As I search for answers to the problem I've had, I'm struck by just how many other enthusiasts have posted their issues. Almost all are the same problem but various 'solutions' are given. Most entail a favored method of bleeding the air from the Clutch Master Cylinder and/or Slave cylinder.

Here's the usual pattern...

• Guys clutch won't disengage after new clutch or slave cylinder installed.
• Guy searches for prior posts on this.
• Guy is overwhelmed that everyone and their dog has had this issue and only a few post it was ever resolved.
• Guy bleeds the system by pumping slave cylinder. No improvement.
• Guy bleeds the system by using MightyVac per someone elses post. No improvement.
• Guy buys new slave cylinder. Bleeds per instructions. No change.
• Guy buys new clutch master cylinder. Bleeds per instructions. No change.
• Guy tries every 'bleed' procedure any one has ever tried EVER. No change.
• Guy reads about 'adjustable' Clutch Master Cylinder mod. Cuts up his master cylinder rod, adds adjustable nut. Works for a little bit, then same old issue returns.
• Finally, guy either dies by suicide, old age or just doesn't post the answer if he did fix it.

Sound familiar? I've just done all the above except the last two. I sat here last night thinking, 'What good will an adjustable M/C rod do when there's no physical travel left in the pedal? It starts moving the slave as soon as I touch the pedal. I just doesn't move it enough by the time the pedal hits the floor". I ended up just removing the 'spacer' between the slave and the bellhousing and put in a shorter spacer so that the slave cylinders rod is fully compressed (the gap between the slave and the bellhousing is about half the width of the original factory spacer). Now, the clutch fully disengages at the bottom of the pedal travel and shifts fine.

 

I wonder if it isn't a bleeding problem but instead a release problem that requires changing master or slave cylinder diameters.

I just went through a Street Twin install - twice. Bleeding the Tick Performance master/Mcleod slave was the least of my problems, in fact it wasn't a problem at all. I really didn't have to use the bleeder valve on the slave, just pumped the slave piston (off the bellhousing) with the master's fluid reservoir full. Bleeding the system was surprisingly easy.

As far as I can tell the reason for using an adjustable master cylinder (adjustable rod length to be accurate) is to take advantage of a larger diameter master cylinder (more fluid displacement thus more slave movement) without, *without* running the clutch fork into the pressure plate. The idea is to adjust the master cylinder rod length so the clutch pedal hits the floor BEFORE the clutch fork hits the pressure plate.

The stock LT1 slave is 1" diameter, the stock master is 3/4" diameter, it seems there is not enough slave cylinder movement using the stock hydraulics to cleanly release a Mcleod Street Twin. That is why the adjustable master is recommended. The Mcleod master is 13/16", the Tick Performance master is 7/8", the Mcleod slave is 7/8". Any one of those three by themselves will increase the clutch pedal travel/slave cylinder travel ratio. In my case I used the Mcleod slave (smaller diameter than the stock 1") and the Tick Performance master (larger than the stock 3/4") and even with the clutch pedal height adjusted to about half the brake pedal height the clutch fork ran into the pressure plate bolts breaking off a tooth on the brand new McLeod aluminum flywheel the first time I tried to start it.

One thing to remember when putzing with the pull clutch setups is there are ratios everywhere;

1.31 to 1 = Clutch fork slave cylinder / throwout bearing ratio. (There needs to be .655 " movement of the slave cylinder to achieve the recommended .500 release at the throwout bearing. The problem I had was the clutch fork hit the pressure plate bolts at about .270 throwout bearing release. The cure for that was shortening the clutch fork pivot about .132. Shortening the pivot moves the entire fork away from the pressure plate.)

Ratios of the various combinations of master and slave cylinders;

1 to 0.5625 Stock master 3/4" / stock slave 1"
1 to 0.6601 McLeod master 13/16" / Stock slave 1"
1 to 0.7347 Stock master 3/4" / McLeod slave 7/8"
1 to 0.7656 Tick master 7/8" / Stock slave 1"
1 to 0.8622 McLeod master 13/16" / McLeod slave 7/8"
1 to 1.0000 Tick master 7/8" / McLeod slave 7/8"

Note; I have the highest ratio possible using the Tick master and the Mcleod slave, kind of a perfect storm scenario.

Then there is a pedal to master ratio, I don't know what that one is yet. I do know I'm at the 1:1 master/slave ratio and the clutch pedal force is much harder than stock and much less travel, the pedal is down quite a bit from stock. My plan is to put a 13/16 or 3/4 Tilton cylinder on the Tick master to get more travel and less force on the clutch pedal. The less travel and more force there is on the clutch pedal the harder it is to control. I think the 3/4 master will work with the 7/8 Mcleod slave with the clutch pedal height and force ending up very close to stock.

Reference; Clutch "chatter" or "buzz" what is it?

 

Great info here Jesse. Thanks for posting your findings.

 

Well the 3/4 master is on and we took a 600 mile trip this weekend and it's great! Clutch travel is stock, pedal force is a little more than stock. The slave cylinder travel is exactly .655.

The hex shaft between the rod end and master had to be lengthened about 1 3/16 for more thread engagement, there was not enough with the 3/4 master.

 

When you guys had this problem, were you able to put the car into reverse? I was able to force it into reverse (it was hard) with the stock shifter, but tonight I put in an MGW short throw, and now it's not happening!

I did Dave's fix, which helped a lot, but it wasn't 100%. If the car is on a lift, the tires will spin still. I went to the point that the clutch pedal vibrated like somthing was rubbing on some bolts. Because of that, I know that I can't pull the fork out anymore (I obviously didn't leave it adjusted that far).