Hello all,
Having managed to obtain a complete set of trials ratio gears, I am in the process of rebuilding the gearbox of my C15T and have a couple of questions that I hope someone can shed some light on.
End Float And Thrust Washers.
I fitted the mainshaft without the 'A' shim and then fitted the inner timing cover with 3 screws. Using a DTI I measured 105 thou of end float. Great I thought, I'll fit the 103-104 thou shim (40-3127) and I'll be done, the shim mic'd up at about 103.8 thou. No such luck, I fitted the shim screwed up the case and the mainshaft locked up solid.
I then fitted the next shim down, 98-99 thou (40-3126) thinking that will give me 6-7 thou of end float, my DTI said 10 thou. I know, it's only a 3 thou difference, but just because I could, I started again. No shim 105 thou, 105.5 if I pulled really hard, fitted the 103-104 thou shim again, shaft locked up, fitted the 98-99 thou shim, 10 thou of end float and the shaft spins nice and free.
Ruper Ratio's book says 'perceptible end float', my question is, is 10 thou considered perceptible end float? There are 3 recommended shims so I don't see that I have much option, I'd just like to be sure, feel free to chip in.
The Mainshaft and Layshaft B thrust washers
What is the purpose of these? I'm thinking that either they allow the spinning gears to slip against the end of the splines, or they give the sliding dog gears a bit more space to move between the 2 spinning gears. If they are just there to hold the spinning gears away from the splines then why are there 2 thicknesses for my box, .070, .075. How is the correct washer thickness selected? There's no real information on how to select them in RR's book or any where else when I have searched. I have both thicknesses and would appreciate some wisdom on how to select which one to fit.
Trials Gearbox Selector Forks
I discovered a bit late that the trials gearbox uses different selector forks and unlike the standard selector forks each of the 2 forks has a different part number. I have manged to obtain a Layshaft Selector Fork, but can't find a mainshaft Selector Fork anywhere. :-\ .
Ruper Ratio says that standard forks can be made to fit, 'File where necessary until they don't rub' but my 2 standard selector forks don't appear to be rubbing anywhere. Am I lucky enough that my original gearbox came with 2 trials selector forks, I'm not that lucky, so I don't think so. My question is where do they normally rub, if I know that then I can work out where to file them, or just file one of them because I have a trials fork for the layshaft.
I have done a trial fit of the gearbox and could select all 4 gears and neutral, but before I apply sealer and screw it together for good, a confidence booster would be good.
I would appreciate any input.
Bill.
My initial thought , given the shims that you have , is to double check that the high gear is firmly pressed into its bearing and then rewarm the bearing housing and double check that the bearing is fully home in the gearbox.
Once ascertained , redo the shims and see where you stand .
As far as selector forks , if you're getting all 4 gears smoothly and silkily , then I'd be happy at that.
It could be that the shim needs to be countersunk so it sits fully on the mainshaft.