I have labored for quite some time on the new hydraulic clutch system I have been working on and I felt it was ready to be bled and tested on the road. It appears that no fluid will get to the slave until I first bleed the m/c (per Tilton's instructions). I even took the brake line off @ the m/c and nothing would squirt out. The bleed screw may as well be on the moon. I can't get a wrench or socket on the damn thing and might have to take it out and cut one of the unecessary mounting ears off to effectively reach it with a wrench. Has anyone been there and done this with a Tilton m/c? I thought I could just bleed the slave and get 'er done. Looks like it is a bit more involved than that. Apparently this m/c must be "primed" via bleeding in order for it to squirt fluid? I'm done fu__ing around with it tonight.

Bill

Heh, I've been there with my mustang's hydraulic clutch. I'm using a tilton master cylinder on it now. What I do is set my air compressor regulator to like 3 psi and pressurize the reservoir with the slave bleeder open. Works like a charm.

So you could disregard bleeding the Tilton m/c and just pressureize it? I'll try that tommorrow. Thanks for the tip.

Just like when you power bleed a brake system...

Note: Make sure you have PLENTY of fluid in your reservoir, and don't get it above 14-16psi... You'll crack that slave bleeder valve open too far and get a big gush of fluid, followed by a surge of air if the pressure is real high and the reservoir is low.

OR...

You can use a MityVac hand held brake bleeder and SUCK the fluid through the slave bleeder.

Twystd1

The mitty vac is really bad about pulling air into the system. Pressure bleed systems work really well.

didn't the instructions say to "bench bleed" or "prime" teh master prior to installation?

vacuum draws teh air out of teh fluid itself. its like uncapping a soda can; as pressure drops, teh gasses expand. if you draw a full vacuum on teh fluid for 10 minutes prior to using it to fill the resivoir, it will minimize this issue. also using MUCH less vacuum to get the job done helps alot. less vac takes longer but ...use less than 10 in of vac to prevent off-gassing

Hey Sean,

The Tilton instructions never mentioned bench bleeding the unit before install. I'll just power bleed the bitch and be done (or suck it throught the slave).

Bill - did you get this figured out? I can assure you that you must either

1. bench bleed the master cylinder (which can be a PITA getting into the car without spilling fluid out onto paint, etc), or

2. pressure bleed after install. this is what I do to keep fluid out of the interior of my car. I bought a Motive pressure bleeder since I have 3 masters in the car and will need to flush fluid regularly with a track car, the $50 was "cheap" v. the time I save with changing out brake fluid. It works with my clutch as well. I think you can buy cheaper ones that work just as well. My first time with the setup I borrowed a buddy's home fabbed one made from a pesticide sprayer and it worked like a charm as well. I was too lazy to make my own

The Tilton instructions say to bench bleed, but you are just like me - I doan need no steenking instructions Any time you have a new master, you have to bench bleed the air out of the master before install, or pressure bleed after install.

Those handheld MightyVacs are a PITA v. a pressure bleeder. I can pressure bleed a line in under a minute. the Mighty Vac, man I haven't needed to pump something like that since I turned 13

Bill,

When practical, I always prefer to REVERSE bleed everything. It always seems to produce better results quickly. You'll need a way to pressurize a reservoir of brake fluid; a pressure pot works well. Just make sure you clamp the line to the bleed screw, or you'll have a mess; use a regulator. After initial bleeding, come back the next day and do a traditional bleeding (though you should always do this anyway).

Andys

I bled the system through the slave with a Mityvac. It worked well enough so that I could do a traditional bleed. I got all the bubbles out only to find that my 3/4" Tilton only moves my slave 5/8" and i need a minimum of 3/4" to release my KEP pp! Great luck...huh? Anyone need a nice new tilton 3/4" m/c? It apparently works for other people with pps closer to stock. I will try a 15/16" Tilton next and live with the extra 56% increased pedal effort. Still better than the 2000 lbs of pressure i had with the old cable. This hydraulic clutch conversion has turned out to be a stubborn bitch...but I will have it all sorted out by wednesday when my new m/c shows up. All the bracketry, lines, slave bracket...etc have been fabbed and all i need to do now is install the larger m/c. I'll let you all know how it works and feels when i finally get this red headed step child of a problem solved.

Oh man, been there too. I went through 2 master cylinders and about 5 slaves before getting the "baby bear" combo on my Mustang. (now it's "just right"..)

Hey,
I assume your using a 7/8 slave along with the 3/4 master and floor mount pedal. I had the same trouble, I went up to a 1" plus and just couldn't depress the pedal. In fact at first I thought it was locked up Ha nope it was took about 150 lbs of pressure to move it. I ended up changing the pedal angle, maxing out the use of the master via the piston and adding 1 1/2 inch to the pedal length. If your using a 7/8 master with a short fork it will be a real challenge to depress the clutch more than a few times. I'm not saying don't do it just be ready.
I'm no expert, but I did spend a lot of time on the same project. I have something that works, now I am getting all new parts because of all the hammering and grinding on the old ones they look like crap.

I'm using a 15/16" master and i may have to change the angle of the pedal casting and refab the pedal length like you did. i expect it to be a bitch to depress. What m/c & slave did you use? I'm using a Tilton m/c and a Wilwood 7/8" slave.

Does anyone know if it would be possible to hook a booster up to the m/c for a little power assist? Does the m/c have to have special provisions built into it to utilize a power booster set up? I think it would be trick to have a boosted clutch m/c....but the only problem is where do you mount all this shit...not to mention the added weight. I would prefer to keep my car less complicated than the space shuttle!

Bill

Bill,

Don't know how you'd make one of their products work on the Tilton pedal setup, but try a company called MICO. They're more geared to industrial applications. They make a dual stage master, i.e. high-volume low pressure/low-volume high pressure. Street rod guys used to use them when power assisted brakes were not an option.

One more thought, in case the above is not an option. Does your Wilwood slave have a spring return? Most modern slaves are forward sprung in order to keep the pedal up, and avoid constant adjusting. With this, the throw out bearing constantly rides against the diaphram fingers (though at a very low force). If you did the same, you might realize enough travel and keep the pedal effort at a reasonable level.

Andys

Thanks Andys for the info on MICO. I'll check it out.

First thing I tried a booster and I didn't like how it felt, at the time I had a skewed pressure plate and didn't know it. I had that repaired (KEP) and now I have a short 3/4 master cheep ones sold on EBAY and a Wilwood pull type slave which is 7/8. The master has about 1.3 inch throw and the slave about 1.4 .
My clutch fork is 6 inches long and I use 95% of the available slave travel to get it to work. I had it at first set up too tight against my T/O bearing and waisted my crank thrust bearing. That meant going through the lower end of a new motor. Not fun but sh*t happens. Just be careful not to ride on the T/O at all. Using a floor type pedal I removed some of the pedal metal so I could gain a little more travel in the rod area. There is a natural stop set up in the pedal where the pedal hits the rod or its threaded block. I removed some steel there , then added some more pedal length for leverage. In doing that I had to move the fuse block from under the dash to the speaker grill area. That was not hard to do, there is enough wire slack to move it there. I am sure there are other ways but it works well for me. I like to do everything and most times I have to do it multiple times to get it right.
Below is a link to a master, its just like the one I used.

Much like my master

Issue I've always had with the little hand-held mityVac is that it will suck air past bleeder nipple adapter.

Hey Drivability,

I've seen many of your posts and I like your project. I had trouble with my KEP's pressure plates too. My 915 set up was sent back 5 times and my 930 set up twice. They just love to send shit out before checking to see if it actually works...what quality control?

I called Tilton and they said a Tilton 3/4" m/c coupled with a Wilwood 7/8" slave will yield only 5/8" travel at the slave. I unfortunately verified this with my 5" lever arm. I remember my stock 5 1/4" arm needed 3/4" sroke travel to release my pp. That is why I'm moving up to a bigger Tilton. Everything is already fabbed up for a Tilton. I suppose I could easily use something else though.

More bad news on my hydraulic clutch fiasco. I installed a 15/16" Tilton M/C to get the proper slave travel to release my King Kong KEP pressure plate. It released just fine ONCE...then my pedal shaft (in the pedal cluster bent under the fu__ing pressure and I am now officially DONE working with the stock pedal box. It was never designed to handle the forces I'm putting on it. I will now commence building my own HD overhung reverse mounted clutch pedal/bracket/m/c mount. It will look similar to a Tilton or CNC pedal and I will make sure it is strong enough to land an F-14 on it... because it has to be fu__ing strong to handle the abuse & torque required to actuate my WAY TOO stiff PP. I'll let you know how it all goes.

Sorry to here your having so much trouble with this. Hang in there man, you'll get it.

I am still amazed to think something that seems simple can be so much of a pain. I spent a long time getting my hydraulic clutch to work at all. Then had to get it so I could push it down more than once with out blowing out my leg. I have it working now but it looks like Frankenstein. You just have to keep going forward, it will get there

Well...I can say this was a royal PITA but it was worth it in the end. The hydro clutch is now fully operational and my only complaint is how much force is required to actuate the clutch. I have a few ideas that may help in this regard including lengthening the clutch fork lever arm attachment point outwards from 5 1/2" to 6" and making a bigger pedal face to distribute the load across the bottom of my quivering foot!

Pics to follow

Well, you bleed a little but get results Glad to here your on the right track. Once you get it working you can fine tune it..

PICS:

I'm going to use a nicer clevis at the slave...but this one will do for a few days.

Parts list:

* Tilton 15/16" M/C
* Wilwood 7/8" pull type universal slave cylinder
* custom brackets at firewall for M/C
* custom bracket at engine to hold slave
* 3/16" brake line and a few fittings

I decided to follow the path of others who have popped a hole in the firewall directly opposite the clutch lever arm (where your old cable attaches) and fabbed up a bracket to mount the M/C. Made a large hole for the M/C to poke through the firewall (just like the brake M/C)...and two smaller holes for the 2 1/4" bolt spacing on the Tilton M/C (& most other M/Cs made). If you don't get the holes popped into the correct spot the first time...you do alot of extra work. Luckily I got this part right the first time. I did however have to massage the holes w/ a rat tail file to get everything to line up perfectly. The bracket was fabbed out of heavy guage sheet metal to allow a flat mounting area for the M/C to marry up against. I also tapped 10mm 1.25 threads into the two mount holes on the M/C so I could just hold it up against the bracket and drop two allen headed bolts throught the firewall bracket to feed directly into the M/C. If you decide to use bolts & nuts...good luck getting a wrench on the nuts. It took two tries on the M/C size to get the necessary stroke travel at the slave. I started with a 3/4" M/C and it wasn't quite good enough for stroke travel (3/4") and I need about 1" to release my KEP stage 1 PP. I may have gotten by with a 7/8" M/c...but decided to pop for a 15/16" size to give me a little room for error and provide the comfort slop I want. I was warned from Bobby Hart @ CA Motorsports (the guy who built this box) "That if I don't allow the clutch fork arm to relax fully and release fully...I can expect another very expensive bill for new synchros, sliders and so on. They will burn out in less than a week if the clutch isn't adjusted properly...not to mention damage to thrust bearings inside the engine. Not a good thing to do to a new $7500 930 turbo box...or your powerplant.

The worst part of this whole fiasco was that the stock pedal box was not strong enough to handle the extra force acting upon it. Specifically, the clutch shaft would bend & distort. SO.............I rebuilt the pedal box using a bigger 5/8" (4140 B 7 hardened) shaft that necessitated almost everything in my pedal box to be duplicated in larger diameters including custom lathe work performed on 1" ID 1 1/4" OD stock bushings. The 5/8" ID 3/4" OD bushings I bought worked well with the tube I purchased. The brake pedal had to be removed from the stock shaft...the hole clearenced for the bigger tube...etc...etc... hence the cuss words flowing freely from my mouth.

If anyone wants to do this (and learn new cuss words) and want more detailed info...PM me and I'll shoot you my cell...then we can talk directly if you would like.

Cheers!
Bill

pics

Dude, when I had a '80 AMC Spirit and it had a hyd clutch system.

The master cyl was on the firewall and of course the slave cyl was on the the tranny beneath it. I used a technique that bled it manually with a hand held pressure operated bleeder from the bottom to the top. The unit was a small hand held oiler/grease small unit that looked like a small baby spray bottle of Windex with a long tubular spout to it. Kinda like the old oil cans that train engineers used on the old steam locomotives. Attached the hand unit via a rubber/surgical tube to the slave cyl . opened up the bleeder valve and pumped a few times and closed the valve on the last pump. Did this several times making sure the hand held unit never went dry and closing the bleed valve on the lower slave cyl kept air from entering the system. Of course the pressure forced the hyd fluid up thru the system until the upper resevoir was filled then proceeded to do it some more to make sure there was no air in the system.

Of course the maintenance manuals said to bleed it from top to bottom but bleeding manually form the bottom to the top was easier and better. In a 914 you would probably have to jack the front end up considerably than the rear end is in order to simulate the up hill travel that I had to go thru on my AMC,

Give it a try and see if you can't bleed the hyd. system competely that way.

Just mu $0.02 worth on this subject. BTW using a Mighty Vac to bleed my hyd clutch system on my 2 Fieros works when I bleed from the rear slave cylinder. I jack up the rear ond on my Fieros to make it easier for any airbubbles to travel up hill instead of horizontally or down hill. No problem there either.

Great job Bill!

I lengthened the clutch fork lever harm out to 6 3/8" (stock is 5 1/4") and I'm starting to notice the pedal effort diminishing a tad bit (still too strong). My next step is to increase the size of the pedal pad surface to distribute the load on my foot a little more. Right now it still feels like I am standing on a "pin punch". My foot hurts so bad from the clutch pedal that I think a steel toe work boot would be in order.

Bill

Dumb question, why does a hydraulic system take so much effort to move the clutch? I would think the mechanical advantage would be huge compared to the cable system. Would you have no chance of pushing in the clutch on this super strong pressure plate if you used a cable? (I'm not saying go back to a cable, just wondering why it's so hard to push). Would a bigger (or dual) slave cylinders help?

I'm not a V8 guy, not a fluid dynamicist, etc.

Hey Bill, AWESOME JOB!!!


Now, how do you feel about me driving up toWi and letting you do this on my car when I get home? No, seriously, will a case of beer cover labor? OK, KIDDING!!

I hope I dont have as many problems like you had when I get ready to do this, but thanks for being point man on this!! I will read this several times before I attempt it. I will be watching for updates.

Ian in Iraq

3 days and a wake up till I leave Baghdad
10 days till stateside
17 days till driving

Since I have been through this the reason is the heavy pressure plate used on some V8 cars. All the geometry is set up for a light pressure plate. Once there is a greater demand theres just not much room for the leverage needed. A larger master would help but you must have a longer clutch fork. The problem is the slave will only move about 1- 1/3 inch so you can't go much more than 5 1/2 inches with the clutch fork. That length just doesn't give you the leverage needed for a soft pedal. The only way is to find a way to make a slave with a longer pull, like 2 - 3 inches. Then you could build a long clutch fork and use the extra master volume. Not to mention theres just not much room to build up a master.
John