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Posted by: PRS914-6 Sep 1 2007, 10:29 PM

Seems like there is always interest in converting to a hydraulic clutch. Using a 911 clutch gives a bit of a stiff pedal but my biggest complaint was I didn't like the modulation and feel especially using a performance clutch disk. The 914-6 cable is much smaller in diameter than a 911 cable and aggravates the problem. In addition, my first gear is really tall and with a clutch that felt like it was on/off was a little annoying and down right scary when stopped on a hill with someone on my ass.

I picked up a new generic master cylinder and pull style slave (available at most any buggy shop for under $150.00 I also picked up a 4 ounce remote reservoir.

I made a plate that fit under the brake master cylinder and a bracket that fit on the side cover of my 915 tranny and ran the hydraulic lines down the tunnel. I also installed a bracket from the plate to the I beam of the suspension to eliminate any flex.

I'll cover the entire installation in a future issue of Excellence with the project car (at Pete's discretion) but here are a few pictures to show the method I used. The "feel" and modulation of the clutch is dramatically improved. Absolutely smooth as silk now.

Posted by: PRS914-6 Sep 1 2007, 10:33 PM

And a few more......


And Ron S. This is for you.....

Posted by: brp914 Sep 1 2007, 10:58 PM

That is something to be proud of. BTW, how are you shifting that 915? WEVO? Or did you do something wild there too? If WEVO, how do you like it?

Posted by: PRS914-6 Sep 1 2007, 11:05 PM

WEVO. I like it a lot. It shifts better and more precise than my 911 (but takes a tad more effort)

Posted by: 76-914 Feb 21 2013, 10:00 AM

I know, I know. 3 demerits for bringing an old thread back to life but..........Paul would you mind posting some more on this. I wasn't around here then and don't have the Excellence article to peruse. TIA, kent

Posted by: KaptKaos Feb 21 2013, 01:33 PM

It is me or does that master cylinder seem to be in the right most (throttle) position?

EDIT - NVM - I see it's being actuated by the clutch pedal.

Posted by: URY914 Feb 21 2013, 01:41 PM

The clutch pedal is on a shaft that passes thru the brake pedel base.

I'd like to see an update to this as well.

Posted by: biosurfer1 Feb 21 2013, 02:56 PM

I'm sure Paul will be along shortly but I've had the pleasure of testing this out in person and it really is a big difference and would make stop and go traffic a LOT more manageable.

Posted by: 396 Feb 21 2013, 04:56 PM

If Paul would offer "kit" I'm in....

Posted by: PRS914-6 Feb 21 2013, 05:11 PM

Here are a few pics that should help. You simply make a plate with 90 deg flange that goes under the brake mounting holes and extend it over to mount the clutch. Make a brace to the I beam. There is not much pressure for the clutch so it doesn't take a lot.

The pedal rod gets flipped forward and you will need to adjust length

FYI....it does not make it easier since it is a 1:1 ratio on cylinders. It does however make it MUCH smoother

Posted by: RonW Feb 21 2013, 05:14 PM

nicely done. subscribed.

Posted by: RON S. Feb 21 2013, 05:34 PM

Paul,

Welcome to the hydraulic world...


I've had quite a few years of driving on mine, and it's always been a smooth linear motion.


You'll quickly get used to the nicer feel. No looking back now


Cheers

Posted by: racerx9146 Feb 21 2013, 07:40 PM

Larry hubby did a nice write up back in 2008 with some nice detailed diagrams using 944 factory parts. Halfway down this thread

http://www.914world.com/bbs2/index.php?showtopic=90342&hl=

I am following Larry's example using the longer 911 clutch shaft and a bell crank at the transmission side to allow use of the 944 slave.

I did not create the nice aluminium shim Larry did due to my lack of machining skills but did a flat plate like Paul S.

The thicker plate also between cluster and brake move the master away from the cluster by 1/4" but you can make it up with adjustment on the rod. I also shim my brake, clutch pedals down a little bit to give my self more legroom.

Created a brace at the same time.

I also created a splitter down at the brake to share the rear fluid supply with clutch slave so I don't need an extra reservoir for the clutch.

I have not done the rear but my front looks like this, similar to Paul S.

Hardest part is running the hard line through the tunnel and back to transaxle cleanly.

Daron

My master setup.



I think this is Larry's slave setup. Could not find original post on this pic...

Posted by: GeorgeRud Feb 22 2013, 05:47 PM

Any info on the size of the master or slave cylinders used for the clutch hydraulics? Was the positioning of the clutch pedal arm changed from stock? I can't quite understand what was changed, but certainly like the concept.

A bolt together kit would be nice!

Posted by: 9146986 Feb 24 2013, 09:20 PM

In '95 I used a 928 clutch master cylinder and put a Y in the brake fluid line to supply it, and a CNC pull slave cylinder.

Posted by: PRS914-6 Feb 24 2013, 09:36 PM

The sizes of the master and slave should be the same. That gives a 1:1 ratio just like the cable. 3/4 is an easy size to get. Look at buggy shop/sand rail/dunebuggy web sites. The entire hydraulic setup was only about $150.00 new and their generic design makes them easy and cheap to install and/or replace

It should be noted that you can get pull or push style slaves so you don't have to use a bell-crank. I used a pull style.

Posted by: 76-914 Feb 24 2013, 10:01 PM

Paul, this is a great help. Thx again.

Posted by: dfelz Feb 24 2013, 10:57 PM

Hey Paul, whats the bore diam. of the master cylinder you used?
And what is the "WEVO" thing referenced a few times in the thread?? Thanks!

Posted by: Dave_Darling Feb 25 2013, 10:18 AM

The exact diameter is not very important, just that the master and slave diameters should match. As he said, 3/4" is easy to get ahold of and use.

WEVO is Windrush Evolutions, and they make (among other things) a shifter base that Paul is using.

--DD

Posted by: euro911 Feb 25 2013, 01:11 PM

Posted by: 9146986 Feb 25 2013, 01:43 PM

I ran the hydraulic line through the clutch tube. The only issue I ran into was heat from the exhaust system cooking the seals in the slave cylinder. I made a heat shield and wrapped the heat exchangers.

Posted by: dfelz Feb 25 2013, 02:38 PM

Ok thanks. At the moment i am planning on using a Howe pull type slave cylinder with a tilton 76-series MC (I have both a 13/16" and 1" bore), so since the howe says best use with a 3/4" MC should i use the 13/16" bore MC i have, since thats closest?

Posted by: euro911 Feb 25 2013, 03:38 PM

David, as long as ID is the same in both cylinders, you'll maintain a 1:1 ratio.

I so much want to do this

Posted by: Elliot Cannon Feb 25 2013, 07:11 PM

Well, that's just great! I get started on one big project and another comes along.

Posted by: 76-914 Feb 26 2013, 08:53 AM

Man, do I know that feeling!

Posted by: charliew Feb 26 2013, 10:47 AM

Good info and pictures. I like having two reserviors as if one system leaks at least the resiorvor won't get drained. I will be using the wrx tranny with a performance pressure plate so the pedal pressure will be more and the hydraulic cylinder is already on the suby tranny so this is good stuff to me. I never though about the clutch tube but it seems logical. Somehow I missed this thread or the paint fumes erased it for me.

I have equal length headers on a v6 fiero and the heat can be felt in the pedal feel on a 105 degree day.

Posted by: Mark Henry Feb 26 2013, 10:58 AM

Of course I'm looking to do this with cheaper and more common parts from my local FLAPS

I can use a common Dorman 3/4" master cylinder for $35, but I haven't found a car that uses a pull style slave yet.
I can get a Dorman push style slave for $18.

Posted by: skeates Feb 28 2013, 03:52 PM

I'm curious how the clutch pedal was modified for a return spring? It looks like the stock return spring is disconnected (makes sense since it would be pulling the clutch pedal to engage the clutch) and another spring added onto the clutch pedal. With the hydraulic set-up how important is a clutch return spring?

Posted by: PRS914-6 Feb 28 2013, 04:08 PM

The pic was taken during the prototype process and the spring was ultimately removed. You don't want downward pressure with a hydraulic system. The stock spring pushes down and is NOT a return spring. Like brakes, you want the master cylinder piston to completely retract allowing the internal port to be exposed at rest.

On my 915, there is enough spring to push everything back properly.

As a side note......if you do this system, make sure the push-rod you make that is attached to the pedal has a small amount of clearance between the rod and the master cylinder piston at rest (again to keep the internal port open)

Posted by: skeates Mar 1 2013, 05:01 PM

Thanks for the response! You are correct - the stock clutch pedal spring adds some pre-load to the clutch cable and I can certainly understand why it would be removed for the hydraulic set-up. I had "return spring" in my head at the time and used it without thinking.

It sounds like with the 915 transmission one can get away with not adding a return spring to the clutch pedal when doing this conversion. I'm planning on using a Subaru transmission in my project and haven't seen much detail in the suby conversion threads on this subject. I noticed that in the original pictures (at the start of the thread) a return spring had been added to the clutch in the background so I thought I'd ask the question. BTW Great set-up PRS914-6!

Posted by: 02loftsmoor Mar 2 2013, 03:23 PM

do realize your though out bearing will be always incontact with the clutch release fingers, thus always loaded

Posted by: Dave_Darling Mar 2 2013, 07:22 PM

The stock one is as well. So?

--DD

Posted by: tscrihfield Aug 27 2021, 09:56 AM

Resurrecting this thread because it is awesome. Planning a lot of work on the old girl this winter and this is high on the list.

Posted by: strawman Aug 27 2021, 11:42 AM

On my Suby-swapped 914, I'm using a Honda Civic master cylinder on a custom forward firewall mount and the stock Suby slave cylinder on the Suby transaxle. Details are sprinkled throughout my build thread. Works great!