G2CS gearbox, trouble with 1st gear

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Thu Jul 25, 2019 4:22 pm

Hi Ethan,

Your clutch studs will be longer than the normal ones, because you have the 9-plate "scrambler" clutch.

Unfortunately, the gearbox and transmission documentation for these bikes is very poor and confusing.
I've tried to make sense of things in the following files...

Lightweight transmission parts: https://1drv.ms/x/s!AreW5w5WmJsqgR7NQGmVPA9RWR8l
Lightweight clutch variants: https://1drv.ms/p/s!AreW5w5WmJsqg0QG63BAGQgEfvQq
Lightweight fixings & fasteners: https://1drv.ms/x/s!AreW5w5WmJsqrFeLbZTlUbrrf_C7
Lightweight main crank bearings: https://1drv.ms/p/s!AreW5w5WmJsqrGpywwfk6pSLAqrk

Please feel free to add to/amend the above.

Oh, and welcome to the club! :beer: :D
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Fri Jul 26, 2019 1:11 am

I'm noticing that the documentation on these bikes is less than great lol. Clanger, Your links are incredibly helpful, I'll be printing them off and stapling them into the workshop manual. Hopefully I'll be able to dive back into the trans in a few days and see what's what.

I also did the dating service showing this frame is a 61 G2CS. The engine and trans numbers were hidden though.

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Mon Aug 12, 2019 6:16 pm

An update on the bike, I went back into the gearbox and found the layshaft bushing was super loose. I was actually able to pull it out with just my pinky. The fit on the shaft itself was still really nice so I prick punched the outer face and pressed it back into the case with a bit of loctite for luck. I then played around with shimming the end play and rewound the kicker spring. Now it works just beautifully until you give it the beans and itll kick out of gear. Kind of a bummer but I have a buddy who has offered to undercut the dogs. I'll be taking him up on that offer later on, right now shes good enough to cruise around on and take to a couple shows. Thanks again for the advice guys.

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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Mon Aug 12, 2019 6:23 pm

Excellent! Thanks for the update, glad to hear it's working better now. :beer:

If it's still jumping out of first, might be worth checking the detent spring and plunger first.
The plunger should be pointy, but they can wear flat. You don't have to dismantle the gearbox to check this.

Pic here:
https://www.ifixit.com/Guide/AJS-Matchl ... 77#s171895
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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Re: G2CS gearbox, trouble with 1st gear

Postby Redbeardindustries » Mon Aug 12, 2019 8:33 pm

Image

Image

The detent looked good and has a positive engagement. The dogs on the other hand are pretty well worn. The plan is to reshape them for a more positive engagement and undercut them while we are at it. Should end up being pretty stout at the end of the day

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Re: G2CS gearbox, trouble with 1st gear

Postby clanger9 » Mon Aug 12, 2019 8:53 pm

Wow, those dogs are proper worn! Yep, that'd make it jump out of 1st. I guess it's had a hard life ;)
1966 AJS Model 14 250 CSR "cafe racer"
1993 Ducati 750SS

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