Repairing leaky differential?

[Slonaker]

I'll try to refrain from referring to it as a "leaky rearend."

I have a 10 bolt, and it is leaking around the pinion/yoke/whatever you call the front. What does it take to change that out? Any special tools? Is it difficult?

Slonaker

[Greenlee]

I have the same question as mine is leaking in the same place. I put in a request on the parts board for an entire rear end with 3.73's and was told that the pinion seal is easy to change and only cost about $10.

I haven't decided if I want to fix it or replace the rear end since I want new gears. I have heard that you can get an entire rear end (10 bolt) for $125 at Pick-a-Part. Does anybody know if 3.73's were more common in certain years or models?

[Prerunner1982]

i have the same problem, but again not sure if its something i want to jump into... i just keep putting heavy weight gear oil in there...

[screwballl]

i'm kinda curious as well for my 91 burb R2500...

[Hoods69BadBowTie]

I have changed that seal out on my '81 K-5 Blazer. It was the 12 bolt rear end. I gently hit the yoke <I think> with a block of wood and a hammer to get it off. Then pryed the old seal out with a phillips screwdriver. Put the new one on and used a flat piece of wood and a socket and got it really damn close but not quite touching the front of the pinion. Not sure but I heard it might need to be pressed on there. But mine was about 1 year ago and I have not had any problems since. Seal was like 8 $$.
-Later

[Captkaos]

You have to remove the yoke. It also needs to be retorqued.

[Zilverado]

On my old 12 bolt (I assume the 10 bolt would be similar), the yoke is held on the pinion shaft by a big nut. I cant recall exactly what size, but I believe somewhere between 1" and 1.25".

Here's what I did...

**** secure the rear of the vehicle on good jack stands!!! **** This is important because when you remove the driveshaft, the rear wheels are then free to turn, with no connection to the tranny (e-brakes help too.)

1. Remove the drive shaft
2. Remove the pinion nut - to do this, you need to be able to hold the pinion and yoke from turning while you turn on the nut. This is easier done if you have an impact (less torqueing), but I rigged up something "home-made" - - see description below
3. Now remove the yoke
4. Pry out the seal CAREFULLY!
5. Grease up the new seal and hammer (lightly) it in CAREFULLY.
6. Reinstall the yoke, and nut and torgue to specifications.
7. Reattach drive shaft.
8. Top up differential fluid and your done!

Home-made tool to hold yoke for nut removal and replacing.
- take a short length of 2x4 - - say 18"
- drill 4 holes at one end - spaced to match the holes in the yoke used to attach the driveshaft retainers
- drill another larger hole in the center of these in line with the pinion bolt
- use bolts to bolt the 2x4 to the yoke with the 4 holes.
- now with an extention on your socket, you can access the pinion nut through the large hole in the center
- while turning your wrench to loosen the nut, you can hold onto the 2x4 "wrench" to hold the yoke/pinion.

So, overall it's a relatively easy (and cheap) job, just take your time and have fun - - that's how we learn.

[Slonaker]

Thanks for the info, everyone.

Slonaker

[raceman6135]

Before you remove the pinion nut, scribe a line so that everything gets reassembled and tightened to the correct place. The pinion nut, pinion shaft and yoke must be reassembled so that your scribe lines match up, otherwise you'll be loading the bearings a different amount.

When you screw the nut on, apply a little non-hardening Permatex #2 on the nut threads. That will help prevent differential fluid seepage past the threads.

DJS

[jermasaurus]

Like raceman said, make sure that it gets reinstalled in the correct place. There is a collapsable spacer in there which sets pinion bearing preload when you collapse it. The collapsable spacer is not meant to be reused. You are actually supposed to do this with the differential unassembled and tighten until a specified amont if inch pounds is required to turn the pinion.

I'm not trying to discourage anyone, but just trying to explain it in case anyone wanted to go all out and do it perfect to specs and everything. It can definatley be done without all this and never have any problems if you are careful.

[JustOneTruck]

My two cents.

Chuck the wheels and or e-brake it .I think it would be easier than the drilling of the 2x4 .

This meaning neither one of the tires will slip nor will the pinion. Thats if you can slip under the truck without jacking it for space for working . Thats if you use your e brake and it is not froze up.

Scribing the placement of the nut is the best thing .My torque wrench dont go to 140lbs . So i went a tad bit past the scribed mark on my nut. :-)

[MylilBowTie]

Doesn't the pinion nut torque also have to do with setting up the backlash of the ring and pinion? I'm not trying to put water on the fire or anything. But if it does, then that could wipe out the rear if it isn't reinstalled correctly.

[jermasaurus]

A little, but it is mainly the side carrier bearing shims that deal with that.

[86-C10-V6]

It's not that expensive to have it done by the Dealer and if it's not done right you will cause premature wear and failure of the Pinion and Ring gear.
Just my opinion.

[Slonaker]

You guys are starting to talk me out of it. I don't know squat about rear ends.

Slonaker

[grape]

4 things are important on a ring and pinion. pinon depth, pinion bearing pre-load, carrier bearing pre-load, and back lash. The back lash is the easiest and least important of the 4 adjustments, it is also the last adjustment made after all others are within spec. This is done by moving the carrier back and forth with shims between the races and housing. .005" to one side or the other is worth .002" - .003" in backlash. Backlash's only purpose is to create a gap for oil, like bearing clearance so that heat can be carried away from the teeth. pinion depth is checked first and is the ONLY thing the pattern will indicate is correct or not, lash has to be correct each time you move the pinion in and out to check the pattern. It is a pain in the ass on anything but a 9" ford, with all the assembly and disassembly. After the depth is correct you are ready for final assembly which includes new crush sleeve and pinion seal, you tighten the pinion nut till the pinion has enough resistance with an inch/lbs torque wrench, usually 18-22 inch pounds for new bearings on most rear ends. IF THE PRELOAD IS NOT RIGHT THE REAR END WILL MAKE NOISE. Bearing preload on the carrier is also a normal sound maker, Lash is the last one of the 4 adjustments that will make a rear end whine.


As for the original question, you can change the seal without affecting any other adjustments but pinion bearing preload. The hard part is that the torque specs don't include brakes dragging carrier bearing preload and everything else that will be dragging on the pinion while you do this. You can get close by marking the pinion nut and pinion threads and line them back up.

damn, i've been building rear ends waaaay to long.


edit.........don't bother trying to crush a new crush sleeve with an impact unless you have 400 ft/lbs worth of impact wrench. It takes a breaker bar about 3 feet long with my skinny ass.

[86-C10-V6]

As I remember the brakes must be off and the wheels should be easily movable, the torgue is applied with the pinion actually free to turn as it is being torqued.
The GM dealer use a special tool that torqued the nut without having to pull on the tool.
I think this how I remember it was done.

[86k10]

Oh you can do it yourself, just get your bearings as close as you can to there original setting. The rule I go by is 25 inch pounds of rolling torque for new bearings and 10 inch pounds of rolling torque with used bearings. But you cannot check that with a click type torque wrench you need a needle kind.

[iceship]

Lol... people make it sound so easy to remove the yoke

[donut]

Considering the OP has had almost 10 years to work on it, I assume he got it.
Yoke removal is easy, as long as you remember it's been on there for about 30 years and deal with it accordingly.

[Tx Firefighter]

A 2 pound hammer gently against the back of the ears will remove most of them. A two jaw puller will get any that are more stubborn. Make sure the washer isn't wedged in there thwarting your efforts.

[ssxty8]

IMO, all of the info mentioned is of great value, but returning to your concern about pinion leak, I always put some silicone sealant on the pinion splines before mounting the yoke.