UUC BBK - Uneven Pad Wear

[markseven]

Approximately three months ago I installed UUC's E30 BBK. With this kit I am running:

• Hawk DTC 30 pads at the front
• Stock rear calipers
• Hawk HP+ pads at the rear
• SS lines
• Summit Racing bias valve set the 60% front (the maximum setting, had this prior to the BBK install)

I was doing some routine work on the car and found that the passenger-side pads have 40-50% more wear than the driver-side. I didn't have uneven wear prior to the BBK install.

The strange thing is that the car does not pull to the passenger side under light, medium or hard braking. However, when I was bedding the pads after the BBK install, the front right locked up (a few months before the BBK install the light on the dash came on. I disabled the ABS).

Your thoughts / insight / advice is appreciated.

[Bearmw]

Calipers upside down?

[markseven]

Calipers upside down?

That is an excellent question, however, they are not.

[BigD]

I'd guess the bias valve is hooked up wrong, and you're biasing the front circuit instead of only front to back.

[2002maniac]

I noticed that I would lock the right front first on my old track car. After I deleted the ABS unit I had even pressure to the fronts.

[markseven]

I'd guess the bias valve is hooked up wrong, and you're biasing the front circuit instead of only front to back.

A definite possibility... I will check it out :up:

I noticed that I would lock the right front first on my old track car. After I deleted the ABS unit I had even pressure to the fronts.

Interesting. You removed the unit completely? At the moment mine's disabled but flowing fluid...

[Brandon12V]

grab an extra guy and bleed both front brakes in separate jars. see if both are getting the same amount of fluid by the same number of pedal pumps. i would attempt this three separate times and see if the average amount is consistent, and even, between the two. just a thought. it would at least rule out the amount of fluid being bias between the two fronts.

[markseven]

grab an extra guy and bleed both front brakes in separate jars. see if both are getting the same amount of fluid by the same number of pedal pumps. i would attempt this three separate times and see if the average amount is consistent, and even, between the two. just a thought. it would at least rule out the amount of fluid being bias between the two fronts.

Worth a shot. What to do if the pass side is flowing more fluid that the driver side?

I thought this was would have little impact on the issue at hand, but in the interest of full disclosure: The passenger side front wheel bearing was bad - I had it replaced a few days ago. Could a bad wheel bearing affect pad wear? could the increased friction necessitate a "harder working" caliper?

[Brandon12V]

If the pass side is flowing more, then you may have a restriction on your driver's side line somewhere..... That, or maybe the restriction is somewhere on the passenger side and a venturi effect is being created. I'm not sure if that's even possible, but I would contact UUC if the devil is in the fluid. I cannot comment on your other question as I do not know.

[markseven]

Thanks for the advice, guys.

Why isn't the car pulling to the passenger side????

[Wh33lhop]

Worth a shot. What to do if the pass side is flowing more fluid that the driver side?

I thought this was would have little impact on the issue at hand, but in the interest of full disclosure: The passenger side front wheel bearing was bad - I had it replaced a few days ago. Could a bad wheel bearing affect pad wear? could the increased friction necessitate a "harder working" caliper?

If the bearing was bad enough that you had significant runout, then yes--the brake could be dragging yet operating normally otherwise, explaining the lack of a pull to one side under normal braking. However this would likely be reflected by a nonuniform wear pattern on the pads in question.

[Fidhle007]

My guess is your ABS pump isn't letting your pads return fully on the passenger side. I had the same thing but on both of the fronts and it was resolved by deleting the pump entirely. I think the pump can freak out when it's still flowing fluid but not plugged in. This would explain the breaks not pulling under load but would explain the uneven wear as the pads are most likely dragging on that side. Drive gently for a few miles with minimal braking and feel your wheels, if the side with more wear feels warmer then the other side you've found your issue.

[markseven]

By "runout" do you mean lateral movement? If so, then yes, there was enough walk to allow a clip-on wheel weight to tap the strut on full-lock turns.

[markseven]

My guess is your ABS pump isn't letting your pads return fully on the passenger side. I had the same thing but on both of the fronts and it was resolved by deleting the pump entirely. I think the pump can freak out when it's still flowing fluid but not plugged in. This would explain the breaks not pulling under load but would explain the uneven wear as the pads are most likely dragging on that side. Drive gently for a few miles with minimal braking and feel your wheels, if the side with more wear feels warmer then the other side you've found your issue.

Cool, will do.

[markseven]

So I am thinking the wheel bearing is/was the culprit... I will report back in a few weeks with confirmation.