1986 Chevy 1 ton 4x4 Front End Shaking


dh302
01-30-2006, 10:06 AM
My son has a 1986 Chevrolet 1 tone 4x4 pickup with hydra boost brakes. When you apply the brakes at 40 mph or more the truck's front end will start shaking violently. Even after you let off the brakes the truck will continue to shake until the truck slows down. It's not just a slight shaking, it shakes so hard it throws things off the dash, seat, etc. It even broke the exhasut pipe hanger! The ball joints, tie rod ends, etc. seem to be tight. Iíve hade the tires rebalanced. A couple of weeks ago my son changed out the power steering pump (which also runs the hydra boost brakes) because the pump was leaking. I donít know if that has anything to do with it or not. It has larger than factory size tires and wheels. Next I was going to take the shimmy shock off and check it. Does anyone have any suggestions? Thanks.

Doug

jveik
01-30-2006, 04:53 PM
sounds tricky. Did you check the braking system to make sure crap isnt getting stuck? im assuming they didnt have abs yet, at least my 73 c-10 didnt lol, thats prolly only on fuel injected models, but just a stab in the dark...

dh302
01-30-2006, 05:00 PM
Yes, I checked the brakes as best I know how. No, this truck doesn't have anti-lock brakes. Thanks.

Doug

abaird
01-30-2006, 06:46 PM
Brake rotors may be warped.

broughy84
01-30-2006, 07:37 PM
My fire department's 79 Chevy k30 mini pumper did the exact same thing that you are describing. We NEVER could figure that out.....we could never get the carb working right either.

mbumgua
01-31-2006, 04:09 PM
I recently had a 84 3/4 ton chevy 4x4 do the same thing. The passenger side tie rod ball joint had been replaced by a shop. When we got it back it did the same thing as the 86 1 ton described above. The solution after a lot of other parts being replaced was to check the toe-in/toe out on the front end. Ours had toe-out of two inches. we adjusted this to factory specs(Basically a small amount of toe-in) and stopped the shaking. We used a tape measure on the distance from tire to tire (front of front tires and back of front tires) to discover the two ich difference. Good Luck!

mbumgua
01-31-2006, 04:12 PM
Inch
We replaced bearings, seals, gearbox, springs, shocks, tie rods and balanced the tires.

dh302
02-01-2006, 04:10 PM
Replacing the drag link ends fixed 98% of the shaking. I think we still need to turn the rotors. The tow in was 3/16Ē. Thanks.

Doug

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