Intermittent vibration

[gjm 3193]

Actually, very, very intermittent.

A few weeks ago we were driving (quite gently) when the steering began to vibrate quite badly. It was a sudden onset - no deterioration or similar. Just a sudden significant vibration, bad enough that it felt almost like th front of the car was shaking.

Slowing to around 50km/h meant the vibration appeared to go away. Above that it came on, and while the severity doesn't vary significantly with speed, it is bad enough that I wouldn't try to 'drive through it'.

We stopped, I got out and checked wheel nuts (a similar previous experience, years ago, could be traced to a loose wheel) lifted and spun tyres, shook the wheels... No obvious issue.

Back on the road, problem persisted and then... It was gone. Completely. Back to normal smooth as silk driving.

I assumed I'd picked up a stone or something and while I did think about it, didn't worry unduly.

...

Several thousand kms later...

...

Yesterday, it happened again. It is quite a violent vibration. The steering wheel visibly moves, and you can feel it through the seats. Reduce speed, drive gently... And it was gone a few minutes later. OK - note to self: this needs more investigation. Write off next weekend.

But this morning it happened again. (So the investigation is more urgent!) However, it has been impossible, so far, to replicate the issue. It 'just happens', then 'just stops'. If it happens again, we're going to try the IT 'reboot it' solution - stop, switch off car, remove key from ignition, restart car - just to check that doesn't resolve the problem.

Thoughts so far: a misshapen tyre (although I'd expect a much more persistent issue if that was the case), CBA bushings (again, I wouldn't expect the vibration to seemingly turn on and off, and these were done a couple of years ago), or sticking brake caliper (most reasonable and likely-seeming candidate at the moment).

Any thoughts? Recommendations for somewhere that will do caliper refurb?

[elmarco 56]

Tyre bulge or delamination? Guess those would be more consistent. No heavy lumps of mud stuck inside the wheel? Had that before after some off road action.

[gjm 3193]

Tyre bulge or delamination? Guess those would be more consistent. No heavy lumps of mud stuck inside the wheel? Had that before after some off road action.

I'll recheck the tyres, but I agree - I'd expect something more consistent if that was the issue.

[Ahmedsinc 414]

Have had an old Escort suffer from tyre bulge, and I can assure you the vibration is speed sensitive and constant. Id've thought a sticking caliper would also cause the car to pull in the same direction as the dodgy brake?

Steering box failing?

Strut mount bearings failing?

Loose adjuster on tie rod? (Lock nut loosening and retightening of its own accord, producing intermittent symptoms?)

Redid CAB on my car a couple years back, felt more like a combination of warped rotors and unbalanced wheels. Again, symptoms were speed sensitive and always present.

Sounds like a proper head scratcher man!!

Edited September 1, 2014 by Ahmedsinc

[gjm 3193]

No pulling that I recall, just the steering wheel juddering: juddering probably describes the feeling better than vibrating.

It does it above about 70km/h, does it for a few minutes, then stops. All fine before and after.

Disconcerting. And very puzzling. And I want to fix it!

[sonic_attack 89]

I'd be lifting the front, grabbing the wheels and checking where the play is coming from, by the sound of those symptoms the problem should almost leap out and be fairly obvious having a good look while rocking a wheel.

[gjm 3193]

I'd be lifting the front, grabbing the wheels and checking where the play is coming from, by the sound of those symptoms the problem should almost leap out and be fairly obvious having a good look while rocking a wheel.

Tried that, although I have so far only lifted one side at a time. Time to get the whole front in the air.

[sonic_attack 89]

If it's that bad something will jump out and be clear. tierod/balljoint. Grab the strut and give it a good shake too top and bottom.

[gjm 3193]

This just gets stranger.

I've had the car in the air. Nothing seems loose or worn.

And the problem is still very intermittent. There's no pattern to when or where it occurs. Rough roads, gravel, highway...

It happened again this morning. First time in about 3 weeks.

However...

I obviously stopped and was lucky enough to get on to a reasonably smooth, straight and traffic-free piece of road. Usual quick check revealed nothing (engine left running) so I got back in and very, very gently eased away. It was immediately evident that something is wrong - it felt like a badly warped brake disc, but not necessarily with the regularity I would expect from a warp - it seemed there was more than one rotation between the rubbing sensation. There was a definite resistance to moving, and it was easy to feel a regular 'grab'. Not enough to stop the car, but sufficient to notice it.

So... A brake-related problem, perhaps. The brakes work well, and all discs and pads were replaced not very long ago with good (but not genuine BMW) parts sourced from a very nice and reputable, well-known to the BMW community, supplier.

I stopped again, checked the discs - no evidence of a high spot, but this was at the roadside and as such not a thorough inspection.

A few minutes later and there's no issue of any sort, again.

I've not come across this before, but could something duff in the ABS cause this?

[jeffbebe 1559]

Are you sure it's coming from the wheels/suspension? When my car was running on 9 cylinders it would shake under load like worn thrust arms. I guess if you've only got 4 cylinders to start with it would be pretty obvious if you lost one though!

[gjm 3193]

Feeling the vibration is definitely road speed related; I don't think engine speed plays a part.

When the problem is occurring, there's very little noticeable vibration below 50-60km/h. Above that it becomes quite pronounced. (I've underlined 'vibration' to acknowledge something is happening at lower speeds.)

It's only by being critical that there is any obvious issue at very slow speed. It's definitely there, but manifests as a repeated 'rub' rather than any sort of vibration. It's almost as though the caliper is being repeatedly activated and momentarily pressing on the disc, over and over again. Not to actually brake and stop the car, just to control speed.

Hmm... Cruise control? Don't think so - it happens without cruise control being activated. Mrs M doesn't use (know how to use?) the cruise control, and she has experienced the problem too.

Bear in mind that this rubbing sensation is far from normal. Ordinarily - 99%+ of the time - there is absolutely no issue of any sort: no vibration at any speed, no slow speed rubbing sensation. It is only after the higher speed vibration has manifested that the slow speed issue can be detected.

Using the brakes may, or may not, help alleviate the issue.

It's quite difficult to describe. One of those "if you were there you'd know what I mean" things!

I think a code read is in order. It's easier and faster than trying to take things apart in the hope of finding what is going on.

[Allanw 1051]

Could it be this???

[westy 614]

How do the wheel bearings sound? Any rumbling? Movement? Use a piece of wood or similar in the wheel to get leverage.

[gjm 3193]

How do the wheel bearings sound? Any rumbling? Movement? Use a piece of wood or similar in the wheel to get leverage.

I've replaced wheel bearings before. This doesn't come anywhere close to that experience.

There's no problem. Then there is. Then there isn't. There's no middle ground, no gradual worsening or reduction in severity. It does or it doesn't. My experience with bearings is that they rumble and the effect is noticeable pretty much all the time.

F'rinstance, I had the issue this morning - left home and all was fine, slowed coming off the two-lane piece of SH1 on the way south into Huntly and suddenly there was the vibration. Completely cleared a few minutes later (during my investigation) and I've since driven from Huntly to Hamilton, Hamilton to Manukau, and back to Te Kauwhata with no hint of any problem.

I'm hoping something comes up on a code read.

[gjm 3193]

This looks likely to be due to a binding left front brake. Beyond that, not sure at present...

Anyone have any experience of rebuilding E46 calipers? May as well make a go of doing at least both fronts, and maybe all of them.

[jeffbebe 1559]

Google has... http://www.bmwforums.info/guides-how-tos/4394-guide-to-rebuilding-calipers.html

EDIT: If it's the brakes, have you checked that you haven't just lost one of the silver anti-rattle clips? If the pad's wobbling about it might be causing the issue you've got.

Edited October 3, 2014 by jeffbebe

[gjm 3193]

Google has... http://www.bmwforums.info/guides-how-tos/4394-guide-to-rebuilding-calipers.html

EDIT: If it's the brakes, have you checked that you haven't just lost one of the silver anti-rattle clips? If the pad's wobbling about it might be causing the issue you've got.

Ta. I wasn't being lazy, really... I just had a few minutes between getting home and going back out again and being at a loose end, though I'd post a quick update.

I'll check for the clips.

[gjm 3193]

Read the piece on bmwforums, checked my stack of service history, and spoken to Fabian at BMW in Hamilton. I'll have some rebuild stuff tomorrow.

The rebuild may not be absolutely essential, but it seems a sensible servicing thing to do regardless, and could easily fix the problem.

[KwS 2376]

Did you note when stopping during the vibration if one of the wheels was significantly hotter to touch than the others? Thats usually a pretty good indicator if a caliper is sticking as itll created friction, and heat.

Missing caliper clip is very unlikely to cause an issue like this, just a horrendous rattling noise over bumps.

[gjm 3193]

Hadn't noticed any temperature differences, but hadn't checked. I should have.

Got the wheel off to sort the caliper seals. Disc and hub spins freely. No binding whatsoever. Today...

Sticking piston.

Incidentally, BMW don't sell many caliper rebuild kits, and the kits they do sell don't include a piston. Wish me luck.

[yng_750 247]

Lots of pistons are stainless which wont need doing. Its the chrome ones that get pitting and rust

[gjm 3193]

So today, having taken a day off work, I removed the caliper form the hub. This was, in fairness, a bit of 'half a job' - I've not (yet) disconnected the brake hose from the caliper, nor have I removed the piston.

The sliders that the pads run on were dry, and it seemed possible the pads had been sticking. The pins were also not lubricated, so I rectified both problems. Lots of cleaning, lots of brake dust. Reassemble. Test.

Unfortunately I was easily able to provoke the vibration behaviour, and this time checked Kelvin's suggestion. Yes - the nearside front rim was significantly warmer than the offside. Back in the drive, lift the front nearside, and the wheel was hard to turn - the brakes were binding. Leave it a few minutes and all seemed well again.

It could be that the piston is sticking - the inside of the piston, the bit I could see, is quite rusty so possibly not stainless. (Thanks for the suggestion Jason - I had hopes!) But it could also be a fluid return issue (although I think this is unlikely, having flushed the fluid a few months ago).

The piston is favourite culprit at present. The problem is... What do I do if I remove the piston and find it is duff? BMW don't sell them. I can clean and replace it as a temporary measure, I guess, and search for a new piston. Or carefully measure it and get two made in stainless (one for the offside, too).

I'll do some RealOEM stuff later and see if the calipers are common across several vehicles. I suspect they are.

I've not used my seal kits, yet, and the seals I could see seemed fine. No sign of any leaks of any sort. I suspect I'll be using them sooner rather than later, though..

[yng_750 247]

You can clean it up with a wire brush. Then abit of brake fluid and a scouring pad to polish any crap off the surface.

Any pitting can re rust but fresh fluid wont let that happen.

Also bad pitting can slowly cause seal leaks from being abrasive But again not quickly.

In my experiance most sticking is from the pad sliders. So if it looks too hard you could try just lubing the sliders in the mean time.

Stuck piston will cause excess wear. Sticking sliders often cause uneven wear. As one side sticks more than the other.

[Allanw 1051]

I got stainless steel pistons for my E23 Calipers (that are going on my VW van ) from www.biggred.co.uk - I thnk they were about NZ$300 all up... but there is 8 of them!, though I didn't see you car listed....

www.rexbo.eu - 2x front caliper piston = 101 euros, shipped ( about NZ$165).

Pair of front calipers = NZ$390 for TRW's, but they have cheaper ones - NZ$330ish for ERA Benelux.

If you send your old ones back, you get the core charge back... but the shipping will probably be more than the core. I dunno how that compares, as I didn't look anywhere else (That's your job !)

I've not had any issue with anything from them and have used them a fair bit:

- Mate from work wanted 4 shocks for his poked old mid 90's Pajero, lowest quote locally that HE got was NZ$900. Set of 4, shipped from REXBO in Germany was just over $300 NZ (cheap brands - Metzger and Japanparts - his truck is an old peice of crap (Pajero) and he just wanted something better than the knackered ones)).

- My old Suzuki Wagon R Turbo (I had a few years back) needed shocks and a clutch, CV joint, tie rod ends and brake pads. Locally, just the shocks and clutch were NZ$900. Complete tie rods (not just ends) and everything else, plus a few little extra bits, from REXBO (and not the cheap/nasty no-name brands - I went with stuff I knew like Exedy, TRW, etc) was NZ$700 shipped by German Post, and no GST on import for some reason!

Hope somthing in there helps.

[gjm 3193]

Thanks Jason.

Pads were new a few months ago and wear appears even. Nothing obviously wrong there.

The sliders may have been sticking. May still be, of course - they were dry, but I've cleaned and lubed them. The pins were a little more tricky as I was unable to find either silicone grease of red brake grease anywhere... I smeared the teensiest bit of Moly slip on them. The bracket seemed to slide freely in and out, but I'll keep looking for the correct grease.

So, it's into the deep end, so to speak. If the piston has seen better days, I'll polish it up and put it back.

I now have a litre of Elf Dot4 fluid. May as well make use of it.