Gearbox-Jumping out of 3rd

Seems like a few gearbox threads on the go at the mo.....
Mine has started jumping out of third if I change down from 4th and accelerate. Going up through the gears it does not do it (yet!). Since 3rd lay and 2nd lay are the gears connected should I take a close look at their dogs and slots or are the camplate and selector pin more likely candidates? I've never thought about it before but what contributes most to the gears staying in mesh, the selector or the gear dogs? Appreciate all and any comments, cheers.

I'm having the same issue w/ my MK3 right now so i'll follow along

When this type illness stuck my AMC back when, discovered some jerk off was running around too much in lower gear joys [& miles of timid creeping safety] so wore out the sleeve bushes that only ever get lube by splash drainage in 4th, let the cogs tip enough the dog faces didn't mate squarely so also wore the dog faces down like a beat on chisel head. Full disassembly and renewal with full filling of sleeve bush space & oil grooved and grinder to square up dogs got it going again. On the other hand may just be the pawl spring.

Full disassembly and renewal with full filling of sleeve bush space & oil grooved and grinder to square up dogs got it going again. On the other hand may just be the pawl spring.

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Thanks Hobot. Replaced the sleeve gear a while back with fully bushed and circlipped Mk3 version. Are you saying the pawl spring has an effect on staying in mesh? It changes gear nicely up or down and only jumps out once the revs start to rise and the load and speed increases and only on downshift but I think I can see what you're saying.

Ugh yeah, pawl spring in my cases made shifting mean but stayed in once engaged. What has let my gears pop out of engagement was the bushes dissolving inside the cogs too but usually on let off of loads not while under much throttling up. Anything beyond this I'm just guessing or wishful thinking till you tell us what did the trick.

Finally got so annoying not being able to downshift to 3rd that I bit the bullet and pulled the gears. 2nd lay had quite rounded dogs and more wear on one of the three. The slight taper (like a sloppy wood joint dovetail) on the dogs on both 2nd and 3rd was barely noticeable but on the new gears it is obvious. Of course replacement wasn't that simple as 2nd slides on the layshaft and it was tight and would only tap on in one spot. Some 'Blue', Dremel work with a mini drum sander tool and valve paste got her sliding nicely in all 6 positions (6 splines). In addition I had modified the K/S shaft for a needle race and that had lost a needle and was Loctited in place. It took some extracting. Here's hoping that's solved it. Will advise either way!

Well Keith, you made it to Oxford - did you get back home OK? :roll:
Alan (NOC Oxford branch)

Well Keith, you made it to Oxford - did you get back home OK? :roll:
Alan (NOC Oxford branch)

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Hi. That was quick! Yes I did, thanks to Graham's facilities the gearbox outer cover was off and gearchange assy screws tightened this time. D**khead had not tightened the screws on the gearchange stop plate. (for those not in on this I lost all gearchanging facilities on Saturday and arrived at the Oxford branch Cafe Racer day in 4th. I managed to nurse her 10 miles to a member's workshop after the show and carry out the fix, ie. do the job properly and then double check everything) What was amazing was that the gearchange went from perfect to both screws falling out in less than 2 miles. It was a great day with the Oxford guys and they were kind enough to award a plaque for furthest travelled, only because of the problem, having having missed my exit due to messing with the gear lever while riding. Once again thanks to all for the offers of help, especially Graham. I owe him a pint! It was something to meet Ken Sprayson and Stan Dibben. Stan is quite a character.

Glad you got it sorted and that you still managed to enjoy the day. I'll endeavour to put some pictures (that Graham took) up on our branch website later today. Yes, Stan Dibben is indeed a character and we are lucky to have him grace our events. For those that don't know him, he's well worth a google. Here he is chatting earlier in the year http://www.youtube.com/watch?v=6prVNNnfxDA.

Alan