4wd Weird Shake when Braking
 

Hi everyone, I have an 82 K20 pickup that drives amazing, it has a 99 vortec 454 with 4l80e and Np208 that I swapped in a few years back. Well about a year ago, the 9.5” 14 bolt rear end chunked the gov-bomb. So i had a wrecked van on the property, a 2004 express 3500, I ripped the disc brake rear end out of and swapped into the 82. I cut all the old perches off and welded on new from Barnes 4wd, set my pinion angle, all that.

When stopping lightly, the truck has a very weird up and down shake to it.

I have changed the shocks, turned the rotors (they were new originally) new calipers, akebono brake pads, new wheel bearings, and It still does it. Hard braking is no problem. Stops smooth and very well!

I have a disc/disc prop. valve, a master cylinder for a 2000 c3500 pickup, and the factory style calipers.

Need some advice, it is driving me nuts.

Re: 4wd Weird Shake when Braking
 

Maybe check pinion angle again, go through every single nut and bolt and retighten.

I would also put a go pro under there and take some video to diagnose with.

Tires wearing uneven/balance issue?

Just throwing out suggestions

Re: 4wd Weird Shake when Braking
 

U-bolt torque. Are they nice and tight. should be a 5/8 u-bolt with a torque of at least 150. Leaf spring bushings?

Re: 4wd Weird Shake when Braking
 

Old brake hoses can some time cause shaking when stopping if they are partially collapsed in side.

Re: 4wd Weird Shake when Braking
 

I may buy a go pro just to see, good idea.

Re: 4wd Weird Shake when Braking
 

Yes those are torqued as tight as I could get them. I had a set that go over leaf spring with the nuts under the axle, so they are the flat kind, instead of the round shaped u bolts that go around the axle tube.

Leaf spring bushings are a good possibility. I’ll check them as well.

Re: 4wd Weird Shake when Braking
 

It very well could be the fronts, the sensation seems to be coming from the rear of the truck, but you never know. In the rear I have all new components from the initial swap. Bad out of the box brake hose would be unlikely, however not impossible.

Re: 4wd Weird Shake when Braking
 

I know this is probably a dumb question because it sounds like you know what you're doing, but did you check the pinion angle with the truck sitting on the ground and level, and not up on jack stands with the rear end hanging down?

If you think it's possible it's coming from the front, it could be death wobble. I would check the ball joints and tie rod ends for slop (with the front wheels up in the air.) If it's not that, then check your steering stabilizer.

Re: 4wd Weird Shake when Braking
 

No problem. Pinion angle was set with weight on the axle, on the ground. All front end components are brand new as of January. All moog ball joints and tie rod ends, bilstein steering stabilizer.

Re: 4wd Weird Shake when Braking
 

have you tried stopping with the ebrake and not the brake pedal to see if it still shakes?

Re: 4wd Weird Shake when Braking
 

Out of round drums?

Re: 4wd Weird Shake when Braking
 

Pics of rear u-bolts and plates please

Re: 4wd Weird Shake when Braking
 

shot in the dark here but have you checked u-joints or driveshafts for any binding in the slip joint? Any wheel interference with the axle hub? I believe the stock van wheels would have been hub piloted with 4.59" (116.7mm) center bore per google but I can't remember what the center bore of the stock 1982 wheels were. Have you rotated tires front to rear?

Re: 4wd Weird Shake when Braking
 

We/You need some video to diagnose with.

Grab an old phone out of the drawer, tape it under there, go for a spin, and post.