Supa 5 3rd gear selection

[‘AAA Dummy]

I’m having a problem getting third immediately. Quite often, after selecting second, there is no third. The lever lifts as if it’s already in top gear and there are no more gears to select. A little later, after time or a few declutchings, the lever has resistance again and I can get into third. A good change is helped by preloading the lever prior to declutching and changing.

Presumably, I need to do a full strip to rectify this but, as it’s not half as bad as writing about it sounds, I can live with it provided I’m not heading down the slippery slope to worse damage or finding that one day I can never get to third and have to ride home in second, inevitably on a long ride!

Anyone able to enlighten me as to what is happening and whether I do need to take action?

Cheers Simon

[Peter Fielding]

I acquired an ETZ engine recently (same gearbox) which was described as having a very similar fault to yours. Difficulty in selecting 3rd gear and frequently jumping out even if it did select.

When stripped I found that the circlip that holds 3rd gear in place had come out of its groove. It had moved about 6mm towards 1st gear. My diagnosis was that this prevented full selection of 3rd gear most of the time hence jumping out. Occasionally it would select sufficiently for the undercut to pull the gear fully engaged but not enough to pull the circlip back into its groove. Next time 2nd gear was selected it pushed the circlip back again so repeating the cycle.

I have yet to establish why the circlip came out of its groove and it does not appear to be worn. Nor is there any serious wear on the bits that normally cause 3rd gear jumping problems so running with it like that does not seem to have caused any collateral damage. However, I am not confident enough of the diagnosis to rebuild the engine as yet so cannot prove my diagnosis.

Regradless, sooner or later you are going to have to strip the engine to investigate.

[John Gray]

If you are lucky the problem might be with the gear selector mech, rather than the gearbox. If the washer works loose on the end of the selector drum, the selector arm can occasionally jam in the gap rather than riding on the cam. I once had this happen on an ETZ and struggled to get above 1st or 2nd – I forget which, it was a long time ago.
Obviously the fault could be in the gearbox but checking this only involves removing the clutch and primary drive gear, and can be done with the engine in the frame.
Warning: if you remove the cam for inspection take careful note of which way round it goes!

[‘AAA Dummy]

Thanks Peter and John,

Although I’ve stripped quite a few engines an MZ is yet to join the list. I think I’ll ‘observe’ it a while and then make my way in!

Cheers Simon

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