Violent shaking in front end only when applying brakes

[Razor1941]

I have a question, that I am hoping one of you may have the answer. I own a 2005 GMC Sierra 4x4 extended cab, that I recently did a complete brake job on, (rotors, pad's caliper, drums, shoes & rear cylinders) Shortly after all the work was completed, I experienced a violent vibration in the front end when braking over 80 Kms per hour. But if I am travelling under 80 I get very little to no vibration. A friend of mine suggested changing the ABS pump, so I did change it and it made a little bit of a difference. Now one week after, the violent vibration is back. To give you an example, when I brake at 80 Km or over, it feels like a warped rotor, but I know it's not because I just replaced them brand new. I am at a loss now as to what it could be. So I am sending out an SOS for help.

 

[O_J_Simpson]

What are your run out measurements on the rotors?

[Razor1941]

Not sure what you mean run out

[SouthernSilveradoGuy85]

Did you clean off the rotors and drums? They're shipped with some kind of oil or something that keeps the rotor or drum from rusting.

[Razor1941]

yes I used brake clean on them and made sure there was no oil when I installed them

[Chubbs878]

Did you replace with cheap aftermarket parts? I have bought rotors that were bad or compromised "off the shelf" and had to immediately return & exchange for a more premium make/model rotor and the problem was solved.

 

Also, if you did not properly burnish pads (break-in) the new assembly you could have high spots, heat spots, or glazing of the rotors. Return everything on the front and redo it again with new parts and bed-in the pads per manufacturer specs after assembly.

[Bad Bowtie2]

I've seen tech's have to "turn" new Chinese brake rotors right of the new box!!

Just showing me they were out of round and not true already!!

[Mike GMC]

Did you clean the hub face around the lug studs before you put the new rotors on? If there is rust or debris in there, it can act like warped rotors.

[dkjbama]

All above are good points. Other thing to look out for is proper lug nut torque. Unevenly torqued lug nuts or lugs not torqued to spec is a BIG cause of rotor warping on any rotor that floats floats on the hub to be secured by wheel and lug nuts.

 

Also, did you lube the stainless clips that the pads slide on? On a floating caliper, if the pads cant slide freely, one side of the pad can get stuck and wear unevenly. This happened on my truck and I had to throw out a set of half-worn pads.

 

I only use OE Delco rotors and OE Delco pads (brown box, not the durastop line). Haven't had a problem since.

[sdeeter19555]

Rotate your tires and see if it moves...I've had tires with slipped belts do this same thing. The front position seems to amplify the tire's defect.

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Chubbs878]

I don't think that o/p is tracking thread any longer but balancing or rotating tires will not help if the problem did not exist before replacing the brakes.

Well, unless he rotated the tires @ same time but now he has the heads up on that, if not just to attempt a free fix.

He really should remove everything from at least the front if not all 4 corners & exchange for a completely new setup under warranty and redo the whole thing with a proper break-in procedure.

 

If he drove in traffic without burnishing the new pads to rotors, then the rotors would have hot spots where the brakes were held while everything was good & hot. That, or, something was not assembled or lubricated properly.

I just replaced everything on the front brakes of a new-to me vehicle bc it would shudder/pulsate when slowing from high speeds; my major concern was getting them burnished properly after the R&R

[sdeeter19555]

I don't think that o/p is tracking thread any longer but balancing or rotating tires will not help if the problem did not exist before replacing the brakes.

Well, unless he rotated the tires @ same time but now he has the heads up on that, if not just to attempt a free fix.

He really should remove everything from at least the front if not all 4 corners & exchange for a completely new setup under warranty and redo the whole thing with a proper break-in procedure.

 

If he drove in traffic without burnishing the new pads to rotors, then the rotors would have hot spots where the brakes were held while everything was good & hot. That, or, something was not assembled or lubricated properly.

I just replaced everything on the front brakes of a new-to me vehicle bc it would shudder/pulsate when slowing from high speeds; my major concern was getting them burnished properly after the R&R

Obviously you have never had a tire with a slipped belt...

 

Sent from my SAMSUNG-SM-G900A using Tapatalk

[Razor1941]

Sorry guys I just got back from work out of town up north no internet or cell service. I'm getting new tires next week and going for a wheel alignment too but until than I'm still up for any info from you guys thanks so far. I'm looking at everyone's idea's and will try all of them, just not all at once lol baby steps

[grampadirt]

Warped rotors gets my vote.Had the same problem,even new some rotors are warped.One new rotor had to be turned so much that next time I did brakes I'd have to replace the rotor instead of doing a simple skim job.

 

Have the runout checked,there are tolerances set by GM.

[Supreme Pizza]

I skimmed, so sorry if I missed a detail or if this is already covered:

 

I would make absolutely sure that the front wheel bearings, tie rods, and all the other ball joints in the front end are in good shape with no free play. I would also take a second look at the all the lug nuts. Long shot, but it could be a bad shock causing a tire to hop. If you suspect any part of the ABS system, just disable it by unplugging the module or pull the fuse. Is it possible that you got a warped rotor from the factory? If you spin the front wheels by hand, does the caliper move back and fourth at all by itself? Just throwing stuff out there.