172 Cup Brake Peddle Problem (Non ABS)

[chrispy.clio]

Does anybody know what could be causing my brake peddle to be so soft for 3/4's of the travel and only the final 1/4 actually does anything!

I have all new copper brake lines, Braided hoses, 172 cup Master cylinder, Brake servo & bias valve. The front pads have quite a bit of pad left and the discs are pretty much new

I cant see any leaks from the pipes i've blead them lots of times so i'm pretty sure theres no air in the system.

Any thoughts?

 

[Dan@SJM]

Standard calipers?

 

[NorthloopCup]

The compensators/bias valves can be a bit of a pita to bleed up as well I've found. Try to zip tie it in the fully closed position and bleed it again. This is assuming your on the cup compensator valve of course.

The only other thing I can think of is if the rod on a 182 servo isn't as long as the one on a cup??? Failing that it may be the master cylinder that's knackered.

 

[Daniel]

I had this in my track car. Tried everything (constant bleeding of the system, checking everything etc)

Dan@SJM has now fitted a new master cylinder and all new brake lines so i'm hoping the next time I drive it, it will be cured!

 

[chrispy.clio]

Yes Standard Calipers, the brakes work very well but i dont like the fact the most of the peddle does nothing!

I will try to bleed the brakes again with the Cup Bias/Compensating valve tied up!

 

[MG cup]

How does your brakeline routing compare to a standard cup?

 

[chrispy.clio]

I think I piped it up the same way as standard!

 

[MG cup]

Single pipe to the rear I'm guessing if you have a bias valve or is it just cup valve you have fitted?

 

[chrispy.clio]

No aftermarket bias valve! Just the standard cup compensating thingy

 

[ben lee]

have you still got rubber flexis fitted?

 

[chrispy.clio]

Nope no rubber at all. I've replaced all brake lines with new copper ones that I made

 

[Alex H]

Can you get a photo of the compensatory thing? Not that I can offer help, I just think mine's set up wrongly and a photo of one that isn't rotten would help

 

[MG cup]

Hhhmmm not sure, if it was a single line to the bias/compensator valve and then split to 2 then you would have to bleed both rears at the same time.

Have a look at Northloop's recomendations.