1G Did I just destroy my rear diff?!?

[XC92]

So I was trying to install a new pinion seal on the rear diff of my '92 AWD Talon, and I used wrong-sized seal installation ring that had too narrow an inner opening (actually a part from my bearing installation kit), and after it drove the seal part of the way in, instead of contacting the outside surface of the seal, it contacted the pinion itself, the part with the outer splines that the companion flange goes onto, and drove that in instead of the seal! I realized this after a few whacks with the hammer, when I noticed that the seal wasn't going in any further.

Needless to say, the pinion is stuck now and will not rotate at all. Turning either axle side gear doesn't move the other side gear, which makes sense if the pinion is jammed. Looks like I have to open up the diff case to see how bad the damage is and see if I can fix it with a minimal if any replacement of parts.

Based on the above, how bad is the damage likely to be, and how do I fix this? Did I likely merely jam the pinion & drive gears together, and some light taps with a punch & hammer could unstuck them? Or could I have damaged some bearings and/or races, perhaps some shims, something else, or even the case? Are the parts I might need to replace even available, stateside or from Japan?

This is what happens when you try to rush the conclusion of a month+ long restoration project, it's 90 outside, and you're beat and just want to get it over with. I'm not beating myself up, stuff like this happens, I just want to figure what I need to do and do it, and get it over with.

 

[1990TSIAWDTALON]

Can you get the pinion nut off? Would it give you enough room to pull that seal back out?
Isn't this hot weather hard on ALL of us?????

 

[XC92]

Pinion nut wasn't on when I did this. But another issue this caused was smashing the outer tips of the splines such that the flange could no longer slide back on. Some quick and careful grinding with a rotary tool & bit fixed that.

I took the case cover off, then the caps, and with a bit of effort the diff case assembly (i.e. the drive & side gear assembly), which looks fine after a cursory examination. So now it's just the pinion & case.

The pinion has a lot of play in/out, more than a few mm. I'm guessing that I hammered the pinion shaft backwards, and best case scenario I have to remove it and drive everything back to where they should be, and the existing shims, spacer, bearings & races are still usable.

Otherwise I need to order some parts and get this fixed. But I have to first remove the pinion assembly and have a look. Is this just a matter of hammering it gently on the front, using the old nut (which I have to replace anyway and already have the new one) installed backwards, same as with an axle shaft?

Anything else to look for or do?

And yes, the weather is really not very auto repair-friendly. I'm having to bring parts inside where there's A/C to have a look at them and have my brain work.

 

[1990TSIAWDTALON]

Well the only thing holding the pinion in is the nut that is removed. Use a rubber or plastic mallet and start tapping the pinion out (A BFH and a block of wood also work). The bearing race "should" stay put, with its shims. If it comes out, just keep the shims together and reassemble it in the same fashion.
Usually, once the pinion nut is off, the gear will slide out the back with the carrier removed.
I'm crossing fingers that you didn't hurt the bearing and can get that stupid seal out and get the correct one in and re-use all of your components.

 

[XC92]

So, I did some research here and it's a lot simpler than I thought. With the flange, washer & nut off, I tapped with a dead blow hammer and out came the pinion assembly, with the spacer & shim.

With the pinion out I was able to punch the seal out from the back of the case, carefully with a long narrow tool & easy dead blow taps. It looks fine, brand new when I tried to install it earlier today, so I can reuse it.

Out came the front bearing, but the outer race stayed in place. I checked the bearing and it looks good, as does everything else. Looks like I'm good to go, just have to re-press in the bearing then everything else goes back together.

Looks like I basically just punched in the pinion as if I was trying to remove it, but just a few mm instead of all the way, and with the drive gear still in place and cover on, just enough to throw everything out of whack and jam things, but looks like the drive gear, assembly & rest are ok. Had I kept hammering the pinion, I could have actually broken something (assuming I didn't, of course).

Thanks for the quick responses. I'll post an update when I have it all back together and let you know how it went. Might as well check the backlash and all that while it's open. I have the tools, other than that special yellow gear marking paint. Is there anything else I can use instead I might have lying around?

 

[1990TSIAWDTALON]

You could use red grease or prussian blue to check the pinion contact point on the ring but it all should be just as it was before this little mishap. I had a bit of the yellow paint left from a ring and pinion change in my sons Camaro, but there wasn't much left......and finding it now, 2 years later would be a stretch.

 

[XC92]

Yeah I'm going to just rough measure everything as I'm beat and just don't have the mental energy to do it by the book. I might revisit it later this year as removing the diff isn't that hard if I keep everything else in place, e.g. subframe, arms, axles, etc. Or not.

I'm trying to figure out how to reinstall the front bearing onto the pinion. There's a special tool the FSM mentions but I don't have and won't buy it. I'm thinking of using the flange, washer & old nut to reinstall it, as a forcing screw, with perhaps another washer that goes between the flange & bearing.

It's basically what the special tool does. There's just enough pinion thread for the nut to thread onto, although I could also gently dead blow hammer it the first few mm then use the nut the rest of the way. I assume that I keep pushing until the bearing bottoms on the front shim that sits on top of the spacer that looks like a small exhaust reduction tube.

 

[1990TSIAWDTALON]

You have it correct. Luckily, I have a press but the nut will "press" it on like you are describing.

 

[XC92]

Yeah, presses aren't that expensive and if I had the room I'd get one, but I don't so I have to improvise. I keep meaning to build one using a bottle jack and some heavy duty threaded rods and metal plates but never get around to it. But this doesn't look like a high force interference fit situation so I think this will work.

And now I have experience opening up and "fixing" yet another part of my car. Later this summer I'll be overhauling the intake and exhaust including the turbo, so add that to the list. I have the parts already. The only major parts I haven't yet taken apart and have no immediate plans to are the engine, CV axles & prop shaft, and I'll probably do the latter sometime soon as the rear yoke is kind of notchy.

 

[1990TSIAWDTALON]

Very glad that you talked yourself thru this. I always feel like I have learned something new when I do. I have built cars for 44 years, never owned a new one (and was poor) and have done everything you can imagine EXCEPT a rear dif gear change. My son and I finally tackled that new project a year or two ago, so we both learned what to look for and what was acceptable and what wasn't. We did get lucky in a few places but his rear end works like a charm with new LOWER ratio gears in it so it will come off the line quicker now. We replaced 2.92:1 gears with a 3.73:1 set. Boy what a difference!

 

[XC92]

Wait, your rear & front wheels don't spin at the same speeds, assuming all 4 wheels get the same 1/4 power? How does that work w/o slipping on one axle or the other, or "confusing" and messing up the center diff?

And yes, it's often easier than it might seem. Unless, of course, it's harder!

 

[1990TSIAWDTALON]

Oh...........it is in his 1986 Z28 Camaro that I built him for his High School Graduation gift.
My auto DSM has a welded center dif and it does spin all 4 equally.
Take a look thru some of that thread and you will see all of the "other" stuff we do.

 

[XC92]

But, welded, won't the front & rear wheels spin at different speeds with the new gear ratio in the rear diff? Or is this on the Camaro, which is RWD, so no front/rear issue? Sorry for the confusion.

Btw, reading further into the FSM, it's kind of confusing, but it appears to explain that you have to install the front bearing onto the pinion twice, and the second time it says to use the flange as the installation tool, per my idea. Weird.

Finally, it says to use high mileage multipurpose grease on the bearings & seals during installation. What does that translate into? Silicone, e.g. Sil-Glyde? Lithium? Moly DiSulfide? Whatever's in the grease cartridge closest to you?

 

[1990TSIAWDTALON]

The last one, .
On his Camaro to clear that up.
You install once to check the pattern then the 2nd time to get the final torque preload on the pinion bearing.
Just reinstall it with the flange and save yourself the extra step if the dif was operating correctly to begin with. The pinion and ring "mate" so changing them will put a different pattern on the ring and pinion, possibly wearing them down prematurely.
When you took the ring gear assembly out did it have any shims on either side? It's very important to keep them correct so your ring engages far enough but also not too deep. Set it back up exactly the way it came apart and you'll be fine.

 

[XC92]

Yeah, there were shims, and I made sure to keep each side's shim & race separate from the other side's.

I got the front bearing about as rearwards on the pinion as I could, with just a TINY bit of fore-aft play, like a mm if that. I don't have an inch-lb torque wrench that goes down into the single digits, so I'm going to have to assume and hope that the proper shims were already in place and that tightening the new flange nut to the correct torque setting will do the trick.

Btw when installing the pinion seal (the right way this time, using the flange flipped over as a tool), should it be flush with the "ring" it goes into, or with the outer "ring" that the front side of the flange ends up resting on? Using the flange as a tool leaves the top of the seal 2-3mm or so above the inner "ring".

And, any grease for the lip, like silicone? Moly?

 

[1990TSIAWDTALON]

I honestly can't answer that, I haven't had the pinion nut off of a DSM. Seal's usually rest flush with the front of the case. Do our seals not have a flange that stops the seal from going in too deep? Wish I could answer but I don't want to dish out bad info.
DEFINATELY lube the seal lip though.

 

[XC92]

They don't have flanges so you have to either use the FSM-indicated tool or wing it. It's just that there's no uniform case surface there, rather concentric rings of different heights. It probably doesn't matter so long as it's at least flush with the outer, higher ring. I hope! I'll grease it of course, probably with moly grease.