1962 Lotus Super Seven Clutch Master Cylinder

[TEM]

I am getting ready to replace the clutch master cylinder on my car due to a broken mounting flange.  My clutch master cylinder is a 3/4" and so is the slave.  My brake MC is 5/8" (I think).  Dave Bean thinks my brake and clutch MC's are reversed (5/8' on the clutch and 3/4" on the brakes).  I have never driven this car so I don't know how it feels with these parts.

 

What is the correct stock size of the MC's?  This will be a road car only, no racing (at least not yet ).

Thanks,

Terry

[Rodnok]

I'm certainly no authority but in my billing for parts from Chris at Sevens & Elans I have a .75" brake master cylinder for my S2.

[TEM]

That's helpful and matches what I heard from Dave Bean.  Just hard to imagine someone would go to all the trouble to change the size of both the MC and slave cylinder.  And for what purpose?  To make the clutch... heavier?  Maybe they didn't have enough pedal throw for some reason?

[jbcollier]

Maybe they didn't know what they were doing?

 

I run an 5/8"/0.625" clutch master and a 11/16"/0.70" brake master which gives a bit more "feel" than a 3/4"/0.75" brake master.  YMMV

[MV8]

Clutch hydraulics are usually 1:1. Reducing the brake from 3/4 to 5/8 reduces the pedal effort for the same stopping power but the pedal travel needed will increase. I think I'd replace the clutch with 5/8" and swap the masters.

[ianashdown]

The official S2 manual states that the brake M/C is 3/4”

 

Ian

[TEM]

Thanks all.  The Elan manual calls for a 5/8" MC and 7/8" slave.  I'm thinking MV8 is right, I need to swap the MC's.  But I'll keep the slave at 3/4"...for now.

 

I'm thinking the previous owner swapped the MC's not to change the clutch effect but the brakes.  Perhaps he felt the 3/4" brake MC required too much effort.  Swapping them would help braking effort at the cost of a little heavier clutch. Maybe worth it to him.

[NSXguy]

my very early cat s3 came with a .70 brake master (lockheed AP). the clutch master is 5/8.