[QUOTE=SaltiDawg]For the sake of argument, say the clutch will move from full engaged to full disengaged if one cubic inch of fluid is moved from the Master Cylinder to the Clutch Slave Cylinder. Now replace the Master cylinder with one of twice the original diameter. Still takes 1 cubic inch to fully disengage the clutch. However, the amount of motion of the Master cylinder that is required is now ½ of what it was originally. The mechanical linkage from the pedal to the master cylinder will now reflect the fact that half the pedal motion compared to the original will be required to go from clutch engaged to clutch disengaged. You will still be able to adjust the point at where the clutch pedal being depressed starts to disengage the clutch as it will not have been changed by the change in Master cylinder diameter![QUOTE]

Now I think we are starting to get on the same page.....

So, to put your thoughs and my thoughts together we come up with:

Say the clutch catches fully at 4 inches from the floor. Now, I replace the master cylinder with one that moves twice as much fluid, so, THE CLUTCH NOW CATCHES AT 2 INCHES FROM THE FLOOR! Then, I adjust the pedal height to account for this new shorter clutch stroke and ouila! a clutch that catches sooner with a shortened overall pedal motion (personally I don't mind the height of the clutch pedal, just that it engages so close to the top of its stroke).

This is exactly what I am hoping for. Replace the master cylinder to truly solve the problem of the clutch catching too high.

Mind you, this is all theory and still may be totally wrong. I do not pretend to be a clutch expert, but I am willing to do the research to see if this solution can work.

JZ

 

When you say "CATCHES" do you mean the Clutch has COMPLETELY disengaged? The point where depressing the clutch pedal just starts to disengage the clutchwill not change as a result of changing the diameter of the master cylinder.

Doubing the master cylinder diameter does not translate directly into a 4" to 2" from the floor point... what it does translate into is a halving of the difference in pedal heights from 'just starting to disengage' to 'fully disengaged.'

Again, if you only want to change the pedal height at which the clutch starts to disengage, you only adjust the pedal linkage. If you are trying to re-design the car than that is a different exercise.

I'll await hearing what your mechanic tells you - I only have access to a 2004 350-Z Shop Manual - and the procedure seems straight forward starting on page CL-5.... it seems the basis for the Fresh Alloy thread. Sorry to have tied up your thread.

Again, best of luck.

 

You must keep one thing in mind in the doubling the cross sectional area of the master cylinder piston. Eventhough it will take half the amount of travel of the pedal from fully engaged to fully dissengaged position of the clutch, it will take twice as much force to push the pedal. Work = Force X Distance (a little physics here) and the amount of work to dissengage the clutch (work to be done by slave cylinder) will not change, thus the work done by the pedal will not change, so if you travel is half the distance, then the force has to be doubled. I don't mean to sound like a smart a**, I'm just trying to tell you what to expect with the mod.

 

Mr. GEE,

Thanks for the gentle correction - I had incorrectly asserted the required effort would be reduced in an earlier post - I have corrected my post giving you due credit for the correction.

 

I guess in a way I am trying to redesing the car.

My whole objective is to have a nice, tight clutch like I have had in many other manual cars:

What I mean by tight is: when I begin to let the clutch pedal off of the floor, the clutch begins to engage immediately compared to the stock set-up in which you have to let the clutch out very far before you begin to catch. And, to do this the correct way so that the life of the clutch, etc. is not compromised.

Is there any way you can send me the pages from the manual?

My friend is a master tech. for Acura (how I wish the clutch worked like that of the CLS!) so I'll be picking his brain over beers on Wednesday.

As for hi-jacking the thread--this kind of discussion is exactly what I wanted to get into.

JZ

 

To clarify, I don't care where the clutch DISENGAGES, my whole point is to make it engage sooner when the pedal is coming up from the floor.

 

I agree with everything you said 100% the only thing i disagree with is that it will not half the force needed to depress the master cylinder it will double it making clutch disengagement harder.

Nevermind I see someone spotted this first. I guess I should read all the posts before I post a reply.