Chassis/cabin vibration at highway speeds only

[Mozza1219]

I'd suspect something went wrong with the driveshaft remanufacture.
Check the caps on the joints to see if they all protrude from the yokes the
same amount, then see if there are any shiny spots where a weight might have
flung off.

You can stick a little camera and a light down there, and see what it's doing at speed.

I've had numerous driveshaft vibes, and yes, the cabin resonates in a way that
you start to recognize after a while.

hth

t

Thanks TobyB.

I did have a look to see if any weights had come off and everything looked ok there, but I didnt check the caps. Even if everything looks ok, would you suggest taking the driveshaft off and bringing it back so they can check the balance?

[jbontke]

I cased a similar vibration at 75-80 for a year. It went away when replaced the engine and trans mounts. Drive line angle is important.

[Mozza1219]

I cased a similar vibration at 75-80 for a year. It went away when replaced the engine and trans mounts. Drive line angle is important.

Trans mounts replaced. Not sure that it can be engine mounts seeing as it is only speed sensitive.

I still haven't figured this one out and I've just been dealing with the vibration, but it does get on my nerves and gets in the way of me really enjoying the car.

I had the car on jack stands (under the trailing arms so there was some weight on the springs) and ran it up to speed. Vibration was still there and felt exactly the same. I don't know if I'm game to run the car with the stands on the subframe, I heard you shouldn't put the CVs at that angle and run the car? Let me know if I'm wrong about this.

[jbontke]

If you want to get precise on driveline angle, start checking it and see if something is off: https://www.moderndriveline.com/driveline-angle-finder/ It can tell you is the engine/trans mounts or the rear diff is out of what in relationship to one another. If they are spot on or very close, then its either driveshaft balance. You mentioned that the driveshaft has new joints. Was it balanced after that?

[twright]

Have you checked the wheels for straightness?

If you have and they're OK, change your Front Control Arm Bushings. These can be bad and look fine. The good news is that they are cheap.

[Mozza1219]

If you want to get precise on driveline angle, start checking it and see if something is off: https://www.moderndriveline.com/driveline-angle-finder/ It can tell you is the engine/trans mounts or the rear diff is out of what in relationship to one another. If they are spot on or very close, then its either driveshaft balance. You mentioned that the driveshaft has new joints. Was it balanced after that?

I'll have to look into this link, so it's like an app or something.

Correct, driveshaft was balanced when the UNIs were replaced.
Even after putting the reconditioned driveshaft in, the car drove fine and maybe a week or two after the vibration started.

[Mozza1219]

Have you checked the wheels for straightness?

If you have and they're OK, change your Front Control Arm Bushings. These can be bad and look fine. The good news is that they are cheap.

I took a closer look at the wheels and yes, one wheel is definitely in worse shape than the rest. The other 3 are ok, with the exception of 1 which also has a slight warp in it. So that makes 1 bad wheel and 1 sort of bad wheel right?

So I got my spare wheel from the boot and went through each wheel, swapping it out one by one. The spare is in perfect condition and the tyre seems ok.

The vibration was exactly the same on each drive. I get why it would seem like a bent wheel is causing this, but after swapping each wheel out individually I don't think this is the issue.

I've already swapped the front control arm bushings out.

I'm leaning towards a bad rear wheel bearing, rear trailing arm bushings or subframe bushings. But I havnt summoned the will power to drop the subframe and replace the bushings yet...

[twright]

You're testing with 1 bad wheel won't tell you much if you have two bad ones on the car. It will still shake. Get 4 good wheels on the car and see where you are. Wheels can be straightened. It usually costs about $100 a wheel.

Bad wheel bearings make noise. I haven't seen one cause a vibration problem unless its so bad that the balls have all fallen out of the bearing.

I've changed a lot of bad bushings. None of them caused a vibration problem. You can tell they're bad because of handling problems.

[Mozza1219]

Update!

So I went all out today and changed the following:
1. CV boots
2. Rear subframe bushings
3. Rear trailing arm bushings
4. Rear wheel bearings

took the car for a drive afterwards and my vibration is complete gone!

I personally suspect it was a bad rear wheel bearing (driver side), it just didn't sound quite right when I was spinning it by hand. Again, this did not transmit into any noise in the cabin, but instead I think it was the cause of my vibration.

The reason I do not think it was the subframe or rear trailing arm bushings was because when I pulled them out, they didn't look like they were in that bad of a condition. For example, the subframe bushing came out all in one piece.

Hope this helps anyone who may have the same symptoms as myself. It was busy 2 days, but I'm so happy I got my car finally sorted.

Cheers all! Happy to take any questions about dropping the subframe or doing the rear wheel bearings as it's all fresh in mind.

[Mozza1219]

Sorry to revive a dead thread...but guess what. It's back! or it was never actually gone?

The car has sat in storage for months and low and behold when I took it out for a drive, vibration is back. It's not as serious as it used to be, but its still just as annoying.

Starts at 90km/h on the dot and it changes a little as the speed increases, almost like its getting smoother but you can notice the rear view mirror shake more and more as the speed increases.

Doesn't matter if I'm coasting, accelerating or braking.

I've put the car on a lift and run it up to speed with the rear wheels and brakes removed - still vibrating. So this tells me its something with the driveshaft or alignment with the driveline.

I replaced the transmission mounts ages ago, but I never touched the engine mounts as they 'looked' ok.

The refurbished driveshaft honestly looks good, can't see any missing weights, points where its contacted the chassis etc. And the Uni's look to be set up correctly.


Could this issue be due to me replacing the transmission mounts and not changing the engine mounts and this has somehow caused the entire driveline to be at a strange angle which causes a speed sensitive vibration?

Engine mounts are in the mail and will be replaced hopefully this week.

[ADEN]

Let someone set in front seat then move to rear seat trying to locate where it feels more or all the same?

[OSAH racing]

I have had this problem with an 325i and a 318 M42 car. the solution each time was new OEM bushing/mounts at the engine, trans and differential. The 325 was smooth with rubber on the driveline and poly on the subframes. The M42 car I am still chasing last bit of it and I am removing the delrin trailing arm bushings and frame bushings in favor of poly.

[82eye]

I have had this problem with an 325i and a 318 M42 car. the solution each time was new OEM bushing/mounts at the engine, trans and differential. The 325 was smooth with rubber on the driveline and poly on the subframes. The M42 car I am still chasing last bit of it and I am removing the delrin trailing arm bushings and frame bushings in favor of poly.

every poly bushing i've seen transmitted more nvh from the driveline to cabin. oem rubber is the best way to get rid of it.

[Mozza1219]

I've figured that if I leave the car for an hour or so and then drive it, it is initially smooth and then after a few minutes it starts vibration, which then gets worse within about 10 minutes of driving. My theory is that either the CSB is faulty from the factory, or it was damaged by the mechanic when it was installed on the shaft.
Because of the above, I doubt that the issue is alignment or a bushing because that would make itself evident straight away. It seems to me that the vibration occurs when a bearing or something heats up after being rotated multiple times.
I'm going to take it back to the driveshaft shop today and ask them to run it on their balancing machine. I had a long chat with them about bmw shafts and phasing and they do seem very knowledgeable on the subject, but they agree that bmw shafts are a pain to work on.

I havnt replaced the engine mounts or diff bushing yet. I've got the engine mounts ready to go but I haven't had the time to install them yet.

This is a strange vibration, it defies all logic and I can't get my head around why it's initially smooth and then starts vibrating after a few minutes of driving. Thoughts?

[twright]

I have a crazy idea: Exhaust systems grow significantly as they heat up. Is it possible that your exhaust (after being driven a while) has grown and is now touching something on the body?