Gearbox Problem 1950 Twin

[Jim Richardson]

This sounds very similar to a problem Chris from the Lancs section had on the way to the lakes rally, not sure how old his bike is, he had managed a repair at the roadside once before but this time it wasn't to be, we couldn't pull the G40 shaft fully out, it felt like a bush was jammed and I think he was reconciled to stripping it down.

I have my D in bits at the moment and I can't see what can can cause this problem, but as mentioned earlier engines may be slightly different.
On a more positive note the gear box now it's in bits doesn't seem too scarey, but then I haven't got it back together yet.

 

[timetraveller]

The 'D' is different and much superior. You would have to strip the engine to change to all 'D' parts and you cannot do a partial change over but my guess is that the tube comming adrift is the problem.

 

[notap]

I think you and Greg are correct. Looking down the shaft seems to indicate the tube is missing. The good news is that I just happened to have a magnet that fitted nicely into the shaft. The bad news is that it couldnt find anything loose in there. I'm now resigned to a gearbox stripdown. So, lots of reading and preparing... my next decision will be about my own competence to undertake the job.

Thankyou all. Most helpful.

Rob

The 'D' is different and much superior. You would have to strip the engine to change to all 'D' parts and you cannot do a partial change over but my guess is that the tube comming adrift is the problem.

 

[ogrilp400]

G'day Rob,
With the bike up on the rear stand and rotating the rear wheel you should be able to select five definite positions (four gears and neutral) by rotating G40 from about 11.00 to 3.00. If you cant do this then the problem is in the box. Why this should happen is the unknown.

Phelps. Victoria

 

[greg brillus]

Back again Rob, just as a final note on your problem....if you can select any gear, maybe with the back wheel on its stand, squeeze in the clutch perhaps with a second pair of hands, and try spinning the back wheel back and forth with a decent spin....don;t get your hand jammed on anything.....this may just flick the displaced tube off the problem area and end up in the bottom of the box, where as i said earlier, it will do no harm as there is plenty of clearance between the gears and the bottom. If all else fails then you will have to open up at least the gearbox G2 cover plate and go fishing with your magnet. Cheers and good luck.....Greg.

 

[Garth Robinson]

I believe you will have to strip the gearbox anyhow if the sleeve is missing.The fork in the bevel gear will get forced open over time if used without the sleeve.When this happens you will need to dismantle the whole bike,as you need to split the cases to replace it.Get in early!

 

[vibrac]

Yes
Go on strip it you know you want too....

Before the hallowed 1999 IOM rally with just a few days to go my gearbox played up I stripped that box down and back complete with road tests so many times I lost count. Angela helped me when I got to tired and swears she could also do it now. In the end it was worn selectors and no-one had any on the shelf....
Which is the story of how I got my first 5 speed surtees gearbox...

 

[bmetcalf]

One positive note is that after the job, you'll be much more familiar with your machine!

 

[b'knighted]

Familiarity breeds contempt.

 

[b'knighted]

If you find that enjoy learning more about your bike -

Familiarity breeds content.