Dana 44 Setup

Hello,
I'm in the process of setting up the Dana 44 rear axle in my M38A1. I took it apart because the yoke had up/down play even though the nut was properly torqued.

Once I got it apart it became clear that someone had been in there previously. The bearing caps were switched side to side and the hubs had no shims.

One of the carrier bearings had a bad cup so I'm replacing both of those. I'm replacing both pinion bearings because they ran so long without proper pre-load.

What I'm uncertain of is if I want to adjust the shims any. I checked pinion depth with a micrometer and it is correct. I'm not seeing any odd wear marks on the gears. I checked tooth pattern with the best marking material I had on hand and as far as I can tell it is correct. The problem is backlash - I'm getting 18 thousandths. I'm not seeing any obvious heel or toe bias to the pattern so I don't think I should mess with side to side shims. And as I said the pinion depth appears correct per the micrometer. I also don't know if I should alter a setup that has been running this way for so long. Any thoughts?
Here is my best photo of tooth pattern.

Thanks,
Ken

 

If you think that someone has been in the assembly and put it back together incorrectly, you have a couple failed bearings and you need to take it apart, well I think you answered your own question about if you should do the work.

It might run this way for a long time or it might fail completely. If you don't want to spend a lot of money, get a master rebuild kit only and run those old gears if they look ok.
Dana 44 Master Overhaul Kit replacement | RANDYS Worldwide

 

WARNING: it can be dangerous to take out backlash on used gears. The pinion gear will wear into the ring gear, creating a ridge. If you start removing backlash, you can drive the edge of the pinion out of the worn area and onto the ridge. Insure the pattern is correct and doesn't turn into a thin hard line on the tooth flank.

If the R&P have been run with the improper pattern or loose pinion, you may be able to still run them, but be aware, you may have a noise you will never be able to remove.
I'm having trouble seeing your pattern. I find if I mix a little prussian blue with the zink oxide it gives the wipe contrast. Also, be sure to load the ring gear to get a cleaner wipe.

 

I see people buying used gears and running them. If they have no idea what the backlash was, how do they set them up correctly? And what is "correctly" if they are used? I'm not questioning your post and I see your point, but what are some others experience doing this? Did they set the used gears to spec? Was there noise or issues?

This is relevant to the OPs question, because he seems to have found some mismatched parts and bad bearings that need to be replaced. Upon reassembly, what is best practice?

 

I don't know about the Dana 44, as I've never looked, but there are new and used published figures for the Ford 8.8, if you're running new vs used gears. The backlash setting on a used set is a fair bit more loose than a new set.

 

I've actually installed a number of used gear sets and just went though the process as if they were new gears and starting with no former shim pack information. I've not had a single problem doing that. Maybe just lucky?

It is a little amazing what you find digging into axles. On disassembly of the FC 150 axle I want to use in my 3B, I found the caps both switched from side to side and inverted. I suppose I should give the guy who was in there credit. It got it 100% wrong. There also wasn't any side preload and the Powr-Lok just fell out of the housing, not to mention shot pinion bearings/seal-no doubt also due to insufficient preload.

 

I too have setup several used R&P sets.If the ring gear was worn to the point of having a ridge on the tooth that would be scrap. Looking at the condition of gears I would use the preferred backlash and go toward the outside number. Say .008"-.012" go toward .012".Like others I have been very lucky with used gears and no noise problems that you could hear over engine and tires,etc.

 

I know several gear guys (shops) that prefer a good quality used gear set over a brand new set.

 

Thanks for the replies. I got a container of purpose made gear marking stuff now. Planning to assemble with new bearings using the previous shim settings and see what pattern that makes and go from there.

 

Simple:
Go for the picture, forget the backlash.
As long as the picture is correct you should be fine, even if you have "excessive" backlash. Many times out of spec backlash is due to the pinion bedding (wearing) into the ring gear, especially if the gears have long or hard miles. Reducing the backlash in an attempt get in spec can push the edge of the pinion up out of the wear pattern (up into the black in the picture) and cause chipping and breakage.
I've installed well over a hundred used gear sets (used to do it for a living) and many of them had .005 or more over the specified max and ran fine.

 

This sounds like what I found in mine, both caps and preload for carrier and pinion. Aside from the loose pinion I would not have known anything was amiss from the way it drove.

This was the main point of my question. I think I have correct tooth pattern now, and the literature I've read doesn't make it sound like I can close up the backlash without changing tooth pattern.

Hopefully the next day or two I can get it mocked up with new bearings and see what things measure and look like.

 

Used gears are a case unto themselves and sometimes the book specs simply don't work. Any time one is going to R&R used gears, it is always a good idea to get a picture and backlash reading prior to removal so you have a baseline for replacing them. Abused gears (high mileage, loose pinion, bad carrier bearings, high loads, etc) may never get the picture or backlash you want or be noisy when reset. My daughters Bronco ran with a loose pinion for years. The gears are solid but the diff whines at higher speeds. I check it periodically now but shutter to think of trying to reset them if there is an issue in there in the future.

Reducing backlash will usually change the pattern. Although it is labor intensive, if you feel the lash is excessive, you can still take a couple thousandths out and run the picture again. You may find the picture has stabilized or even improved more and the lash has been decreased. The important point is to insure the picture is good.

It is becoming hard (expensive) now, but back in the day, obtaining a used Ford 9" and using it to vary pinion depth and backlash was an excellent way to see how patterns changed.

 

Here is the best photo I could get of the side of the gear.

There is a black arrow indicating a mark across the gear. Is this a wear pattern? Or is the wear mark down by the black arrow?

I couldn't see much on the other side besides the obvious color transition.

As I'm sure you have guessed this is the first time I've been inside a differential.