AJS & Matchless Owners Club

My 250 is fitted with a 14/CSR gearbox from 1963 according to club records and I am in the process of getting it ready for the road. I decided to change the gearbox oil, but on checking the manuals I found on line it states that the gearbox should be filled to "just below the orifice for the inspection plate". When I removed the plate just in fromt of the kick start there was no oil to be seen. Am I right in assuming that this is where the oil is topped up or am I looking in the wrong place?. If so that it appears that there may have been a serious leak. I have never had the bike on the road so I have no idea what the gearbox condition is.

Peter

That's right, it needs to be up to the inspection plate hole. 3 pints of SAE 50!

It looks like it's been empty for a while - I can see a bit of surface rust on the selector spring bracket.
The gearbox bay have been rebuilt and never refilled. These gearboxes can be very leaky...

Thanks Clanger9 I'll fill it up and see what happens. I have visions of the Torrey Canyon

Well after 24 hours no sign of a leak. The real test will be when I eventually get it on the road and get all the parts moving. Clanger your idea that it may have been drained and never refilled might just be right, fingers crossed.

Well it seems that I spoke too soon . Over the course of a couple of days the leak(s) started to show when I found a small pool of oil under the bike. There was a trickle from the kick start shaft but I doubt if this would account for the amount I'm seeing, perhaps an egg cup full so far. There was nothing from the gear change shaft and as the only reference to seals I could find were on these two shafts I wondered if there was any other possible source of a leak?. What level of striping is required to replace the shaft O rings, can it be done in situ or is it necessary to strip the box?. Although I am happy enough working on the engine I have no experience of gearbox work.

Peter

pecon wrote:I wondered if there was any other possible source of a leak?

You want the long list or the even longer list?

Which end is it leaking from? On the outside, they leak mostly from the kickstart shaft as the seal arrangement here is poor. It's not so easy to fix, but you can try sticking another o-ring on the shaft. Leaking from the gear selector shaft can be easily cured without dismantling the gearbox - just replace the o-ring on the shaft and the two small ones on the gear selector indicator.

The can leak from the two mating faces in the middle of the box.

Finally, they can leak from the output shaft oil seal, the bearing retaining pin (if loose) and if the pivot shaft for the selectors is loose.

You should find most of what you need to know in my guide: http://archives.jampot.dk/technical/Tra ... erhaul.pdf

Hi

An egg cup full of oil will form a very large pool, (depending on how absorbent the surface is), you may be surprised at how little oil you are losing.

My advice would be to clean the gearbox area of oil, take the bike for a ride to get things up to temperature, and then thoroughly clean the area again.

Now get a good torch and maybe a mirror for those hard to see areas and observe - have a look every few minutes for around half an hour.

You will then see where the oil is leaking from and to what extent, (once you see a source wipe the oil away to prevent it obscuring other potential sources lower down).

Report back and I'm sure others more knowledgeable than I on lightweights will advise as to how to best rectify the leak(s).

Regards Mick

I had a similar problem trying to trace a leak on my G2 gearbox. I ended taking it out of the bike and resting it on the bench after a thorough clean.
Gearbox was topped up and observed. Turns out the main part of the casing was porous at one point with oil seeping out of two tiny black spots.

Not sure what just happened as I posted a reply it disappeared. Anyway here goes again.

Clanger9, I had that guide bookmarked without realising it was yours, very comprehensive and very useful. I never knew that there were so many possibilities for the leak. The oil is leaking from the right side of the box, from the kickstart shaft and a drop found on the casing at the gasket directly behind the kick start but the gasket seems OK and the oil appears to be running to there. I take it that the O ring on the kick start behind the case as there some outward movement on the shaft when the kick start is depressed, about 1/4 inch ?. Not looking forward to removing the outer cover having read about the difficulties others have had refitting the spring but if theres no option...

Mick, all good advice and exactly what I'm doing at the moment. Unfortunately the bike is a bit away from getting on the road so any warming up will have to be done on the bench, not ideal I know.

Dodger, hopefully thats not what I'm experiencing. How did you rectify that or was it a case of a replacement box?.

Yes, you've got it. End-play on the kickstart shaft means there's no effective seal here, so it will weep.
If you take the cover off and pack it out with another o-ring, it should be OK.

I improvised a quick fix using a rubber cable grommet with an o-ring around it, sandwiched between the kick start and the gearbox casing. Not pretty, but it saved taking the gearbox cover off again and it works...