Hydraulic Clutch w/Aftermarket, Pedal Cluster Options

[Chris Julian]

Guys, I have searched the site and found lots of info about converting the 914 clutch to hydraulic actuation. (IMG:style_emoticons/default/welder.gif) Problem is this, I have a high force V8 clutch and can't seem to get the 914 pedal cluster to provide the travel and force I need without a lot of mods and a lot of force applied to the 914 floor pan. The Titon m/c that I have installed in the floor next to the brake master isn't aligned perfectly to the pedal bellcrank, is too tight to fit nicely under the car, is really hard to access for line fit up and removal, ect.... So I am opting to mount an aftermarket clutch pedal cluster on the floor next to the 914 cluster. I found one forum topic about an OEM Porsche cluster but no info about aftermarket clusters. I know it has been done, even without cutting through the floor. But I want to try and retain the pedal board and roughly the original pedal position.

Tilton has recently released a shortened (3.5") m/c, has anyone tried this unit yet? Floor or cluster?

I have seen CNC, Tilton and Wilwood pedal clusters. So are there any other manufacturers?


Brad, any thoughts


Thanks, Chris Julian


BTW, the car is ready for a test drive down the driveway once the clutch is working.
That's with no doors, no windshield, ect.. Just the basics.

Here's a shot of the car w/dad.

[skline]

Wow, you may want to resize the photos, they are a little large for a lot of people. I like your car, is that a tube frame? I can take some pictures of Joe's car where his is mounted. He has a hydraulic clutch installed in his V8 car. I was thinking of copying it for mine. The guy who did it said it only cost him about $100.00 to do the whole thing. I can get over there tomorrow and take the photos if you want. Let me know. Sweet car by the way.

[Chris Julian]

Hey Scott,

No tube frame but alot of tubing. Check out my original post and you will see the other features on the car and yes, please send some shots of his clutch conversion.

Chris

[Chris Julian]

Nudder shot

[skline]

That thing looks radical. I hope to see it someday in person, Tell me some more specifics about the car. You can PM with them if you like. I got a thing for V8 cars. I will go over there tomorrow and take some pics and send them to you. Get me your email address, or should I post them here?

[Jeroen]

Post 'em here!!!

[d914]

I've also seen some conversions where they are using hanging pedals and using the m/c's and c/m on top. mainly track cars

[spare time toys]

Isnt this the car that had the Webber intake set up and 4 Supertrad exhaust?

[Jeroen]

I've also seen some conversions where they are using hanging pedals and using the m/c's and c/m on top. mainly track cars

Chris Foley (racer chris) has a setup like that in his car

Another idea is to use the pedal cluster from a G50 equipped 911 3.2 ('87 - '89) which also has an hydrolic clutch

[skline]

Well, Joes car has a seperate pedal installed for the clutch, I will go over there this morning and take a few pictures of it inside and the underside. It works pretty good.

[lylegd]

Chris, regarding the hydraulic clutch. I'm installing one on a '75 914/6 conversion. I have grafted the pedal cluster housing from a '87 911 Carrera welded onto the top of the lower and front housing of a 914 pedal cluster. This allows me the use of: 1) The brake master cylinder location doesn't change., 2) The hydraulic clutch master cylinder is located above and behind the pedals, 3) The accelerator linkage pivot arm remains in the original location although the angle of the pedals relative to the Carrera part of the housing do change. I will use the original 914 accelerator pivot linkage arm. It is not yet done so its too early to claim success but it looks like eveything is going to work and it certainly does fit right into the car body without any mods to the firewall or the tunnel. I'm certain I will have to modify the plywood board that covers the pedal cluster but to be honest, I haven't got that far yet. I also still need to verify the accelerator pedal still works. The top surface of the housing is much higher then it was originally. This job requires access to a machine shop, a mig welder, die grinder etc. and plenty of patience. The center line of the shafts used by the brake and clutch pedals also remain in the original location. I'm trying to figure out how to mount the microswitch used for the brake lights at the present time and I'm still shaving off metal here and there with my die grinder. I think its going to work! So far I have $100 invested in this job but then I was fortunate to find a used '87 carrera pedal cluster Lyle

[Sean_S]

I like the look of the Center-line "Convo-pros".

I've considered those for my car since my wheels are a bit "dated".

Sean

[groot]

I tried a different path to getting more travel at the clutch end. I added a linkage that essentially amplifies the input from the slave cylinder by using a lever to activate the clutch. (the slave cylinder pulls on a lever that is attached to the clutch pull rod, with the slave cylinder attachment closer to the center of rotation than the pull rod)

I did this for two reasons. 1-get the slave cylinder away from my exhaust and 2-more travel at the clutch lever.

I also have the overhung pedals, but I didn't have enough travel for some reason.

Unfortunately, I didn't search the archives before doing this modification, so I probably could have saved myself a DNF or two.

[andys]

Chris,

I am not that far along with my conversion, but I too will need to configure a hydaulic clutch set up for my 6 speed. After some pondering, I first decided to retain the stock pedal arrangment, and adapt to that. Here's the plan (and only a plan at this point): Mount the clutch master in the center console, hidden behind the vertical console upright. From the stock cable bellcrank attachment point, actuate the clutch master with linkage. Direction can be reversed with a simple lever, if necessary. You would of course have to calculate the appropriate lever ratio's, but that's no big deal. I've done similar things with clutch master cylinders on race cars.

Andy

[Chris Julian]

Guys, thanks for the information.

For the moment, I have chossen to try and reduce the travel requirement on the clutch side. As it turns out, the travel requirement on my current layout is too high. Of course I am not using a Porsche box (I'm using the ZF) so things are layed out a little differently then most. I need ~ 1.5" of travel at the slave output and that is just to much for a typical slave. The guys at Tilton are telling me that a diaphragm "street/strip" 10.5" pressure plate requires about 500 lbs @ the fingers. They also claim a 30 leg input to be average??? That seems really low if you ask me. Additionally, they think a clutch finger displacement of ~.400" is common.

Most pedal assemblies including the 914 offer no more then a 6:1 ratio and ~1" of travel and I am not sure if you would have any mechanical advantage at the clutch, so the rest of your force has to come from the hydraulic system. With a 3/4"bore m/c and a 7/8"bore c/c you only pick up 36% increase in force. So 30lbs in * 600% ratio @ the pedal and 0% increase @ the clutch brings it to 245lbs @ the throwout bearing. Too little right? And the travel is borderline @ .734". Input 75 lbs and the result is 612 lbs, same travel of course.

BTW, I have created an excell spreadsheet that helps with these calcs, If someone tells me how to add a file to this topic I will, otherwise you can e-mail me your contact info and I'll send it along.

Here are a couple of the hard design constraints I have found:

1, Most pedal clusters, including the OEM 914 unit, offer ~600% (6:1 ratio) mechanical advantage

2, Tilton & Wilwood master cylinders offer 1.1" travel max

3, A typical high force diaphragm pressure plate requires ~.400" travel to disengage, and don't forget about throwout bearing/pressure plate finger gap, flexing brackets, pivot slop, ect... So you really need somewhere around .75" clutch disengagment travel

4, Don't expect a whole lot of mechanical advantage at the clutch lever.

Basically your playing with bore sizes on the cylinders and of course leg input.


There's also the whole question of clutch type, that's another topic all together.

So for now, over and out.

Chris

[Jeroen]

Chris, I shrunk your pics for you.
Next time, try resizing them to a width between 600 and 800 pixels

cheers,

Jeroen

[skline]

Here are the pics of the hydraulic clutch setup in Joes car. First the pedal and then the actuator. I posted them here by request. (IMG:style_emoticons/default/biggrin.gif) And yes, Joe has a bit of an oil leak, Just got off the phone with him and he is spending all day tomorrow fixing oil leaks.

[skline]

Next

[skline]

The entire setup is Wilwood, a little jury rigged but effective

[skline]

Uno mas