hydraulic clutch non engagement

[small blockhead]

have a 65 4 speed toploader with ram finger clutch and pull type slave will not disengage . I have a wilwood slave and a tilton master.

[Barnsnake]

What diameter is your master cylinder?

[Burgs]

What side is the pivot, or which direction does the slave pull to?

[small blockhead]

master was 7/10 bore' now 7/8 bore as per wilwood, pivot on driver side left. I'm out of ideas

[Tony Radford]

If that's a long throw clutch, you'll need considerable travel to get full disengagement. I'm running a long throw Ram and it took me a while to get it right. I run a Wilwood 3/4" master and a 7/8" push type slave. I upgraded to the large capacity master and it gave me a bit of extra travel over the small one. Clutches are a pain in the arse.

[small blockhead]

thanks guys. Just hate to toss parts at something without doing homework.Looks like another upsize. And yes it is a long throw ram.

[Tommy]

If you know how far the clutch fork must travel to disengage the clutch, and you know how far the master cylinder rod moves when you depress the clutch, you can calculate what size master cylinder and slave cylinder you need. The basic relationship is that the slave cylinder rod travel times the square of the slave cylinder diameter equals the master cylinder rod travel times the square of the master cylinder diameter. For example, for every inch a 7/8" diameter master cylinder rod travels, a 3/4" slave cylinder rod will travel 1.36" So, if your clutch pedal moves the master cylinder rod 2" at full travel, the slave cylinder will move the clutch fork almost 2 3/4".

[Tommy]

Here's a little chart showing the inches of slave cylinder rod movement for every inch of master cylinder rod movement for some common size cylinders. Master cylinder sizes are shown across the first row and slave clyinder sizes are down the first column. Where the rows and columns meet is the slave cylidner rod travel per inch of master cylinder rod travel.


Sv/M> 0.625 0.750 0.875 1.000
0.625 1.000 1.440 1.960 2.560
0.750 0.694 1.000 1.361 1.778
0.875 0.510 0.735 1.000 1.306
1.000 0.391 0.563 0.766 1.000

[Tony Radford]

Part of the problem is coming up with a master / slave combination that not only works mechanically, but is half way comfortable to use. When I upped my 3/4" master to a 1", it became unusable. Clutch worked great, but it took all I had to depress the pedal. I had to drop back to a 3/4" master with a little bit longer throw. I think the smaller the master is in relationship to the slave, the easier the pedal is to push. As you increase the master (slave remaining the same), it gets commensurately harder to push (to the point of requiring steriods).

[Burgs]

Originally Posted by Tommy

for every inch a 7/8" diameter master cylinder rod travels, a 3/4" slave cylinder rod will travel 1.36" So, if your clutch pedal moves the master cylinder rod 2" at full travel, the slave cylinder will move the clutch fork almost 2 3/4".

The wilwood slave only has 1 3/8" of travel. The 3/4 slave with the 7/8 master should give you close to the max. Have someone push the pedal in to see how far the slave is actually moving.

On a different note,... make sure the geometry on the clutch fork, and pivot bracket, allows for the maximum throw at the TO bearing. I had to add washers under the pivot bracket to accomplish this.

[small blockhead]

Just remembered,had to cut the fork to fit inside the frame rails. Almost a 3/4 inch. The kit was supposed to be a new build, but 2 65 mustang parts cars made this build a little more complicated than antcipated. I love the feedback. I have tried most of what you all have recommended. Stumped I am. Sounds like I need you all in my garageto get this up and running. I've been thinking, more volume ie large lines or more pressure. Thanks for everything

[small blockhead]

I'm seeing something pretty good . I'm A Georgia Bulldog younger brother a Tide and sisters are Wolverines. Sounds like home.

[427 S/O]

Small, I remember tossing the fork setup for the reason you mentioned (cut the fork). If I had it to do over, I would simply move the bellhousing fork hole 'up' enought to clear the frame. A few cut-off wheels plus a little welding and your done.

[hound dog]

Originally Posted by small blockhead

have a 65 4 speed toploader with ram finger clutch and pull type slave will not disengage . I have a wilwood slave and a tilton master.

This may be a stupid statement because I don't know your setup, but with my toploader in my Unique the cylinder has to push. Is your cylinder in front of or behind the clutch?

[small blockhead]

thought I could get this done Another master leaks. Thanks everyone for your replies. Time to regroup . This has been the longest stump I've every run into. Starting to beleive can't teach this old man new tricks.