Jim Wilson

From what I've read, the amount of play and from the looks of the pinion and ring, I need to shim the drivers side and shim the pinion deeper into the case. My question is where to start? Although it seemed tight, there were just 1 ring behind the race on each side of the diff and no spreader was required to pull the diff out. I have no idea, but I'm thinking of .015 on the driver side and bringing the pinion in .020 and going from there, but if someone with a good feel for this has a better starting point, that would be great.

sooty

the ring gear pattern looks good by your pic, was it noisy?

Jim Wilson

No noise, but it just seems like alot of play. Even if the pattern is good, I can't imagine 15 Degrees of backlash is good. There also doesn't seem to be any wear at the tip of the pinion, but maybe that is normal? I don't know what I was thinking it is more like 45 degrees. I was thinking 12:00-1:30 and somehow put 15 degrees.

sooty

if your measuring pinion rotation, shouldn't be much play rotating back and forth, with pinion depth correctly set, ring gear is set for back lash roughly .006"-.009" off the ring gear tooth, how you measuring angle?

torquefan

Often, the "slop" in the pinion is made up of wear between the splines in the axle shafts etc. True, the fact that you had no preload in the carrier bearings isn't a great sign, in my opinion, the best way to attack this would be to put it all back together the way it was, then use some gear marking compound and analyze the contact pattern to decide what, if anything, needs to be moved. Also, using a dial indicator to measure how many thousandths of backlash exists between the gears would be important too as a guideline, although a good pattern would be a priority. The factory service manual should have a section regarding the interpretation of mesh patterns.

sooty

theres some good setup info on pirate 4x4, and east coast gear supply for bigger dana diffs, do the search if you don't have the service manual.

samiam4

You need to carefully measure backlash and not angle.

Let me say this.. there is only 1 depth/contact pattern for any ring/pinnion setup that will be quiet. If it's 6 thou or 10 thou- or 7.5. You cannot simply make it "tighter" like a wheel bearing. You will shift the pattern lower or higher on the tooth and it will make noise.
That said- there side bearings should have some preload. Download the dana 80 manual online and follow it to a tee. At least it's an 80 so the shim is not under the cone.

IF you decide to adjust anything. Be extremely methodological and keep perfect notes. I setup my dana 70u with new bearing on a worn gear. It was quite a challenge, but the results were good.

M

BigIron70

Most likely race has spun in housing on left side (load side) when that happens backlash will increase. If there was no preload and the carrier came out easy that may have happen. Inspect the cap and housing where bearing race fit into on left side. On high mileage diff changing pinion depth may result in noisy gears. If pattern is good and in center of ring gear on both coast and drive I would not change that. Bearing preload if new bearings are installed is more critical. Backlash has wide range and gear pattern should be checked before any changes are made in backlash. Also check carrier bearing make sure it has not spun on carrier. Special puller is needed but you can cut with die grinder and then race to remove without a puller.

Jim Wilson

Thanks so much for all the input. I know all about centerlines and how tough it is to properly mate bevel gears from scratch. The only way it could be this far off is that the person I got it from had it apart and just threw it back together. There were no shims for the differential and only 1 on the outer pinion although the pinion didn't move in and out there may have been some between the bearing and pinion- don't know because I didn't press it off. I'm thinking(hoping) it wasn't tightened all the way. I know I had to take my 3/4" drive 45mm down about .060" to get it to slide down around the nut, so maybe the guy just got it on as tight as he could before the socketgot bound between the yoke and nut? I'm hoping that is it, but I never checked to see if could have been tightened(should have because there was no preload) more so that will be the first thing I check. All the splines are good and the gears don't look to bad, so I know it couldn't have been run in it's current condition. If a loose yoke nut is not the issue, I will get it in the ball park of where it needs to be and then start checking patterns. When assembled, the yoke could move from 12:00-1:30 before making contact- obviously way off. After that, I'm going to pull my 70 and take notes and measurements on all the shims so that it will be right for the rebuild. Only 117K on my stock 3.07 with very little pulling, so it should look pretty good.