Wednesday, 11 July 2012

Master Cylinder

Now the basic clutch/brake pedals are in place, I think its time to fix the master cylinder and push rod for the brakes. I was looking for a short job and this was just perfect - about an hour or so.
Started off reading the Kitspares guidance, and also other blogs. There seems to be a tendency to cut the push rod bold too short which will either leave not enough travel on the brake pedal or not enough in the cylinder itself. The final length of the rod will be determined by where you want the brake pedal to rest (idle) and the throw of the pedal once the brakes are bled. As I can't determine either at this point I have opted for the safe option - just cut the head off the bolt i.e. push rod at maximum length - for now.
Next job the link pin connecting the pedal to the fork end and push rod. As you can see from the picture the pin is 8mm and the pre-drilled hole in the pedal is not. I don't think this is a design floor on the part of GBS, rather an efficiency measure. This allows them to make one pedal for both the clutch and the brake.
After drilling the 8mm hole for the pin and filing down the push rod end to fit the master cylinder, it all went together cleanly. I tightened the master cylinder securing bolts just enough to hold in in place and then pressed down on the brake pedal a few times to exercise the push rod inside the cylinder. This moved the position of the master cylinder slightly such that the push rod went in centrally and straight. I then tightened up the master cylinder securing bolts. Job done.

I am not happy with the pedal position at rest - it looks far too high, but I am not going to adjust it until the brakes are bled. There is adjustment on the thread of the push rod or I can simply cut a bit off

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