is there a hydraulic clutch kit available or any ideas on retro fitting one?

simono wrote:is there a hydraulic clutch kit available or any ideas on retro fitting one?

Not 'off the self' but anything is possible. The parts are available at the gearbox end easy enough. It's the pedal assembly where its a little harder on a bus.

http://www.limebug.net/product/view/173 ... r-pack-694
Just about to do this on mine found this kit from limebug

I've designed / had made a bracket now for RHD and LHD buses to use Wilwood clutch m/c & a pull type slave.

I did the maths for the various configurations of VW clutch components, (or which there are many), and then added the KEP Stage 1, Stage 2 & Stage 3 clutches to the spreadsheet.

Depending on what you have currently, with the correct component choice you can reduce the pedal effort by around 35%

I'll be doing modified clutch pedal on exchange basis. Options for direct fill into the m/c or remote filling so you don't have to cut the cab floor.

This is the bracket / master cylinder mounted up.

As Jim mentioned it would be eaiser to use a pull style slave cylinder like the wilwood one or CNC (there has been very few production cars with pull type).
Gearbox mounting brackets for the slave can be found fairly easily. A push slyle slave can be found on many many cars but mounting them will be problematic.

The biggest issue will be adapting the pedal to activate the master cylinder here you have to consider a few things.
To disengage the clutch the clutch arm has to move a certain distance this movement is provided by the slave which in turn requires a volume of hydrulic fluid to be moved via the master cylinder. If the pedal movement cannot provide enough stroke to the MC then not enough volume of fluid will be transferred and the clutch will not disengaged.

Ok still with me? Well we are this far down the hole might as well continue down

So how do we get more volume?
1, by using a MC with a larger bore (same stroke move volume) but...
The downside maybe now the pedal is too hard to push, not a problem we can fix this by altering the piviot point of the clutch pedal ie making a longer leaver thus more mechanical advantage but.. "not again" by changing the pivot point you change the amount of throw you have to move the master cylinder rod. and we are back where we started.
2, dont change the bore of the MC but increase the throw provided to the increase the stroke of the MC (MC have a fixed stroke is its full stroke enough...)
To increase the throw of the pedal we need to move the pivot point and you guessed it this effects the mechanical advantage and makes the pedal harder to depress.

In short unless you fancy a game of trial and error or are happy with some fairly involved maths go with Jim's solution he has done all the heavy lifting for us

Jim don't suppose you fancy sharing the spreadsheet?

Yes, there's some fairly involved formulas converting leg effort into mechanical leverage (rotational) into hydraulic forces out of the master cylinder into linear pull forces out of the slave cylinder back into mechanical leverage force at the gearbox arm.

Lots of variables as there's five elements to the system, plus up to five clutch pressures (if you don't include dual mass clutch designs), plus three gearbox arm lengths.

If a bus had a 'poor' selection of parts beforehand then swapped over to more ideal components, pedal effort could be reduced by around 35%. I've not got the spreadsheet with me this weekend, to give calculated pedal efforts, but I reversed the process and also worked through "what would be the human pedal effort with stock / stage 1-4 clutches with traditional cable pull" then compared that to hydraulic system.

I've found the slave mounting brackets don't allow for the various gearbox designs. So some work, but don't work with all types.

I've got the gearbox in this weekend to my test vehicle, so next time I'm here working on it I'll be mocking up an engine to test stock pressure plate to stage 2 pressure plate, (i haven't got a stage 3), and how they feel in reality / measure the actual pull.

Future design development is around push style slaves mounted in the bell housing. But made the decision to get the pull slave version working first as that would allow testing of the rest of the components.