12-bolt pinion nut torque question - Chevelle Tech
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post #1 of 15 (permalink) Old Jul 11th, 19, 10:06 PM Thread Starter
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Steve
 
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12-bolt pinion nut torque question

Hi. I just finally got around to replacing my leaky pinion yoke on my used 12-bolt with 4.10 gears (see thread here: https://www.chevelles.com/forums/33-...ce-wanted.html) and have a question about the pinion nut torque.

Before I replaced the yoke and put on a new nut, I measured the specs with a dial indicator and a in-lb torque wrench. It had about 0.0011 backlash (I've been told that is ok for a used gearset) and about 15-20 in-lbs of preload on the pinion bearing (measured by turning the pinion gear with an in-lb torque wrench and watching the breakaway load.)

Then, I used my impact gun to remove the old pinion nut. It flew off - wasn't very tight apparently (this will be important.)

I then pulled out the old yoke, old pinion seal, cleaned things up, checked the front pinion bearing (it seems just fine), put in a new pinion seal, put on the new yoke after applying a little black RTV.

I then used the old thick washer and a new pinion nut and tightened down the nut. Here is my question. It only took 35 ft-lbs of torque to get back to around 15-20 in-lbs of preload on the pinion bearing (again, measured turning the pinion gear with an in-lb torque wrench and watching the breakaway load.) Backlash still measured the same, right around 0.0011.

So, my question is - is only 35-ft lbs of torque on the pinion nut ok? Going any more than 35 ft-lbs on the nut quickly gets the bearing preload increasing significantly. I didn't measure it, but as mentioned above, apparently the old pinion nut was not very tight either.

I didn't loctite the nut because it was dimpled, and I thought I would be tightening it much more. I can always take it off and loctite it for more security.

Any thoughts on what to do here?

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #2 of 15 (permalink) Old Jul 11th, 19, 10:15 PM
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Chris
 
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Re: 12-bolt pinion nut torque question

One of the team members told me to torque it to 150 ft lbs and run it. This was when replacing my pinion yoke, not during a rebuild.

Moser said because my Moser 12 bolt doesnt have a crush sleeve, that they torque to 250 ft lbs!.

1971 Chevelle SS454, T56 Magnum 6 speed, 3.31 Posi

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post #3 of 15 (permalink) Old Jul 11th, 19, 10:21 PM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

Yup, that was what I have been told as well, and it was my plan originally. But if I do that, it puts an insane amount of preload on the pinion bearings (on the order of 60 in-lbs!) I don't want to burn out the bearings with them that tight.

And I figured it was safer to put them back to where they were when I started in the 15-20 in-lb range (which appears to be a reasonable range) - but it only took 35 ft-lbs on the pinion nut to get there.

Quote:
Originally Posted by -SS454- View Post
One of the team members told me to torque it to 150 ft lbs and run it. This was when replacing my pinion yoke, not during a rebuild.

Moser said because my Moser 12 bolt doesnt have a crush sleeve, that they torque to 250 ft lbs!.

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #4 of 15 (permalink) Old Jul 11th, 19, 10:27 PM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

BTW - just a thought - would it make sense to get a solid spacer and shim kit, and just pull out the crush sleeve, and replace it with a spacer, and shim it until I get the proper bearing preload with the requisite 125-150 ft-lbs of torque on the pinion nut?

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #5 of 15 (permalink) Old Jul 11th, 19, 10:58 PM
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Randy
 
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Re: 12-bolt pinion nut torque question

Quote:
Originally Posted by lucifershammer View Post
BTW - just a thought - would it make sense to get a solid spacer and shim kit, and just pull out the crush sleeve, and replace it with a spacer, and shim it until I get the proper bearing preload with the requisite 125-150 ft-lbs of torque on the pinion nut?
^^This is what I would do/did.
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post #6 of 15 (permalink) Old Jul 11th, 19, 11:32 PM
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mike
 
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Re: 12-bolt pinion nut torque question

FWIW, nothing you do will change the backlash, and it is way too tight.
Preload should be taken with out ring gear.
That being said, it should take way more than 35lbs to start crushing the sleeve again, make sure your seal isn't rubbing.
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post #7 of 15 (permalink) Old Jul 11th, 19, 11:47 PM
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Gary
 
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Re: 12-bolt pinion nut torque question

if everything is seated properlyand it should be since it was running your crush sleeve has been over crushed if you get the right bearing preload with only 35 lbs. that's not much more than finger tight on a nut that size . it will come loose. unfortunately it needs to come apart and a new crush sleeve installed. i have used a thin washer under the old crush sleeve before but best to get a new one
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post #8 of 15 (permalink) Old Jul 12th, 19, 12:10 AM
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mike
 
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Re: 12-bolt pinion nut torque question

I don't think your nut is tightened enough to remove the free play yet?
You can....1 Hold yoke, tighten to 100-125ft lbs
2 remove ring gear, tighten nut to around 9-11in lbs.....rotating....not breakaway.
3 remove ring gear, replace sleeve, tighten to 9-11 in lbs.
or use shim pack.

BTW, I think backlash is .011? not .0011 you should be good

Edit....I had to use Ratech 6109 seal on mine to avoid rubbing
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post #9 of 15 (permalink) Old Jul 12th, 19, 6:15 AM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

Quote:
Originally Posted by gnicholson View Post
if everything is seated properlyand it should be since it was running your crush sleeve has been over crushed if you get the right bearing preload with only 35 lbs. that's not much more than finger tight on a nut that size . it will come loose. unfortunately it needs to come apart and a new crush sleeve installed. i have used a thin washer under the old crush sleeve before but best to get a new one
That's exactly what my theory is - some PO must have crushed the sleeve just a little too much, which is why the old pinion nut was on there as loose as it was (and I guess lucky for them, it didn't come off.)

There is no rubbing, I did use the Ratech 6109 pinion seal (which is short enough to not hit the bearing) and if I crank the nut to anything more than 35 ft-lbs, preload shoots sky high.

I ordered up a solid spacer and shim kit. When it arrives, I'll pull it apart, get the shims set correctly so I can put the proper torque on the nut, and then put it back together.

Luckily, I'm paranoid, and figured that something could go wrong, so I ordered 2 pinion seals so I would have a spare. Looks like I'm going to be using that spare as I'll have to remove the one I just installed...

Thanks all.

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #10 of 15 (permalink) Old Jul 12th, 19, 6:20 AM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

Yeah, too many 0's.

0.011 backlash.

I did use the Ratech 6109 seal. I am also using a pinion yoke holding tool (bolt it to the yoke, hold it with a breaker bar while I put the torque wrench on the pinion nut.)

If I go more than 35 ft lbs on the nut, preload goes through the roof, quickly. I knew it was bad because even with no axles installed, you pretty much need two hands to turn the pinion by hand. The highest I tried was 100 ft lbs, and it was that bad, and you could almost feel the pinion bearings binding up. I suspect a PO at some point crushed it just a little too much and just ran with the nut looser than it should be.

Quote:
Originally Posted by slowmo55ss View Post
I don't think your nut is tightened enough to remove the free play yet?
You can....1 Hold yoke, tighten to 100-125ft lbs
2 remove ring gear, tighten nut to around 9-11in lbs.....rotating....not breakaway.
3 remove ring gear, replace sleeve, tighten to 9-11 in lbs.
or use shim pack.

BTW, I think backlash is .011? not .0011 you should be good

Edit....I had to use Ratech 6109 seal on mine to avoid rubbing

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #11 of 15 (permalink) Old Jul 12th, 19, 7:43 AM
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Freddie
 
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Re: 12-bolt pinion nut torque question

There is no need to remove the pinion seal to replace the spacer. The spacer will come out with the pinion when you remove it. I agree that someone tightened it too much and ruined the crush space that is it there now. Seems like you are already on the right path to fix it.
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post #12 of 15 (permalink) Old Jul 12th, 19, 11:50 AM
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Re: 12-bolt pinion nut torque question

I see, remember to preload pinion by itself, on the rotation @ used brg. specs.
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post #13 of 15 (permalink) Old Jul 15th, 19, 2:56 PM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

I just realized - Doh! I do have to remove the pinion seal. You're supposed to set the pinion preload without the seal or carrier installed, and then install the seal, new pinion nut and then the carrier and double check the backlash.

So, this is my plan as of right now (once the parts arrive):

Carefully disassemble and peek at it all looking for any signs of bad bearings or other ugliness.
Remove pinion seal.
Use old pinion nut to set preload using new solid spacer and shims (might take a few tries) getting preload to approx. 10 in-lbs (using old bearings) without seal or carrier installed and using 125 ft-lbs of torque on the pinion nut (since I'm using the solid spacer and shims, and this is what they call out for pinion nut torque.)
Install new pinion seal, torque down pinion nut to 125 ft-lbs and check pinion preload (open question - how much should I expect the pinion seal to add to the preload?)
Reinstall carrier with carrier shims exactly where they were, torque caps down to 60 ft-lbs.
Check backlash hasn't changed (it shouldn't, but I'm paranoid so I'll check it anyway.)



Quote:
Originally Posted by big gear head View Post
There is no need to remove the pinion seal to replace the spacer. The spacer will come out with the pinion when you remove it. I agree that someone tightened it too much and ruined the crush space that is it there now. Seems like you are already on the right path to fix it.

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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post #14 of 15 (permalink) Old Jul 15th, 19, 5:06 PM
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Freddie
 
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Re: 12-bolt pinion nut torque question

You can not set the final pinion bearing preload without installing the seal first when using a crush spacer. You just can't do it. It's a little different situation when using a solid pinion spacer, but still no need to remove the seal. Don't remove the seal to set your pinion bearing preload. Just be sure that the seal is not dry and set the preload to the required spec.

I know that a solid spacer is supposed to cure a lot of things, but don't be fooled into thinking that you can tighten the nut as much as you want and not change the preload. I know a lot of people think that they can install a solid spacer and then tighten the nut as much as they want if they have to replace the seal or yoke. That is not true. You can make adjustments to the preload by tightening the nut more. I usually go at least 150 foot pounds when using a solid spacer, but you can add a few more inch pounds of preload by going as high as 200 foot pounds on the nut. The 9 inch Ford uses 200 foot pounds of torque on the nut when using a solid spacer. If you find yourself with not quite enough preload with one set of shims, but too much preload by removing .001 from the shims then go with the thicker shims and tighten the nut some more.
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post #15 of 15 (permalink) Old Jul 15th, 19, 8:10 PM Thread Starter
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Steve
 
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Re: 12-bolt pinion nut torque question

Gotcha, thanks Freddie - I'll do this once the parts are in and let you know how it goes.

I got the solid spacer and shims today, but since I already used the new pinion nut before I found the problem, that one is now an old pinion nut, so I ordered another one (two to be safe ) and now I'm waiting on them... I can do everything except the final pinion nut install, which means I must wait.

Quote:
Originally Posted by big gear head View Post
You can not set the final pinion bearing preload without installing the seal first when using a crush spacer. You just can't do it. It's a little different situation when using a solid pinion spacer, but still no need to remove the seal. Don't remove the seal to set your pinion bearing preload. Just be sure that the seal is not dry and set the preload to the required spec.

I know that a solid spacer is supposed to cure a lot of things, but don't be fooled into thinking that you can tighten the nut as much as you want and not change the preload. I know a lot of people think that they can install a solid spacer and then tighten the nut as much as they want if they have to replace the seal or yoke. That is not true. You can make adjustments to the preload by tightening the nut more. I usually go at least 150 foot pounds when using a solid spacer, but you can add a few more inch pounds of preload by going as high as 200 foot pounds on the nut. The 9 inch Ford uses 200 foot pounds of torque on the nut when using a solid spacer. If you find yourself with not quite enough preload with one set of shims, but too much preload by removing .001 from the shims then go with the thicker shims and tighten the nut some more.

1972 Chevelle, 454, 2004r, 3.08
1981 Camaro Z28, 355, TH350, 3.73
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