Gearbox bent selector shaft

[davro]

Hi All,

Just a little update why I did not make it to Stoneleigh kit car show, was gutted that the gearbox started popping in and out of second under heavy load a few days before the show, I decided it would be best to strip the engine/gearbox to find the issue rather than risk running all the way to the Stoneleigh short shifting and potentially doing anymore damage.





There is about 4mm run out on the bent gear fork lay shaft.
https://goo.gl/photos/6XbKbuDc7GRThoP39

Made some replacement solid layshafts out of surface ground tool steel with a better tolerance.


Then during reassembly this happened during final torque settings (bastard









Just waiting on parts and gaskets now


.

[Fury1630]

Not trying to be clever here, but is tool steel wise? I'm just thinking that you have a rod bent by 4mm, it's stopped you changing gear a bit, but you got home & after a strip down it'll be fine.

Tool steel is very hard, but not very tough. Like glass or cast iron it's brittle, so if it get's a bending load it could shatter, filling the gearbox with very hard, very sharp lumps.

As my daughters would say - Jus' sayin'.

[davro]

I'm no Metallurgist but moving from a tube to rod seems to be a common upgrade on the Hayabusa gearbox selection shaft.

The original was a tube, not a solid rod and these are known to bend it's a common issue, it's a layshaft so I think that a 14mm silver steel (BS1407) will be OK, personally think the forks will bend first causing major selection issues, guess time will tell ... thanks for the Jus' sayin

The bent tube caused quite a lot of damage really, I had to replace all the shifter forks as the edges were badly worn where the forks were selecting gears at an odd angle and not fully engaging the gears as the selection layshaft was deformed for so long.

I did look into aftermarket ones and APE is using solid tool steel also, but they had quite a long lead time.
https://store.schnitzracing.com/ape-shift-fork-shafts/

[Fury1630]

I did look into aftermarket ones and APE is using solid tool steel also, but they had quite a long lead time.
https://store.schnitzracing.com/ape-shift-fork-shafts/

Yep - seems to work for them, so that's goo enough for me .