I have a difficult problem. My MCS has a TCE Wilwood BB kit. Wheels are 17's with 10mm spacer. Problem is under braking the front vibrates and sends a "shimmy" through to the steering. The intensity of the shake is proportional to the force of the braking. I assumed this was due to a bad rotor since I had bought the brakes second hand. I checked the runout, which was nil.....but I replaced the rotors anyways. Shake is still there. Changed pad compounds per Todd at TCE with no change....had done this before the new rotors.

Sometimes under very hard acceleration, I think I feel a similar shake, though if it's there it's pretty subtle.

I've changed to new tires, multiple balances, rotated wheels, etc. No change....smooth under cruise....shake under brake.

Someone mentioned maybe a front wheel bearing. Any thoughts on this? The service manual says bearings and hubs are integral.....sounds expensive to just replace. Any other ideas?

Thanks

Fabian

 

If it's only under braking then it is NOT bearings you would hear them just rolling along. I would have guessed as you did warped rotors. Is your 10mm spacer hub centric? If it isn't there lies your problem, if you can find the inner diameter which is the stock hub some one here probably knows and the outer diameter which would be the diameter of the spacer you might be lucky enough to find a hubcentric ring ( made mostly for aftermarket wheels) to fit or they can be custom made. I had some exprience with this on a BBK for my old car. Hope this helps good luck.

 

The spacer is hubcentric to the hub and is high quality. Then I have an aluminum centering ring to fit it to the spacer to the wheel.

I would think that if it was a "centering" problem, the vibration would always be present, not only under braking. I had an issue with that before using the aluminum rings....and prior to the BBK.

I suppose it's possible that under the torque loading delivered by braking, the centering is somehow disturbed. I think this may be reaching a bit though

 

This isn't an unheard of situation with a BBK. What you didn't say was how long after installing the used BBK was it that you noticed the vibration? If you installed new pads, was it just after that? I have experience with the TCE Street Sport kit and I know that it is easy to make a mistake while bedding pads and that can induce vibration. I switch between various race compound and street compound pads once or twice a month and I occasionally get vibration when I don't bed-in properly. as easy as it is to cause the problem, proper bedding can also get rid of the problem.
If rotor run-out is good and the bed-in was done right, then some have noticed a vibration with a BBK and worn stock struts. I have never had this particular issue since I abandoned stock struts long ago.

 

What are the suspension mods on the car?

I am one who had this problem a few years back. I know the frustration of it. I also know one or two others that have experienced the same frustration.
My problem, after doing the whole "I blame the rotors" thing, was found to be bad struts. Bad due to the fact that I had been on lowering springs for about 10K miles, which is long enough to destroy the factory struts here in New England.
I believe that another person here on NAM found that it was his bearings.

The BBK seems to highlight any suspension problem that you may have had for a while, where the stock brakes never did.

 

hmmm, interesting..
i have had lowering springs for about 4-5000 miles. other mods are fixed camber plates and slightly larger front sway bar and much larger rear bar.

i realize the factory struts are not the best, but they only have a total of about 33K miles on them.

also seems an odd symptom for struts.

now the question is.....how to diagnose the problem without just changing parts. i'm not a fan of just throwing money at the problem. but if the struts NEED changing than i'm happy to do so.

regarding the bedding problem, i followed Todd's recs on bedding. after putting on the new rotors on, i was using the pads that Todd had recommended (Willwood BP...if i recall correctly) which were bedded using the old rotors. i then re-bedded the new rotors and old pads. vibration was there immediately and has been getting worse with time.

i've had numerous street and race cars with all kinds of monster brakes, including lots of wilwood stuff, and never had this persistent of a problem. frustrating.

fabian

 

I've also found here that the zinc build up on rotors can cause some issue until you really burn through it all. Assuming all other things are good- not crap under the hats, bolts tq'd nicely, centering rings good, hats sat flush, etc. etc. then I'd run some sand paper over the rotors and pads and re bed them way hot. Most experiences I see with customers bedding pads they just don't get them hot. I go around the industrial area here and get them smoking seriously to burn the zinc then let them cool before I park. You're not going to hurt them.

 

Im failry sure your rotors are warped, I had this for my Cherokee and I just had to go out and buy new rotors and I also got some new calipers while I was at it, everythin worked fine after that

 

Sounds like an issue I was just having. Are your calipers far enough from your rotors?