Gearbox Problems

[G.I]

I've rebuilt a 150 special engine but can't set up the gears.

New bits include...

Bearings/seals
Sliding Dog
Selector pins, balls and spring

Old original bits include

Gear cogs and cluster
Selector wishbone
Layshaft
End plate

It all fits together well and shims up nicely.
The 2 piece selector shaft is aligned correctly in 2nd and 4th according to the good book.

Will move through all gears freely either using the handlebar selector or just the selector shaft with the rest of the linkage disconnected.

But there's a neutral between 2nd/3rd and 3rd/4th.
It doesn't take much to knock it out of the neutral and into gear but it's obviously not right.

I've tried another gearbox and it's still showing the same problem.

Can someone please take a guess at what I've done wrong so that I can get some sleep tonight.

Cheers.

[Ilango]

Are the selector T-pins worn out?

[jason frost]

Is this with the engine running ?

[alanscottj]

This happened on mine but when I got the engine running the gears were perfect

[G.I]

Gear changes with the engine running were really lumpy and it struggled to go to 3rd past 2nd so I took the chaincase off for a look.

With the case off and changing gear by manually moving the selector the "false neutrals" were really apparent.

I've had some help over on the other channel and have rebuilt it with the old balls and spring.
This has made the gear selection a lot better so as soon as I get time I'll get the chaincase back on and take it for a run.