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MG MGA - 3H2865 laygear bearing

I have just returned from the garage in huge frustration

I have a gearbox to rebuild and the new "improved" laygear bearing from Moss doesn't even come close to fitting into the laygear itself (and yes I have removed the circlip and removed the remnants of the old bearing.

Has this gearbox an unusual laygear (it came out of my own car so I know the provenance of the laygear which came from Moss) or are the new bearings not fit for purpose or even fit?

Dominic Clancy

Interesting!The bearing having a complete casing will mean the rollers run on the outer cage.This means that the rollers should be smaller in diameter than the previous series.They should fit of course.....
Dirk/Antwerp
Dirk Van Ussel

I measure the ID of the laygear at 22.3mm or 0.878"

The bearing is OD 23.00mm or 0.906"

It seems that here
http://mgaguru.com/mgtech/gearbox/gt204.htm

the correct dimension is the laygear so the Moss part is wrong
Dominic Clancy

The old bearing had no cage and more rollers. Managed to get the old style for mine a way back from Quantumechanics. Have to phone him he ignores email
Art Pearse

reading Guru 204,is there a snap ring? Maybe the needles have to be pushed out of the cage inside the laygear.
Dirk
Dirk Van Ussel

I haven't heard of "new improved laygear bearing" from Moss". Got a part number?

Some time ago they came up with a revised laygear using longer full compliment needle bearings (and still selling it). It has to be installed as a set, new laygear, new bearings and new shaft. Never clear if a shaft of original design would work (maybe oil drill holes in different location). Also no replacement parts available, so if the shaft wears out they expect you to buy another special laygear set?

Perhaps this "new improved laygear bearing" may be a replacement part for the non-original type replacement laygear?
Barney Gaylord

If it looks like the attached picture, the tin-can type shell on the outside is a shipping container and assembly device, but is otherwise not part of the bearing. Once the bearing is installed, that thin metal shell is excess and to be disposed of.

Now, want to ask how to assemble the bearing into the gearbox?

Barney Gaylord

Seems they forgot to include the instructions. http://www.mossmotors.com/graphics/products/instructions/461-868_INST.pdf

Now I know I have to remove the sleeve and it doesn't fit as a cartridge like the old ones
Dominic Clancy

Glad to see they are making the old 20-roller bearings again
Art Pearse

According to Moss, not new manufacture but NOS
Dominic Clancy

The instructions were no use. Unbending the dimples to slide out the bearing as a unit wasn't a success because I couldn't get it perfectly round to slide the insides out of it. When it fell apart it was easier to install the end ring of the bearing into the laygear, then all the needle rollers one by one (magnetised them first to get them to stick to the wall of the laygear) and then the second end ring followed by the snap ring. Worked fine and was quicker than the other fiddling about.

40 minutes later the gearbox assembly was finished with all new bearings, seals and synchro rings. Should be off to its new owner in the next few days. I am just wondering what horrors the exchange box will contain.

The "new improved layshaft" appears to be physically identical to the older substandard ones, with the same drillings and dimensions. The shaft I took out of this box lasted just 800km because it was so soft, and had a HUGE step in it at the rear laygear bearing. This failure was the final straw that drove me to fitting the five speed box, which is a massive improvement.



Dominic Clancy

Since September 2015 (maybe slightly earlier), Moss Motors has "new" layshafts manufactured with good dimensions and appropriate hardness. These are I think as original issue, so calling them "improved" is only a reflection on the poor quality of the parts having been supplied for many years prior (and maybe still supplied by other vendors).

They first appeared at Moss UK, soon followed by Moss USA. I bought one Sept 1, 2015 (not available in May 2015), got it installed (along with full compliment needle bearings) Sept 4, 2015. So far run 42,000+ miles and still doing well. Huge improvement as the preceding softer shaft with cage bearings was shot at 25,000 miles.
Barney Gaylord

This thread was discussed between 10/01/2017 and 15/01/2017

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