New owner: Diagnosing a small steering issue when braking or uneven road

[mynamenumber]

Hi, I picked up an '05 ZHP knowing that I'd need to address this issue, and I THNK I might know what I should do first, but as an non-expert, here's the symptoms:

-- Sometimes (not always) when braking, the steering wheel will pull a bit to one side. Doesn't seem consistent which side.

-- Also, sometimes when driving straight (no tension on the steering wheel), and encountering a road inconsistency that travels in the direction of travel (e.g. not a perpendicular bump, but something like a trench or crack), the wheel sometimes tries to "follow" the road, instead of staying perfectly straight.

There seems to be an answer based on my search and reading here, but I'd love any thoughts on what to check out first, and whether to DIY some of the fixes needed or not.

Thanks!

[Vas]

First thing would be the front control arm bushings.

Tires could also be a culprit.

[KevinC]

+1. FCABs are shot by about 50k miles. Chances are yours have never been replaced. Chances are the entire suspension system has never gotten any attention. How many miles now? A full refresh of components may be called for. Not cheap, but it will drive like a new car again once addressed.

[mynamenumber]

Mileage is right around 60k, and I haven't found a record of the control arm bushings getting replaced.

Not sure if this is an appropriate question, but is that job best for an authorized dealer or is a reasonable local BMW specialist a good choice?

Is this also a good time to check the engine mounts? There's a slightly increased vibration at certain idle frequency, especially right around 550.

Thanks again!

[BCS_ZHP]

Here's a test:
- jack up the front right side of the car, get the right front wheel off the ground
- grab your tire at the 3 & 9 o'clock position, try to wiggle the tire toward/away from the car
- slight play there is normal, medium or lots of play means the FCABs (front control arm bushings) should be replaced, it there is an actual metallic clunk then the bushing is gone and this should be done immediately

Also why you have the car with right front wheel off the ground:
- grab your tire at the 12 & 6 o'clock positions, try to wiggle it
- there should be no play for this one, if there is play you'll need ball joints

FCABs cost $100-150 for the set depending on where you buy them. The dealer will likely charge you 3 hours labor for this job, an indy specialist should be 1-2 hours. A fellow Mafiaso and I replaced his FCABs in just over an hour. Depending upon where you live, reach out to the Family and someone can likely help you out with this job.

If the above shows your FCABs are good and if your back tires have good & even tread, then try swapping front & rear tires. I know, the back ones are wider than the fronts but for this short experiment it is okay. After swapping, drive the same road to see if it pulls or "crack walks". If not, then you need to replace your front tires. If it still pulls and your tires are good, plus your FCABs are good, then find someone with a Hunter front end alignment machine to dial in your 4-wheel alignment.

You can check engine mounts but those are normally good to well past 100K miles. The certain frequency at idle and some vibration is likely a dirty idle control valve (ICV) and your DISA valve needing to be cleaned too. Both are on the driver's side, you'll have to remove the intake boots to get to the ICV, you might as well replace those intake boots too because by 60K miles they have become harder from thermal cycling and are now less flexible so are a potential source of vacuum leaks. Think the 2 intake boots cost less than $50, don't forget to get the accompanying "F" connector cause its cheap and the old one will likely break when you remove it. This is also a fairly straight forward DIY that a fellow Mafiaso can help you with. You will need Torx sockets for this job, buy a decent set [Craftsman (Sears), Kobalt (Lowes)] since the Torx headed bolts are all over the e46.

[ecrabb]

The FCAB's on my car are pretty bad, and my '04 vert only has 43k miles on it. The tell-tale sign for me is sitting in a parking lot or at a light on a light incline. If you quickly release and "stab" the brakes again, you can feel a clunk run right up into the steering wheel - usually on both release and application. Also, like you said, the car can be a little "darty" on heavy break application. I was already suspicious of FCABs, but asked here and everybody confirmed my suspicions.

I could swear my car also feels like it yaws ever-so-slightly from power-on to power-off, so my guess is the trailing arm bushings are also worn. Plan is to work on the suspension this winter since I won't be driving it anyway.

I got quoted $150 for labor from a local indy shop to do FCABs. Another mechanic said it would take 3-4 hours which made no sense at all considering I've watched a guy do it on YouTube in what looks like about 15 or 20 minutes on a hoist with the proper tools all ready. Looks like an hour or two total for me to do it myself on stands, including finding tools, cleanup, etc.

Cheers,
SC

[slater]

I got quoted $150 for labor from a local indy shop to do FCABs. Another mechanic said it would take 3-4 hours which made no sense at all considering I've watched a guy do it on YouTube in what looks like about 15 or 20 minutes on a hoist with the proper tools all ready. Looks like an hour or two total for me to do it myself on stands, including finding tools, cleanup, etc.

Cheers,
SC

yep, it is an easy job. the RTABs are easy too, provided you have the right tool - but it's not expensive and makes the job a LOT nicer to do.

you could do both in an afternoon.

peter

[danewilson77]

Here's a test:
- jack up the front right side of the car, get the right front wheel off the ground
- grab your tire at the 3 & 9 o'clock position, try to wiggle the tire toward/away from the car
- slight play there is normal, medium or lots of play means the FCABs (front control arm bushings) should be replaced, it there is an actual metallic clunk then the bushing is gone and this should be done immediately

Also why you have the car with right front wheel off the ground:
- grab your tire at the 12 & 6 o'clock positions, try to wiggle it
- there should be no play for this one, if there is play you'll need ball joints

FCABs cost $100-150 for the set depending on where you buy them. The dealer will likely charge you 3 hours labor for this job, an indy specialist should be 1-2 hours. A fellow Mafiaso and I replaced his FCABs in just over an hour. Depending upon where you live, reach out to the Family and someone can likely help you out with this job.

If the above shows your FCABs are good and if your back tires have good & even tread, then try swapping front & rear tires. I know, the back ones are wider than the fronts but for this short experiment it is okay. After swapping, drive the same road to see if it pulls or "crack walks". If not, then you need to replace your front tires. If it still pulls and your tires are good, plus your FCABs are good, then find someone with a Hunter front end alignment machine to dial in your 4-wheel alignment.

You can check engine mounts but those are normally good to well past 100K miles. The certain frequency at idle and some vibration is likely a dirty idle control valve (ICV) and your DISA valve needing to be cleaned too. Both are on the driver's side, you'll have to remove the intake boots to get to the ICV, you might as well replace those intake boots too because by 60K miles they have become harder from thermal cycling and are now less flexible so are a potential source of vacuum leaks. Think the 2 intake boots cost less than $50, don't forget to get the accompanying "F" connector cause its cheap and the old one will likely break when you remove it. This is also a fairly straight forward DIY that a fellow Mafiaso can help you with. You will need Torx sockets for this job, buy a decent set [Craftsman (Sears), Kobalt (Lowes)] since the Torx headed bolts are all over the e46.

:wavy

Sent from my SM-G925V using Tapatalk

[ELCID86]

The FCAB's on my car are pretty bad, and my '04 vert only has 43k miles on it. The tell-tale sign for me is sitting in a parking lot or at a light on a light incline. If you quickly release and "stab" the brakes again, you can feel a clunk run right up into the steering wheel - usually on both release and application. Also, like you said, the car can be a little "darty" on heavy break application. I was already suspicious of FCABs, but asked here and everybody confirmed my suspicions.

I could swear my car also feels like it yaws ever-so-slightly from power-on to power-off, so my guess is the trailing arm bushings are also worn. Plan is to work on the suspension this winter since I won't be driving it anyway.

I got quoted $150 for labor from a local indy shop to do FCABs. Another mechanic said it would take 3-4 hours which made no sense at all considering I've watched a guy do it on YouTube in what looks like about 15 or 20 minutes on a hoist with the proper tools all ready. Looks like an hour or two total for me to do it myself on stands, including finding tools, cleanup, etc.

Cheers,
SC

DIY for sure.


Thumbs, iPhone, TaT.

[BMWCurves]

Everyone above has pretty much said what I would say.

I just refreshed my suspension for ~$1,000 in parts. I did most of the work myself since it was pretty easy. The FCABs and RTABs I left for an indy to do. I recall you're from Oregon but I'm not sure which part. If you're in the Portland area and want to use a mechanic for this work, I suggest Autobahn Motorwerks over in Beaverton. They're fairly priced and do good work. It's where I took my car for a PPI and have had it for any other mechanical work I need done.