Dana 80 broken part-what is this?

[DownByTheRiver]

I'm in the process of overhauling my Dana 80 due to gear whine, a rear end vibration, drivetrain clunk and a cracked ring gear tooth that I noticed when I changed my fluid a few weeks ago. When I got it open, I found the carrier bearing had spun on the carrier stub (housings look good though) and that there was a ton of play. This explains why the vibration would sometimes go away around a corner, I guess the bearings were preloaded correctly again. Trashed the carrier and went with an eaton true trac.

I got everything else apart, and found what's left of this large washer hiding in the little valley below the pinion shaft, below where the gear oil gets sent over top to the pinion area. I cannot for the life of me find out what this is in any dodge/ford/chevy parts diagram, dana manual, or dodge service manual. It's an 1/8" thick, with an OD of about 3.5" and an ID of about 2". I can't put it back together to tell exactly because there's at least one piece missing. It does have wear marks on the outside of one side, and the inside of the other like it was being used as a shim. I'm guessing this is what cracked the ring gear tooth. When I got the pinion gear out, I found a tooth cracked on that, too. Does anyone have an idea of what this is, and why it's in 8 pieces? Maybe left over from the last time this rear end was rebuilt?

 

[DownByTheRiver]

Cracked pinion gear

 

[NIsaacs]

It looks like a side gear thrust washer.

https://torqueking.com/product/40295/qu40295-35-spline-dana-80-differential-internal-parts-kit/

 

[DownByTheRiver]

It looks like a side gear thrust washer.

https://torqueking.com/product/40295/qu40295-35-spline-dana-80-differential-internal-parts-kit/

Wow, thanks...that would certainly explain why it's in so many pieces. I'll open the old carrier tonight, but I think you are correct.

The previous owner should buy a lottery ticket, because if that came through the spider gears and differential stuff and minimal damage happened, that's really unbelievable.


edit: just noticed that washer is for an open diff. Not to say this axle isn't from a different vehicle though. Glovebox shows limited slip as an option, but truck has a ton of miles so who knows.

 

[Joseph Donnelly]

IIRC, in your year range, Dana used cast iron shims at the side bearings, and almost zero preload. Just a little wear, and things could get loose and hammer around. For decades, they had been using about .010" preload and steel shims behind the side bearings, on the carrier.

 

[DownByTheRiver]

IIRC, in your year range, Dana used cast iron shims at the side bearings, and almost zero preload. Just a little wear, and things could get loose and hammer around. For decades, they had been using about .010" preload and steel shims behind the side bearings, on the carrier.

This rear end had those large washer shims outboard of the carrier bearing housings, and then 3 thin shims on the inside of the bearings. The carrier and ring gear actually damn near fell out of the housing once the caps came off. I could also pull the driver side bearing off the carrier by hand. Attached is a picture of the driver housing...are you thinking this washer is in addition to those shims on the outside of the carrier bearings?

 

[Joseph Donnelly]

Probably was. Look closely for evidence that the carrier bearing outer races spun in the housing. If they did not, you are good. If they spun, depending on how bad they wore the housing, it might be toast.

 

[GAmes]

edit: just noticed that washer is for an open diff. Not to say this axle isn't from a different vehicle though. Glovebox shows limited slip as an option, but truck has a ton of miles so who knows.

A "ton of miles"? I just changed the oil in my D80 yesterday. I have a MagHytec cover with a magnet in the drain plug. Nothing but fuzz. I sent in a sample today to see if I can extend my drains from 75,000 to 100,000 miles. More than half my miles are towing, sometimes pretty heavy. Other than replacing the pinion seals and axle seals twice I've never had a problem with mine. It, and the injection pump, are original equipment. I'm pretty confident yours is the original too and I doubt it has been rebuilt in the past. They just don't fail all that often.

 

[DownByTheRiver]

I opened the carrier tonight, and here's what I found...wouldn't believe it if I didn't see it myself. Looked like a thrust washer, but it was flat so I figured it was some kind of shim. Wonder how long it was riding around in there.

I can still see the original machining marks on the housing and bearing cap, but I'll put bearing retainer on just in case. Can't feel anything with my fingernail either.

 

[DownByTheRiver]

A "ton of miles"? I just changed the oil in my D80 yesterday. I have a MagHytec cover with a magnet in the drain plug. Nothing but fuzz. I sent in a sample today to see if I can extend my drains from 75,000 to 100,000 miles. More than half my miles are towing, sometimes pretty heavy. Other than replacing the pinion seals and axle seals twice I've never had a problem with mine. It, and the injection pump, are original equipment. I'm pretty confident yours is the original too and I doubt it has been rebuilt in the past. They just don't fail all that often.

When I bought the truck from a guy that got it from an underground utilities company, I knew it was rough, but this thing has been flat out neglected. I don't mind the work and it's far cheaper than buying a new truck, but there's certainly been plenty to fix. I know it'll be reliable and exactly what I want when I'm done though, and the really expensive stuff is in pretty good shape. The cluster said 325k when I installed it, but when I was gutting the interior, I found an oil change sticker that said 380k miles, and that was from 2015. Put it this way, no oil in this thing has been analyzed by anything but concrete...it's a shame but I can see it being a great truck pretty shortly.