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Alternative clutch master or slave cylinders?

turboren

Well-known member
Joined
Aug 20, 2003
Messages
538
Location
Norfolk, VA
I seem to recall reading somewhere that there were some alternatives for our clutch hydraulics that would lessen the pedal effort for our cars; I thought it was from a 3S, but maybe not.

I just got a new ClutchNet Red 2X PP and Kevlar disc for #224 (thanks Terry Posten for the recommendation via searching old posts), and want to replace the master and slave cylinders while I'm at it. I've heard just replacing these makes a world of difference, although I can't really understand how, since any inefficiency from the old ones would be evident via leaks somewhere, and corresponding lowering fluid level in the reservoir. And, Terry had mentioned that after about a week of driving, this setup supposedly feels about the same weight as stock, yet holds lots of power.

Prior to about a month ago, I would just say, oh, that's something you have to deal with in a performance car. However, I had the opportunity to test the clutch on a 2010 Shelby Mustang at the local Ford dealer, and the clutch in that thing was WAY lighter than the 2600 currently in #1571; about the same as or maybe a little lighter than the stocker in #224. The Mustangs's clutch felt sufficiently heavy, to me, just not something that would make your left leg disproportionately large like the 2600 seems. Considering the power and torque in the Shelby, I'm sure the clutch in there is at least as robust as the upgraded street/strip ones used in the DSM community, so the difference is likely in the hydraulics (or perhaps in the leverage of the clutch fork or pedal). I realize Ford uses those internal slave cylinders, but still, I'm sure whatever they use produces more mechanical (hydraulic) advantage than what we have.

I understand that in order to decrease pedal effort, either the slave cylinder needs to be bigger, or the master cylinder needs to be smaller. Either way will by default increase the required pedal travel for a given slave cylinder piston travel, but that may not be too much of a problem, since there is at least one company out there that makes a longer slave cylinder actuating rod.

After thinking about this a bit and doing some searching through online parts catalogs, I'm not so sure that a 3S clutch system would work: the master cylinder has the same diameter as ours, but the slave cylinder is smaller in diameter, thereby increasing the required pedal force.

Any ideas? Other than just suck it up and be a man, I mean. /ubbthreads/images/graemlins/smile.gif

Ren
 

turboren

Well-known member
Joined
Aug 20, 2003
Messages
538
Location
Norfolk, VA
Nothing? No one has heard of this? /ubbthreads/images/graemlins/confused.gif
 

HHIVR4

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Joined
Oct 6, 2003
Messages
5,446
Location
Hilton Head Island SC
For a clutch to be able to handle more power it needs more clamp force.In return its going to require more effort through your foot to disengage it.If you want to hold a ton of power and don't want to have to push yourself throught the seat try adjusting the engagement point and make it shorter.
 

HHIVR4

Well-known member
Joined
Oct 6, 2003
Messages
5,446
Location
Hilton Head Island SC
Did a little searching around but I couldn't find any options on master/slave combos for our cars or dsm's other than stock replacements.. /ubbthreads/images/graemlins/dunno.gif
 

Muskrat

Well-known member
Joined
Jun 13, 2004
Messages
2,107
Location
Lexington, KY
Well, in a simple hydrolic system we have:

Fin - Force applied to the clutch master piston
Fout - Force applied to the clutch slave piston
A1 - Area of clutch master piston
A2 - Area of clutch slave piston.

Fin/A1 = Fout/A2

So:

Fin * A2/A1 = Fout

If Fout is constant (whatever force is required to disengage the clutch) and we want to reduce Fin we need to either reduce A1 or increase A2.

So this means you need a larger slave cylinder or a smaller master cylinder. Doing either of these will increase required piston travel to disengage the clutch (aka, you'll be moving less fluid), so you'll need to make sure you have enough travel in the system to do this.

The difficulty in changing anything will be in mounting it up, and making all the appropriate connections. In this regard it'd probably be easier to replace master cylinder.

You could also play with the lever arm on the clutch pedal, but this would probably require much more fabrication.
 
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