Replaced pinion seal but did I do it right?
 

After reading and watching videos I replaced a leaky pinion seal today. It was super easy if I did it right.

Marked the yoke, nut and housing, then counted 1-1/2 threads showing so I'd know how far to go when putting it back together. I pulled the nut using an impact so I can't say how tight the nut was but it zipped it off without a problem.

When I put it back together I used a 1/2" drive ratchet and ran it up til the marks were lined up and 1-1/2 threads were showing past the nut, same as before. I felt a little resistance but I never felt the nut get tight. Almost snug maybe but nowhere near tight. I'd say it was similar to setting a crown nut on the spindle after changing a wheel bearing - except using marks and threads as a guide.

I know it's critical to set it right but for some reason I thought it would be tighter.

This may be a dumb question but does my description of the reassembly sound right? If not what should the nut feel like going back on?


Thanks

Re: Replaced pinion seal but did I do it right?
 

Best way is to mark pinion verse nut . I did not see where you marked the pinion . I take a Sharp chisel and mark the pinion and nut . Yoke to housing can move and give false reading . If you can still turn the nut buy a ratchet it is still to loose . I usually have to hit it a couple times with a impact to get the marks to line back up .

At this point I would tighten it as much as you can with the ratchet . Counting threads don't get it . We are only talking 1/8 of a turn difference if that to be correct . Then bump it with a impact or with a breaker bar . Most will tighten it past about 1/16 of a turn past the original .

Re: Replaced pinion seal but did I do it right?
 

The few I've done, I used the same process but they were older axles with plenty of miles on them so I tightened the nut just a hair past where it had been. That's been at least 10K miles ago (more like 40K on my C3500's FF 14 bolt) and they're still running quiet.

Re: Replaced pinion seal but did I do it right?
 

I left that out by mistake but I did mark it. Even though it didn't feel right I put it back like it was because that's what I thought I was supposed to do. I'll pull the driveshaft and snug it up some more but I'm entering uncharted water since I don't know how much is too much.

Re: Replaced pinion seal but did I do it right?
 

That nut will feel tight when it's back into it's original position. This is the point where it's trying to compress the crush sleeve.

Re: Replaced pinion seal but did I do it right?
 

I think the nut should be fairly tight. The pinion depth is set by the shims isn't it? I'm not an axle guy but I have replaced a seal or two and I tightened them to roughly 50-70 ft lbs.

Re: Replaced pinion seal but did I do it right?
 

The depth is set with a shim but the bearing preload is set with the nut compressing a crush sleeve. The nut is self locking.

The effort to crush the sleeve is significant. I would estimated hundreds of pounds of torque on the nut to crush the sleeve.

My technique is using an 1/2 impact and watching the point at which the socket meets resistance. This is the point the nut came off.

Re: Replaced pinion seal but did I do it right?
 

"Fairly tight," and "self locking." So am I hearing right that I should go back tight and not worry about the thread count or marks? Right now it's just snugged up to the thread count prior to removal. It's loose enough that I could take it back off with a 3/8 drive ratchet if I had to.

The thought that the bearing could be worn or maybe just loose crossed my mind when I removed the nut because it didn't fight the impact much at all. I have heard a slight whine at highway speed that goes away when I let off the throttle. Not sure how long it's been there because I have to listen hard to hear it.

I'm not driving the truck until I get it figured out so at least I won't be making it worse.

Thanks for the info!

Re: Replaced pinion seal but did I do it right?
 

I would un-bolt the driveshaft from the yoke and see if you have any in and out play (axial). There should be zero!

Re: Replaced pinion seal but did I do it right?
 

The crush sleeve is not re-usable. The correct way would be to replace the crush sleeve and pinion nut. Then tighten down until you reach the bearing pre-load of 12-14 inch-pound- that means it takes 12-14 inch-pounds to turn the yoke.

Re: Replaced pinion seal but did I do it right?
 

I'd believe that if it was spelled out in the service manual but it is not. The warranty time to replace the seal is like .5 hour. Nobody is going to completely dissemble the axle to replace a pinion seal.

Re: Replaced pinion seal but did I do it right?
 

Okay. Pulled the driveshaft off and checked the nut. It was a half turn from being tight so I ran it up until I hit a hard stop the gave it a couple of hard grunts. There was no in-out play at all.

Went for a drive and there were no leaks so hopefully it's fixed. Still has a very slight whine at highway speed that goes away when I let off the gas. It had 104K miles when I got it and has 108K now. It may have had the whine when I got it but I never listened for it until now.

Do these old diffs take any special kind of 90W oil? It's an open 3.73 and I changed the old oil months ago using regular Valvoline gear oil. Not limited slip or synthetic.

Re: Replaced pinion seal but did I do it right?
 

Sounds like the OP's axle should be disassembled anyway.......
Without a new crush sleeve there's no way to get the pinion bearing pre-load right. If you know what you're doing you might get it close enough to get by, I know.

Re: Replaced pinion seal but did I do it right?
 

That's a possibility. I've never rebuilt a diff before so it may be safer in the long run to find a complete replacement and do a drop and swap. I've checked my closest wrecking yards and so far have come up empty handed.

I wouldn't mind tearing it apart if I had one to practice on first but this is the only one I've got. If I screw it up I could end up worse than when I started. From what little I know about rearends, if they are not done perfectly the whole thing is screwed

What year range would be are interchangable? I saw an 81 C-10 parked behind a house but no one answered the door.

I'm assuming not 70's-80's are 12 bolt?? Mine has a 2 pc driveshaft. I had a 77 LWB that had a 1 pc but don't remember much about the diff other than it had 3.08 gears and lasted 180,000 miles. That was a very long time ago.

Re: Replaced pinion seal but did I do it right?
 

What year of truck are you working on?

The truck 12 bolt was used '63-'82 on the C/K series and the truck 10 bolt '79-'86 in the C/K series and '87-'91 in the R/V series.

Re: Replaced pinion seal but did I do it right?
 

74 long bed C10 454, TH400

I wasn't aware they went to 82. Would a 12 bolt between 63-82 be a straight swap? If so my odds may not be as bad as I thought.
Thanks!

Re: Replaced pinion seal but did I do it right?
 

There is no need to replace the crush sleeve when doing a seal swap. It is crushed to the correct spacer length for preload when it is assembled. Tightening it back down as tight as you can get it with a standard 1/2” ratchet will be fine. Unless it has unusual bearing wear, it will be good for years. If there is a part you should consider replacing it is the pinion nut. They lose a lot of the locking characteristics on re-use.

Re: Replaced pinion seal but did I do it right?
 

Other than a very slight whine at highway speed it seems fine. It may be from the bearing but it's hard to say for sure. I can't feel any end play at all.

I'm hoping it lasts many more miles, but if I could find a complete diff with gears somewhere between 3.08 - 3.42 I'd like to swap it out. I don't need the 3.73s and it sucks gas like it's still 1974 when gas was $.32 a gallon. It's not terrible bad if I keep my foot out of it, but it doesn't take many squirts to drop the MPG from 10 to 7

I really appreciate the helpful info!
Randy.

Re: Replaced pinion seal but did I do it right?
 

A '73-'82 truck 12 bolt would be a direct bolt in into your truck. Also a '79-'87 10 bolt would be as well, but you may need a different u-joint?

Re: Replaced pinion seal but did I do it right?
 

E-Brake cables too? That would be great. I don't think the rearend going to grenade anytime soon but I'd sure like an excuse to get rid of those 3.73's. I wouldn't expect any great bump in MPG but I like to run 70+ on the highway but don't want to run 3300 RPM to do it. MPG drops from 10 to about 7 when it reaches 3000.

Re: Replaced pinion seal but did I do it right?
 

Qq..........

Re: Replaced pinion seal but did I do it right?
 

[QUOTE=YoungPup1977;8271793]A good used rear with 3.08 gears may help that 454 out on gas mileage, you might get an extra mile out of it....the thing about used rear ends is you really dont know if it has noise in it or any issues until you install it....than you back replacing the pinion seal and/or anything else thats bad, thats how you got here in the first place....

bearing kit = 100 bucks, 3.08 gears = 189 bucks plus you have the free forum to build this rear for ya.... how much is a used rear end that is perfect ?

This is only an opinion of mine with used stuff, I rebuild things and do not put used stuff in my vehicles......than I know what I have if I want to drive my vehicle cross country....[/QUOT

Thanks for the reply. I'm not really expecting MPG miracles with the 454 but would like to see RPM below 3K at highway speed. That's probably more of a want than a need but I do know the MPG jumps fro 8 to a whopping 10.5 if I stay around 2600.

I found a 12 bolt about 2 miles from me for $300. It's in an 81 C10 but I don't know the axle ratio. The truck has been parted out so no glove box sticker. There are no obvious leaks but you're 100% right about buying used parts - it's a dice roll.

To shift the topic a little I bought the truck last fall as a project and would normally go for new without much thought. It was a runner when I bought it but very neglected. I've taken care of the mechanical and maintenance issues and now have\had a reliable, albeit ugly, daily driver. Now my plan is on hold....

My job was eliminated after a buyout and I now spend a lot of time on the fence with some of the more costly decisions. I'm not in a bind but with no income my priorities have naturally changed. I still work on it but for now the needs outweigh the wants.

What I'd like to do is keep it running until I can resume the body work, trim, etc. Right now my conscience won't let me drop a crap load of money in it, but if it would I'd rather rebuild it myself. Never rebuilt one before but everybody starts somewhere and this forum is a living encyclopedia of knowledge.

The diff isn't shot but I'm now certain that's where that slight whine is coming from. What I don't know if it has 50 or 50,000 miles left in it.

Re: Replaced pinion seal but did I do it right?
 

I guess its all about how lucky you are at dice.....I dont play dice games, I never was very lucky. Good Luck !!

Re: Replaced pinion seal but did I do it right?
 

It's nice to avoid the table and go straight to the store but I'm at a point where I have to play or leave the game, and I don't like either option.

Re: Replaced pinion seal but did I do it right?
 

Qq........