other side has anything to do with it. Maybe something is bent.

Also re-torque your front sway bar bushings.

[Nanniepoo]

Red is out of range, not negative. The caster is 3.2 deg left, 3.4 on the right.

- - - Updated - - -

I do plan on re-torqueing pretty much everything.

[Eric93se]

Oh, ok, I can see now.

Yeah, you should be able to fix it.

[Nanniepoo]

More and more I read about steering rack symptoms, the more I think that's the cause. Won't jump to conclusions but that sucks... I'll need another alignment.

[ultimatetester]

I've had this exact same thing forever with my car... always had the feeling it wasn't the wind pushing the car side to side... it's like you feel the car pulling to one side so you compensate by steering to the opposite side and then suddenly the car decides that it is pulling to the other side instead causing the car to steer a lot to that side because you were already steering to that side to compensate the pull...

Always had the feeling something in my alignment is dynamic.. only thing I didn't check are top mounts for the struts but must say that I haven't touched the steering rack in a long time

[B328iC]

Have you lowered the car? If so the stock numbers are junk. I remember a while back there was a lot of discussion on what a lowered car should be set up to.

[Nanniepoo]

Have you lowered the car? If so the stock numbers are junk. I remember a while back there was a lot of discussion on what a lowered car should be set up to.

I have not. I DD year round, and with the snow in Michigan, I already scrape at stock height. Hence why my underpanel is destroyed.

[Nanniepoo]

I don't think I'm going to get to it today. Finished my lawn work around noon and it's already pushing 90

[Nanniepoo]

Also re-torque your front sway bar bushings.

I think you're the winner. Found the sway bar link bracket to control arm nut loose, and the bushing bracket was also loose on the same side. Unfortunately wasn't able to finish with my motor mounts last night so couldn't go for a test drive.


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[flyfishvt]

I think you're the winner. Found the sway bar link bracket to control arm nut loose, and the bushing bracket was also loose on the same side. Unfortunately wasn't able to finish with my motor mounts last night so couldn't go for a test drive.

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Only problem is that there is nothing about the sway bar that would cause wandering. You can take it completely off and the car will still drive straight

[JEC928]

Only problem is that there is nothing about the sway bar that would cause wandering. You can take it completely off and the car will still drive straight

Agreed. Wandering front end while holding steering wheel tight means the front wheels are not being held tight from rotation around the steering axis, which swaybars do not affect (they only transmit up-down motion/rotation around rear end of lower control arm from one side of car to other).

The main things that keep the front wheels straight from steering-rotation are the steering rack (with it's 4 tie rod ends) and the wheel bearings, which make awful noise when dying/dead.

How much play in steering?

Keep in mind inner tie rods are wear items just like outer tie rods. Shoot, as far as E36s are concerned it appears the whole steering rack is a wear item.

[john318is]

When you say you changed the tie rods, did you just do the outers or the inners too? My car was wandering a bit (amongst other things like vibration under braking on certain road surfaces) and it turned out to be the inners.

I've also read about the steering guibo allowing some movement in the steering - might be worth a check.

[Nanniepoo]

Literally changed everything.

Brakes perfectly straight. No weird vibrations, no oddities while turning.

If I do decide it's the steering rack I'll be doing some of the steering column components as well.

[Tazman861]

Have you checked the steering guibo? My car used to wander with me having to make constant changes while driving in a straight line. I fitted a solid metal steering guibo and it has lost all of the straight ahead vagueness


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[Nanniepoo]

I haven't. To be honest I haven't really driven it much. I do have a pretty strong leak from both my driver's side tires, with the front being much worse, so I need to get that addressed before diagnosing further. Takes ~3 weeks to go from 32psi to below 20.

[blckstrm]

I haven't. To be honest I haven't really driven it much. I do have a pretty strong leak from both my driver's side tires, with the front being much worse, so I need to get that addressed before diagnosing further. Takes ~3 weeks to go from 32psi to below 20.

I've felt some similar symptoms recently. I have 220k on my M3, there's play in the rack, a new clunk (which I think is from the loose rack), and the steering input shaft seal leaks, too, so I finally decided to bite the bullet (I have been putting it off for years. Literally for years).

I have a (verified) ZHP rack on the way, and got the E34 steering joint delivered yesterday. I should be able to have it installed by Saturday morning.

And by the way - you can find a used Z3 or ZHP rack WAY cheaper if you find one in a salvage yard. Most do not require a core charge and are in fairly good shape. My original rack lasted 20 years and 220k miles - I think a rack with 110k on it from a 2005 will be good for quite a while.

[ovation1000]

Did you install front control arm bushings and rear trailing arm bushings correctly. Trailing arm bushings need to be pre loaded before tightening them, front control arm bushings have to be pushed on to the end of the control with lubricant then lower the car, let it sit until the lubricant dries. Also if you worked on the rear control arms or replaced them they also have to be torqued with the weight of the car.

[Nanniepoo]

Did you install front control arm bushings and rear trailing arm bushings correctly. Trailing arm bushings need to be pre loaded before tightening them, front control arm bushings have to be pushed on to the end of the control with lubricant then lower the car, let it sit until the lubricant dries. Also if you worked on the rear control arms or replaced them they also have to be torqued with the weight of the car.

FCABs are poly, from my understanding they don't need to be preloaded. RTABs were done a while ago, did my best to preload, and asked the alignment shop to check them. RTABs have been through two alignments now. I didn't touch the rear control arms. I'll be getting back to driving it again shortly, and will update when I find something.

[ilikemycar]

Did you just do a front end alignment? Do you know if the tech checked tire pressure before aligning your car?

[JDStrickland]

Is the car following the rain grooves that they cut into the highway to mitigate hydro-planing? This is something that your tires want to follow. You may not like it, or might not care but just wonder what's going on, but it is what it is. You paid extra for a car that goes where it's told.

[blckstrm]

I don't know why I didn't think of this earlier, but I noticed a significant improvement in high speed stability when I got an undertray for my car (the factory one was damaged when I got it).

Just an option. I'm finding more and more you can't ever predict what will cause some of these odd handling issues.