Lightweight gearbox removal & overhaul

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Re: Lightweight gearbox removal & overhaul

Postby colinlinden » Sun Jun 18, 2017 6:55 pm

I can confirm that the oil seal from Villiers Services is indeed the correct fit.

Thanks again clanger9.
With your brilliant step by step guide, the link to Villiers website and the help from Ozmadman & Steve S, I have finally rebuilt my leaky gearbox.

I think the hardest part was removing the gearbox & putting it back in again!

So far I have only run the bike down the drive & back but all gears are selecting perfectly.

I replaced the 18 tooth sprocket with a 19 tooth one that I had from a G2 box which I bought for spares.

Ozmadman, I am interested to hear your thoughts on the 20 tooth sprocket?

Hope to get an MOT later in the week and get her on the open road to see if my repairs hold up!

Thanks again guys, I couldn't have done this without your help :beer:

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Re: Lightweight gearbox removal & overhaul

Postby clanger9 » Sun Jun 18, 2017 7:52 pm

Brilliant news and well done! :beer:

I'm very glad to hear the Villiers seal is the right one. That information will be very helpful for other owners, as club spares don't stock this item.
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: Lightweight gearbox removal & overhaul

Postby Ozmadman » Mon Jun 19, 2017 4:15 pm

colinlinden wrote:Ozmadman, I am interested to hear your thoughts on the 20 tooth sprocket?
Good to hear you have the box back together AND working properly, yes clanger9's guide is priceless and very well put together and will be a great help to all who follow us in the future. As for the 20 tooth sprocket, I know you have posted in the G2 section but is yours a G2/G2CS/G2CSR or a G5? I only discovered recently that the later G2CSR'S (1966) had internal ratio changes so without the manual and a look at the gear ratios it could be difficult to tell. If it is a G2 or a G2CS or a G5 then it appears that the internal gear ratios were all the same, the difference being differing amount of teeth on the clutch.. crank sprocket and final drive resulting in slightly different final drive ratios. Having said that it looks like the G2's (19T) (final drive ratios)were a bit lower geared than the G5 (standard 18T) so I can't see too much of a problem using a 20T on either a G2 or a G5. The bikes evidently are designed to rev a bit but I find a 20 tooth on my G5 gives a far more relaxed ride at say 60MPH than either an 18 or 19 AND first gear becomes useable as a proper pull away gear!!! the only downside is that you really need to change down at anything lower than 3omph so if you do a lot of town riding then may be sticking with a 19 would be better... 18 is out totally in my opinion
Paul
1960 Model 8
1974 Yamaha RD250B US Model 6 speed

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Re: Lightweight gearbox removal & overhaul

Postby clanger9 » Mon Jun 19, 2017 5:04 pm

I agree with Paul's recommendation for the 20t sprocket on the 350. It's a long-stroke motor and has more low-down torque than the 250.
I have a 19t sprocket on my 250 and it feels about right - a little busy, but then the 250CSR is a short stroke/high compression motor and likes to rev.
It feels very under geared with an 18t sprocket.
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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