Pinion angle

[dean jendro]

What is the correct method of correcting the pinion angle on a coil spring rear end? I have some vibration that I am trying to eliminate and everything else looks good. The driveline has been balanced and the wheel/tires also. I have not checked the angles on the ground yet, but hanging from a hoist there is about 3 degrees difference between the trans angle and pinion angle. I want them to be within one degree of each other after all adjustment.
The truck is a 64 short bed. Thanks for your input.

[siggyfreud]

When you say 3 degree difference what do you mean? Is one -3 and the other +3? Or do you mean something else?

[dean jendro]

No, the trans angle is down and the pinion is up like they should be but one is say 2 degrees and the other 5. I know I need to get it back on the ground and check it there. I just need to know what to do about it if it's still off more that one degree.

[siggyfreud]

Gotcha. Yeah not sure what people do with coils. Leafs you can shim. If the rear is rotated 5* up you'll need to find a way to nose it down a bit. Not sure if they make shims for coil setups, or how those would work . . .

[PGSigns]

They make shims for the coil spring setup. Easy place to find them is stock car supply places. The cars with truck arms use them all the time. Speedway motors had them at one time.
Jimmy

[dean jendro]

Thanks PGSigns and Rocknrod. That's what I was needing. Now I just need to figure out how much angle to correct.

[The Rocknrod]

https://www.performanceonline.com/19...ar-Suspension/

[chevy_mike]

Other option that I have done, if you have the clearance, I have shimmed up the transmission mount (assuming you are using the rear mount setup and not bell housing setup). My guess is a 1/8" or 316" piece of flat stock would move the trans angle up the amount you needed.

[dean jendro]

Thanks ChevyMike. I'd rather not mess with the motor end because I don't want to create any new problems. It would be easier and quicker, but..

[siggyfreud]

I would assume that if your rear is angled 5* up the ideal would be to nose it down a bit, rather than adding a more 'extreme' angle to the transmission. But someone more knowledgeable than I can chime in. I'd just keep wedging them in until you're at 3* up, assuming the trans is 2-3* down.

[dean jendro]

Originally Posted by siggyfreud

I would assume that if your rear is angled 5* up the ideal would be to nose it down a bit, rather than adding a more 'extreme' angle to the transmission. But someone more knowledgeable than I can chime in. I'd just keep wedging them in until you're at 3* up, assuming the trans is 2-3* down.

Sounds good. Thanks.

[dean jendro]

Update. I had the company that built my drive shaft re-check the balancing to see if that's what's causing my vibration and of course they said it was fine and charged me $60 bucks for the effort. I could tell that it had been changed because the balancing washer/weld was a lot bigger and the whole shaft had been re-painted. They claimed they checked it up to 3000 rpm and that was the limit for that shaft. I need a lot more than that, like 5000 or so.
After installing the shaft it had the same vibration at about the same speed and rpm (2050 rpm/60 mph and higher). I put the truck back on the rack and had someone else underneath while running it up to the same speed. .
Turns out it has a lot of drive shaft wobble so we put an indicator on the shaft and it runs out .065 at the tail end, .007 at the trans and .020 in the center.
Monday I will be taking it back and see if they can actually make me a good shaft that doesn't run out more that .010 and will run above 3000 rpm. If not I guess I'll need to go elsewhere. This shop has been in business in Seattle for years and I would never have guessed I would have a problem with their product.

[Captainfab]

That sort or runout I would expect to see from a driveshaft shortened and welded up on a garage floor.

[dean jendro]

Originally Posted by Captainfab

That sort or runout I would expect to see from a driveshaft shortened and welded up on a garage floor.

I agree. Before I go off half cocked though, I read somewhere that you should rotate the shaft in the rear pinion yoke 180 degrees and re-check the runout. That will eliminate the possibility of a bad yoke. Since the rear end was also rebuilt and it has a new yoke, I guess I better check that first.

[Crazy Rusty]

Dean - In case that place doesnt work out, I've had good luck with the Drivelines NW down in Fife by the Poodle Dog. They worked on my 69 Chevelle, 62 C20, and 29 Ford without issue.

[dean jendro]

Originally Posted by Crazy Rusty

Dean - In case that place doesnt work out, I've had good luck with the Drivelines NW down in Fife by the Poodle Dog. They worked on my 69 Chevelle, 62 C20, and 29 Ford without issue.

Thanks. I'm still diagnosing the issue. The pinion yoke looks fine. It's looking more like either the yoke on the pinion end of the drive line got cocked a little when they welded it or the u-joint on that end is made poorly.

[dean jendro]

After several in and outs with the drive shaft and much measuring and indicating I have determined that the drive shaft was indeed made correctly and the culprit was indeed the pinion yoke. It was machined off center .060, 90 degrees to the universal joint caps.
Once I figured it out and removed it from the truck it is easy to see with the eyeball. Just another reminder that just because you pay good money for what should be a precision machined part doesn't mean it will be.

[chevy_mike]

Wow, that would be a hard one to figure out. Glad you found it.

[dean jendro]

Originally Posted by chevy_mike

Wow, that would be a hard one to figure out. Glad you found it.

No kidding. As soon as it stops raining for more than a day I'll give it a good road test.

[Captainfab]

Glad to hear you found the culprit. Yeah anymore, just because it is new doesn't mean it is right.