Brakes

[cp17]

Hi all, Got a question for the masters!

I have a 08 sierra single cab 1/2 ton 4wd w/t with 11000 miles, it has steel chrome wheels, disc front drum brakes in rear. all maint has been done by the dealer. 2 oil changes and 2 tire rotations. Within the last 2000 miles the brakes feel like the rotors are warped, but not all the time, seems like only when i get off the highway, at times it shakes hard other you can barely feel it. and then for about 5 minutes after that,when brakes are applied, then they are fine. the truck doesnt pull one way or the other, tracks straight. seems odd to me that it doesnt do it all the time. Any ideas...thanks, chas

[Zembonez]

Well. I am no master but what you describe may well be a warped rotor. It's also possible that you could have a tire issue. I'd have them look at it.