G2 gearbox - 3rd gear fault

Information relating to the Matchless G2 or AJS Model 14 250cc Lightweight
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sej
Posts: 13
Joined: Tue Feb 26, 2002 12:00 am
Location: CHESHIRE UK

G2 gearbox - 3rd gear fault

Post by sej »

Hi, My 1959 G2 has just developed on fault on 3rd gear. When changing into 3rd gear under drive the bike lurches forward constantly like the old kangroo juice when learning to drive. The manual only mentions jumping out of gear. When slowing down going back through the gearbox from 4th to 3rd the bike does not lurch forward unless I try to excelerate. When engine is switched off the gears all seem to select smoothly and pushing the bike forward in 3rd it feels ok and seems to be selected ok. Anyone had a similar problem?
Thanks Steve

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Tolly
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Posts: 647
Joined: Mon Jan 01, 2001 12:00 am
Location: KENT UK

G2 gearbox - 3rd gear fault

Post by Tolly »

Hi Steve,

I've had my G5, which is almost the same box, jump out of 3rd. I don't think it can be the gear as it would not go back in if it had jumped out. This sounds more like the drive chain jumping over the sprocket. Check the rear sprocket and tension of the chain as this will occur in the higher gears when there is more load. Does it do the same in 4th gear? Does it make a noise when doing this? What engine revs are you doing, approx, when this happens?
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sej
Posts: 13
Joined: Tue Feb 26, 2002 12:00 am
Location: CHESHIRE UK

G2 gearbox - 3rd gear fault

Post by sej »

Hi Tolly

Thanks for the reply. I checked the final chain tension and the gear box oil level, both seemed ok, though the final sprocket is getting a bit worn. Its strange as it does feel like it is in gear though constantly lurching forward. It does not make a noise though it does feel like something may be slipping. 1st, 2nd and 4th gear are normal. I will double check the final drive chain just in case.
Thanks Steve
56G80S
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Posts: 3353
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

G2 gearbox - 3rd gear fault

Post by 56G80S »

It's a long, long time since I had 66 AJS CSR lightweight and I did rework the gearbox because the bearings were shot, but I didn't have this problem.

Not wanting to be awkward, but are you sure it is the gearbox? There are others who would understand this better than me, but is there any possibility that it's the clutch alternately slipping and biting? Although IKBA!

I really enjoyed the AJS and they're much better in my opinion than they're made out to be. Good luck.

Johnny B
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