I am having a problem with my friends 97 blazer LS (4wd, abs) i believe.
he said it was fine until this winter, using 4wd alot and running over snow banks and such, he said it developed a loud thumping when u push the brakes above 20 mph, it does not pull to either side, and feels to brake normally. it does however, violently shake the entire vehicle and gets worse with more speed or brake pressure

so i looked at it for him and initially found a...

leaky dr. side rear wheel cylinder[replaced]
worn rear shoes[replaced] (back shoe,passenger side worst)
(1 barely worn to the rivits, the other 3 had roughly 30% left on them)
rusted/nonexistent front sway-bar end-links (passenger side rusted/worn but attached,driver side gone)[replaced]

still it persists, the front is where the problem lies, as the parking brake alone produces silky smooth stops.
i think the next step is to check the rotors for warpage but i c nothing visibly wrong as of yet
any different/better suggestions from the knowledgeable bunch here?

 

Go with rotor warpage.

 

Have you replaced rotors and pads yet? I probably would have started there first lol.

 

thats the plan tomorrow,
he'd rather try to turn them for 25 bucks each than go with new ones for 45 bucks each (against my personal opinion and advice) so we shall see how it goes, regardless of the actual cause of the problem, the issues i found so far needed attention

but i did learn a 97 chevy blazer can go 5 years and 30000+ miles with no maintenance at all besides the 6 month oil changes

and thanks for your opinions and a quick response

 

Is it like the dreaded "death wobble"? Have you checked all the steering linkages, idler arm, pitman arm, ball joints, etc.? If it is warped rotors, they would need to be really warped to cause what you described. You should be able to get those rotors for about $32 or about $22 online. http://www.rockauto.com

 

i didn't find any play in the ball joints, didn't check the steering system too much, i feel no excessive play or "Dead Spots" in the steering wheel,
BTW thanks for the tip on cheap rotors, they wanted 45 bucks each at advance auto and 25 each for turning at the local shop
no progress today either due to rain

 

I would vote against turning the rotors. If hes the kind of driver that likes hopping snow banks and such, then he probably likes driving it like a NASCAR too. Theres nothing wrong with that, but when you turn the rotors they will warp that much easier next time because they are now thinner and cant take as much heat. I have a wife that drives a NASCAR Ford explorer with extremely warped rotors that I wont change anymore cause they are A) Expensive, B) a bugger to change with the 4x4 dissassembly, C) too much work for me when she wont change her driving habits. The shaking steering wheel keeps her from speeding too

Jack up the front end and give the steering linkages a nice look over. With one side up, have him shake the tire from side to side while you look at the idler and pitman and tie rods for any play at all. Have a look at the shock absorber bushings too or for missing fasteners on the shocks. Sway bar bushings that hold it to the frame. Ball joints - to test you pry the tire upwards from underneath the check the lowers, and pull/push the top of the tire toward the engine and back to check the uppers. There should be no play that you can see in them when they are new, if they move more than a MM or two then they are shot. Also check the tires themselves for out of round or flat spots or separation. Oh and the control arm bushings where they bolt up to the chassis