Technical Problem with banjo axles locking up after bells tightend

Help! I am reassembling this banjo after replacing carrier bearings and having an interesting problem. This is off of an unfinished project I bought recently and am basically going through everything. For that reason I am not sure if this is a problem that is new or was already an issue I was not aware of. With that all said, here it is;
I have replaced the carrier bearings and races, checked the pinion preload and set the carrier preload and pinion backlash. All good so far. I assembled the diff assembly and all good on the bench. Turn one axle and the other turns the opposite direction like it should. When I install the diff assembly into the housing with the bells attached the axles lock up solid like a welded diff. When you turn one axle the other turns in the same direction. Turns fine with little effort and not tight, just the axles are locked. With a LOT of effort (visegrips) I can turn one axle while holding the yoke and it feels way tight like you can count the teeth on the axle. Loosen the bell a bit and they turn opposite directions like they should. Tighten back up and it's locked again.

Pretty sure this is a '46 carrier and housing (open driveshaft), '39 bells and '37 axles with 18 tooth axle gears and 12 tooth pinion gears. I have torn it apart way too many times trying to see why, but no joy. I don't see how tightening the bells could put any kind of pressure on the spider unit to bind it up. Hopefully I have enough info that someone may have an idea.

Thanks, Matt

 

you need shim gaskets to fit the bells to the center section

 

Thanks, I have set the carrier preload and pinion backlash with gaskets ending up with .019 on the left and .010 on the right. I have .006 backlash on the pinion. The carrier assy turns fine when all is tight, just the axles lock up.
Matt

 

Bearings are not fully seated or are incorrect for the application

 

Carrier bearings or ? Everything turns fine and free, just the axles are both spinning the same direction. Carrier bearing preload is good. There are no bearings inside the actual diff assy so I don't understand what bearings could cause that.
Matt

 

For some reason it seems that the carrier is compressing enough to bind the spider gears and I assume if you pull the pinion out the results of locking will be the same

 

I think Roadster1927 is right about needing shims.
Seems like I remember seeing brass shims, shaped the same as the banjo gaskets,
on one I had apart about 45 years ago.
That does the same thing as loosening the bolts.

 

But wouldn't my carrier preload be way loose then?

 

The guys over at The Ford Barn might be more help.

 

Yes

 

This is the verbiage in the 39-40 manual for adjusting the side bearings.

(Earlier instructions state using .008 to .010" thick gaskets at the bells to banjo on both sides.)

"With both the left and right axle housings bolted to the banjo, the differential side bearing clearance may be checked by rotating both axles in the same direction at the same time." (A later manual says to have two people do this.). "The differential should show a perceptible drag yet be free enough to be turned by hand. If the clearance is too great, reduce the gasket thickness between the right axel housing and the banjo housing. If the adjustment is too tight, increase the gasket thickness. This adjustment should be made entirely by adding or removing gaskets between the right axle housing and the banjo.

CAUTION: Do not disturb the gasket thickness between the left axle housing and the banjo while making this adjustment."

The left axle housing gasket and the pinion adjustment sets the backlash. .006" is good.
Add enough thickness to the right housing gasket until you get the differential to free up.

I hope this helps you out.

 

If the spider gears lock up the axle endplay might be too tight. Also have you tried installing the hubs and bearings to test it? the axles droop without support and might lock up.Good luck.

John

 

First impression is that you have mixed up the spider gears. First you must ID the axles that you have. 18T that is 32 3/4" long is 35-8, uses a 12 tooth spider, 16t axles use an 11 tooth spider, 39-41 are 32 3/4 and 42-8 are 33 3/4". Blow your rear axle apart count the teeth on the axle and measure the length.

 

Thanks to all, I haven't checked the length but I did do a tooth count early on as I thought a gear mismatch seemed like the most likely culprit. They are 18 tooth axle and 12 tooth spider. I have put it back together temporary as I am mocking up my chassis. I can pop it back apart and get a length.
Axle endplay seems like a likely possibility but I would think it would bind up as soon as the carrier is assembled on the bench?
What confuses me is why it only becomes an issue when the bells are tightened up. I don't see how the carrier can be somehow compressed enough to bind up internally but still rotate free. With the diff carrier all assembled the axles rotate opposite as they should until put in the housing and the bells tightened up all the way, then they lock together again but still rotate fine as an assembly. I turn one axle and everything rotates, unless I hold the yoke then I can't turn anything of course. Hopefully this all makes sense?

 

Your axles free float in the carrier, Pulling on each axle you should have about .010 end play on the axle. To check: Wrap a coat hanger thru the axle cotter key hole to make a handle, with a soft hammer tap the axle inward to remove any play. Now pull on the axle it should move outward just a touch to indicate it has clearance. If there is no clearance pull all the pieces apart and recount the teeth on both axle and all 4 spiders, if you have mixed the spiders it will bind.

The wrong carrier spacing with the side bell gasket will have no effect on the axles the side bell shim gaskets set the carrier bearing crush pressure and the alignment of the ring to the pinion, nothing relating to the axles.

 

Well, finally got the banjo out of the chassis for a while and took it apart again. End play is good. Axles are 32 3/4 inch 18 tooth and all 4 spiders are 12 tooth. this was set up with the spring in front of the axle and in the process of returning it to behind I had inadvertently put the bells on the wrong side so the spring mount was upside down. When I took this apart this time I also corrected that and now after putting it all back together the axles turn opposit directions like they should. Now I really don't know what to think! Even though it turns it is not real even and you can feel resistance come around at times. What may be the problem is the axle gears themselves have some deep wear and that may be binding up. The spiders look fine. I don't see how changing the bells side to side would matter so maybe it is a matter of the spiders being in a different order this time it was reassembled. I guess for now I will put it together while looking for another pair of axles.

 

When you changed the bells from side to side (the first time), get the gaskets go with the bells or stay with the housing? The gaskets would have to stay on the same side of the housing, if they happened to get mixed up that would be an issue.

 

Wow, those ARE really worn!

 

Yeah, pretty nasty and the tapers are a bit rough too.

 

Those axles are junk. You'll need to find a new set. Were the spider gears NEW or used?

 

That is a really strange wear pattern. What do the spider gears look like? Back to the original problem, would the wear lock up the axles? Seems like they would just be loose. Seems like something else is wrong.

 

Not sure on the spiders, guessing they were used when this was originally assembled (not by me). I don't think they were originally mated with these axles as the spiders look quite good. I am looking for a pair of decent axles.

 

60 years of wear there...maybe another 10-20 left...RUN um.

 

You could also just install them so the forward drive surface is on the other side of the teeth for now... but I would find better ones, they are not that tough to find and not that expensive.

 

would be surprised it if the housing was bent..accidents and welding on them can thro them way out

 

Just a follow up and thanks to Dick Spadaro and all who replied; got a set of very nice axles (thanks Andy49) and that took care of the problem. Turns nice and smooth in opposite directions.

Matt