Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
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.
 

Welcome Guest ( Log In | Register )

> Hydraulic Clutch w/Aftermarket, Pedal Cluster
Chris Julian
post Oct 28 2004, 09:54 PM
Post #21


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)
Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
 
Reply to this topicStart new topic
Replies
Chris Julian
post Oct 29 2004, 06:37 PM
Post #22


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)
Attached Image
User is offlineProfile CardPM
Go to the top of the page
+Quote Post

Posts in this topic
Chris Julian   Hydraulic Clutch w/Aftermarket   Oct 28 2004, 09:54 PM
skline   Wow, you may want to resize the photos, they are a...   Oct 28 2004, 10:18 PM
Chris Julian   Hey Scott, No tube frame but alot of tubing. Che...   Oct 28 2004, 10:33 PM
Chris Julian   Nudder shot   Oct 28 2004, 10:34 PM
skline   That thing looks radical. I hope to see it someday...   Oct 28 2004, 10:37 PM
Jeroen   Post 'em here!!!   Oct 29 2004, 06:02 AM
d914   I've also seen some conversions where they are...   Oct 29 2004, 07:12 AM
spare time toys   Isnt this the car that had the Webber intake set u...   Oct 29 2004, 07:37 AM
Jeroen     Oct 29 2004, 07:44 AM
skline   Well, Joes car has a seperate pedal installed for ...   Oct 29 2004, 07:47 AM
lylegd   Chris, regarding the hydraulic clutch. I'm in...   Oct 29 2004, 09:48 AM
Sean_S   I like the look of the Center-line "Convo-pros". ...   Oct 29 2004, 09:52 AM
groot   I tried a different path to getting more travel at...   Oct 29 2004, 09:57 AM
andys   Chris, I am not that far along with my conversion...   Oct 29 2004, 10:14 AM
Chris Julian   Guys, thanks for the information. For the moment,...   Oct 29 2004, 06:37 PM
Jeroen   Chris, I shrunk your pics for you. Next time, try ...   Oct 29 2004, 06:55 PM
skline   Here are the pics of the hydraulic clutch setup in...   Oct 29 2004, 07:50 PM
skline   Next   Oct 29 2004, 07:51 PM
skline   The entire setup is Wilwood, a little jury rigged ...   Oct 29 2004, 07:52 PM
skline   Uno mas   Oct 29 2004, 07:52 PM
Chris Julian   Thanks Scott   Oct 29 2004, 11:03 PM
Jeroen   here's a link to the input/output spreadsheet ...   Oct 31 2004, 02:12 PM
Chris Julian   Well a couple of weeks and 600$ and it’s do...   Nov 11 2004, 12:51 AM
Chris Julian   Not sure why the pics are so large there set to 80...   Nov 11 2004, 12:56 AM
Chris Julian   fgfg   Nov 11 2004, 12:57 AM
Chris Julian   ghgfgh   Nov 11 2004, 12:58 AM
Chris Julian   gggfg   Nov 11 2004, 12:59 AM
sj914   Is that bottom plate that the hydraulic pedal asse...   Nov 11 2004, 01:57 PM
RON S.   That unit is sure pretty,but I went for a more sim...   Nov 11 2004, 02:34 PM
RON S.   Installed pic Ron   Nov 11 2004, 02:35 PM
Mueller   damn Chris...that looks killer :) Ron, have you h...   Nov 11 2004, 02:56 PM
Chris Julian   Hey Ron, I wish I could have gone that route, I me...   Nov 11 2004, 03:10 PM
RON S.   <...   Nov 12 2004, 05:57 AM
rick 918-S   How did you reinforce the floor where the peddle a...   Nov 12 2004, 08:32 AM
soloracer   So does this mean you are using dual brake master ...   Nov 12 2004, 11:22 AM
Chris Julian   Guys, yes this is a custom setup, not a kit. I t...   Nov 12 2004, 02:53 PM


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



- Lo-Fi Version Time is now: 15th June 2024 - 02:36 PM