vibes at highway speeds! Pinion angle???

[BillyL]

My 86 K5 has the same running gear as your 85 but i don't have a lift on mine yet. I get the same exact vibration you described im running 3.73 gears with 31" tires. I do have some play in my rear driveshaft so i am hopeing it's just u-joints.

 

[obijuan]

i hope so too! those are easy to fix! it probably is because you have good pinion angles with stock size. you may be sagging though which may do the same thing. time for a lift!

 

[obijuan]

in other words can i do this?

 

[BillyL]

I don't mean to hijack your thread

I think i found my problem the rear ujoint doesnt fit the yoke on the rear diff it looks to be a little bit to small. I went to get a new ujoint today and the parts guy asked me if it was a 1310 or 1350 series yoke. To be honest i don't know

 

[obijuan]

well theres measurements on teh first page i think that could help you. thats what i used to ID which one i needed

 

[obijuan]

ok little update, if i reweld my perches it will bind. i did the math and it seemed great and the angles would be perfect, then i got out there to adjust it, but when i got to the point to reweld, i saw the problem. even at riding level it was binding. so, i cant run the regular ujoint type shaft, i am lookin around for a good cv shaft, new is like $500. i cant afford that. any tips i could use that would be great but just lettin yall know whats up. thanks for all yalls help so far.

 

[guz71]

You get what you pay for I think. I had this guy make a cv shaft for the rear for pretty cheap and it only last about 1500 miles. The shaft pretty much destroyed itself and the transfercase yoke...learned my lesson. If you set up the driveshaft as in the last diagram you posted(non-cv) it will cause vibes. On a regular dirvshaft, the angles have to be the same so they cancel each others vibes out.