pinion gear double cup bearing issue

[Lee Mitch]

In preparation for a Mitchell overdrive I removed the torque tube from the banjo and the drive shaft with pinion gear and double cup bearing just fell out of the banjo housing. I'm pretty certain that is not supposed to happen! There is some scoring where it appears the double cup bearing was turning inside the banjo. What say you? Is this a complete replacement of the double cup bearing and the banjo?

[Jim Brierley]

The pinion gear is secured to the drive shaft by a nut, like the axles are. It came apart as it should.

[ursus]

How can a new bearing race be secured in a banjo when the interference fit of the casting has been spun out as shown in the photo? A new double cup race shouldn't be floating around in the banjo.

[DJ S]

Originally Posted by ursus

How can a new bearing race be secured in a banjo when the interference fit of the casting has been spun out as shown in the photo? A new double cup race shouldn't be floating around in the banjo.

Probably best to find a new casting at that point.

Should it be the last one on earth, you could bore it out and make a sleeve.

[Joe K]

There is a "preload" required on that bearing. Somebody may have "overloaded" the pre-load, the bearing caught and spun.

It normally takes a "tool" to pull the bearing/shaft from the housing. An "extractor." Mitchell sells something similar to the KRW tool traditionally used.

It is possible to use a "scissor jack" and a block of wood on the disassembled punkin.

$15 housing part on Ebay. Provided it too hasn't been "wallered out."

Have your NEW bearing in hand before purchase, so you can do a "receipt inspection."

Joe K

[rotorwrench]

Sponsored Links (Register now to hide all advertisements)

The double bearing cup is a tight fit and generally requires a puller such as in Tom Endy's tech articles on The Santa Anita A's web site. If it has spun in there then it may not be practical to repair it. I'm not a big fan of using Loctite on something that large since it depends on what the clearance is. Loctite 600 series cylindrical part locker can work on clearances as large as .015". The caveat is that it may be difficult to disassemble at next overhaul. It will have to be completely clean for the stuff to work but it's going to be the only way to tighten that set up up enough to avoid complete disassembly of the rear axle. Make sure the tapered bearings are still smooth to operate with no sign of shake or looseness. Preload is likely not what it was at last assembly due to bearing wear. Preload on used bearings should be less than new bearings but it may still have some preload depending on how long it ran before the double bearing cup started to spin.

[40 Deluxe]

Chances are the pinion bearing locked up sometime in the past due to a small flake of metal circulating in the oil getting caught in the rollers. The metal could come from a broken axle, gear tooth or pitted bearing surface. Not thoroughly cleaning the housings after a failure can cause this.

[Terry Burtz, Calif]

Please don't use a gasket between the torque tube and the banjo housing.
The gasket does not appear in the original Ford parts books.
The torque tube presses against the double-race to keep it in place.
If a gasket is used. there will be no press fit.

[Y-Blockhead]

Originally Posted by Terry Burtz, Calif

Please don't use a gasket between the torque tube and the banjo housing.
The gasket does not appear in the original Ford parts books.
The torque tube presses against the double-race to keep it in place.
If a gasket is used. there will be no press fit.

Thanks Terry, that's what I was thinking also but wasn't sure.

[Joe K]

Not to dispute.

And what is the point of the normal "semi-interference fit" between double shell bearing and the punkin housing - a fit which requires the tool for pinion/shaft removal?

Not trying to puncture a statement - but there must be a reason. It might be as simple as "positively locating" the pinion in the proper relationship to the ring gear. That would be the point of the pre-load.

An axle minus the torque tube recently arrived (thank you Craigslist) with a home-made removal tool attached and in place. Somebody had started the disassembly and lost heart. The axle had been sitting in a Maine field for the last generation. I was glad to actually now own the tool.

Joe K

[Ed in Maine]

Last summer I went thru the process of rebuilding the rear end because of a ring gear failure. Please see Tom Endy's rebuild paper. It is absolutely essential that you use it. In your case, I think the preload was incorrect This is a very difficult adjustment to make. There are two nuts at the pinion bearing. The inside nut adjusts the preload and the outside nut is a locking, jam nut. What I found while making this adjustment is that you have to set the preload very light with the inner nut because when you tighten the jam nut it increases the preload on the pinion bearings. Why? I can't tell you, its just happens. I would find that I liked the preload that I had with the inner nut but after tightening the outer locking nut, the drive shaft was too tight!

Rebuilding a rear end is not for sissies! It took me 6 weeks working alone and over $500.00 of parts. You never want to take a rear end apart for an oil leak. Torque the bolts to 35 ft-lb. and hope for the best. Ed

[Tom Endy]

The reason the double pinion bearing race fell out during disassembly is because it had spun in the banjo housing mounting. You can see the spin marks in the banjo photo. This is because the last person to have it apart tightened the two double nuts down tight instead of using them to set the pre-load. The bearings were probably locked up tight when the rear end went back in the car. Henry's 40 horses broke them loose and spun the race. I have encountered this a number of times.

The banjo should be replaced, and it is what I do, because you will have difficulty setting the pinion bearing pre-load, if you are able to do it at all. The new race may continue to spin, and the pinion bearing assembly will not be riding on bearings.

Be sure to not use an early 28 banjo that does not have support gussets top and bottom of the torque tube flange. They are prone to crack in this area, and most are already cracked at four of the mounting bolts.

It is true Henry did not put a gasket at the torque tube mounting flange. He also had oil leaks. I have been putting a gasket there for years and no ill effects have been reported back to me.

The web site of the Santa Anita A's Model A Ford club has my full library of technical articles on it and there is a couple dozen articles about differential rebuilding that is available to everyone. You are free to download and print out any of them.

Go to:

www.santaanitaas.org. On the home page click on my name to pull up the articles.

Tom Endy

[Synchro909]

I've had to redo a number of diffs all because someone set the preload too high. It is very common but can be easily avoided IF the directions are followed and not rushed. To do the adjusting, I made up two special spanners out of 3mm (1/8 inch) thick steel. They are NOT pretty, in fact, I refer to them as my fugly spanners. They are thin enough to be able to get both on a nut each and still be able to swing them, yet thick enough to be able to lock up the nuts well. When setting the preload, be prepared to spend some time doing and redoing it. As has been mentioned, the preload changes when the lock nut is done up. I believe that is because VERY LITTLE longitudinal movement is need to significantly change the preload and the small amount of slop in a thread (in the first nut) is enough to change the preload when the second one is tightened against it. The adjusting nut goes from having the bearing pushing it in one direction to the lock nut pushing it in the other. Looseness in the thread will allow it to move slightly as the lock nut is done up.
In this case, I agree fully with those saying the preload was set too tight and this is the result. I'd find a new diff centre.

[duke36]

How does one using an inch pound wrench get an accurate reading on the end of the driveshaft ?

[Joe K]

Originally Posted by duke36

How does one using an inch pound wrench get an accurate reading on the end of the driveshaft ?

When I did this I clamped a vise-grip wrench onto the driveshaft, and using arithmetic figured the weight of a handful of nuts which I put on a loop of string and hung from the adjustment knob on the wrench.

I was looking for the "break away" setting - and as some have said, the second nut has to be used "in concert" with the first one.

But that was before better tools - or even a common description. I think I was following Rick Freeman as that was the "modern" instruction that was available.





I'm "dating" myself here...

Joe K

[Tom Endy]

Originally Posted by duke36

How does one using an inch pound wrench get an accurate reading on the end of the driveshaft ?

A 1&1\16" six-point, deep socket will slide over the splines on the end of the drive shaft.

Tom Endy

[Lee Mitch]

Thanks everyone. It is not what I wanted to hear, but suspected that a replacement banjo was needed.

[rotorwrench]

A good modern flange sealant is either Loctite 515 or high temp 518 anaerobic flange sealant. I use the stuff on any metal to metal joint flange set up that has any tendency to leak with no sealant. A person needs no gasket with this stuff and there are no clearance change issues. I used to use Hylomar but this stuff is better.