I have this annoying slight pulsation when braking fat 35-40 MPH. If I slam the brake it is less noticable. The pulsation at high speed braking (70-80 MPH) is more noticeable. I did the following:

Driver side:

1. Measure run out and it was .003". resurface the rotor and used the old brake pad ( scuff it with 180 grit san paper to get rid of the glasing). Problem still exist.
2. Changed to new rotor and pad tonight and re-bedding the pad. Problem still exist.
3. One thing that I noticed was that with the wheel off the ground, I could hear the high spot noise between the rotor and the pad. New rotor is only have .002" run out. If I didn't put the wheel (rotor fastened to wheel hub with those 2 retaining screw only), the noise is less noticeable.
4. I checked the wheel bearing by trying to move the tire in and out, I didn't see any play. The tie rod and upper ball joint are tight and the lower ball joint have very very slight movement ( prying the LCA to the knuckle showed a very slight movement).
5. Dealer couldn't even detect this during recent alignment.
6. I put dial indicator on the edge of the hub and it's got at the most .002 run out. I probably get better reading after I clean the surface by light sanding.
7. I checked both caliper pin and they are good (they spring back on their own).

I checked the passenger side rotor and the rotor has .003" max run out but there id no noise at all when I spin the wheel/rotor.

The only thing that I haven't done is to isolate if the rear is actually the root cause of the problem. I don't think this is the case since I felt that the pulsation is at the pedal and steering wheel. I guess I'll tear down the rear this weekend just in case.

Overall the braking is good. It has good bite and stopping power but the pulsation drives me crazy.

Any inputs or thoughts.

Thanks

 

You machined the drivers front rotor only and are wondering why you still have a brake vibration?

 

Phootbacg,

I machined both front disks.

Thanks

 

Maybe it's the rears. Have you ever (slowly) pulled the e-brake at speed to see if it induces vibration?

I had a pretty bad vibration on my 01 V6 that returned fairly shortly after machining the OEM rotors. It didn't return after I replace the rotors with Brembo blanks.

 

I'll do the test you mention tonight..Good idea. The more I felt the pulsation the more I feel that it is actually on my seat.

Thanks

 

lol. The way you worded your first post I thought you only machined one rotor!

 

Problem solved.

It was the rear rotors all along. I should've isolate the rear brake first before replacing good front rotors that I thought was causing the pulsation. I used the e brake during crusing speed and sure enough the pulsation was felt much worse. Measure the run out on the left rotor and it was almost 008". Replaced both rotors and pads and now it is smooth.

Thanks