Hydraulic Clutch w/Aftermarket, Pedal Cluster |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Hydraulic Clutch w/Aftermarket, Pedal Cluster |
Chris Julian |
Oct 28 2004, 09:54 PM
Post
#1
|
Member Group: Members Posts: 159 Joined: 19-March 04 From: SF Bay area Member No.: 1,821 |
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. Attached image(s) |
Chris Julian |
Oct 29 2004, 06:37 PM
Post
#2
|
Member Group: Members Posts: 159 Joined: 19-March 04 From: SF Bay area Member No.: 1,821 |
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 Attached image(s) |
Lo-Fi Version | Time is now: 22nd September 2024 - 12:03 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |