2005 Acura TL Automatic with 32k. Dealer replaced REAR pads and rotors due to calipers that were binding and ate the rotors. Calipers were saved after cleaning and greasing slider pins.

There had been a shimmy in the steering wheel and pedal when stopping from high speeds. After the rear brakes were serviced, this condition didn't go away.

Front rotors had been turned once already. So, I ordered Rotora OEM replacement rotors and pads. Installed them today without any issues. The shimmy in the steering wheel is gone when stopping from high speeds, but the brake pedal still has a shimmy when stopping from high speeds!

Also, I noticed that on the right front side, the rotor has a surface that is very shiney -- it's a ring that goes around the rotor where it appears one portion of the pad hit it more than the rest. It's not groved, ruff, etc. It's just really shiney. I'm not sure if that's an issue, or it it's just the spot where the new pad is hitting the most -- i.e. a "high" spot on the pad?

Anyway -- I'm stumped as to what could be causing a continued shimmy in the brake pedal when stopping from high speeds? All pads and rotors now have less than 200 miles on them!!

Thoughts?

Thanks!

 

Wow! 45+ views and not one response? Yikes...

 

You still have a disc thickness variation (DTV) issue, which is what causes a pedal pulsation. Excessive runout eventually causes DTV.

The correct way to diagnose this problem is to measure the lateral run-out of the rotor. If it's more than 0.003", then I would make sure hub flange is sparkling clean. If that doesn't resolve it, you'll need to use runout correction shims or have the rotors resurfaced using an on-the-vehicle lathe.

 

Did you clean and grease the slider plates where the pad end tabs have to move when the brakes are applied?
and the pad backs-lightly greased with caliper grease?
And flushed the brake fluid?- that needs to be done every year and greatly effects pedal feel

the shiny rotor part is where the pad isnt touching at the rotor yet
Think of the pads and rotors as each having little hills and valleys, all
those have to match into each other with brake use, then there is full pad contact
and good braking
There may be shimmy issue while this happens- go use the brakes more!
500 miles street driving is not unusual for new brakes to get seated

If they were performance pads-rotors you would have to do a special bedding method/ drive to put some serious use on the parts and get them working right away.

 

Pads and rotors that aren't broken will not shimmy. They may not stop as well, but they will NOT shimmy.

If your peaks and valleys are that big, then there is something wrong with your rotor finish. This should not be an issue with new rotors.

 

Excellent post

Although, I would have allowed .005 tolerance on the runout.

On-the-car lathes are the best way to resurface a rotor. But if you are experiencing pulsation in the brake pedal or shimmy when you apply the brake, I suggest you contact Rotora and see if they will be willing to swap these out with another set before resurfacing them.

 

Can someone define shimmy for me? I think I may have the same problem. When I press the brake pedal, I kinda feel like a slight vibration or resistance when pushing on the brake pedal, and its only in the beginning when pushing the pedal. I seem to notice it more if i just tap on the brake. Dont know how else to explain it...do i have the same issue?

 

I cleaned and greased the slider pins -- all four of them on the front. I also greased the tabs where the pads sit so they slide in that mount easier. I also applied disk brake quiet to the covers that go over the pad where the piston presses against. I can't tell you if the dealer did it to the rear, though. I'd like to think they did since they told me the reason for the issue back there was seized caliper pins, but who knows.

Yes, the hub was cleaned and there appeared to be no rust build up, really. I don't want to sound like I am challenging anyone, but I do have a hard time believing that new rotors would be warped. I guess it's possible, but I'd be shocked.
Can one tell, for certain, if it's the front versus the rear? I.E., if you feel it in the pedal, it's the rear. If you feel it in the steering wheel, it's the front? I feel it in the pedal and really only after they are warmed up. Cold, I don't feel anything but a smooth stop.

Thanks again to everyone for the suggestions!

 

It's possible that the rotors are fine, but there's runout in the hub assembly itself.

That's why I suggested measuring lateral runout and reporting back to us with the results.

 

UPDATE: This is shocking, but maybe not at the same time. National Tire and Battery (NTB) in Northeast Ohio, replaced the rear pads and rotors for me 3,852 miles ago. I took it in this week and told them what was going on. They looked and realized the rear pads had been inverted! As a result, they "ate" the rotors in the rear that they installed. So, they installed new pads and rotors for free. Condition went away about 70%. Took it back and they showed me that the DTV was out on the Rotora front rotors. Saw it with my own two eyes. I'm upset I didn't pull the rotors back when I installed them (3,852 miles ago) and send them back. Instead, I paid $100 to have them resurfaced. Needless to say, I'll never buy a thing from them again. That condition was there with those rotors from the second I put them on. Again, I should have pulled them and sent them back. Oh well...

Car is smooth as silk now...