Clutch master cylinder and slave cylinder questions

[Mike Summers]

Good Evening group...……...I wanted to throw out a concern that I have relating to clutch pedal pressure and movement but may not have all of the relevant information needed.

So just putting the finishing touches on my MK10 LeGrand FF, the conclusion of a 6 year long project. Got in the car to adjust pedals and belts and found the clutch pedal pressure was so hard that it is not practical to be raced. Let me tell you what I have as far as parts go...…...the master cylinder is a new but older style Wilwood. Has .07 stamped on the side. The slave cylinder is new but only has "county" stamped on the side with a 7F stamped on the body opposite the plunger end. I went to the Wilwood site and could not find a picture of the master cylinder...…….most shown are newer styles that have a longer body with a remote reservoir. The m/c that I have looks like a traditional Girling...…..screw on cap, round reservoir is part of the body.


So, first question is what would be the correct size for the M/C and the slave cylinder?? I cannot tell you what the spring on the pressure plate is...……..purchased past my date of memory.


Can I get some input as to what parts and bore sizes I should be using??

Thank,

Mike Summers
Sacramento, Ca

[Mondial]

Good Evening group...……...I wanted to throw out a concern that I have relating to clutch pedal pressure and movement but may not have all of the relevant information needed.

So just putting the finishing touches on my MK10 LeGrand FF, the conclusion of a 6 year long project. Got in the car to adjust pedals and belts and found the clutch pedal pressure was so hard that it is not practical to be raced. Let me tell you what I have as far as parts go...…...the master cylinder is a new but older style Wilwood. Has .07 stamped on the side. The slave cylinder is new but only has "county" stamped on the side with a 7F stamped on the body opposite the plunger end. I went to the Wilwood site and could not find a picture of the master cylinder...…….most shown are newer styles that have a longer body with a remote reservoir. The m/c that I have looks like a traditional Girling...…..screw on cap, round reservoir is part of the body.


So, first question is what would be the correct size for the M/C and the slave cylinder?? I cannot tell you what the spring on the pressure plate is...……..purchased past my date of memory.


Can I get some input as to what parts and bore sizes I should be using??

Thank,

Mike Summers
Sacramento, Ca

Mike
I am in the process of building a Legrand Mk21 and ran into a similar problem. after bleeding the clutch the pedal was like hitting a wall. I have since found that there are different clutch bobbins depending if you have a F3 clutch or a standard clutch and they are not interchangeable. You might want to check that you have the correct clutch bobbin installed for the pressure plate.

Jeff
Dallas Texs

[DK540]

I had a similar problem and though I don't have the info with me (at work) I can tell you different diameters will make it harder or easier to press that pedal. Also, if there is an adjustment on your pedal as to where the master cylinder yoke connects, that can also make a difference. The previous advice - checking the bearing - can involve disconnecting the gearbox from the engine... major job! So, before you do that, do a search on here for the master cylinder diameter, call Taylor Engineering, ensure your lines are not pinched, ensure no binding in the slave cylinder lever, etc. Simplest solution ideas first.

David

[tstrong]

From you description sounds like the clutch is working but the force is just too high. If so It is just a pressure vs stroke question. Going down to a .62 dia master cylinder will lower the force, but for the same pedal travel you will get less travel at the slave cylinder pushrod. This is usually only a problem if you have lots of play in the linkage and/or a very stiff pressure plate (causing deflection in linkage). That would be my first try if the clutch is actually disengaging properly but just with high force. Todd

[kea]

The common slave cylinder bore back then was 7/8" There are some in 3/4", that if used, would give you a shorter stroke but higher pedal effort.
Also, racing clutch covers (diaphragms), like AP come in different spring rates.
Be sure you don't have one with an very high rate.
.