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-   -   Vibration in Rear at 35-40+ (http://forum.e46fanatics.com/showthread.php?t=905598)

lukevp 02-25-2012 12:53 AM

Vibration in Rear at 35-40+
Hey guys, quick question, want your thoughts.
I have a vibration and wobble (wobwobwobwob) in the right rear that starts at 35 mph, gets pretty bad at 40 (real bad if I bring it up to 45 and then coast it back down to 35), increases in pitch as you get faster, taken it up to 70+ and it never goes away. Can't feel it in the steering wheel. Had my girlfriend drive the car while I sat in all the other seats and felt the panels / listened / etc. It's definitely isolated to the right rear.

Had my wheels balanced and rotated a few weeks ago. Didn't make any difference in the noise. Before that I wasn't sure where the wobble was located so I didn't know if the rotate moved the wobble (maybe a bent rim?)

Today I swapped on the spare (fullsize) to the right rear - no difference. Then I swapped rear wheels left-right (with the spare off again) and the vibration stayed at right rear. Swapped them back now and the vibration is still in the same spot.

So by my count I've eliminated
- wheel
- tire
- balancing issue

And things that could still be a problem
- sticking caliper
- wheel bearings
- wishbone bushings
- ??

What do you guys think?
One other thing that is of notice is that I have warped rotors or uneven pad deposits, I get a lot of steering wheel vibration and I can feel a jerking when I slow down at a certain pace. This has been going on for a long time (longer than wobble.)

My research seems to make it seem like sticking caliper is most common. I think I noticed right rear wheel was hot but didn't think much of it at the time until i heard that was a symptom of sticking caliper.

If I can tell if it's a sticking caliper I might just do a 4-wheel caliper rebuild and probably replace rotors / pads while I'm at it (checked them while they were off, rear pads are very low, front pads pretty low, rear rotors are pretty worn and fronts aren't a whole lot better). But how can I know for sure?

Any help/advice appreciated!

EDIT: By the way, car is at 115k, had it since 105k, no service history on it prior to my ownership (of course I keep history of all service I do to it.)

mwt330i 02-25-2012 05:03 AM

WHen you were swapping wheels, was there any visual wear on the brake rotor? Usually when you have a stuck caliper the rotor shows it with a pronounced "wipe" mark from the pad. Often it can be just on the back side. But if the wheel assembly is hot after driving a short distance, there's your answer. The vibe is probably coming from the rotor that's dragging and most likely warped some.....

dmax 02-25-2012 05:20 AM

See if it is sticking as mentioned by comparing rotor temps...drive on highway and pull off without using brakes. If one rotor is hot...there you go.

There might be fixes short of replacing everything. You might just, for instance, clean and lube (with brake grease) the guidepins/bushings and the surfaces on pad/caliper where they slide.

Of course, inspect other components while around there too...check shocks for leaking, end links for torn boots, anything that doesn't seem to look quite right.

Oh, wheel bearing is another possibility. Had you happened to notice any whoop/whooping sound in tempo with wheel's rotation? You may have moved past that warning sound to more severely damaged wheel bearing...may have hit a severe pothole (you'd probably see evidence in your wheel rim, though, especially on the inside. Spin wheels while watching the rims for a hop. When balanced on a high speed machine, the tech wouldn't be able to notice the hop, but you could just by having someone push it around by hand as fast as they can. If wheel is damaged, even though it's balanced, and even though you moved the wheel around, it might be evidence that you had a hard knock there, which might have damaged bearing/shock.

Also, if it's a shock, you might notice scaling on the tire tread...as in fish scales...where the treads don't feel flat, but 'scaled.'

IxNay 02-25-2012 08:40 AM

As far as a sticky caliper you should try this test. I live in a sparsely populated area that has a divided highway with a 50MPH speed limit that is a 2 minute drive from my home. If you live in an urban area, the test could be a little more difficult to find a safe place to perform. To test for a sticky caliper I start out with the brakes cold, drive to the highway (without using the brakes - there are no stop signs or traffic lights between my home and the highway). After driving a short while, say a mile or two, I slow down (again without using the brakes - but my car is a manual, so I just downshift) pull off on the shoulder and coast to a stop. Then I check to see if any of the rotors have heated up. Since I have not used the brakes, if the rotor has heated up, I then know the caliper is sticking. Another possiblity is your parking brake shoes are sticking. In this case, the area where the brake pads contact the rotor will be cool, but the area where the parking brake shoes contact the rotor will be hot.

lukevp 02-25-2012 02:17 PM

drove at 50 mph for about 5 minutes (best I can do around here) felt all wheels and all rotors, none of them were hot at all. No difference in heat. Not sure how to feel where the parking brake shoes connect? is that the metal plate right behind the rotor?

Could it be that my bearings are out AND i have warped rotors? two separate problems? one causing the vibration and the other causing the pulsing brake?

as I said, I have not had the car long so I do not know how the previous owner drove it.

I'll do some tests for wheel bearings later today, and jack it up and see if I can get the caliper to stick and inspect the dust boots and all.

BimmersGarage 02-26-2012 09:21 AM

Because of your descriptions of noise and felt vibrations -

Some other things you might need to have checked/done:
1. Check the condition of your LCAs, FCABs, RTABs because @ 115K+ those components are more than likely shot (beyond doubt, if originals.) If one or more of them are failed, focusing on brakes/calipers will not solve your problems.
2. Double check the tire's tread face*. Inspect the inner & outer edges and look for feathering and what Doug(DMAX) calls "fish scales"... Finding evidence of this would indicate deviance from standard suspension specs. Assuming your tires are all in good state of health: proper tire pressure, no internal tire damage, etc.**
3. Lastly, [Once those parts are checked out > those items listed in #1, if ok.] Then have an Alignment done, but you Must make sure they're good. Otherwise, you're just wasting money on alignment.

By the way.. a Very complete "help request".
Appreciate the details of what you have already tried and their results. Wished more New members would put forth the effort and give this kind of clear info. and thoroughness.

*Do you have any photos: tread-face of the tires, wheels/rims, brake rotors/calipers/pads, etc. for us to review (instead of verbal descriptions)?

**Also, (as Doug has mentioned) you're assuming your wheel itself is NOT warped/damaged from possible potholes (some of which are quite insane). Dallas have quite a few of those on LBJ...
So, Check to see how Many counter weights were used to balance your wheel(s). If there's more than average than that's another sign.

IxNay 02-26-2012 09:35 AM

As long as the vibration is always there (not intermittent) then jacking up the car and checking is a good way to proceed to check for a sticky caliper or parking brake. If there is a problem you should be able to feel whether there is resistance when rotating the wheels by hand with the car jacked up, if this is not the problem then the wheels should spin freely. It is clear to see where the brake pads contact the rotor, but the parking brake shoes make contact towards the middle of the rotor assembly nearest where the wheel mounts. Essentially the rear rotors incorporate both a disc brake (for the regular service brakes) and a drum brake (for the parking brakes) set up. Look at a picture of a rotor on realoem.com and you will see what I mean.

lukevp 02-27-2012 01:01 PM

I only have access to tools on the weekends, and I ran out of time to check these things out. Next weekend I will go through the list, check all the items out as best I can (bushings, brakes, bearings, rotors, etc.), and upload pictures of everything. I'll put the car up on 4 stands and check all the wheels / rotors / etc. and post an update. Thanks for all your help so far!

Mango 02-27-2012 01:09 PM

I vote tires or wheel bearings.

You could also have a bad balance if the balancing machine was not calibrated regularly (which happens a lot more than you think)

Have a friend ride beside you too as you drive to see if there's any bouncing or weirdness to your wheel. You won't see a balancing issue like that but you might be able to see if a wheel is obviously out of round.

As a side note, a sticking caliper in and of itself will not cause a vibration. You'll just overheat/kill prematurely your bearings, brake pads, and/or rotors.

What's the age/brand/model/condition/mileage of your tires?

lukevp 02-27-2012 01:41 PM

Tires are Falken Ziex 512's.

These came on the car when I bought it. I have receipts, they were purchased in 2009.

Lone Star Bavarian (indie BMW shop in DFW) did a pre-purchase inspection on the car for me before I bought it and said everything looked excellent except tires were worn & would need to be replaced. That was 10k miles ago & I'm still using them. They're still not down to the wear bars so I haven't replaced them but they're not the greatest tires (lots of road noise, not much traction, etc.) I'm not in a position to buy a lot of parts but tires / brakes / anything safety related I will spring for provided it's a necessity. I'm in the midst of starting a business so I don't have immense amounts of cash right now - hence my desire to diagnose the issue as far as possible before spending any money on a fix. Tires that are on it do not feel unsafe just not enjoyable to drive.

The spare I swapped for was a Goodyear RS-A. When I swapped the suspected tire the vibration continued (which is why I was thinking wheel bearings / suspension / caliper issues.) I wish I had a full set of 17's I could swap out and test.

One of the tires had a nail in it causing it to leak air over 3-4 day period. Got it repaired and at that time I got a balance + rotation. It's quite possible the balance was not done right / machine was uncalibrated, but if caused by an improper balance wouldn't the vibration follow the wheel (i.e. when I swapped laterally wouldn't the other side vibrate, and when I took off that wheel and put on the spare wouldn't the vibration stop?)

Mango 02-27-2012 02:46 PM

You would be right if only one tire was causing the vibrations. What if both rear tires are causing it or all four? Maybe we should have a look at your tires. Post a pic of the wear pattern maybe? It is true as someone mentioned bushings etc as being important maintenance items, however they will not cause vibrations no matter how worn they are. In fact, worn bushings would only quell vibrations.

you could also swap a front wheel to the back see if that changes it and put the spare on the drivers rear side.

How bout when you lift the rear end and spin the right rear tire. any abnormal noises or wobbles?

lcoleman 02-27-2012 03:23 PM

Swapping wheels front->back is a good suggestion, but I'm guessing it won't help if swapping left->right didn't. I suspect this problem will continue to get worse until you replace the wheel bearing.

lukevp 02-27-2012 04:16 PM

Thanks guys, I'll do all these checks this weekend when I have my tools back. I'll upload as many pictures as you can handle :P

Mongo: good point about multiple tires causing it. I'll do some rotating around and see what happens. The wheels have been curb checked a lot (they have major rash - they had this when I bought the car) so it's possible they are bent. I don't remember the vibration being bad when I bought the car, but I could've hit a bad pothole or two.

By the way, I'm in San Marcos, TX, if any fanatics in the Austin / San Antonio area want to look at it, I'd appreciate the help and throw in a lunch or something :)

Doza88 03-01-2012 10:50 AM

I have the exact same vibration/humming noise coming from my rear. I have a 2004 330CI with 109,000KM.

two weeks ago i had a leak coming from the rear differential. turns out i had a bad seal which caused the leak. I took it in and fixed for about $300. i didn't drive alot so didn't notice the vibration noise at first. i returned from a 5day vacation and noticed the vibration/humming which increases in pitch as I accelerate. took it in this morning to get it checked out. body shop says its the rear bearings. sounds like a pain in the butt to fix. they said the leak 2 weeks ago could have caused the bearings to wear down. they've flushed and topped up the fluid levels in the rear differential. they said if the noise does not subside, i'll have to replace the bearings. they said total cost of parts and labour should come to $1100. Does that sound reasonable or am i getting hosed? keep in mind i'm in Canada.

lukevp, you may be experiencing the same issues i'm dealing with....

lukevp 03-05-2012 10:37 PM

well I didn't have time to lift up the car or anything but I did have my girlfriend drive it at 40-60mph while I drove next to the car. All the wheels looked perfect, no wobble visible (reminded me how good looking our cars are) BUT there was a really loud (i.e. I could hear it from the next lane with 60mph winds rushing in the window) scraping sound coming from the right rear wheel (where I identified the vibration was coming from). I moved forward and backward next to the car and it was definitely coming from that wheel. Went around to the other side and no noise.

It sounds very similar to bearings going out on a PC fan. kind of a rattly scraping tick tick kind of sound. Sounds like bearings to me unless you guys think something else could be causing that sound (I don't think sticking caliper as it does not heat up the wheel or appear to be sticking). Also I drove in a parking garage to see if I could hear the sound and I can hear it at various speeds, reflecting off the wall back into the cabin, when my windows are down. Definitely coming from right rear.

If y'all agree or have a smoking gun test I can do to make 100% sure it's the bearing, I'll go ahead and order the parts, going to have next week off so I'll do the replacement then.

@Doza88, I will check my differential, it's a touch dirty so I may have a slight leak but I haven't cleaned it to see if more gear oil builds up on it yet. I'll clean it when I'm under it next. As for cost, I don't know if that's reasonable or not as far as mechanics go, but that's why I long ago started doing my own maintenance. The cost of the rear bearings on a 325ci (my car) is $39 a side, and for yours is $50 a side from pelican parts. I'm not sure what you do for a living but if you enjoy working on cars / having tools, I'd say take 75% of what you'd pay someone else to do it, save yourself 25%, spend the rest on the tools you need for the job and any other tools for other jobs you may want to do. I do something similar and have saved a whole lot of money. I did my ICV / throttle body in about an hour today, and tomorrow I'm going to repair my DISA, next week, hopefully, I'm going to do my bearings and maybe thermostat too. Most tasks on our cars are not very difficult, and are very expertly documented online.

dmax 03-06-2012 05:27 AM

Probably not been mentioned yet...I doubt I did...but check your air pressure...really.

After having been to a few meets now, I have to say that one thing seems to account for a lot of issues.

I met a guy who described his problem to me just like yours...I said wheel bearings based on his description. When we went to the car to look at it, one other guy notices how low the tire on the side is...sure enough, it was at 16 psi when it should have been 34.

Work up from the basics before buying parts.

lukevp 03-06-2012 02:09 PM

dmax, i had an air loss problem with one of my wheels so I got in the habit of checking my air pressure every few weeks so I don't think it's that. I'll do a check and go for another cruise just to make sure though! I just do 35psi all around. I checked it all around before doing the wheel swap a few weeks ago and aired up the low ones.

dmax 03-06-2012 05:24 PM

35 all around is a little high in front...doublecheck your door jamb pressure...I think you probably want to drop it a little, though it does vary based on tire/wheel size...but almost always, the rears call for more than the front. The way you have it, you probably have a bit of oversteer...not horrible, but I think you'd notice some 'lightness' up front. You might like that. I prefer keeping the steering neutral, and using the throttle to push the car around in turns. Try it...I think you'll enjoy the stability and the ability to steer more with the gas.

Stinger9 03-06-2012 05:34 PM


Originally Posted by E46Mango (Post 14126282)
I vote tires or wheel bearings.


I'm honing in on the wheel bearings. Have you tried the cornering test. Try a sweeping left hand turn to see if the noise gets more intense.

No such thing as warped rotors. Read the white papers at:
http://www.stoptech.com/technical-su...l-white-papers to completely understand brakes.

gymrat1965 03-06-2012 08:43 PM

I recently purchased a 2004 330CI with steptronic transmission and have a similar noise problem. Sounds like a woob woob noise from the rear of the car. I have the 17" M68 staggered wheels with summer ultra performance Dunlop Direzza DZ101 tires. I can see some minor feathering on the tire edges. I hear the noise above 20 mph with the speed of the oscillating woob woob increasing as speed increases. Above 70+ mph the noise either goes away or is not discernible over road noise. The local BMW dealer did a post prepurchase inspection. I mentioned the noise and after the inspection they told me it was tire noise, not a wheel bearing. They did say the alignment is likely off a bit but suggested not aligning it until I replace the tires. Any insight would be appreciated.

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