rear end pinion angle issues
 

I took my 49 gmc on its maiden voyage today to the muffler shop. on the way back i noticed under acceleration the rear end is literally rotating up to 30 degrees from where it is at stopped. needless to say this scared me to death. I will explain what i've done so far below.

1995 s10 frame
3" Belltech lowering leaf springs
1.5" home made set back plates to center the rear tires in the wheel well.
blisten(sp) drop shocks.

i might need pinion angle shim? whatever it is is scary as hell driving it and it starts vibrating pretty violently around 30mph.

Re: rear end pinion angle issues
 

Is it moving back and forth of just stuck there? Did you weld the perches on?

Re: rear end pinion angle issues
 

Right, if it's actually rotating back and forth, shims aren't the answer. Are the leaf springs wrapping, is the housing rotating on the tubes, or are the tubes rotating on the spring pads?

Re: rear end pinion angle issues
 

the tubes are rotating on the spring pads. i've got everything bolted down tight. If by chance it is the leaf spring wrapping. i'll have that fixed in a few days. i have a set of cal tracs I'm putting on just to be safe

Re: rear end pinion angle issues
 

The tubes have to be welded to the spring pads. Also the blocks need to be a bit wider than the spring pads. How much is the rear offset from the locating pin? That can have a effect on the spring.
Jimmy

Re: rear end pinion angle issues
 

right around 1.25 inches. on the spring pad. i plan to eliminate any chance of spring wrap with these caltracs

Re: rear end pinion angle issues
 

To reiterate: The spring pads must be welded to the tubes.

Re: rear end pinion angle issues
 

Pgsign right..you gotta weld the spring pads to the axle tube..don't rely on bolts to hold it..if its moving that much I'm suprised you havnt broke somethimg yet..30 degrees is pretty drastic..make sure your pinion angle matches your trans angle..usually around 3 degrees

Re: rear end pinion angle issues
 

i apologize for my idiocracy, i'll post an image so you guys can clear it up for me. I think you're telling me to weld A to B in this photo?

http://i1383.photobucket.com/albums/...psnplwjbbl.jpg

Re: rear end pinion angle issues
 

the perch is secured to the axle tube because it came stock that way. i have no clue why this thing is rotating now.

Re: rear end pinion angle issues
 

The way your post #4 read it sounded different.. in your picture the perch lS welded to the axle tube..that's ok .don't weld a to b ..from what I see there should be no way that differential will rotate 30 degrees as long as the perches (a) is welded to the axle tube..if it would rotate 30 degrees i would think your u-joints would be broke..if it is 30 degrees then you've got a serious problem elsewhere

Re: rear end pinion angle issues
 

yeah i'll do some more investigating but I'm pretty sure i have a serious problem. problem is it only does it when accelerating so its hard to actually see my issue.

Re: rear end pinion angle issues
 

Hang a gopro underneath..

Re: rear end pinion angle issues
 

Post pictures of your entire setup if you can. We may be able to see something amiss.
Jimmy

Re: rear end pinion angle issues
 

The pinion nose of the axle moves up and down quite a bit under acceleration and deceleration, due to leaf spring wind up.

I had an opportunity to drive my '87 pickup without the box on it and was surprised at how much motion there was going on back there.

Assuming that the perches are welded to the tube it could very well be normal.

K

Re: rear end pinion angle issues
 

This is just a thought..keith is right that there's a lot of movement in the rear..but..does your driveshaft have a slip joint in it? If so do you have the u-joints in time? If not it will shake your teeth out..also, check for bad u-joints

Re: rear end pinion angle issues
 

drive shaft is all new, it is 2 piece from the s10. all the joints are new. i'm not near the truck it will be next week before i can post a few pictures of the entire setup.

Re: rear end pinion angle issues
 

Won't matter if its all new or not if it isn't timed correctly...get a good pic of the entire driveshaft...are you familiar with u- joint timing?

Re: rear end pinion angle issues
 

no I'm not familiar with U-joint timing

Re: rear end pinion angle issues
 

The yokes on your driveshaft need to be lined up..here's a video about u joints that explains a lot..https://m.youtube.com/watch?v=gmV4qwLfOMY

Re: rear end pinion angle issues
 

Maybe this'll help explain as well...

Re: rear end pinion angle issues
 

Re: rear end pinion angle issues
 

i'll try to phase the U joints on tuesday and take better pictures.

Re: rear end pinion angle issues
 

Re: rear end pinion angle issues
 

Were the u joints outta phase?