How does an adjustable MC work?
 

From what I can tell, an adjustable MC is just a stock MC with a threaded shaft that runs to the pedal. Shortening this shaft will bring the clutch pedal closer to the floor. However, due to the lever action of the pedal setup, the amount that the shaft is shortened is multiplied by the pedal ratio. Shortening the shaft length will simply change where engagement occurs but will not actually cause more or less engagement. The exception to this would be if the clutch was not fully engaging and the pedal was on the floor, shortening the clutch MC shaft would move the engagement off the floor and allow full engagement.

Is this correct?

Thanks!
Ben

Lengthening the shaft will move the engagement point off the floor, not shortening it as you stated.

Got it, thanks for the reply.

You have it exactly right (with Onyx's comment in mind) Ben. The only other thing to consider is that aftermarket masters not only have adjustable length rods but different sized bores. This moves more fluid which does induce more movement of the slave. This can be good or bad. If you just throw in an aftermarket master without knowing if you need that extra throw you can push the pressure plate fingers too far and/or over-extend the slave ram. They are more trouble than they are worth IMO.

The best way to do it is to yank the tranny, measure the diatance from the back of the block or bellhousing to the pressure plate fingers, then measure the distance from the front of the tranny or bellhousing to the end of the throw out bearing that is compressed all the way. (all depends on if you remove the bellhousing which I'm not sure what the F-Body guys do). Then you can figure out how far the compressed slave is from the pressure plate fingers is. When you put the new clutch in, measure the distance from the fingers to the block/bellhousing again and shim the slave to make up for and change. Ideally, if I remember correctly, you want ~.125" distance between the compressed throw out/slave and the fingers of the pressure plate.

HTH

Check out AtlantaRTA's procedure for this in this thread:

https://ls1tech.com/forums/showthrea...highlight=.125

Really good info IMO.

Thanks very much, I think most of the hydraulic clutch mystery has been erased in my mind.

One question- you measure to the tip of the clutch fingers (where each comes to a point), correct?

Just bear with me and make sure that I'm understanding the measurements:
(My tranny will have the bellhousing on it)

1. Measure from the block to the tip of the clutch fingers. I'm thinking this is going to be tricky to be really exact. Any suggestions on a good technique?

2. Measure from the bellhousing (the surface the would mate to the engine) to the tip of the TOB with the spring removed. It should be relatively easy to get an exact measurement on this (straight edge on the bellhousing and measure down from there).

There should be a .125" difference in the two measurements (the TOB/compressed slave should be the shorter distance).

Sound right?

Thanks!

Here are instructions on setting up a hydraulic throw out bearing/slave setup (like the LS1), if anyone is interested:

http://www.stockcarproducts.com/clutch8.htm

This will take the guess work out of clutch installs.

Ben