2 months ago..... Brakes were fine, no pulsating...but my brake warning light came on, so time for new pads. Since the brakes were smooth, I figured the rotors did not need turning. They didnt look scarred, so I figured I was ok.

I replaced my front and rear pads. I did the pad bedding as recommended.

A few days later I had pulsating in the steering wheel (not the pedal), so I replaced the front rotors. That fixed that. I did the same bedding procedure again.

Now (2 months later), when I first drive the car (brakes are cold), the brakes are fine. But as they heat up, I get slight pulsating that gets worse the more I press the brake pedal. It is a sensation of the car getting pushed/pulled front to back, not side to side. The pulsating is NOT in the pedal, and the steering wheel does not pulsate either. Since the steering wheel doesnt pulsate I figure my problem is with the rears. Would you agree?

Is my problem that I just replaced the pads and didnt have the rotors surfaced or replace at the same time?

Thanks.

 

I'm fighting the same thing on my E320. I replaced the original rotors at 95k last week and still have that sensation. The only thing I can notice is slight play in the front wheel bearing. I'll fix that and recheck. It's possible it's in the rear brakes too, which I've never checked, but have had similar issues on customer's cars that ended up being rear rotor warpage.

 

^^^Thanks. Anyone else have ideas?

 

I'll go along with possible play in wheel bearings which can also cause low brake pedal. You could also have a dynamic imbalance on a front tire. If you have a heavy spot through the central plane of a front tire, you will experience a front wheel tramp. If you have an imbalance on either side of the tire, you will experience a front wheel shimmy. You can check the trueness of the rotor by setting up a dial indicator, and checking run out.

 

Thanks hiney. Not sure wheel bearings or tire imbalance would be the case here as those would cause a shimmy even if the brakes were not applied. Car is perfect and smooth at all speeds....all conditions.....cornering and straight line driving.....unless I am braking.....

 

I wouldn't rule it out. In my 30+ years experience I have seen it. Before I became a professional mechanic, I was an electronics technician for about eight years. There is science and theory and then what really happens. Don't forget to check the run out on those rotors with the dial indicator. That will definitely eliminate one thing.

 

I had a similar problem, but it was solved.

- Have a look at the surface of the rotors. In my case, in just one place, there was an "imprint" of the pad. This is apparently a known phenomenon - pad material gets transferred to the rotor while the car is parked and that spot has different friction than the rest of the rotor. Very light machining may help, but I was away when it happened so just bought new rotors.

- Check if the rotors have an edge that has become rusty. My back rotors had this and because the new pads were not exactly the same as the old ones, they caught on that edge. The did not do that when I installed them, but again when parked an ocean side airport for 3 weeks.

Your problem may be different.

 

As a follow-up, I replaced my rear rotors over the weekend (finally got warm enough) and that cured what you described.

I would have resurfaced them, but new chinese rotors were $25/ea vs $20/ea to resurface. Plus I beat the hell out of them to get them off.

 

Funny you should post! I bought new rotors and pads and tried to put them on last weekend, but the rotors would not come off. Hate to have to take it in for rotors, but I have no choice. Have to wait until the 2 feet of snow melts though......

Thanks for the post!

 

We had one warm day (30 deg) before more snow and ice, so I took a couple hours and did it. Just make sure the caliper is out of the way (remove the sensor on the right side) and pound away from the inside out. A normal hammer probably won't do it. Don't be afraid, but wear eye protection cuz pieces will chip off. Maybe use some PB Blaster around the hub too. I did not have to adjust the parking brake.

I have a friend who comes over for this stuff to learn and he couldn't believe the force to remove them.

Took me about 20 whacks on the right and 3 on the left. Funny, since I forgot to remove the set screw on the left! It broke right through the rotor, no damage to the screw.

I smeared anti-sieze on the hub surface, so the new ones will come off easy later.

I also sprayed silicone on all of the rear bushings to rid the winter squeaks.