Replaced pinion seal but did I do it right?

[BigRandy]

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

[homemade87]

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 .

[BigRandy]

Originally Posted by homemade87

Best way is to mark pinion verse nut . I did not see where you marked the pinion .l .

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.

[Alex V.]

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.

[Bigdav160]

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.

[cadillac_al]

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.

[Bigdav160]

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.

[BigRandy]

"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!

[Bigdav160]

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

[ElKotze]

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.

[Bigdav160]

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.

[ElKotze]

Originally Posted by Bigdav160

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.

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.

[BigRandy]

Originally Posted by ElKotze

Sounds like the OP's axle should be disassembled anyway.......
.

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.

[Captainfab]

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.

[BigRandy]

Originally Posted by Captainfab

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.

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!

[BigRandy]

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.

[YoungPup1977]

Qq........

[BigRandy]

Originally Posted by YoungPup1977

by any chance when you had the pinion seal out, did you pull the front pinion bearing out to see if it was bad along with looking at the front pinion bearing race in the housing....the whine could be a bad bearing going south on ya....

with the leaking seal, maybe the axle "wheel" bearings were not being lubed the way they should be and ya got a bad wheel bearing....just a thought.

I would suggest to take the rear cover off, and pull the axles and pull the carrier, along with pulling the pinion out of it to inspect the bearings....a bad bearing should show its ugly arse.....this way you would know for sure before spending 300 bucks for used stuff...a bearing/gasket/gear oil may only cost ya 50 bucks...seems to me if cash is a issue this would be the chosen path....only labor on tearing it a part and if there is no bad bearing....option B.....

Good info.

I'm not planning a swap until I've had a look inside and verify what's what. If it is hosed I'd take a shot at fixing it myself if I had a way to press the bearing off. I could always see if one of the shops would do it.

I've been around part swappers most of my life and really don't like replacing anything can be fixed as long as it's done right. Lots of people I know start replacing things without understanding them. I'd much prefer to fix the rearend than replace it but will have to see what I have to work with.

The money really isn't a huge deal - not at the moment anyway. I'm just not one to spend much on my hobby when I don't have money coming in.

[YoungPup1977]

so I guess you didnt check the front pinion bearing and race when you pulled the pinion seal out....with noises (whine) when letting off the gas vs noise (whine) getting on the gas mean different bearings could be defective......either pinion or carrier bearings, so once you have taken the carrier and pinion out of the housing, you can take them to a machine shop to have the bearings pressed off....again its easy for me to spend other peoples money but I would replace all the bearings meaning I would spend your money and buy the bearing kit to replace all bearings in this differential....GOOD LUCK !!!!!!

oh yea, I almost forgot the other reason for replacing the gears for a higher gear ratio to save on gas....I think you just fix the noise and forget about spending the money on getting different gears...454 CID, no matter what gears you use will only yield 12 miles to the gallon if you are lucky, if you use this truck as a daily maybe a honda is in your future....keep the truck for weekend activities....just an opinion, just like what we all sit on, everyone has one...

[BigRandy]

Originally Posted by YoungPup1977

so I guess you didnt check the front pinion bearing and race when you pulled the pinion seal out....with noises (whine) when letting off the gas vs noise (whine) getting on the gas mean different bearings could be defective......either pinion or carrier bearings, so once you have taken the carrier and pinion out of the housing, you can take them to a machine shop to have the bearings pressed off....again its easy for me to spend other peoples money but I would replace all the bearings meaning I would spend your money and buy the bearing kit to replace all bearings in this differential....GOOD LUCK !!!!!!

oh yea, I almost forgot the other reason for replacing the gears for a higher gear ratio to save on gas....I think you just fix the noise and forget about spending the money on getting different gears...454 CID, no matter what gears you use will only yield 12 miles to the gallon if you are lucky, if you use this truck as a daily maybe a honda is in your future....keep the truck for weekend activities....just an opinion, just like what we all sit on, everyone has one...

I did not check the bearings. Just tapped the new seal. Hindsight being what it is I know now that I should have. The whine is at speed when warm. It stops when I let off the gas.

My other truck is an F150 that stays parked most of the time. Not exactly sure why, but I just prefer driving the old Chevy for short trips. No Hondas for me.

The MPG isn't a huge concern. I can live with 10 and it will do that if I keep my foot out of it. Years ago I had a 73-454 and it got 11. I don't remember what gears it had but I do remember it got 11 most of the time and didn't seem to care if it was loaded or not. They may not have a ton of HP but they pull like a mule.

As soon as the temps drop back to double digits I'll pull the yoke and check the bearings. Thanks.

[Bigdav160]

The pinion bearings are pressed on to the pinion. There is no way to "inspect" the bearing without removing the pinion. At that point you are at least reconditioning the axle.

Was the whine there before the seal replacement? Then likely you had a bearing problem combined with the leak. Pinion bearings spin fast and are lubed by splash lubrication. They starve for lube when the axle is run low.

If the whine started after seal replacement it's likely the pinion bearing preload is off. Those tapered bearings are not tolerant of too much preload (nut too tight) and too loose they let the pinion walk back and forth messing with the meshing of the ring gear and pinion.

[YoungPup1977]

The front pinion bearing is not pressed on......

[Bigdav160]

Sure it is. But not as tight as the big bearing. It has to be to keep the inner race from spinning on the gear.

BTW, I am an old pup.

[YoungPup1977]

Originally Posted by Bigdav160

Sure it is. But not as tight as the big bearing. It has to be to keep the inner race from spinning on the gear.

BTW, I am an old pup.

Dont let the name fool ya...

So how do you PRESS the front bearing on when you install the pinion gear thru the housing ? The bearing has to slide onto the pinion NOT PRESSED on....

BTW, I am a experienced PUP.....

Its a tight fit for sure, but its not a PRESS ON fit......when he had the pinion seal removed he could of removed the front pinion bearing and inspect it along with the bearing race.....no press needed to remove this bearing....please dont confuse the situation.. thanks...

[Bigdav160]

Once the ring gear and case are removed does the pinion fall out?

No, you have to drive it out.

When reinstalling you have to use the yoke and nut to drive the front bearing back on the gear. It doesn't just slip on.

No disrespect meant. I was a transmission man at GM dealers for 15 years before I retired to teach auto repair.