Bigredwing

Long story short, I have a pinion seal leak. The differential was rebuilt by a vendor for the first time two years ago and I have had it out three times since and taken it back for leaks. The first return also included noise which I was told was a bad (new) bearing. Due to work, weather, other car problems I probably have less than 100 miles on the original rebuild. At the rebuilder's request I also re balanced the drive shaft and replaced the U-Joints. I've been told the yoke is good but it still leaks. I don't have the tools or skills to rebuild it myself but I do have a question for our forum experts... If I pull the diff again can the yoke be replaced and a new seal installed without breaking the cases (leave the batwing attached)? Is this something I could do with the proper size socket or are their internal specifications that need to be remeasured? Thanks - Chris.

tracdogg2

What year?

Bigredwing

Sorry, I'm working on my 82 Collectors Edition.

tracdogg2

Chris,
Yes it can be done without pulling everything. But it's not going to fix the problem. There is something wrong with the pinion set-up.
Mike

lvmyvt76

done mine while on the car.

Kevin BC

Mike, you may recall that I was going to send my 81 pumpkin to you to rebuild, but with the Canadian $, shipping cost and you being too busy we agreed that I should get it done locally, which I did.

But my recently rebuilt 1981 unit also has a pinion leak with only 1,000 miles on it. It if is "something wrong with the pinion set-up" then it will be best to remove and take this back to the shop for them to fix.
Is there a better description of what is likely wrong with the pinion set up that I can give them. Otherwise I am sure they are going to say to me "and how would you know there is something wrong with the pinion set up" (I am an accountant but do most of my own wrenching)

Thanks Mike.

Kevin

Bigredwing

Right, Just like Kevin, I am stuck. I even went to far as to spend the
money on new UJoints and and drive shaft balance to no avail. I never thought it would help.

A long time ago I was told by another vendor that they didn"t work on '82 diffs because they are aluminum and get "tweeked" (whatever that means). But they difficult to rebuild. I guess I hoped mine would be the exception. What next? Can't drive far with the juice seeping out.

tracdogg2

The pinion preload is very hard to set on these diffs. Shim pack thickness is usually around .103-.108. There is also a special shim that goes between the pinion yoke and the front bearing. many cases when setting the preload you need .0005 difference to get it right. Too loose or to tight you get a leak. Also it requires the correct design seal. Cr and skf seals are not correct. It needs to be a national seal. If they are using ratech shims it will never set up.
These housing are very delicate around the pinion races. There is a special tool for removing them. If someone is too aggressive installing the races they can ruin the case. The front race sits very deep in the housing. Special drivers are needed to install it. And a special tool to install the seal. This is why no one wants to rebuild them.
Mike

Bigredwing

So this just sucksl. I guess my choice it to scrape up another $1K or more and take my chances on a tear down of mine which could prove to be a bad case or setup, or buy a rebuilt which I can only hope is done right. Who to trust? Looks like another year with the car on blocks unless I just sell it, but I hate to make it somebody else's problem. I know this is the Technical Forum, but technically I am depressed.
-Chris

CA-Legal-Vette

As Lars used to post at the beginning of any of his papers "have a beer and relax." These cars are certainly frustrating. They also leak. That's what they do

My 73 currently has no leaks but that's a function of dilligence, not GM engineering. It would never occur to me to park it in the garage without cardboard or a catch pan underneath it. I don't think a leak, other than a catastrophic one, is a reason not to drive it. Top off the fluid and get some miles in. Tends to improve your outlook.

One specific trick that I picked up on pinion leaks from reading posts from Mike and Gary is to put flexible sealer on the splines of the pinion before inserting it. The other that really helped me was to let the pumpkin sit overnight with a pinion down orientation. It's a lot easier to deal with the leak while its out than after you've installed it.

mikem350

Very Important, like Permatex #2...applies to all years!!

0Willcox Corvette

It's probably leaking past the splines on the yoke and it would be a fairly easy fix for you to do yourself without paying out big bucks.

Since the Dana doesn't have a crush sleeve inside it's very easy to remove the front yoke and seal up the threads and re-torque the front nut. You can't goof it up like you can on the earlier design rear ends.

And just a FYI, the 80-82 pinion seal can be put in backwards and I've had customers do this in the past. If the shop did this I assure you it will leak.

Willcox

Bigredwing

Thanks for every reply. I have been at VIR this weekend for the IMSA race and watching Team Corvette kick *** on the Ford GT. I plan on saving all this information and when the weather cools down a bit yanking the diff again and try to fix it myself. I don't believe I can make it any worse. Only problem is convincing my son to come back over and help me lift it off for the fourth time. I do have beer so that should be the easiest part.
-Chris

0Willcox Corvette

Why pull it? You can remove the flange and pinion seal with the rear end in the car... It's tight on the 1980-1982 cars but very do-able. We never pull the entire rear to do this job but then again we have lifts, it would be harder laying on your back but it's still something you can do without removing the rear.

Willcox

Bigredwing

I do have a 4 post lift so I'll have to consider not pulling the diff. I know I need a seal removal tool but is it a special one? I currently don't have it in my tool box so I'll need to buy, beg, borrow one.

Another quick question; if I find the yoke has a groove worn (even though I've been told it's good) and I replace it, is re-torquing all that is needed or does that then require a more complete set-up? I've been reading about counting threads and making witness marks to get the original yoke back into position. But if I understand Wilcox that is not an issue with the '80 - '82 Dana's. Maybe I'm miss-understanding?
-Chris

0Willcox Corvette

The dana doesn't have a crush sleeve inside so there is no worries about counting the threads, on the older cars 1979 and back there was a crush sleeve inside and it is imperative that you set the back exactly where it was.

I doubt you'll find any issue with the yoke, the sealant should stop the leak if the seal was put in correctly.

Willcox

corvette427

Hi BigRedWing - sorry to somewhat hijack the post, but I have am 82 CE as well and a few weeks after brining her home, I noticed a few drops of something on the garage floor, but from the rear end. Long story short, and as you can see from the pic, I found the places where the drops were coming from. I've cleaned off the area a couple of times and what I've noticed is: 1) If I clean it and park the car for a few days, nothing really drips 2) If I clean it and drive it, I'll probably get a total of 5 drops or so over the course of a few days after she's been parked. Also, the drops form not only on what I assume is the pumpkin, but the cable next to it that appears to come from the bottom of the battery compartment (I checked there is no leak or liquid coming from there).

Problem for me is that I am nowhere mechanically inclined enough to work on this myself and I'm a bit hesitant to risk making the problem worse by going to a dealer or mechanic that might not quite know how to fix it or that would want to take me to the cleaners.

From what you are experiencing, and see in my picture below (taken from driver side looking towards the back), am I experiencing a pinion leak as well? Given what I noted above, and the slow rate it leaks at, should I even be overly concerned? Thanks in advance!

Bigredwing

I would have to guess from your picture that your pinion is seeping a little bit. I have a lift so it is easier to see on mine, but I I have oil on the bolt and washer you see hanging down that secures the front of the differential. I also have it on the bottoms of the battery box and the box behind the passenger seat. I can see where it is slinging from the pinion yoke. Pull out the tray on yours where the jack is and make sure there isn't a leaky bottle of oil in there. Now that would be an easy fix! You really need to get it up on a lift or jack stands so you can get a better view. Good Luck!
-Chris

corvette427

Thanks Chris. I hadn't thought of checking the area under the passenger compartment tray just to see what, if anything, could be going on there or if there are any "Bubba" surprises. I did have a drop or two on the bolt and washer like you noted, but since I wiped it clean, it never came back. Just always seems to be in those same two spots in the picture. So I'd venture to think I'm not looking at a "must repair ASAP" situation and am OK continuing to drive the car a couple hundred miles a month?

Like I said, not very mechanically schooled, but learning. I've gotten good at fixing interior stuff (door locks, door panel replacements, AC control switch repair), but still a novice with anything under the hood or the car. I pickup a lot of great info on this forum though, that's for sure! Thanks,

Gary

Kevin BC

Willcox, Thanks for your insight.
I will have at this with my winter projects also. If the seal does need to come out, what is the special tool for the Dana 44 seal removal? and how much does it cost.

Kevin