I was getting ready to cross post over here, too. But I figure anyone with information on this is probably keeping up with this thread.
Bad assumption. I stopped frequenting Pirate4x4 last year when I had to make some priority choices about how I was spending my time. I elected to focus my efforts here, because I couldn't keep up with both.
IMHO, the toughest dimension to get set up on tranny swaps is the axial alignment of the tranny input shaft and the engine crank shaft -- there is an X and Y dimension that have to be just about perfect, and the angle of the axis HAS to be PERFECT. Just about every other dimension has to do with depth of engagement (input shaft tip relative to bell flat face, clutch disk splines relative to input shaft, etc.) and most are 'in-the-neighborhood' dimensions, not ten thousandths of an inch.
Ideally, when you bolt it all together, the following things fit:
* tranny input shaft into the pilot bearing
* clutch disk onto the input shaft splines
* clutch disk against the pressure plate and flywheel
* throwout bearing against the pressure plate springs or spring actuators
* throwout bearing on the input bearing retainer's (a.k.a. tranny nose)
* clutch lever arm on its pivots, its actuator, and on the throwout bearing
There's probably more, I'm kinda in a hurry right now. <img src="/forums/images/graemlins/shiner.gif" alt="" />
There's also range of movement issues. This is a little harder, because as you drive the clutch fork (whether you do this mechanically or hydraulically), all the parts have to move within a limited range (for instance, if you slide your clutch disk further than the splines of the input shaft, you're bumming!) to make/break controlled contract between the intended friction surface.
This is a system that has to work together to get the desired effect -- luckily, just about every piece is adjustable:
* flywheel spacers are available or can be machined to insert between the flywheel and crank. Also, a good machine shop can thin the bolt-hub if you want less length.
* pilot bushing/bearing, either buy or machine from oil-impregnated bronze an extended or shortened setup with the ID/OD you need (you can also machine your own disk spacers for the inside/outside of existing bearings)
* input shaft, either by swapping it out entirely, by cutting it down, or by adding a short extension
* clutch disk -- a good friction house can build/blend just about anything you need out of existing parts if you can spec it... and Advanced Adapter and Centerforce carry loads of special applications
* pressure plate -- lots of custom applications available here, as well. You can vary TYPES of clutches if you need less throw, more thickness, etc.
* throwout bearing -- dead-nuts easy to swap, since there really are only a few handfulls of inner-diameters, and a few handfulls of available lengths. Use this to help keep the clutch disks well engaged on the splines through the full range of motion, and at the same time, you can vary the type of clutch fork you use based on the back-end of the TO bearing. You could also use a hydraulic TO bearing.
* input shaft retainers can be turned down or sleeved-up, and/or lengthened or cut down.
* clutch fork/levers can be cross-bell, short-side, or bellcranked and can be welded/bent/lengthened to fit just about any need
* clutch fork pivots can be lengthened/shortened/adjusted to further efine the throw.
Most all of these items require you to get in there and test-install it, then start tweaking to make it work. Once you have the tranny and engine axes in line, almost everything else can be moved or not based on its role in the overall clutch engage/disengage system. Each piece affects the next, so I think of it as a fun 3-D jigsaw puzzle! <img src="/forums/images/graemlins/kewl.gif" alt="" />
HTH, and good tech thread! <img src="/forums/images/graemlins/kewl.gif" alt="" />
Randii
