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Driveline vibes - pinion?

subzali

subzali

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I’ve been chasing some driveline vibes on my 80 with the OME heavy lift. It only vibes when the front shaft is installed. Tried double Cardan, tried stock shaft. Both vibe. Found yesterday that I can move the pinion nut by hand. Just a little but it knocks the stake in both directions. I think I can feel a slight wobble of the pinion too. I think this means I have no preload on the pinion. I’m going to pull it and have someone look at it. Recommendations?

Other thoughts/opinions/discussion?
 
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SteveH

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I have just retighted the pinion nut to spec in several cases with no ill effect, even long term.
 
Rzeppa

Rzeppa

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SteveH said:
I have just retighted the pinion nut to spec in several cases with no ill effect, even long term.
Click to expand...

I even had one come unstaked and I retightened and restaked and was good to go. Like Steve said, try retightening first. And of course, check your u-joints as they are the more common cause of driveshaft vibrations.
 
subzali

subzali

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If it was my 40 I would. But with an 80 and its crush sleeve design on the pinion, I am wary. Especially as this is a family DD. But I might be convinced with a little more nudging...
 
60wag

60wag

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The force required to actually crush the sleeve is large compared to the bearing preload. Tightening the nut to see if the vibration goes away should be pretty low risk.
 
AimCOTaco

AimCOTaco

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Agree with your concerns but I have also done this to an 80 recently (last fall) and watched it rack up lots of miles since... on 37's.

I might get a new nut so it will stake properly but other wise I'd torque to spec, re-stake and then just keep an eye on it for a bit.
 
subzali

subzali

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Well I decided to give it a try. Nut was definitely loose. Will drive it a little bit and re-check the preload and see what happens.
 
subzali

subzali

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Is it just in my head? Feels smoother already even without the driveshaft connected.
 
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Pz10420

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Glad I read this as I have been trying to figure out the same issues as you and have a similar setup. I checked the flange for any play and seemed good but didn't think to check the nut.
 
Cruisertrash

Cruisertrash

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This happened on my 60 - rear diff pinion nut was loose and the staking was the only thing holding it in place. Retightened and at 12k miles it's fine.

I also had vibes from an out-of-phase driveshaft so check that - easy to overlook when you're reassembling. (Special thanks to the previous owner for that)
 
subzali

subzali

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My other 80 front pinion is leaking. Who to send it to for rebuild?
 
Cruisertrash

Cruisertrash

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Before I knew my pinion nut was loose I stopped by Western Driveline in Aurora to have a profession look at the diff. Nice folks, decent shop rates, and they seemed really knowledgable (both in muscle cars and off road vehicles). I'm sure somebody else has got an inside track on a shop that knows these vehicles though....
 
coax

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I'll give two thoughts:

1. Re: retorque-ing a loose pinion nut. If the nut is that loose, there really is not much preload on that bearing, which isn't a good state for it to be in. The proper way to sort that is to pull the 3rd and set it up. However, like ToolsRUs said on 'mud--just tighten it back up because if it works, great! If not, you are right back to having to pull the 3rd anyway, so not much sense in starting by pulling the 3rd. If the bearing gets upset you'll hear about it and can pull it all out and fix.
2. My sample size of 1 yielded good results. I had a leaky pinion seal (which is of course less critical/more risky to dive into than a pinion who's nut has loosened up) but I went ahead pulled the nut, flange & seal, put new seal in, and then torqued to about 100ft/lbs. No idea if its a crush washer or solid spacer but either way 100lb/ft shouldn't crush the washer any more if thats what's there. About 10k miles on that and still working well and no more leaks!
 
subzali

subzali

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coax said:
I'll give two thoughts:

1. Re: retorque-ing a loose pinion nut. If the nut is that loose, there really is not much preload on that bearing, which isn't a good state for it to be in. The proper way to sort that is to pull the 3rd and set it up. However, like ToolsRUs said on 'mud--just tighten it back up because if it works, great! If not, you are right back to having to pull the 3rd anyway, so not much sense in starting by pulling the 3rd. If the bearing gets upset you'll hear about it and can pull it all out and fix.
2. My sample size of 1 yielded good results. I had a leaky pinion seal (which is of course less critical/more risky to dive into than a pinion who's nut has loosened up) but I went ahead pulled the nut, flange & seal, put new seal in, and then torqued to about 100ft/lbs. No idea if its a crush washer or solid spacer but either way 100lb/ft shouldn't crush the washer any more if thats what's there. About 10k miles on that and still working well and no more leaks!
Click to expand...
That's exactly what I've debated. With a little nudging between you and Mr. Zepp, I might just replace the seal and run with it.

I'm still curious who one might choose to send it to if it does require a rebuild. I guess I would look to Zuk above all others unless told otherwise.
 
coax

coax

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I’ve only had experience w zuk and Robbie. Both were great. Doing locally sure is more convenient vs sending out and back in a big tub. Shipping is crazy expensive right now.

ive no recommendations for others locally now that Robbie isnt an option, sorry :(
 
rover67

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subzali

subzali

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So, seemingly no more vibes.

-new u-joints
-tightened pinion nut (Bill discovered it was loose) (~8 in lb preload, manual says 4.3-6.9 in lb with a reuse bearing, but allows for higher with a new bearing)
-put driveshaft in phase instead of out of phase (Bill wanted to though I know what the FSM says). Figured what the heck I’ll give it a try

so it was one of those three things.

Bill also took out some excessive runout in the shaft, so as to require less weight to balance.
 
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