Evening all

I have tried the clutch for the first time today and it is VERY heavy! It's an uprated MX5 jobby and way too heavy to be comfortable for very long.

The master cylinder is .75" so I have the choice of swopping to .70" or .625".

How much difference does the bore size make? Since SWMBO will occasionally be driving it I want it quite light but don't want to be pushing the pedal through the bulkhead!

Advice welcome!

pedal ratios are the square of the bore (Pi r squared)

.75 sq = 0.56
.70 sq = 0.49
.625sq= 0.39

thus .75 to .7 is minus 14% [ edit 12.5%]
and .7 to .62 is minus 20% (43%[ edit 30%] lighter than .75 overall)

ie 12.5% more pedal movement, but also 12.5% less 'effort'

edit: corrections

[Edited on 8/2/13 by gremlin1234]

i started with a .75 also (it was the cheapest)

think mines now .625, but i also altered the pedal ratio....

make sure you put a stop on the pedal travel, to stop you overdoing things

dave