SOLVED......

It was the front wheel bearing. Changed it and no problems after ~2k miles.

Read below for the story. Hope it can help someone else.....

UPDATE: 2/8/2012

Replaced the front left rotor with a brand new one (DBA 4000XS) along with New Project Mu B-Force pads up front.
Tore down the caliper and inspected everything. Changed dust boot seals but not piston seals as the new ones seemed a bit tight.....
Performed a proper bed-in and had an alignment done at Touge Factory.
Problem gone. So it was obviously a warped rotor....

BUT......
This was ~500 miles ago and I can feel the SAME rotor/problem starting to vibrate again when braking above 40mph.

My next move: Full caliper rebuild and new front hub. Then a super bleed w my Motive.

ANY OTHER THOUGHTS OR IDEAS APPRECIATED!!!!






Problem: While breaking, I am getting a horrible "shudder" thru the brake pedal while slowing from ~ 70 down to 40. I can feel that it is coming from the front end. The brake pedal pulses and the steering wheel shakes. This is a Track ed with Brembos.

Recent front end work:

Tein S-Tech Springs (All around)
Tokico Blue shocks (All around)
Hotchkis Sways
New DBA Rotors
New StopTech Pads
New Tires all around

I am at a loss as where to go... Here are my thoughts.

1. Possible sticky calipers? (I have the rebuild kit for the fronts..)
2. Alignment needed due to the 0.5" drop from the Teins?

ANY help/direction with my situation will be greatly appreciated...
It feels like a warped rotor(s), but I only have ~1000 miles on all my new front end work.

 

I have also checked for front wheel bearing/hub play and found none.

 

So, you just did all of that new stuff to your car in one service visit - and you want to blame your calipers? Seems like if the calipers were sticking.. they would stick all the time.

The car otherwise drives fine? just a problem when braking from 70mph down..? turns, bumps, etc.. ok?

What have you checked? lugs on tight? brake pads.. installed.. bed-in? This feels like an alignment issue to me - but just a guess.

Who did the work?

 

Warped disk?

 

Did all the suspension work myself. I'm not a professional mechanic, but by no means an amateur. I have gone over my work and all checks out.

I am def leaning towards an alignment issue as you said....??!!

Arrrghh.... Def frustrating as this is the first real stumper I've had w this car after 7 years and 60K.....

 

Check the new rotors for runout and variations in thickness. You'll need a dial indicator and calipers/micrometer (measuring instruments).

Here are the limits from the '07 service manual section BR:

Maximum uneven thickness (measured at 8 positions) 0.015mm (0.0006 in) or less
Runout limit (with it attached to the vehicle) 0.040 mm (0.0016 in) or less

Since the vibration only happens when you're braking, I'd check the brakes before blaming the alignment.

If the suspension was in good shape with proper alignment before you worked on the car, the things you listed should not have changed the alignment enough to cause a problem.

If the rotors check out OK, I'd reinstall the OEM springs to get rid of the drop.

 

Good advice. THANKS. I have access to a dial indicator to check for runout as well as a caliper.

All this work was done because my front rotors warped and my tires were feathered. What came first IDK.... but produced the same symptom (but much worse) before all the new parts were installed, thus the reason I decided to do the entire front and rear suspension work.


I am going to reinstall the stock front springs and see if that makes any difference.

 

More than likely warped rotors might be your issue.

 

It does feel that way.

What could be responsible for warping new rotors (DBA 4000's) after less than 1000 miles of daily driving?????

 

Variances in rotor thickness or runout. While unlikely, rotors can and have come "bad" straight out of the box.

Check to make sure the mating surface for the rotor is flat. I've seen some hubs with so much rust that the rotor refused to sit flush and caused vibration.

 

been in this situation couple of times.

+1 on thickness variations. Did the vibration start as faint, and then become more harsher and harsher as you put in more mileage? If so, then the rotor surface is bad. I assume you did not bed in the system after installation?

I would suggest to get the rotors re-surfaced and get the pads shimmed.
After that, do a proper bed-in. Careful not to put the foot on the brakes while on full stop after the bed-in process. You will have the same problem if you do.

 

Typically, resurfacing the rotor will work but if they are brand new rotors, you should not have to remove life from them. IF this is the case, contact whomever you purchased the rotors from and inform them of the problem. They may refund/replace. If they choose not to since they are "used" (they reserve that right), then I would try resurfacing and going through a proper bedding procedure.

 

I cleaned up my hubs pretty good so they would sit flat on the new rotors. There was some rust, not bad, but possibly enough to cause these problems.

Yes, vibration was unnoticeable when new and has slowly gotten worse. You assumed right about the bed in. Didn't do it....
THANKS FOR THE INPUT!

Great advice. This may all be caused by improper rotor and pad bedding.... Because it sure feels like a warped rotor. Arghhh. I always have to learn the hard way.....

 

good advise from ASNtech too.

Good luck man!

 

Ah haa.. more information looks like you left a few things out from the original post. Let us know what you find out.

 

One thing I forgot to add....while this is rare, I have seen it once before. A bad wheel bearing that was not making noise (yet) caused a "scraping" sound and vibration upon braking. The noise was the pad being pushed back and forth by the pad and rotor. Regular driving was fine. Let's just say, I struggled to pin-point the problem at first.

 

Thanks. Going to start by getting my front rotors turned and new pads.

Followed by a proper bed in....

Will do.. Thanks.

Interesting. I was thinking of replacing the front hubs also. I really can feel through the pedal that it's my front left rotor.

The literature that came with the DBA 4000 rotors states that "Excessive runout will result in disc thickness variation (DTV) being worn into the rotor in as little as 1000-2000kms." They direct this info towards the need to have a clean, not rusty hub. Mine were minorly rusty and I cleaned them as best I could w a wire wheel and some 3M pads.

"DTV will cause pedal pulsation, steering shudder, and vibration during braking."

These are my EXACT symptoms^^^^^^^

 

bump for UPDATE in first post

 

That was the problem. Bad wheel bearing.

Thanks again all....................

 

Thanks.