new rotors installed... now it vibrates a lot

[Stephane Bolduc]

Got the new slotted rotors and Raybestos ceramic pads installed tonight. Got the rear "adjusted" and everything greased/lubed....



Now, when I turn at slow speed (even small radius), forward or backward, I get A LOT of vibrations. I have 6 months old Michelin (never vibrated before).



I don't know if he did a tire rotation and I think he over inflated the tires a bit. I could really feel it on the street; felt like driving a jeep.



Any thought ? Is it just over-inflated or he could have screwed up something causing vibrations ?



Forgot : the braking is awesome; made a huge difference; night & day. On top of it, the car goes totally straight now. It use to pull to the right quite a bit. And my steering wheel is a little bit more aligned, but still crooked (result of an accident back in 2000).

 

[Richard L]

Steph.

If it was a brake problem it would vibrate when you applied the brakes not just when you turned the wheel left or right??? Its also possible that you have dirt, grease, etc on your brake pads and rotors causing your pads to chatter. Or you may have warped rotors from the factory. I have never encountered this but some people have had to have a thin cut removed from their new rotors to true them up.



Another possibility is that the caliper mountin bolts are loose and the caliper is vibrating?



Your rotors may have the wrong tone ring on them for the ABS sensor and the vibration may be caused by the ABS pulsing? Or perhaps you have knocked the ABS sensor out of alignment and it's not picking up the tone ring on the rotors. That could also make the ABS brakes pulse.



Did you install new wheel bearings and properly grease them when you installed your new slotted rotors? Did you torque them to the proper specs to seat the bearings and then back off ?



Also, over inflation should not cause a vibration unless you a getting feed back from the harder tires???



Sorry,but it's kind of hard to guess what someone else did wrong when you have never experience those symptoms after a brake job. The symptoms as you described them do not necessarily mean there is a brake problem.

 

[Stephane Bolduc]

Richard,



thanks for all the hints. What I'll do tomorrow, is go in a parking and engage the ABS to see if they feel right (that way, I'll circulate the fluid too).



I had it done at PepBoys, I couldn't beat the price since I already had all the parts. They chardged me 80$ for the job.



The rotors came with a little coating on it and he grinded them a little to get the coating off. I do not believe he put them on the machine to see if they were truely leveled.



I don't think it is brake related, since the slow speed I'm talking about, is while pushing the accelerator or nothing at all, but not the brakes.



I only drove it 10 minutes; so not many slow turn speed. I'll get a better feel tomorrow.



Thanks again.

 

[Michael Cacioppo]

I would not have ground the coating off. I would have used a solvent to remove it. I have no idea how he left the surface after grinding. That could be your problem. The surace may now be too rough. 15 to 80 microinches should be the smoothness of the surface.



BTW did you "bed" the brakes after the installation? This proceedure prevents uneven build up and proper sets up the pad/rotor interface.

 

[shawn stonbraker 2]

Steph, like you said night and day! I love my dilled and slotted rotors. You will notice a slight vibration when braking alittle harder than normal because of the slots. Plus they make a small "whirr" when it does this. It took me alittle getting used to.

As for your problem, I don't think it's a brake problem. You may have some minor "cupping" on your tires on the outside of the tire that you feel when turning. If they put air in the tires and they are harder now, it will amplify it. Also may want to turn the wheels and get under there and see if the tires or anything that will be moving when the truck is going to see if it's rubbing on something.