Help Diagnosing Steering Wheel vibration
 

I have a pretty significant steering wheel shutter/shake when I am braking within the range of 100km/h-85km/h- but ONLY within this range, haven't been able to replicate it otherwise.

I had the rotors replaced 20,000km ago but had the brake install re-examine the job and even warranty replace the rotors but the shake still exists.

What could be causing this?

FCABS? If so, is a press absolute required to replace them or can it be done by hand with enough force ?

Could be FCABS according to many. Rotors were my first guess but you replaced those already.

Easy enough to see, you can see those from the wheel well if you turn the wheels outward.

I cant imagine doing a FCAB job without having the bushings pressed.

You might have what I have and that's a caliper sticking.

I also have a steering wheel "shudder" when the brakes are applied. I wasn't sure what it was. I did notice that as I applied constant even pressure, the shuddering would finally stop.

Recently, I went in and changed all my brake pads. I wasn't ready to challenge the shuddering yet because I simply wasn't sure where to start looking for the issue so I procrastinated on that for a little while but here is what I found changing the pads. Pushing the right front and both rear caliper pistons back into their bores was pretty effortless. The driver side front caliper? Not so much.

I actually had to use a c-clamp to force that piston back in while the others I used a light weight ratcheting hand clamp.

My prognosis is that the caliper needs replacing. The force it took to push that one piston back was easily two times or more greater than the other three. Can't say for certain but I am pretty confident that is my problem.

Maybe it could be the same with yours?

BTW - I wouldn't suggest anyone just replace rotors due to vibrations. Rotors are expensive and they can be easily checked for wear and runout. Make sure that has all been checked first before replacing rotors.

Cheers
Bernie

Have someone that knows front ends check the thrust arms...the bushing go bad and the front end shakes on breaking.

could b tires

Tension struts. Just order the complete arms with the bushings already pressed in. Be prepared to figure out how you are going to remove the ball joints if you don't have a ball joint removal tool (pickle fork will just tear the ball joints) though (put nut back on, hold arm in vise, hammer time).

If you get the powerflex poly bushings, I had a devil of a time pressing those in. Bimmerworld does it for $10 when you buy the complete arm from them. Would have been money well spent (but I had a spare set of tension strut arms so I used those).

Only way you are doing this by hand w/o a press is if your name is Clark Kent and your alter ego likes to wear blue spandex and a cape.

I did the 20 piece FCP Groton suspension replacement (yes, I torqued everything w/ the weight on wheels) while doing my BC Racing coilvers, then had my wheels checked at a shop (3 had slight bends)...but even after all that, I've still got this 50-70mph wobble in the steering wheel. It has cross drilled rotors on it (there when I bought it, no clue of the rotor or pad brand), but they definately don't wobble under breaking. I've also got this odd shudder when I go WOT. At this point I'm wondering if I've got out of balance CV joints :-/

Nevertheless, I still drove from Seattle to Hollywood to Seattle for Bimmerfest, recently did a weekend trip from Seattle to Eastern WA and back, but I'd really like to get this figured out.

^wouldnt wheel bends cause wobbling at speed?

Yes, but I said had not has, in that I got them fixed.

Start by getting wheels/tires road force balanced, makes a HUGE difference.

If balljoints/arms are in good shape, replacing assemblies is a waste of money. Go Powerflex and do this......

I installed those same Powerflex bushings 3 years ago, I've had my suspension checked by 3 different shops and they each said all components are tight, and I had all 4 wheels roadforce ballanced. But I too have a wobble/vibration between 60-70mph, I've just learned to live with it, seems to be the nature of the beast...lol! It's funny how there are 3 threads going about this subject...lol!

Did you road force balance?

Yes I did, I'm thinking it may be brake related, as in a sticking caliper.

I had mine road forced a year ago and although 90% good, still a slight shake on the highway. I painted my calipers a couple weeks ago and there is a TON of rust on the pistons. I am going to get 4 new calipers and SS lines next year preventativley, even if it is not fully stuck, I think I could have a slightly hung up caliper.

I too have this problem when braking at high speed around from around 75. No wobble though below 60.
My SA suggested using checking rotor temp with IR probe, says temperature deviation left vs right may indicate caliper sticking problem.
I have not done checking as our instrument at work is missing and don't know yet where i could rent one. I am convinced i may have sticky caliper as thrust arm bushings and bj as well as right cv joint have been replaced and no other front suspension parts are suspected.

Ah, gotcha.

Maybe a temporary wheel swap with a known good set if you have access to them?

[QUOTE=switchman;998744].....My SA suggested using checking rotor temp with IR probe, says temperature deviation left vs right may indicate caliper sticking problem.......[QUOTE]

I've posted that a few times on other "sticking caliper/warped rotor" suspect threads.

Hwy drive for over 10 mins, COAST off exit to safe area (NO brakes), set parking brake and IR pyrometer rotor surfaces.

This is part of my spring/fall clean procedure, verify brakes are not dragging. Just did it Mon.

Unfortunately I don't have a set of the stock wheels, but I'm going to look into that. In the meantime, I'm going to throw the truck on jackstands again, put it into gear and look at the drivelines and CV joints spinning to see if they wobble at all. I'm also going to look into hanging calipers since I occasionally have a squeeling from the brakes when I back out of my garage, similar to what happens after washing the wheels when the rotors have that fine layer of rust on them.

I've posted that a few times on other "sticking caliper/warped rotor" suspect threads.

Hwy drive for over 10 mins, COAST off exit to safe area (NO brakes), set parking brake and IR pyrometer rotor surfaces.

This is part of my spring/fall clean procedure, verify brakes are not dragging. Just did it Mon.[/QUOTE]

Thanks, TiAgX5. I'm 90% positive sticky caliper is my problem even without the thermal check. I might just replace both L&R front caliper if i find repaired units. The few times i looked on web, only left caliper is available with Dugeon brand, oem is way too much $$$.

Anyone got any feedback about Dugeon calipers ?