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12-18-2012, 04:29 PM #1
Truck shuddering under med/heavy braking. New pads/rotors front. New pads rear
I just had a local mechanic replace my brake pads and rotors to brand new in the front and the pads only in the rear.
im experiencing extreme shuddering and heavy vibrations under highway speed braking from the truck.
My cousin who is workin on his ASE certification says that my brake rotors are warped and that typically the shuddering is caused from the front brakes. I wondered how could this be when I replaced both the front pads AND rotors, and assumed only the rear rotors needed to be turned, but he then said that cheap pads/rotors will also cause this issue.
Could the rear rotors ALSO be causing the shuddering here? I would hate to have the front rotors turned when its not necessary to do so.
Also, i did buy some of the most inexpensive (still in my opinion of good quality) pads/rotors I could afford. I didnt see anything wrong with them, he said since they were not OEM they may not have been made of the same soft tensile compound required to make the truck brake smoothly.
I guess my question is, should I shave the front and rear rotors or just the rear? the pads are new front and back and rotors are new front only.
12-18-2012, 04:32 PM #2
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- Dec 2011
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I would support the truck and remove the wheel. That way you can rotate it and see if the rotors look misshapened. It should be easy to tell if they are.
1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
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12-18-2012, 05:19 PM #3Ray
'09 Avalanche LTZ - Black
'05 Envoy XL (sold)
12-24-2012, 03:09 PM #4
A few things,
One, in many cases just eyeballing them will not easily indicate them being warped. Your eyes may fool you and a dial gage will not.
Two, not to throw doubt on your local mechanic but improperly installed breaks can ruin new pads and rotors quick.
IE did he use break cleaner to clean the new rotors removing factory protective oil and or after touching them with grease hands? This can soak into pads and create a slick pad and even glaze it. You 'ld be surprised at how many shops and dealership tech's skip steps either because they forgot or think attention to detail is for worriers and noobs.
Three, did he bed the breaks after correctly after installation? Involving several near stops after getting up to near 60 MPH then slowing till just before 0 mph and letting it roll. With most, if you stop completely while doing your passes; you'll hot spot the rotors and warp them or some of the break in material melts and glazes the pad under contact to the blazing hot rotors while at a complete stop, because of the extreme heat do to the nature of break in. I have seen shops bungle this process and F up new parts. You must allow the vehicle to roll till the rotor and pad cool a bit. The speed needed to achieve the necessary heat can be different from manufacturer to manufacturer. Even breaks that don't require bedding can still take some time to wear in leaving a small and slight pulse till break in material is gone..
Three, just because your front disks do most of the breaking dose not mean your rears are fine, just because they have material left on the pad. If your front pads and rotors were beat. guess which ones were doing more of the breaking than normal.
I hope this helps or at the least gives you some ideasI am a American solder, I am a member of the finest fight force on earth, I am the bump in the night. I will defend the United states of American Against all enemies both foreign and domestic. Repent now all those who would do my nation and it's people harm; For when we come it will be too late.
2011 GMC Sierra SLE, Z71 with 5.3 l and max tow/haul package
12-24-2012, 09:00 PM #5
im a tech at a dealer, a GOOD way to determine if the pulse is from the front or rear is to apply the brakes and while the vehicle is shaking, let go of the steering wheel and see if the steering wheel shakes vigorously. also you will notice that you dont notice the pulse as much when you do this (if its coming from the front of course).
if you want to get technical in most cases it is not the "warp" that causes a pulse, its the thickness variation whne one part of the rotor is thicker then the other. IF your pads are free and not stuck in the brackets and your caliper slides are free to move then the whole caliper and pads should slide left to right with the warp of a rotor. now in the long run a warped rotor will cause thickness variation because every time that rotor forces the the caliper over it digs a tad more into the rotor removing the material and causing the pulse."i dont think you got the picture. i got a beautiful picture. this baby happens to have an extra turn of speed, which is the only thing i care about. you dont understnad what happens do you? they make cars. they make 'em exactly the same way. one or two of 'em turn out to be something special. nobody knows why. i know why. i may be kiddin' myself, but i think i can make somethin' out of that sad little bucket of bolts." ~ Tennessee Steinmetz
01-04-2013, 03:19 AM #6
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- Sep 2012
- Lake Worth, FL
01-04-2013, 07:15 AM #7
Been having alot of problems with chinese drums and rotors lately. I usually go to advance and napa after tons of problems with az but last fall even advance had defects that i had to exchange. Truck rotors are pretty thick so they are not as much as a prob as cars but if you dont bed them they will warp. I allways go up to 35-40 and brake hard to about 5 then coast. Do it atleast 5 times but no more than 10. I would warranty both the pads and rotors andvtry again.
Also it is common for pads to be too tight in the brackets on these trucks so take the time to file/ grind the ears so they fit well without binding but are not loose. People ask why i charge $50 an axle just to slap pads and rotors on bc i completely take the braket apart and clean both sides of the clips and bracket channels as well as hone the slide bores and wirewheel everything. Once i do it the next time they need pads i never have a frozen slide or stuck pad. Up here in the salt belt its very important but in dryer places maybe not so much but i do it anyways.01' 1500 LT Z71 ECSB 5.3L
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