Cappra gearbox nightmare.

[Nitram]

Ahoy there Montesa Maniacs !

Is there anyone in the world who can tell me how to shim a Cappra gearbox ?  I pulled mine apart a few moths ago to replace a dicky main bearing and the whole thing fell out on the floor in a million bits with about 20 different shims from either end of the input and layshafts, and either end of the selector drum.  I've got no idea where to start.

I rebuilt this engine about 20 years ago and for a while it would jump out of top gear.  Then I re-shimmed it and sorted the problem, but..............that was then, and this is now- where to begin ??

Also, if I ever get the gearbox together, I'll need a crankcase centre gasket.  Does anyone know where (in Australia) a centre gasket can be found ?

Ta,

Nitram

[cappra]

According to Montesa, the desired shaft endplay is 0.004-0.008 in (0.1-0.2mm)
This is done by the use of a depth gauge to measure from the case halve to the trans bearing,
and measuring the width of the trans shafts and the centre gasket.  This is the fun way!
The down and dirty way is mock up transmission in the cases, put the cases together (without the crank)
with the centre gasket in place, tighten about four of the case bolts around the trans shafts and check the
shaft endplay by hand or depth gauge and add shims as needed.  You should be shooting for barely perceptible end play in
each shaft.  Remember that the selector shaft (the one with the shift forks) must be shimmed equally on
on both sides.  You might have to do this a few times before it's ok, but your only tightning the case bolts
around the trans shafts.  Good luck!

[k2000x]

ive just done the same thing (parts on floor) there was only 2 shim, come out and 2 gears fell off shaft (54m motor). box had never been apart before. cant find good picks or manaul showing were they went any help

[dutchtwinshock]

i shimmed the selectorshaft so that  a selector fork is in the middle of two gears when in neutral posision.
i also looked when a gear is selected the forks not puching sideways agains the gear, otherways it wil be turn to blue.

[Montynut]

If you PM me your email I can send you a PDF of a Manual that goes through the process that Jared mentions step by step. The shimming is pretty straight forward once you have read the procedure 15 times and stare at the components for an hour or so .

The shimming is critical and is based on centralising the shafts to each other. The final set up of the selector drum offset nut is actually done in top gear not neutral.

The whole process is just slow but reasonably straight forward. Jared makes it sound very simple but his years and hundreds of engines make him slightly better equipped than us mere mortals

Centre gasket from Jared at Southwest Montesa. What model Cappra?

[cappra]

Hope this helps.

[09.0]

This is the book you need. I got mine today and flicking through it, it looks very detailed. It covers bultaco, montesa and ossa.
http://item.mobileweb.ebay.com.au/viewitem?itemId=270778132801&index=0&nav=WON&nid=38773689080&trxId=847580115017

[k2000x]

yeah i got that brad but doesnt so the same transmission that ive got

[k2000x]

its a six speed box

[cappra]

Six speed version.

[k2000x]

thats it jared but when i pulled mine apart it never had shims on the shift drum. and picture shows one on either end.. the motor i pulled down looked like it has never been apart

[cappra]

I have seen shims on both shaft ends, shims only on one side, even shafts with no shims. Just a change of a centre
gasket can change the shafts end play. I alway's check the shafts end play by hand before disassembling the motor, just to
see where I'm at.

[dutchtwinshock]

shimming causes a relationship between the shafts when doing wrong it is posible the gears will
touch each other in a wrong way