Gear box Noise

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Gear box Noise

Postby Fergus Mercer » Thu May 16, 2019 1:25 pm

I am new to my AJS 18 48. Is the gear selection from neutral into 1st meant to be quite so crunchy ? I have oil in the box and my clutch seem to be fine. I also know the gear box is refered to as 'industrial' in some hand-books. Can you help ?

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Re: Gear box Noise

Postby Mick D » Thu May 16, 2019 2:04 pm

Hi

Do you habitually free the clutch before starting the bike? (pull the clutch lever in and action the kick start so as the clutch spins freely). If you don't the first engagement can be very 'crunchy'.

In normal riding there should be no significant noise when changing gear, if there is I'd check the clutch pressure plate is lifting off evenly, you may need to adjust the clutch springs to achieve this.

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Re: Gear box Noise

Postby spookefoote1956 » Thu May 16, 2019 2:35 pm

Which gearbox is on it Fergus? I have a B52 on mine and they're renowned for first gear crunch.
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Re: Gear box Noise

Postby SPRIDDLER » Thu May 16, 2019 4:55 pm

Welcome, Fergus.
As said it sounds like a poor set-up of the plate springs or poor clutch adjustment. Be aware that the cable adjuster only adjusts the slack in the cable; it does not adjust the actual clutch assembly. As you no doubt realise there's no synchro so some notchyness selecting first is quite normal. A crunch can be more noticeable if the primary and/or rear chains are slack.
If you don't have them, manuals are available to study/download here under 'Books'......

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Re: Gear box Noise

Postby Group Leader » Fri May 17, 2019 8:57 pm

I also find that mine is particularly “crunchy” if the tickover is fast and sometimes need to retard the ignition and wait for the revs to drop a bit. One day I’ll crack a good, reliable and slow tickover - but that’s a different thread!

Alan
1953 AJS 16MS, 1939 BSA 250 and a 1/3 scale Sopwith Triplane but that's another story ..... :lol:

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Re: Gear box Noise

Postby Fergus Mercer » Tue May 21, 2019 9:26 am

Thanks to All.
I will remember to free the clutch on start-up. I usually ( Ha-Ha ) turn the engine over a couple of times to prime the thing. Make sure its not flooded....
I did some further clutch cable adjustment with ( I hope/think ) some improvement. But, I'm at the limit of the cable adjustment and may need to go deeper.
On inspection the rear drive chain is on the slack side. I will tighten that one up asap.
Regard Ferg

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Re: Gear box Noise

Postby Fergus Mercer » Tue May 21, 2019 9:32 am

Its a CP gearbox

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Re: Gear box Noise

Postby clive » Tue May 21, 2019 9:46 am

If it is a CP box slacken off the cable adjustment, then undo the two screws on the little cover near the kickstart. This will reveal a stud with a nut on it. Turn the nut out to adjust the pushrod in. Then readjust the clutch cable. If this along with a slow tickover does not reduce ( rather than remove) crunching then i think you are going to have to check that the clutch plate is pulling up cleanly and that there are no burrs on the clutch basket. It will still probably crunch but less loudly :rofl:
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Re: Gear box Noise

Postby Fergus Mercer » Thu May 23, 2019 9:01 am

Thanks Clive.

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Re: Gear box Noise

Postby Fergus Mercer » Wed Jun 12, 2019 9:41 am

Dear All,
As you might guess, good clutch adjustment has solved ( er, lessened ) the first gear selection click. Thanks All

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