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Pulsating Front Disc Brakes

I have a 1997 1500 Suburban 4 X 4. The front disc brakes pulsate when the brakes are applied. We bought it use 6 years ago no problem. After about 20-30K miles I noticed slight pulsating of the brakes in sync with the rotation of the tires. I applied the parking brake while in motion without the pulsating taking place,so I ruled out the rear brake drums. I remove the roters and had them turned and replaced the pads. I was fine for a while, then the pulsating started again. Thinking the rotors may have hade a manufacturing defect that the turning did not remove, I repaced rotors and pads. Again this worked for a while, but the pulsating is back and geting progressivly worse, with the vehicle starting to buck pretty good, so it gets real exciting when braking in snow and ice in the winter. Is ther something in the braking computer system that is out of whack? Any Ideas? I would like to fix this myself.



Thanks in advance



Steve Bingham

Boise, Idaho

Sounds like your driving habits or driving conditions are warping the rotors. Common causes are: High-speed driving with sudden stops overheats the rotors. Towing a heavy trailer without brakes overheats tow vehicle’s brakes. Driving through water when brakes are hot. Many replacement rotors are imported and are of dubious quality. They warp all by themselves…

It’s the rotors. When you had the machined you removed even more material from rotors that were already proven to be unable to do their job without warping…almost guaranteeing that they’d warp again.

When you put the new rotors on, did you clean the surfaces with the proper cleaner? If not, you may have a buildup on them that can be removed. If you did, were they budget Chinese rotors? You’re stopping a lot of weight with those rotors, and you’re converting 100% of it to heat. Perhaps cheap rotors just won’t handle it.

Another possibility…have you checked your rear brakes for condition and function? If they’re not doing their part in helping with the load, the front brakes may be trying to dissipate more heat than they’re deigned for.

Agree with all above and I will add one more. If you ride the break pedal with you left foot while driving along, will have the same result.

I worked for GM when your car was new,we had many brake pulsation,short pad replacement intervals and poor brake performance.

The brakes are to small (rotors and pads) you will never fix this problem as it is a design error.

You are just going to have to accept that your Suburban is a vehicle that is a “high maintiance” vehicle in regards to brake performance.

I posted this elsewhere and will post it again. My VW has had pulsating brakes for a long time.

Try this: Just for fun, I snugged up the front wheel lug nuts a little at a time with a torque wrench. Go around the pattern, tightening every other nut or bolt as is the case with my VW. If you have an even number of lug nuts, do half of them and then the other half. I’d try 25 foot lbs, then 50, then 75, then finish torque; should be in your owner’s manual.

The difference was amazing. The pulsating for me is hardly noticable now. If I don’t think to try to notice it, it’s gone!

There are other things that can mimic a brake rotor problem; loose wheel bearing, loose ball joint, loose tie rod end, etc, etc.

The reason it may be fine at first and then deteriorate is that after some mileage is put on them the rotors may warp a few thousandths. This may not normally even be noticeable but if one has something loose or worn in the suspension the few thousandths warp may become magnified and made to feel worse than it is.
Hope that helps.

THIS is important. My Thunderbird is VERY susceptible to unevenly torqued lug nuts and I have solved a shudder problem simply by snugging down the lugs in the correct pattern to a uniform torque value.

Torquing your wheels can be important, but you should also know that not all rotors are created equal.

When I buy new brake components, I spend extra for high quality parts. I find that “imported” and “cheap” parts seem to have much more warping than the “expensive” parts.

Maybe it’s just me, but cheap rotors seem to get warped every time (and it doesn’t take a long time either).