Uneven braking causes.

[bherman13]

I'll try to keep it simple. Some of you may recognize this from the last time I asked, but after having thought I figured out the problem, I'm back with more details.


Back-story:
I replaced the front pads and rotors a few months ago. Hawk HPS pads, Napa Premium rotors. New Ate Typ 200 brake fluid bled with a power bleeder. Rear brakes remain stock pads and rotors on mk4 aluminum calipers with mk4 hard/soft line all the way from axle beam to caliper.

Problem:
Since then, the car has pulled to the right very slightly under braking; more severe pulling with harder braking. Right front wheel has excessive brake dust. Also, the right front tire will lock up easier than the left. The tires are all new-ish and are definitely not the problem.

Inspection:
The outside of the right front rotor has very little wear, while the inside of the rotor is worn down pretty far for its age. The inside pad on the right side is also worn down severely while the outside pad has little use. Left front pads/rotor have even, normal wear.

Solution (attempt):
I replaced the right front caliper with a Napa reman'd "semi-loaded" caliper that comes with a new caliper carrier and therefore new slide pins and boots. Re-bled the brakes with the power bleeder.

I have not yet replaced the pads and rotors (again ). I want to make sure the car brakes evenly before putting new wearables on and potentially ruining them as well.

Results:
Test drove the car with new caliper/carrier/pins on current pads/rotor and the same problem still exists. It might just be my imagination, but it feels like it's a little less of a difference than it used to be. By that, I mean that it still brakes harder on the right front, but more evenly than it used to. I could be totally wrong about that, though. The right front wheel will still lock first under hard enough braking.

Using my infrared thermometer gun, the front left rotor gave a reading of 230F, the right front rotor at 300F. Just for S&G, the left rear rotor was at 140F and the right rear rotor was at 130F.


Questions:
Does anybody have any idea what could be causing the uneven braking? Where should I go from here? Any suggestions are appreciated.

 

[pruzink]

Have you done a good brake fluid flush? If you have vagcom, you might want to actuate the anti-lock brakes in order to ensure that there isn't any air trapped in that circuit of the brake hydraulics. I had a 92 Gran Marquis that I had to replace the brake vacuum booster on 3 times. When it would go bad it wouldn't allow the calipers to release completely making them run hot & eventually warp. Once I learned about this being the source of my problem, I found that if I put my foot under the brake pedal & lifted up it would release the calipers as it should have.

 

[hughesjasonk]

sounds like that you have some air trapped in the system some where.

 

[Tdijarhead]

If flushing and bleeding the system doesn't cure your problem you are probably looking at a new master cylinder .

 

[bherman13]

I bled the system with my Motive Power Bleeder. I only bled the fronts since you're supposed to bleed from farthest away from the master to closest, and I did nothing to get any air in the rear lines.

The fluid is pretty fresh because I bled the full system with my power bleeder a few months ago when I originally replaced the pads and rotors.

Also, I don't have ABS on my car, so that's not the problem.

I had been wondering if the fact that the right side inner pad and rotor had been doing all the work, maybe it was "bed in" a lot better than the rest, causing it to brake harder even when the caliper is new and working properly. Driving the car just this morning, the braking seemed a little more even. I'll give it some time and maybe do a full system flush. I was hoping I would be able to get all the problem parts replaced before spending more money on brake fluid.

 

[artie b]

Hey bbherman, jack up the offending wheel, stab the brakes, feel for a good caliper release. If it's a little draggy, crack open the bleeder, and if fluid comes out and caliper releases, you have it narrowed down to hydraulics, if not, mechanical.

 

[bherman13]

Would that be necessary since I have new hardware on the offending wheel? The only things that aren't new are the brake lines, which I just caved and picked up today and plan to swap them out soon.

 

[914fan]

New does not mean good. I have had many a tire develop a blister shortly after purchase, or DVD that doesn't write, or topped off a tank with contaminated fuel, or.... Or.....


Inspect what you expect

 

[bherman13]

Yes, but I'm thinking it's much more likely that the original brake lines may be bad instead of the new brake caliper/carrier/slides.

I'm gonna give it time to see if there's solid evidence that the new caliper has made a change to the uneven pad wear problem.

 

[bherman13]

Update: Installed new brake lines onto both front sides (after new front right caliper/carrier/slides), then new pads with new rotors. Car brakes perfectly straight now.

 

[Abacus]

Thanks for the update!

 

[tripl-e]

Update: Installed new brake lines onto both front sides (after new front right caliper/carrier/slides), then new pads with new rotors. Car brakes perfectly straight now.

Just out of curiosity, do you surmise that what you really had was an under-performing left side brake rather than an over-performing or dragging right side?

 

[burn_your_money]

From what's been shared in the thread I'm thinking the OPs problem was a weak flex hose on the left side that was expanding when the brakes were applied, and as a result was not providing enough clamping force on the left rotor.

His initial problem definitely sounds like a sticky caliper on the right though.