What size thread is a 1971 pinion nut.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 146
Likes: 4
From: Penville On.
What size thread is a 1971 pinion nut.
I am replacing my leaking pinion seal on my 71 BB. Got everything apart. The pinion nut was real tight all the way off. I know I should put on a new nut but I will lose my reference mark if I do. I would like to just run a tap into the nut to clean up the threads. It looks like a 7/8/14 to me. Anybody know for sure?
Thanks Jackhttp://images.ibsrv.net/ibsrv/res/src:forums.corvetteforum.com/get/images/smilies/Cdnsmilie.gif
Thanks Jackhttp://images.ibsrv.net/ibsrv/res/src:forums.corvetteforum.com/get/images/smilies/Cdnsmilie.gif
Pro
Joined: Feb 2008
Posts: 556
Likes: 13
From: C3 Forum, Colorado
No tap.
The pinion nut is a locking nut and is supposed to be real tight all the way on and all the way off.
Some people suggest replacing the nut anytime it's removed but I think that's a little extreme.
Just reuse the nut and don't use a tap on it.
Some people suggest replacing the nut anytime it's removed but I think that's a little extreme.
Just reuse the nut and don't use a tap on it.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 146
Likes: 4
From: Penville On.
Jack
:
Melting Slicks
Joined: Nov 2001
Posts: 2,668
Likes: 43
From: Eastern US XX
That's because the last person to put it on stripped it! This happens a lot with this type of nut - people don't pay enough attention and keep tightening when the nut is completely on.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
16 thread pitch reading on my gauge for a spare pinion out of my '69. So my guess is 7/8" by 16 tpi.
Last edited by 69 Chevy; Mar 6, 2012 at 10:07 AM.
Thread Starter
Instructor
Joined: Dec 2009
Posts: 146
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From: Penville On.
[QUOTE=69 Chevy;1580200350]If they did that, they would collapse the crush sleeve and the ring & pinion would not be aligned correctly.
16 thread pitch reading on my gauge for a spare pinion out of my '69. So my guess is 7/8" by 16 tpi.[/QUOTE
I think you are right, when I compare my 7/8 14 with the pinion, it is not not quite fine enough. Looking at the thread I don't think it is wise to reuse the old nut at all. Any way to approximate the original torque using a new nut? I am thinking that if I line up the helix of the threads on the old nut to the new one, and transfer the reference mark to the new one I should be close enough. Comments?
16 thread pitch reading on my gauge for a spare pinion out of my '69. So my guess is 7/8" by 16 tpi.[/QUOTE
I think you are right, when I compare my 7/8 14 with the pinion, it is not not quite fine enough. Looking at the thread I don't think it is wise to reuse the old nut at all. Any way to approximate the original torque using a new nut? I am thinking that if I line up the helix of the threads on the old nut to the new one, and transfer the reference mark to the new one I should be close enough. Comments?
Last edited by Jackk; Mar 6, 2012 at 11:39 AM. Reason: More Info.
Melting Slicks
Joined: Aug 2008
Posts: 2,200
Likes: 3
From: Lehigh county Pennsylvania
I'm no differential expert by any means. But I wouldn't use a torque reading when replacing that companion flange nut. I'd try to transfer your reference mark from the old nut. Although using a dial indicator on the inner end of the pinion would be best. Put some sealer like Permatex #2 on the companion flange splines...a leak there is often mistaken for a bad seal. Lock the flange from moving and tighten your nut. Take it glacially slow when approaching the number of revolutions you counted when removing the old nut. Stop when the dial indicator moves even the tiniest amount. That will bring you up snug to the crush sleeve and the relation of the pinion to the ring gear will not be compromised.
You did say you had 'everything apart.'
You did say you had 'everything apart.'
Thread Starter
Instructor
Joined: Dec 2009
Posts: 146
Likes: 4
From: Penville On.
I'm no differential expert by any means. But I wouldn't use a torque reading when replacing that companion flange nut. I'd try to transfer your reference mark from the old nut. Although using a dial indicator on the inner end of the pinion would be best. Put some sealer like Permatex #2 on the companion flange splines...a leak there is often mistaken for a bad seal. Lock the flange from moving and tighten your nut. Take it glacially slow when approaching the number of revolutions you counted when removing the old nut. Stop when the dial indicator moves even the tiniest amount. That will bring you up snug to the crush sleeve and the relation of the pinion to the ring gear will not be compromised.
You did say you had 'everything apart.'
You did say you had 'everything apart.'
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