gear problems

[neddyo]

Hi everyone,

I have just finished restoring an es 250/2, I,m thrilled with the way it all went together
and it looks brilliant, but, the second time I rode it it seemed to keep jumping our of first and second
gear.
Has anyone had experience with this problem and what should I do about it, is it a total strip
or is there anything external I can try.

Nick in OZ

[mr_luke]

The obvious first suggestion is to check that the gear lever isn't fouling on anything, like the footrest mount, which could be stopping it going right into gear. After that, all I can think of which doesn't involve stripping it down completely is the detent behind the large primary gear. Behind the gear is an arm with a pivot in the middle. At one end of the arm is a spring attached to a peg in the crankcase and at the other end is a wheel. The wheel bears against the end of the selector drum, which sticks out of the crankcase. On the end of the drum is a star shaped cam washer, with a normal washer on top of it, all secured with a countersunk screw, and it's the cam washer which the wheel on the end of the arm bears against. I've heard of people having problems with the spring breaking or falling off, and in my current engine I couldn't get the countersunk screw to stay tight, so it would be OK for a few hundred miles, until the screw (and obviously the cam) worked loose and the gearchange became a bit "woolly". A drop of superglue on the thread a couple of thousand miles ago seems to have cured that.

Failing that, I think you're probably going to have to take the engine out and split the crankcases.

My first ETZ used to jump out of third gear whenever you opened the throttle. It turned out the selector fork was badly worn, and wasn't pushing the sliding gear quite far enough to engage the dogs properly. The MZ gearbox relies on slight undercutting of the dogs so that they pull each other together once engaged, so unfortunately once the dogs had been rounded off the two gears were useless as well!

It's a pretty standard problem with 3rd gear in the five speed motors, but I suspect your problem is probably similar, so I'd be looking at the condition of the dogs on the gears and particularly at the condition of the selector forks. The wear the worst on the curved area where they sit in the groove on the gear, and you may well find they've gone a nice blue colour if there's a problem. The other ends of the forks have little pegs which sit in slots cut in the selector drum, and it's also worth checking both the fork and the drum for wear here, although they will probably be OK.

Good luck! At least the bits are all readily available. I had a problem with a worn fork in the Burman box on my Panther a few months ago. Couldn't find a new one, and the best old one I had in the shed really looked just as bad! I reckon there was a fraction of a millimetre in it though, because it seems to be alright - for now!

[neddyo]

Hi Mr_luke,
Thanks for posting about gear problems.
Yesterday I bit the bullet, took the engine out and stripped it.
The gear box is a mess, blue gears and selectors and rounded off dogs,
but no tooth damage.
I have embarked on the job of dressing the dogs back to their original 5 degrees
and with a diamong file reinstating the 5 deree back angle on first gear, I think this is
the gear that started all the problems.
I did think my conversion from left to right foot gear change could have been the culprit
but it started while it was still wih the original gear change set up.
I will post some photos as things progress.
Nick from OZ