Commander jumps out of gear

[PhilipFleming588]

Hello experts,

My Commander jumps out of first gear under heavy acceleration. Under normal riding there isn't a problem.

I believe the gearbox is essentially a T160 gearbox. Any tips or recommendations before I pull it apart to investigate?

Thanks
Philip

[Anthony Duffield]

Phillip,

My Commander occasionally does the same I put it down to not fully engaging first gear. If it becomes an issue I will have a look at the condition of items 14, 15, 16, 17 and 20 page 22 of the parts book with the exception of item 17 all parts are available from ANL.

Tony

[PhilipFleming588]

Thanks Tony

[Richard Negus]

Phillip,
My experience of this problem is more often associated with the condition of layshaft 1st gear and its associated drive dog. Corners of the engagement slots and dogs of these two parts become rounded such that heavy loads force the two apart, producing the slipping you've noticed. Occasionally the 1st gear selector fork becomes worn so that full engagement of the drive dog is compromised.
To examine the suspect parts, you first need to remove the engine to be able to remove the gearbox end cover.
AN have NOS drive dogs in stock but the supply of layshaft 1st gear was exhausted years ago.

The Commander gears are very different to the T160, although the selector forks are the same. Graham may be able to help with a good used layshaft 1st gear, Page 17 Item 32 in the Parts Catalogue.

If removing/replacing the engine is beyond you, you can of course opt to leave well alone and not use full throttle in 1st gear.

R.

[PhilipFleming588]

Thanks Richard, very informative.

I didn't realise I would have to take the engine out of the frame. On balance, and so long as it doesn't get worse, I think I will live with it and not use full power in first gear as you suggest.

Regards
Philip

[Joe]

Hello Philip,

Your symptoms sound exactly the same as those on my bike which actually turned out to be very easy to rectify. My bike would click into gear with an very positive sound and action but unexpectedly jump out of gear. It turned out to be just two broken “pedal return springs” (57-0404) on the “gearchange plunger quadrant assembly” (69-0771) which wasn’t obvious at first.
This is not a difficult job so may be worth checking. To check, drain the gearbox oil, disconnect the oil pump cable (remove inspection cover first), remove M6 x 45 hex head bolt retaining the gear lever and remove 8 x M6 cap head screws from the gearbox outer cover, you may also need to move the foot rest slightly depending on it’s position to access one M6 cap head bolt and remover cover. You can leave the gearchange pedal connected to the cover. Looking at the inside of the gearbox outer cover remove the two M6 hex head bolts retaining the steel “U” shaped Guide plate and retain the two plungers and springs you will now have access to the Gearchange plunger quadrant assembly. Checked the two curved pedal return springs (57-0404) are intact and not broken. Reassembly is the reverse with new gearbox oil.

I hope this helps.

Regards,
Joe

[PhilipFleming588]

Thanks Joe, I effectively did the same thing on my T160. Those springs had shortened through use/age, but the new springs didn't really improve the gear shifting.
As I previously posted I will try to live with the problem so long as it doesn't get worse, but I am a fiddler...!

Regards
Philip