Differential axle assembly

[Rosenfelder]

I am re-assembling the rear end of my T. I have two new axles with the old gears that were OK. When I assembled left and right axles, and the spider gears to the ring gear carrier with a new little bronze disk between the inner ends of the axles, the whole assembly is locked up.
Do I have to adjust the thickness of the bronze disk to create the clearance in the assembly so that the axles will rotate independently?
Thanks,
J.R.

[Humblej]

Yes, or reuse your old disc if that fits better.

[Scott_Conger]

Sure do.
The original part was fiber and was a tad more forgiving. It also tended to disappear over the years.

[Oldav8tor]

Make sure the steel thrust washers haven't slipped off the pins during reassembly. Don't ask me how I know

[CudaMan]

Double check that the axles are fully pressed into the side gears. You can tell by trying to move the locking rings. If you can move the locking rings, the axles aren't pressed in tight enough.

After verifying that, you still may have to reduce the thickness of the bronze disc by sanding (although I did not have to on mine).

[Rosenfelder]

A couple of the pins that keep the thrust disks from rotating had sheared off. I replaced them.

[TRDxB2]

Its always hard for people to offer a solution without a picture. If all you have is the axles into the differential housing holding the spider gears (no thrust plates etc)- then I agree with Jeff H. If the differential housing is set into an axle housing then other possibilities enter. The Bronze axle disc washer is 0.020 thicker than the fiber washer. What's it like with no disc washer?

[Rosenfelder]

I have to check the difference in thickness between the Bronze disk and the fiber disk that was in there. I'm sure that the Bronze is thicker. Both axles locked up tight once the three differential housing nuts are tight. New Ring and pinion installed. I don't understand what is going on because I would think that the bronze spacer would push the axle fears apart making more room for the spider gears, and it would be loose if anything.

[Mark Gregush]

You have to fit the spacer just like anything else. With or without the spider gears in place on the spider the axles have to be able to rotate in the housing. If the spacer is to thick it needs to be reduced in thickness. Fiber or bronze they are sold in X thickness for wear. With fiber, because of wear to the ends of axles may require more then one to be fitted but one of the two needs to be trimmed down some. In this case with new axles, you need to fit it.

[Scott_Conger]

I doubt seriously that it's binding on the spider gears. Think about what you typed...when you tighten down the differential housing nuts, the axles lock. That's because you're squeezing the two axle shafts together end to end. The backside of the 2520 axle gears are constrained within the housing cant move "out" and with the too-thick shim, can't move "in". Spider and pinion gears don't figure into this at all.

You'd better check those housings really well for cracks now that things have been that stressed.

I'm guessing at this point that you are not working with a manual or other aid like the MTFCA rear axle book. If that is so, it's a mistake. There are numerous traps you can fall into, and end up using too-worn parts due to not understanding function or tolerances of good vs junk parts.

[TonyB]

The previous posts have covered just about everything that can cause your problems. But first please buy, beg or borrow the MTFCA booklet covering the rear axle.
Just to go over the main points again.
Make sure the axle gears are pushed all the way towards the center, the two C clips must be held tightly. Generally there is only one fiber washer between the two axles when in the differential case. Try the axles in the differential case prior to installing the differential gears. The axle should have less than 0.020” movement in and out. If necessary add a fiber washer. Install the differential gears and install the three bolts or studs depending on model year. Install the ring gear on the differential assembly, wire the bolts together in pairs. The pinion gear and bearing need inspection. Generally the pinion bearing will be worn beyond the wear limits and should be replaced. I prefer modern bearing set up. They can be either set with shims or set screws, either system has been used successfully.
When setting the ring to pinion gear clearance I prefer using paper as my mentor taught me but a dial gauge gives excellent results when done carefully.
There are many areas to mess up the rear axle assembly but almost all will work with only longevity and noise being the only criteria to determine the quality of the effort.
The MTFCA booklet on the Ruckstell axle gives many pointers on how to correctly assemble the assembly and is highly recommended.
Don’t make things too tight, a common error of modern mechanics who are use to dealing with today’s precision axles. Generally clearances of two to six thou is adequate depending on the location.
I could go on and on, get the booklets and take your time.

[John kuehn]

The fiber washer between the axles was all it took for the axles to bind up on the last axle I did. I removed it and carefully sanded it down a bit on a wide file. Removing just a little material worked OK and all was good. Didn’t think about using a brass washer at the time. Maybe next time. The axle assemblies I’ve taken apart over the years didn’t have the small washer in them as I remember. They were long gone.
It’s always best to read the T manuals to see what’s what and to know what Not to do. You can save yourself a lot of time and head scratching when using them.

[Rosenfelder]

I reduced the thickness of the bronze disk from .080" to .071" (in a couple of iterations) , oiled everything up and re-assembled. All seems well. Now on to final adjustment and assembly.

[Rosenfelder]

When I dissembled the rear end of my '27 T, the gear case that houses the spider gears and carries the ring gear was centered with only one thick steel disk and several thin shims on each side. One of the thrust plate pins was sheared off, and the thin shims were mangled.
I thought that there is supposed to be a sandwich of steel disk, bronze disk, and steel disk on each side. There was no bronze or babbit disks. The ring gear was worn out and probably the source of the 'angry' noises.
I have new ring and pinion, steel (4) and bronze disks (2) and replaced the thrust pin (and additional shims if needed).
I wonder how it worked at all the way it was assembled(?)

[Mark Gregush]

You will need to fit the bronze thrust washers in that location too. There is more to it then just reducing the thickness of those thrust washers. You need to set the mesh of the ring and pinion then fit the other side so the cases do not get sprung when bolted together and not rotate or be too loose.
You need to buy ether;
https://www.modeltford.com/item/RM7.aspx
or
https://www.modeltford.com/item/T1.aspx
We can help you to a point and the rear end is pretty forgiving, but it needs to be done right. Next thing would be to google"mtfca; rebuild rear end"

Service book on ebay right now;
https://www.ebay.com/itm/Ford-Model-T-f ... ondition=4