Pinion splines leaking - advice wanted - Chevelle Tech
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post #1 of 23 (permalink) Old May 25th, 19, 9:55 PM Thread Starter
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Steve
 
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Pinion splines leaking - advice wanted

So, I've seen lots of threads and info on this, but have a few specific questions on this.

I have discovered the 12 bolt I picked up to put in my '72 is leaking from the pinion splines and coming out around the nut.

I am about to overhaul the rear end and put on new backing plates, axles, wheel studs, axle bearings and wheel seals. As far as I can tell, the 4.10 gear set and posi are in good shape and nice and tight so I wasn't going to mess with the pinion or carrier bearings, and I'll just clean up the rear cover gasket surface and install a new aluminum girdle cover.

I've currently got it sitting on a dolly/stand with the yoke down. It's been sitting that way since last fall after I drained the old nasty fluid out and put in about a quart of new fluid because I specifically wanted to check for a pinion seal leak, and it was fine all winter. In just in the past few days, it started to leak right at the pinion nut, a couple of drops. Definitely coming past the splines - there is fresh gear oil all around the pinion nut, but nothing coming around the outside of the seal.

Now, I know the best way to fix it would be to pull the yoke, put some RTV in the yoke splines (and not on the pinion splines) and then seal it all back up.

Question is - do I have to pull the yoke? Or is it possible to pull the nut and washer and just put some RTV behind the washer?

If I do pull the yoke, should I replace the pinion seal as well while I'm at it? It is not leaking now, and part of me says if it ain't broke, don't fix it, because replacing the seal might lead to a new seal leaking. If I were to pull the yoke and not replace the seal, I would do it super-careful to make sure I didn't mess up the seal (and if I did, then I would replace the seal.)

Thoughts/advice? Thanks!

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #2 of 23 (permalink) Old May 25th, 19, 10:19 PM
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Re: Pinion splines leaking - advice wanted

Steve, you need to pull the yoke and RTV the yoke splines. If it were mine I'd replace the seal while you're in there. Mark the nut so you can return it to original spot when you tighten things up.
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post #3 of 23 (permalink) Old May 26th, 19, 9:42 AM Thread Starter
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Re: Pinion splines leaking - advice wanted

Thanks. I assumed so but just had to ask.

Follow up questions.

I know to mark the yoke, nut and pinion shaft, remove the nut and yoke, remove the seal, put in new seal (will use Ratech 6109), put some RTV (I plan to use Ultra Black) on the yoke splines (but not the pinion) then put yoke back on in exact spot and then put washer and nut on, tighten to same spot and then go about 1/16" more.

Now, while I'm there, if I wanted to replace the yoke (say with a Strange U1602) to go to 1350 u-joints, my understanding is to do the same as above but since there are no reference marks, just torque the pinion nut down to between 120-150 ft lbs when I re-install. Oh and use a new pinion nut and washer while I'm at it too.

Sound about right?

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #4 of 23 (permalink) Old May 26th, 19, 9:49 AM
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Re: Pinion splines leaking - advice wanted

Pulling the yolk may be the best way but I have removed the nut & washer, brake cleaned the splines & washer, rtv on washer. It fixed the leak for me.
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post #5 of 23 (permalink) Old May 26th, 19, 10:01 AM
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Re: Pinion splines leaking - advice wanted

I wouldn't replace the washer if it still has the original thick GM washer on it. I've seen people have a lot of problems with some of the replacement washers. The thin washers do not work and cause major problems. I don't know why some of the manufacturers supply these thin washers with new yokes.
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post #6 of 23 (permalink) Old May 26th, 19, 2:20 PM
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Re: Pinion splines leaking - advice wanted

I never use silicone i always use permatex thread sealant on the splines.

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post #7 of 23 (permalink) Old May 26th, 19, 3:55 PM
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Re: Pinion splines leaking - advice wanted

Either one will wok fine. GM uses thread sealant on the splines, but I've used RTV silicone for many years with no problems.
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post #8 of 23 (permalink) Old Jul 13th, 19, 2:49 PM
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Re: Pinion splines leaking - advice wanted

Quote:
Originally Posted by big gear head View Post
Either one will wok fine. GM uses thread sealant on the splines, but I've used RTV silicone for many years with no problems.
I am planning on replacing the entire rear in my car once I get the posi redone. For now..on the rear that is currently in the car I have a leak out of the pinion area. I can't tell if it is the seal itself or the splines that are leaking. I want to drive the car until the new rear is ready then do a quick R&R of the 3rd member. Any idea how I can tell what is happening as far as pinion splines or the seal itself? Either way I gotta take the flange off but I am wondering how one can determine which area may be leaking. Again the solution is more or less the same and I will do the seal once the flange is off. Just curiosity.

As to replacing the seal....years and years ago I did one on a BPO rear in my GTO. I marked the pinion and the nut with a punch..pulled the flange, redid the seal and put it back together. Cannot remember if I sealed the splines...too long ago to recall.I tightened the nut just a bit past where the marks were and drove the car for 20K / 30K miles with no issues until I sold the car. Any tips / suggestions / precautions suggested on this short term seal replacement appreciated. I don't want to chance messing up the rear that is currently in the car. It is a 65 / 66 12 bolt with a 3.31 gear set and it works just fine so I want to preserve it in that condition for later sale.
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post #9 of 23 (permalink) Old Jul 13th, 19, 3:07 PM
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Re: Pinion splines leaking - advice wanted

I think we overwork this repair. Mark the yoke..... pull it off, replace seal and reassemble with sealant on the yoke splines. Been done for years.
I prefer a new nut and thick washer.

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post #10 of 23 (permalink) Old Jul 13th, 19, 3:31 PM
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Re: Pinion splines leaking - advice wanted

Quote:
Originally Posted by LevonH View Post
I think we overwork this repair. Mark the yoke..... pull it off, replace seal and reassemble with sealant on the yoke splines. Been done for years.
I prefer a new nut and thick washer.
How are ya doing up there? Hope all is well.

I do think folks (me included) over think things all to often. Older I get the worst it gets. That said there are lots of "yeah but" or "I tried...and... " comments in some posts on various topics here. Given that Freddy says this is more or less easy and given that I have done it once (with lots less overthinking cause I was young and foolish then) I am going to do it as soon as I get a seal. BGH cautions about this method when replacing the flange but gave it a thumbs up when only the seal is being changed. Going to Atl. airport tomorrow to pick someone up so I will run down to Summit, it is only an extra 10 mile drive for me.
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post #11 of 23 (permalink) Old Jul 13th, 19, 4:13 PM Thread Starter
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Re: Pinion splines leaking - advice wanted

Just a heads up, but see my other thread on this. I had just done this, and made sure I was double checking everything.

Good thing I did. I found that a PO had crushed up the crush collar a little too much and was running the pinion with only about 35 ft lbs on the pinion nut. If I had just slapped the seal in and cranked the yoke back on to 100-150 ft lbs of torque without checking everything, it would have put way too much stress on the bearings and burnt em up.

So, I would agree, the simple way works many times. In my case, I'm glad I checked because the simple way would have wrecked my rear end.

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #12 of 23 (permalink) Old Jul 13th, 19, 4:33 PM
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Re: Pinion splines leaking - advice wanted

Quote:
Originally Posted by lucifershammer View Post
Just a heads up, but see my other thread on this. I had just done this, and made sure I was double checking everything.

Good thing I did. I found that a PO had crushed up the crush collar a little too much and was running the pinion with only about 35 ft lbs on the pinion nut. If I had just slapped the seal in and cranked the yoke back on to 100-150 ft lbs of torque without checking everything, it would have put way too much stress on the bearings and burnt em up.

So, I would agree, the simple way works many times. In my case, I'm glad I checked because the simple way would have wrecked my rear end.
Both rears I am working on are factory set up rears.

With the exception of a few real pros my experience has been that nobody (even GM dealer techs) can do this set up work right. Maybe they were (back in the day) hell bent on beating flat rate, maybe they just were not trained and experienced enough. Today I doubt a dealer shop would even think about setting up one of these dinosaurs. I had more than one howler set up at different dealers before I learned my lesson. Rotate in an entire 3rd member and forget all the BS related to having dealer guys set these rears up. Today finding a stock rear that has not been screwed with is harder and harder. I have had two 12 bolts in storage since the mid 80's when I picked them up at a junk yard (not an automotive recycling center) for $150 each. They have been sitting high and dry in inside storage since then.

Folks who really know what they are doing like BGH or Tom Lowe (RIP) are few and far between! They may be out there but like I said "few and far between".

Going to stop by Summit and get a Ratech 6109 and a Strange R5211D. ...will report back .
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post #13 of 23 (permalink) Old Jul 13th, 19, 5:18 PM Thread Starter
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Re: Pinion splines leaking - advice wanted

The Ratech 6019 worked perfectly for me. It was the "slightly too crushed" crush collar that threw a wrench in my plans - now I'm just waiting for a solid spacer and shim kit and I'm going to replace the crush collar and button it all back up.

Quote:
Originally Posted by oman View Post
Both rears I am working on are factory set up rears.

With the exception of a few real pros my experience has been that nobody (even GM dealer techs) can do this set up work right. Maybe they were (back in the day) hell bent on beating flat rate, maybe they just were not trained and experienced enough. Today I doubt a dealer shop would even think about setting up one of these dinosaurs. I had more than one howler set up at different dealers before I learned my lesson. Rotate in an entire 3rd member and forget all the BS related to having dealer guys set these rears up. Today finding a stock rear that has not been screwed with is harder and harder. I have had two 12 bolts in storage since the mid 80's when I picked them up at a junk yard (not an automotive recycling center) for $150 each. They have been sitting high and dry in inside storage since then.

Folks who really know what they are doing like BGH or Tom Lowe (RIP) are few and far between! They may be out there but like I said "few and far between".

Going to stop by Summit and get a Ratech 6109 and a Strange R5211D. ...will report back .

1972 Chevelle, 454, 2004r, 4.10
1981 Camaro Z28, 355, TH350, 3.73
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post #14 of 23 (permalink) Old Jul 13th, 19, 8:54 PM
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Re: Pinion splines leaking - advice wanted

Quote:
Originally Posted by oman View Post
How are ya doing up there? Hope all is well.

I do think folks (me included) over think things all to often. Older I get the worst it gets. That said there are lots of "yeah but" or "I tried...and... " comments in some posts on various topics here. Given that Freddy says this is more or less easy and given that I have done it once (with lots less overthinking cause I was young and foolish then) I am going to do it as soon as I get a seal. BGH cautions about this method when replacing the flange but gave it a thumbs up when only the seal is being changed. Going to Atl. airport tomorrow to pick someone up so I will run down to Summit, it is only an extra 10 mile drive for me.

Ray, I'm doing fine. Loving the ZL1 and all it offers.


In my years of doing this stuff, I have followed BGH, Freddy et al advice. One other item is to check the seating of the U-joint in the yoke. They spread with age/use and the joint becomes loose in the seat of the yoke. This can set up a vibration at the rear which may be contributing to the cause of the leaks.

Levon Hovagimian
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post #15 of 23 (permalink) Old Jul 14th, 19, 9:11 AM
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Re: Pinion splines leaking - advice wanted

About dealerships working on rears...... I purchased my daughter a used Jeep from the dealership. A very well maintained cream puff Liberty, that had a pinion seal leak. I negotiated the dealer to replace the seal as a condition of the sale.

Several months, and a thousand miles later, she was driving me someplace and I heard the horrendous bearing noise. The dealership screwed up the pinion preload and toasted both bearings. Awesome!

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