Banjo Rear Assembly Questions

53OlderThanMe

53OlderThanMe

Member
I needed to swap a bell housing as someone torched the spring mount off on one end. I am replacing the seals, gaskets all around. The bearings and races appear to be fine so leaving them alone for now.

So my first question is since the axle seals are at the hub end of the axles what prevents the gear lube from going past the carrier bearings into the axle tubes?

Second question is do I pack the carrier bearings in grease prior to assembly the same way I would wheel hub bearings?

Thanks
 
there are seals in the axle tube that prevents the gear oil from getting out . ez to take out , but carefully put them in . they go in from the big end & the lip face the banjo . one on each tube . i lightly grease the bearing , as i do most everything , such as seal to prevent scaring .
 
Unfortunately, you've now entered the "Twilight Zone" of rear end assembly/disassembly by changing out one side trumpet.

There are some differences between trumpets in where the bearing recess presents relative to the casing juncture.

I.e. you can't really change out a trumpet one for one unless you can come up with EXACTLY the same trumpet type. It's possible but where your wear pattern occurs between pinon and gear may be different even with two identical trumpets.

Also the pre-loading of the carrier as its pinched between the two housings may be different. You should be checking pre-load.

It is possible to accomodate different housings by using different thickness of gaskets. Using these gaskets allows you to "position" the carrier/large gear to get the right contact (touch) between the pinion and the large gear. You may require a couple or even several gaskets on one side - and have to settle for a thin coating of wet paint on the other side to act to seal and still attain the correct positioning.

Suggest you read Tom Endy's narrative on rebuilding the Model A Rear End. Also, there are other sources on the 'net which present almost exactly the same information.

Tom will probably be on here in a bit to give you the link.

Joe K
 
Joe K said:
Unfortunately, you've now entered the "Twilight Zone" of rear end assembly/disassembly by changing out one side trumpet.
Joe K
Click to expand...

I'm beginning to feel like everything 'Model A' is in the twilight zone. Shocked at the amount of odd fit and different part combinations across 4 years of car production for what I thought was a cookie cutter 4 million produced car. :confused:
 
V4F said:
there are seals in the axle tube that prevents the gear oil from getting out . ez to take out , but carefully put them in . they go in from the big end & the lip face the banjo . one on each tube . i lightly grease the bearing , as i do most everything , such as seal to prevent scaring .
Click to expand...

There's a "tool" available to make inserting those seals an easy job. Goes on the end of a two foot or so piece of 3/4 inch pipe. Most suppliers have it.
 
JBill said:
There's a "tool" available to make inserting those seals an easy job. Goes on the end of a two foot or so piece of 3/4 inch pipe. Most suppliers have it.
Click to expand...

I've got one of those on order and I understand the seal and where it goes. What I still am not grasping is what keeps the diff lube inside diff? It would seem to me that it would leak past the carrier bearing into the axle tube. The seal is on the far end of the axle tube/trumpet.
 
as mentioned the seals in the tubes are what stops it from exiting..
there will be some oil in the trumpets.
my self i would not reuse old bearings and races in the diff as they are cheap vs the amount of work required.
 
All rear axles leak lube into the "tubes" only when the vehicle is tilted enough for that to happen. When on the level, the lube occupies the lower 3" of the center section, and the crown gear acts like a paddle wheel to distribute lube to the pinion gear and bearings. As others have stated, make sure you have good seals properly installed in the "trumpets" and the axle shafts have smooth seal surfaces.
 
Ok, thanks everyone for your response. I was going to replace the bearings and races but they do not appear original ie no 'Ford' logo or stamp and have no pitting or other problems. This axle was bought separate from my body and already converted to juice brakes so it may have been rebuilt in the past. I am replacing the driveshaft bearing as it is clearly done and all the seals and gaskets.

Thanks for the education.
 
Original bearings are almost always "Timkin" which were and are high quality bearings.

But a lot of other manufacturers now make bearings to Timkin standards - hence the rise of imports now being almost the only bearing available.

Tom hasn't jumped in here (maybe he works for a living?) So I'll give you his instructions for rebuilding the rear end. He won't mind.

www.foxvalleymarc.com/Tech_section/rear_end/diff_seminar.doc‎


Joe K
 
The above link did not work for me. You can obtain the dissertation from the web site of the Santa Anita A's (Southern California) www.santaanitaas.org. Click on technical, then on my name (Tom Endy).

Rear axle assembly bearings as far as I know are only made by Timken and they are expensive, over $300 per set, and they go up every year. The very early cars had the Ford logo on both the bearings and the races. Later cars used Bower bearings and races. Bearings and races were then supplied by Timken with the original Ford part number on them. Today Timken bearings and races use their own part numbers.

Contrary to popular belief, the seal in the outer end of the axle housings is not an oil seal, it is a grease seal. Its purpose is to keep grease pumped in through the grease fitting on the end of the axle housing from traveling down the axle toward the differential. Henry's design was such that grease pumped in through the fitting was blocked by the seal and forced to travel outward between the axle and the bearing hub. It then became trapped by the large seal in the brake drum and forced onto the large rear roller bearing. It was not Henry's best idea as before long the pathway becomes clogged with crud.

I have taken many rear axle assemblies apart and found both seals completely shot and where the owner had pumped a lot of grease in through the fitting and it had centrifuged down the axle half way to the differential . The build up could be an inch or more in diameter.

I have also taken units apart where the seals were intact or the owner had not pumped grease in through the fitting and found the axle shaft rusted with no sign of banjo oil any more than a few inches from the carrier. This tells me that oil from the banjo does not migrate out to the ends of the axle in normal service. I think the tapered design of the axle housing keeps the banjo oil where it belongs. Also the angle of the torque tube prevents oil that passes through the pinion bearings from going anywhere but back into the banjo. The same grease seal used in the axle housings is used at the front end of the torque tube and its purpose it to keep grease pumped in through the transmission rear bearing retainer grease fitting to grease the U-joint and roller bearing from migrating down the drive shaft.

The prudent thing to do when overhauling a Model A rear axle assembly it to replace all bearings, races, seals, and gaskets with new. However, I would try to use original rear wheel bearings with the spiral in the elements. They were well made and over engineered and if not rusted are good to use. The reproductions are hard on the surfaces of the axle housing hubs. I would also obtain the grease seals used in the brake drum from A&L, as they fit properly. Most other repos are too large.

Tom Endy
 
Thanks for the link and outstanding write up Tom. I actually had been using an earlier version of your document I had found elsewhere.
 
Why not weld another spring mount from a worn out axel housing on to your housing. Seems a pity to waste a good one for the want of a spring mount.
There is a real good book out over here called The Complete Model A Ford Restoration Manual by Les Pearson. Covers Right and Left drivers.The section on Differential ( rear end ) restoration is excellent. Ive found out about a lot of things Ive been doing wrong for years. Tells you exactly how to set up a diff correctly. I think you can get a copy from Snyders. As regards grease etc I have always put a thin coating of grease on the surface of both drive shaft and axels when assembling a diff to stop them rusting in service. Happy Motoring
 
The axle seals (at least modern "lip" seals) are directional, in that they keep fluids from going in one direction, but they allow it to go in the opposite direction. The object here is to have all the rear end seals arranged so that fluids (bearing grease OR differential oil) go towards the front of the car (axle bearings into the differential and differential into the U joint / transmission) and NOT INTO THE BRAKES! There are several threads on this in the V8 forum. (I'm sorry that I haven't read all the other posts in this thread and I might be repeating someone else's information.)
 
Was going to change those seal in my 38 banjo,my supplier asked why? He said put it together and if they leak Change them. That was seven years and 12000 miles ago!the oil can't climb out of the carrier,through a spinning carrier bearing,up a tapered axle tube,through a seal and then a bearing and another seal,to get at the brakes! All is well,I've done several since,all the same way! And Tom,very good explanation! Thank you.
 
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