Some vibration at highway speeds

[burrito]

I just had the wheels balanced and rotated. But it didn't do anything to fix the minor vibration I am feeling at highway speeds. The car has 102,000 mi on it now... could it be the CABs need replacing? I don't know what else could be causing the vibration. Thanks.

[Ion Donut]

A "sticking" caliper piston, one that doesn't retract completely and causes one of your pads to lightly drag on the rotor, can cause a slight vibration at highway speeds - it did it to me. But I would most definitely check out your CAB's

[danewilson77]

+1....CAB's are a common problem at the higher mileages..

Don't pay to have it done. DIY=WIN....very easy diy

[burrito]

Originally Posted by Ion Donut

A "sticking" caliper piston, one that doesn't retract completely and causes one of your pads to lightly drag on the rotor, can cause a slight vibration at highway speeds - it did it to me. But I would most definitely check out your CAB's

Would that also cause the steering wheel to vibrate back & forth when braking? I just chalked that up to uneven brake pad wear.

[danewilson77]

Yeah, that could be part of it....but you could also have warped rotors (sounds like that may be your issue).

What kind of rims do you have?

If you have aftermarket rims (stock ones too though), they should be torqued evenly, otherwise, as you break, your rotors will warm up at different rates (due to compressive stress), and you can actually warp your rotors.

When are you due to do your brakes? Recommend new rotors or a full diy brake kit from ECSTuning.

Don't pay anyone to do this stuff and diy....many helpful posts out there for all of this.

You can also buy rebuild kits for your caliper pistons, if you think it may be one of those as Ion Donut mentioned above.

[Sean S]

Originally Posted by burrito

Would that also cause the steering wheel to vibrate back & forth when braking? I just chalked that up to uneven brake pad wear.

From my experience (non-BMW until now btw), steering wheel shake under braking is usually because of worn out CAB's.

[danewilson77]

Copy.....+1

[burrito]

Brakes pads were last done about a yr and half ago. I had an indy shop do the brakes last time but will attempt diy next. I got the feeling they weren't used to working on BMWs.

Thanks for the advice... I'll check into the caliper pistons and CABs, sounds like these are doable diy as well.

[danewilson77]

Yup...good luck bro

[MrButch]

what is CAB short for


my car has 105k and vibrates on the highway at speeds of 50 to 65 and goes away until i hit 121 then comes back

[Ion Donut]

Originally Posted by MrButch

what is CAB short for

my car has 105k and vibrates on the highway at speeds of 50 to 65 and goes away until i hit 121 then comes back

CAB = Control Arm Bushings

Man, you got a death wish going for you at 121mph plus a wheel vibration!!!

[drichct]

I had exactly this situation and it was control arm bushings. If it is the brake rotors, you would also feel it in the brake pedal.

The stock bushings lasted about 80k. The stock bushings are oil filled, one was dry. I put in solid rubber CABs, not Powerflex. (along with control arms and ball joints) It's a bit harsher, but handles superbly.

While I was at it, I put in Powerflex RTABS - a very easy job.

[Grim Reaper]

Top to bottom of most likely the problem area:

CABs
CArms
Tie Rods
Wheel bearings
Steering coupler and upper steering u-joint

That's my best guess based on your mileage and not knowing the maintenance history... DIY and a couple hours later all will be good.