Excessive Brake Pedal Travel

[fishyboy]

Hi all,

Having now installed the upgraded to BCC 4-pot calipers (> Disc Brake Shimming <) the brakes are stopping much better than with the old Girling 14 calipers, but with a markedly longer brake travel.

I assume that switching to a larger diameter MC (3/4"?) would result in a high pedal at the expense of requiring more pedal pressure (I have non-servo BT7). Would this also mean the rear brakes shoes would engage earlier?

I will contact the supplier BCC to ask their advice, but thought it would be worth seeing if anyone here had any experiences to share.

Phil

 

[red57]

If you have a 5/8" master, there is a compromise between that and the 3/4". I have Girling type 16 fronts and Jag rear discs and run the .070 master as a good compromise in mine - a little less pedal travel without too much more force required.
Girling master cylinders
Edit: I see Pagasus shows them not in stock right now, but you might call and ask when they will be available?

 

[fishyboy]

Hi red57,
That's a good suggestion. I'm UK based and pretty sure AHSpares stock the 11/16" MC.
Phil

 

[fishyboy]

Hi all,
Well I couldn't get hold of a 11/16" bore MC in the UK so I changed out the 5/8" one for a spare and there was no change in the low pedal. I spoke to BCC yesterday and they suggested that "sometimes" the 4-pot caliper can be difficult to bleed all the air out. Pumping the pedal a few times doesn't raise the pedal on my car (which is often the case with trapped air) suggesting no-air in the system.It may be that I need to do some more bleeding and eliminate any residual air.

BCC also said they had made a transparent caliper to see if they could see where the air was being trapped, so it must be a fairly common issue. They also suggested that the best approach might be to gravity fill the caliper before connecting the hard line.

Phil