Rear Pinion Seal (re-lash?)

[YeaImDylan]

Hey all, planning/wanting to do the rear pinion seal on my truck and while talking to my dad about it on the phone, he warned about having to re lash the diff after taking that big nut off (the one torqued to 450+ ft/lbs). Is this the case? Truck I'm almost certain has a Dana 80 due to it having the 6sp from factory. Any knowledge or tips or suggestions are appreciated!

 

Thank you all.

[Tractorman]

I replaced the pinion seal on my truck at 206,000 miles.  I couldn't get the nut off.  Broke big sockets trying.  I took the truck to a recommended shop and it took two of us over an hour to get the nut off.  After installing the new seal, the nut was re-tightened with a 3/4 inch drive air gun - no torque wrench.  That was over 160,000 miles ago.  No leaks or problems. 

 

- John

[YeaImDylan]

26 minutes ago, Tractorman said:

I replaced the pinion seal on my truck at 206,000 miles.  I couldn't get the nut off.  Broke big sockets trying.  I took the truck to a recommended shop and it took two of us over an hour to get the nut off.  After installing the new seal, the nut was re-tightened with a 3/4 inch drive air gun - no torque wrench.  That was over 160,000 miles ago.  No leaks or problems. 

 

- John

Thanks for the input! Yeah... I've heard they're a pain to get off! Sounds like you didn't burn up a diff from taking the nut off and lash getting messed up at all... I'm thinking these diffs are a bit different than my dad has owned. He hasn't owned a bigger axled vehicle like this and he's going off his knowledge and experience. I told him I was gonna do the rear wheel bearing seal and he thought I had to have the diff cover open to take a clip out etc lol

[Tractorman]

12 minutes ago, YeaImDylan said:

I told him I was gonna do the rear wheel bearing seal and he thought I had to have the diff cover open to take a clip out etc lol

 

Yes, it sounds like his experience has been with 1/2 ton vehicles.  I don't think he's had experience with full-floating axles.  I am familiar with the C-clips he is talking about in order to pull some semi-floating axles.  Also, many of those differentials used crush sleeves for setting the torque on the pinion bearing.  

 

Tightening the pinion nut does not set a preload on the pinion bearing on the differentials on our trucks.  I think the pinion nut has a torque of about 450 ft/lbs.

 

- John

[YeaImDylan]

6 minutes ago, Tractorman said:

 

Yes, it sounds like his experience has been with 1/2 ton vehicles.  I don't think he's had experience with full-floating axles.  I am familiar with the C-clips he is talking about in order to pull some semi-floating axles.  Also, many of those differentials used crush sleeves for setting the torque on the pinion bearing.  

 

Tightening the pinion nut does not set a preload on the pinion bearing on the differentials on our trucks.  I think the pinion nut has a torque of about 450 ft/lbs.

 

- John

Yes, 1/2's and cars hahaha. Did you check the pinion gear with a dial indicating torque wrench at all? Or is that not required either due to a preload not being set? I've heard of having to do that as well and you back it off until it moves at a certain ft-lb on the indicator wrench.

 

Also, I'm planning to do the rear wheel seal(s) on the truck tomorrow. I've seen guys just torque the lock nut back to x amount of lbs and I've seen guys torque it down and then back it off an 1/8 (one video had that). I'm having issues trying to figure out what procedure to use because I can't afford to have something burn up after work is complete. Truck already costs me enough! hahaha. Also, would you say it's fine to re use that locking nut?

[Tractorman]

I just reviewed the FSM for pinion seal replacement and rear wheel bearing adjustment.  

 

*  Pinion Seal

    *  Rear of truck on jack stands.  Remove rear wheels and brake pads.  Park brake released 

        Use inch-pound torque wrench and record torque required to turn the pinion nut 3 revolutions.

    *  After installing new seal, tighten pinion nut to 440 ft/lbs.

        Use inch-pound torque wrench and record torque required to turn the pinion nut 3 revolutions.  Compare to previous readings.  Should be the same or slightly higher (new seal).

 

So, that is technically how it should be done.  

 

*  Rear Wheel Bearing Adjustment 

    *  tighten wheel bearing nut to 120-140 ft/lbs, then back off 1/8 turn.

 

- John

 

 

 

 

 

[Max Tune]

What could a guy at home use to not only break the nut loose but more importantly, tourqe it back on. Is there anything out there that is reasonably priced as it would probably only be used once or twice.

 

 

Also, yes, you can reuse the nut as long as the plastic ring isn't all chewed up and after it's set, the keeper pin is going into unmolested section of plastic.

Edited September 17, 2022 by Max Tune
Additional thought

[Tractorman]

Possibly a 1" drive breaker bar accompanied with a cheater and the proper size socket.  Of course, a large pipe wrench will also be needed to hold the yoke from turning.

 

Torque could be guesstimated by calculating the lever length and calculating the force applied in pounds.

 

- John

[Max Tune]

😂😂😂 calculating 🤣🤣🤣🤣🤣

 

I barely made it through high skool....

 

Guess you could go by swedish specs....Gootentight

 

 

Edited September 17, 2022 by Max Tune

[Tractorman]

I apologize for using the word "calculating" twice in one sentence.  That was even a lot of pressure for me, too.

 

- John

[JAG1]

15 hours ago, Tractorman said:

I apologize for using the word "calculating" twice in one sentence.  That was even a lot of pressure for me, too.

 

- John

Warning, you came this close  to gettin' banned!

Edited September 18, 2022 by JAG1

[Tractorman]

I won't do it again.  I calculated that I might get this kind of a response.

 

- John

 

[JAG1]

So anyhow you guys are saying that whatever amount of foot pounds it takes to loosen a nut or bolt, is how many ft pounds it took to tighten it? I would think that loosening it would take less, assuming no corrosion or rust. I could be wrong of course. Back to the roof before dark.

[Tractorman]

1 hour ago, JAG1 said:

I would think that loosening it would take less, assuming no corrosion or rust.

 

It will always take more torque than the original torque to break a fastener loose because the bolt was still moving when it reached its final torque value (dynamic friction).  It will require dynamic friction torque, plus static friction torque, to break it loose.  Static friction will always increase over time.

 

- John

 

Edited September 18, 2022 by Tractorman

[Sycostang67]

I think I once used a punch to mark the location of the nut relative to the pinion shaft and tightened it back on until the marks lined up as I didn't have a torque wrench that would go high enough.  I think it was my Ram I did that on but can't rightfully remember.  Either way it's not leaking now.  

[Mopar1973Man]

Might help to use ARP stud assembly lube, clean the nut threads and the stem threads and coat with ARP lube, then torque it up. That lube helps to reach your torque amount much easier.

[IBMobile]

7 hours ago, Sycostang67 said:

I think I once used a punch to mark the location of the nut relative to the pinion shaft and tightened it back on until the marks lined up

One module year, I can't remember right now, there were a lot of Volvos that had pion seal leaks.  These where Dyna differentials with crush sleaves.   I would do the same thing: mark the pion, mark the nut, and mark the flange.   Take the nut off, use a puller to take the flange off, replace the seal, then reassemble.  Never had a problem.