some differential specs for your files

Just in case you ever "need to know"...

Some information that might save you some leg work just in case you get the bright idea of doing some interchanging on the thrust washers between the TR3 (late) and MGB (tube type) axles.

The flat phenolic thrust washers that go behind the sun gears on a tube type MGB rear axle are 0.035" thick, or at least the two that I just received are.

The flat copper/brass thrust washer for the same position in a TR3 ( later ) are 0.046" thick.

They both have the same inner diameter, but the outer diameter of the MG one is greater, 2.6" VS 2.145". The metal one would probably work well in a B even though the outer diameter is smaller, but the thicknesses are quite different so I could only suggest using it in a B if you were in a pinch and doing a full blown "ring and pinion plus all clearances and measuremnts" rehab of an axle. Just sticking the metal ones in when doing the usual thrust washer routine would result in the sun gears being too deep in the planetary gears and problems would obviously arise.

In the case of the cupped washers...

The TR axle specifies a range of thicknesses varying from something close to 0.50" on up in two thou increments for five or six steps. The MG spec calls for only one thickness and seems to be about 0.036".

The OEM MG washers that I just received vary from right at 0.35 to 0.38", outer radius area to inner radius area.

The TR washers that I took out of the axle that I am working on are about 0.025" thick across the board. The thinnest one spec-ed for the TR is about 0.051".

Although the inner diameter of both are the same, the outer diameter of the MG one is considerably larger, 1.54" VS 1.32"

From all of tis I deduce that there are really no interchangable bits here.

As B owners consider yourselves lucky. You can obtain both washers instantly from several sources. The TR bits on the other hand are listed by Moss and a few others but are not available. I am looking into two relatively obscure sources for the ones that I need and may have to settle for used ones.

Jack

Jack, no luck at The Roadster Factory? Charles Runyan is a TR nut and usually carries everything or makes it himself. RAY

Hi Ray !

I checked with them and found that they considerd the parts NLS and that they had no resources for them. I asked then how was it that they had a rebuild program and was referred to their "technical guy". He was very pleasant and seemed to want to help, but he said that they used old washers salvaged from discarded bad diffs. I was a little surprised, but it just thought that "it is what it is" and left it at that.

FWIW I found a guy in Henderson NC, just north of Raleigh that had what I needed. About five times the "published" price from Moss, but when you are dealing with something that has a fairy tale price and is not actually stocked you are just lucky to get it no matter what.

I posted this stuff here just because I had started a thread recently that developed into a discussion as to whether or not you could use the metal flat washers instead of the regular phenolics in a B. I think that my research and experience here tells us that it would not be wise to try it.

Jack

Maybe I should be checking the TR-3 rearends here. I kinda remember that they were those early type that were more of a problem, but haven't taken the time to verify.

Actually Jack, in your previous thread Dave Headly's dimensions for the Banjo axle sound like they would work in the later B axle. What was the inside measurement on the phenolic washers?

Hi Jim !

Didn't actually measure the ID. I just held them up against the TR ones and then slid them down onto the sun gear shafts. All fit perfectly.

I haven't seen any banjo axles in a coon's age so I have nothing with which to do a comparison. Perhaps Dave will be able to confirm something. If so, I'll order a couple of the earlier washers and physically do more snoop work myself.

All of this is sort of moot, in that the phenolics seem to be lasting a very long time and the ones that I am installing these days will probably last for another 40 years too, but it is the sort of minutia about these cars that peeks my interest. :-)

Jack

With high horsepower the clunk returns rather soon. That is why the metal ones would be better.