1953 / 4 G3LS build

[EddieDay]

A question about the drive side main bearing spacers, which are missing from my boxes of parts. The spares list shows 2 washers, one a larger OD and one a smaller OD which go between the two roller bearings. Part numbers are 010628 and 017194. The AMOC Spares website lists only the larger one and quotes dimensions
Length: 48 mm
Height: 1 mm
Weight: 14 grams

I take the "length" to mean OD.
Is the intention that two of these should be used rather than one large and one small?

[SPRIDDLER]

Since (if) your engine is pre '55 it should have one small and one larger washer.

Main bearing spacers sizes.JPG

Main bearing spacers.JPG

[EddieDay]

Thanks Spriddler. The engine is a '54 and you are right, according to the spares list it should have one larger and one smaller spacer. But the AMOC spares website lists only the larger one, and the photo is of two large spacers. That is why I was wondering if two large ones can replace the large + small? It is clear in the illustration you uploaded that the small spacer rests against the inside race of the inboard bearing. The larger spacer must rest against the inner race of the outboard bearing and at least partially cover the balls. So I can't see why two large ones won't do the job, or two small ones for that matter.

[SPRIDDLER]

Thanks Spriddler. The engine is a '54 and you are right, according to the spares list it should have one larger and one smaller spacer. But the AMOC spares website lists only the larger one, and the photo is of two large spacers. That is why I was wondering if two large ones can replace the large + small? It is clear in the illustration you uploaded that the small spacer rests against the inside race of the inboard bearing. The larger spacer must rest against the inner race of the outboard bearing and at least partially cover the balls. So I can't see why two large ones won't do the job, or two small ones for that matter.

I don't really know Eddie, but since the inner races are rotating and the outers of the bearings are stationary it's important that the spacers rotate at the same speed as both of the the spinning inner races but don't contact their stationary outer races. I've always believed that the larger spacer is intended to impede the passage of oil mist past the outboard bearing which is why the larger spacer covers the balls of the inboard race but doesn't bear against its stationary outer races. I can't think of a reason why why both spacers can't be the size of the larger one provided that they aren't so large that they bear upon the stationary outer races. Maybe that's why Spares Dep't only stock the larger one.
(Sorry for the rather wordy reply but I can't explain what I'm thinking in any other way! I guess you've already come to the same conclusion as in my diatribe anyway).

P.S.
I think the clue for the different spacers is in the factory spares list but the text doesn't enlarge upon why the spacers need to be different sizes.

Spacers. Drve side axle.JPG

[EddieDay]

Neville I follow your thinking and agree. I have decided that as long as the spacers are the correct thickness and ID all else that matters is that the OD is small enough not to reach the outer race. I will probably have a couple made locally.

[Duncan]

Eddie, I would be weary about using whole/rounded metric measurements for a part that would have originally been made to imperial dimensions.

[EddieDay]

Made good progress on fitting new main bearings, which are now in the case with the correct spacers.
But I am struggling with the timing side shaft and bush. The shaft probably has some wear and is 1.118" diameter. But is round and parallel. The data in two books I have is clearly wrong. Standard diameter is quoted as 1.2275" - 1.2300". That is larger than the timing side bush diameter which as standard is from 1.1250" to 1.1255". I have decided to have a bush made locally to suit the shaft. But what should the clearance between shaft and bush be? About 0.003" feels right to me.

[SPRIDDLER]

Don't know which books you looked at but if it's a '54 engine the t/s axle was increased for '54 models (i.e. Sept '53 onward) to 1 1/8" dia. (1.125") so yours at 1.118" sounds about right. The manuals say that the t/s should be line reamed in situ with both c/case halves fitted together.

Changes 1954.JPG

Neill's w/shop manual shows dia of t/s bush for '54 on as .............

Changes 54 ts bush.JPG

http://archives.jampot.dk/book/Workshop ... dition.pdf

[EddieDay]

Spriddler, yes the TS shaft diameter was increased to 1 1/8" from 1954. The two books that quote the diameter incorrectly as "1.2275" to 1.2300" are Neil, 48-57 AJS Singles and Bernal Osborne 1939 - 1955 Matchless Motorcycles. Both also quote the bush diameter correctly as 1.125" to 1.1255". Obviously a shaft that size would not fit in the bush.
My question still stands - If I reuse the TS shaft what clearance should I have the bush reamed to?

[SPRIDDLER]

Yes, I see what you mean now and there do seem to be errors in the data.
The only guide I can think of for relative clearance is in the Army Tech Standards for the '53 G3l which gives 0.00325" to 0.00425", acceptable at 6 thou and condemned at 10 thou. I say 'relative' because it would seem to be for the smaller dia axle but I would venture to say that the clearance given would be a good guide for the larger axle.

http://archives.jampot.dk/book/Workshop ... ndards.pdf

Changes wd ts axle bush.JPG