z1B Gearbox problem

[Nobbyrobby]

Hi. I'm posting for the 1st time as i have just been out on my bike and after initially having all gears to select, a few miles into the ride the gear lever seemed to go 'loose' and I can now only get 1st and 2nd. The lever is tight on the shaft, so it's not that. I have limped back home in the cycle lane! Any suggestions as to the cause? I bought the bike in a restored condition and have put about 1000 miles on it this year without any major problems. Well. other than the battery blowing to smithereens under the seat on a ride! Another limp home, misfiring all the way. I put a new reg/rec from Dave at Z power and that sorted that.

[zed1015]

Sounds like the lever return spring has broken.
It lives on the other end of the lever shaft behind the trans cover.
Part number 5 in the atteched pic.

gear-change-mechanism (3).jpg (23.33 KiB) Viewed 965 times

[Nobbyrobby]

Hi. Thanks for your help. I've delved in and it was exactly what you said, a snapped return spring. Got another couple of related issues if I can bounce them off ya?
The sprocket nut was only finger tight (literally).. there's was a tab washer behind the nut and the tab was bent over a flat on the nut, but there's no tab on the rear of the washer to locate into anything in the sprocket. I was expecting a small blind hole in the sprocket or something to stop the washer rotating. How's it supposed to work? I can't fathom what use it is like that. Can you recommend a solution? Lastly, I temporarily refitted the inner trans case to stop the oil weeping out while I course the parts. I though I might as well put the outer case on too so it wasn't lying on the deck. I don't know how, but the clutch push rod seems to have 'grown' in length and the outer case won't mate up with the main engine casting. There is a 7-8 mm gap. I'm sure that the clutch worm drive is all the way back and the rod is engaging in the cup. I'm thinking that while trying to get the inner case off, I may have pulled the clutch rod out a bit and perhaps it's not seating where it should be in the clutch basket. Any tips?

[zed1015]

Depending on model there's two ways of securing the sprocket nut.
There either should be a small hole in the sprocket that a tab on the washer locates in or if the output splines protrude beyond the outer face of the sprocket then the lock washer has corresponding splines to prevent it from spinning and the sprocket nut is recessed on the back to allow clearance for the protruding splines.
It may be the case that the sprocket is pattern and hasn't got the hole and the tab on the washer has been flattened or broken off. .
In that case unless you drill a hole and fit a washer with a tab or replace the sprocket you will just have to loctite the nut and torque it up..
As for the push rod, i'd say the problem is at the worm end or maybe the outer cable end isn't seating in it's recess in the case or at the levers adjuster .
There's nothing that can come adrift at the clutch end if it's all stock and the pusher and ball bearing are all held captive in the layshaft.

[Al]

Washer should be like this.

Sprocket with hole.

AL

[Nobbyrobby]

Hi guys.

That helps. I understand now that the washer (same as in Al's pic) was fitted the wrong way round due to the lack of locating hole. I realise now that the body of the washer is folded over the nut flat. Mines never been bent at all. It's been a long time since I've had to recall the actual uses of such items. I'll drill a small hole in the sprocket on reassembly. I'll double check the worm drive and cable. To be clear, the outer case should mate up with the main engine casting on assembly without the need to pull it together utilising the cover bolts?