spraying rear diff oil after new driveshaft

[95Noobie]

Things haven't been so smooth the few months we have owned this truck but we are determined to learn and try to succeed! Thanks to all for your patience... My son was driving to school and his drive shaft let loose at the back U joint. It was banging on the pavement for a short time then dragging and then finally came loose all together. He was able to limp a few miles to get it home using front axle propulsion.

Very few options for junk yard 1995 rear drive shaft and they looked as bad or worse than ours. OEM available but about $1200. Settled on an option to purchase a new steel driveshaft from a company in Wisconsin. It came quickly and seemed well put together on inspection. I also got a new rear yoke and hardware and new U joint locking straps and 4 bolts for the rear yoke.

The rear yoke nut was pretty corroded but fortunately came out with an impact. The old seal was pried out (also a tough job) The new rear yoke has a seal on it already and was seated in with light taps and then the new center nut seemed to suck it down tight. We then installed the new drive shaft using the new U joint mounting hardware.

Driving it for a day we note oil seems to be slinging around on the rear side of the differential. The shocks, exhaust and under side of the bed have a coating of rear diff oil. Yet the crack where the yoke fits tightly against the rear diff is fresh metal, clean/silver and no oil spray there. i can't see where it could be coming from. I don't imagine it can come from the center nut?

Did we miss a seal somehow? It looked like the metal seal we pried out was the same one that came on the new yoke. I'd like to order what we need if possible as it looks like we will be pulling the yoke and looking for any clues inside.

Looking at the front side of the new drive shaft I see a few drips of red transfer case fluid and that makes me wonder if there was supposed to be a seal of some type on that end. I didn't have one on the old drive shaft as it was simply splines on that side.

thanks for the help!

 

[scott2093]

Looking at the front side of the new drive shaft I see a few drips of red transfer case fluid and that makes me wonder if there was supposed to be a seal of some type on that end. I didn't have one on the old drive shaft as it was simply splines on that side.

Is this a 4x4? Can't recall.
The tail shaft housing of the transfer case has a seal in there. At least on my 93 it's like that...Can imagine it wasn't too happy with the excitement...

i can't see where it could be coming from

Vent tube maybe? weird..
I never messed with my yoke...all that preload stuff makes me nervous... //Although mine is leaking at the seal 2 years after the best driveline shop in town put it in...and the main gasket is as well.... Need to get it in....

 

[95Noobie]

Yes, (4x4) and Yes, I was not aware of the special rules around setting pinion bearing preload. We didn't mark the old rusted nut and didn't measure how much torque it took to rotate the shaft. We set the new nut to a specific torque specification but now I see that was not the correct step.

I'm going to assume we have the wrong pinion seal (although it came with the Dorman kit with the yoke) i have 2 different brand seals coming by Monday and if they are identical can return one. I guess we can add grease to the seal lip to help it seal? Hopefully it is just a faulty seal or maybe we tightened it too tight.

How to guess at tightness of that nut since we have no reference? The pinion shaft should spin very easily when nut is at the right setting?

Tail shaft housing seal up in the transfer case must be inside where I can't see or replace it?

 

[scott2093]

ail shaft housing seal up in the transfer case must be inside where I can't see or replace it?

This is what I remember I think....

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[Erik the Awful]

I'd inspect both the differential housing and the transfer case rear housing for damage and cracks.

 

[RShrimp]

I installed a Dorman kit on mine and screwed up the first one just like you did. The seal comes on the yoke and I ASSUMED, and we all what that means, that it was suppose to stay on there during install. It is not and is destroyed if you do it this way. Remove the yoke, get a new seal, National 710506 for a 10 bolt, and install the seal first tapping it all the in with a small piece of 2x4. Then install the yoke. Too late for the 100%proper procedure as you dont have a baseline torque spec for turning it but just tighten it up snug plus a little. You should use a new nut but if you dont at least lock tite it.

 

[95Noobie]

Thanks for the detailed advise Rshrimp. I'm kicking myself on whether I totally missed a seal or installed it somehow without it. The Dorman box is gone so couldn't go and look for a missing piece in the packaging. But I do recall now that the seal was on the yoke and we put it in that way. I see how we can do better. I have a new seal on the way and should have it put back together and hopefully no leaks by tonight.

The next puzzle is that the new driveshaft seems to be a bit short on the end that goes in the transfer case. I still have my broken factory drive shaft so we can line them up and see what is going on. The new one doesn't push in on the splines as far as the old one it appears. One thing I wonder is when the 4" lift kit (Rough Country) was added if that somehow would require a longer driveshaft? I don't see they took the driveshaft off to do the lift kit but it would also seem likely that the geometry of the angle of the shaft is going to be different and therefore would need to be a bit longer to be safe. I have not seen listings for drive shafts that are say 1 or 2" longer than stock to cater to those who lift their truck?

 

[Schurkey]

Perhaps a moderator will move this thread out of ENGINES and into Axles + Brakes, since we don't have a dedicated driveshaft forum.

 

[GoToGuy]

Why aren't you using the factory service manual for guidance. You've made mistakes. If not familiar or trained use the manual . Avoid doing it twice, learn by doing it right once.
Did you place the drives shafts side by side to compare? ( That's QA)
While you had it apart, that's when " oh yeah well do the seals too" . Check all fluids too.
If it's spraying in a pattern from wheel to wheel over axle. Either the u joint is flinging grease or your losing lube out the front. Wrong seal? Damaged seal? Overfilling of rear diff' ?
RTFM.

 

[95Noobie]

RShrimp was exactly correct on what happened here. The dorman yoke kit shipped with seal already in place which leads the novice to install it as one unit. The correct procedure is to install the seal first to be sure it is the CORRECT seal and is correctly in place before sliding the new yoke through the seal.

When researching this, the parts lookup tools referred to 'old style' and 'new style' that wasn't very helpful to me. Now that I have the Dorman provided seal out I can see that it was completely the wrong seal on top of being installed wrong. I found a youtube video where another helpful contributor showed differences in seals and even in their inner diameter is different. I'll post pictures below. At least for my 1995 I needed the red metal seal. Once it is tapped in all the way around the yoke slides in a bit more tightly (creating the seal of course).

So the procedure was to remove yoke, the old seal already had a rip in the center part of the rubber seal, remove that, clean everything, pound in the new seal, fasten yoke again. Set nut to 'snug and then a bit more' since we have no way to go back and determine preload. I looked for corrosion or rust ring from the former rusted nut to see if we could determine position after the fact but no line was visible.

Then put the clamps back over the U joint and retorqued them. I did wonder why the round 'tires' on the end of the U joint that the straps pin down were so freely mobile back and forth. They easily slide of their axles and I could mount them with the round part slid Inward on their 'axle' which felt more secure but caused the mounting clamps to have a little empty space on the outboard side, or I could slide those 'wheels' outbound on their axles and they would end up being flush with the outside edge of the mounting clamps. That would 'look nicer' but would mean the 'wheels' would be spaced out on their 'axle' and closer to falling off. They slid of the 'axle' quite freely when I tested it. I looked at other pictures online and it looks like it is common to push the round parts as far in as they go and then clamp the clamps over them leaving a bit of a gap under the outward edge of the clamp.

I dove under my 2015 suburban and the rear U joint position of the round 'wheels'under the strap clamps seemed to also match this.

It was suggested the nut holding the yoke could require some loctite (or maybe better I drive for a few hundred miles and pop loose the U joint and check the nut?)

I then was worried with how much oil was slung around through that damaged seal that my rear diff would be very low, surprisingly it only took about 3-4 oz and was rolling out the fill hole. Topped off and some antiseize on the fill plug to keep it easy to service.

I removed the drive shaft and compared to the old one (which is missing part of the u joint) they are the same length.

I then inspected the other end of the new driveshaft as it goes in the transfer case. The seal on the transfer case there is in good shape. The spline tube inserts into the transfer case but does not touch the black (rubber?) grommet. There is about 1.5-2" of tube showing. I saw on youtube videos that other folks had that black piece squished together a bit when the drive shaft was in place. I can only surmise that adding the 4" lift changed the geometry enough that the drive shaft will have to sit like this with a little bit of the splined tube end exposed.

A surprising amount of transfer case fluid must have sprayed out when limping the truck home with no drive shaft. I put at least a quart maybe 1.5 qts in the transfer case.

Took a short test drive around the neighborhood and all seems well now with no leaks.

So hopefully others can see this post and realize there are 2 rear seals with an 'old style' and 'new style' and that the Dorman seal that ships with the yoke is not correct for the 1995.

You can see the rip in the inner rubber part of the seal in the 2nd picture (seal on the left has the slight rip that occurred when installing as provided mounted on the yoke.

Pictures show the National brand (Red) correct seal vs the larger seal that shipped with Dorman kit that is not correct and too large of inner diameter.

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Thanks to all who helped!
Happy to be pointed to a source for the service manual if it is on this forum already?