Rotors

Yep, you will get what you pay for here.

I put new pads on my 99 Suburban K1500 4x4 about a month ago. I then noticed that there was a slight pulsation in the pedal and decided to replace the rotors because the last time they were turned they said it would be the last time and they would have to be replaced. About a month went by before I got around to replacing the rotors, now that they are replaced the pulsation and shaking is worse. Is it because I waited so long before replacing the rotors and the pads have worn uneven and now it is shaking? Any ideas?

Brian

A couple of things may have happened. First problem, you don't say what kind of rotor you purchased. Were they original factory rotors, or did you go with cheaper aftermarket ones? Often, you get what you pay for. Sometimes the aftermarket rotors can be a bit "green" and will warp quite rapidly.

The other thing that might cause this is not cleaning the hub area well enough when you install the new rotor. If you just throw the new rotor on and don't clean the hub area (if it has rust/corrosion built up), then the rotor can have a certain amount of runout (ie: it will not run true). Now at first, you won't notice anything, because while the rotor has excessive runout, it is still parallel....so you don't feel a pulsation. But eventually the runout will cause the pads to touch the rotor every revolution, cause a hot spot or wear at that location, and the rotor will develop what is called "thickness variation". At this point, you will feel a pulsation. Usually...this doesn't occur for about 10-12K kilometres....so I'd guess that you may just have cheap rotors.

Ian

cheap rotors are cheap for a reason. the cheap ones are just made of mild steel. they heat fast take long to cool are thinner and warp easy. and the more they are turned the worse braking you will get and the above problems happen much faster!!

if your going to change them do yourself a favor and get the drilled and slotted ones. they are a much higher grade of steel, take longer to heat up cool off much faster and i've never been able to warp them. (yes i try to warp them everytime i have sold a car)(because the factory ones always need replacing)

What brand drilled rotors have you used? I'll be doing a brake job on my Z71 soon and have been considering drilled rotors.

Thanks Brian

I bought the $80 Ray Bestos made in the USA brand. They appear to be turned ones and not composite ones. They were immediately worse than the ones I took off. Didn't take a few miles. I noticed by the time I got to the end of the driveway. Guess I will pull the wheels off and make sure the hubs are cleaned up good. Didn't appear to be bad at all though.

If the pulsation was noticed immediately, then the problem is with the rotors themselves.

Ian

i have used 3 different brands.. the brand names don't really matter. just look for the ones with a gold sheen to them. if they have the gold sheen they are made from a much higher quality of steel. around 80,000 -90,000 p.s.i. tensile strength

I appreciate the tip, but I'm probably going to buy online and won't be able to see them.

Brian

Do you recommend that I take them off and exchange them?

Did you use an impact gun:

Set at full blast to tighten the wheels?

Refinish King

No, hand tightened.

Pep Boys Assures me that the Ray Bestos Rotors are turned and checked for trueness. Could have I done something wrong when installing them?

Brian

I take it you installed new Pads with the new Rotors??

I don't really recommend anything...but you might want to get a hold of a dial indicator, and/or the proper size micrometer and measure up the rotors. Then you will have some ammo when you go to try to return the rotors.

Ian

The pads were installed about a month ago. I then noticed a slight pulsation and decided to replace the rotors because the original ones could not be turned again.