172 cup braking issue

[percival ian staker]

Sweet s**t all braking performance in short, and occasionally I jump (not literally) on the pedal and get a few centimetres of virtually dead travel.
Feels like a knackered seal in the master cylinder but I'm not by any means a mechanic - anyone experienced anything similar?

In a similar vein, AP kits for the 172 are justifiably worth their weight in gold, but there are cheaper AP callipers for things like the MK1 escort, that fit under 15"s so would definitely fit mine, is it just a case of bracket fabrication, or is the main obstacle going to be difference in brake line diameter or disc size or something I don't even know about, apologies if all this has been answered somewhere else;
I am not great at the internet.

 

[MicKPM]

I assume you've checked that the brake discs & pads are in perfect condition and that each calliper is working correctly. Has it been on a brake tester yet to measure the actual braking forces?

Dead travel seems to suggest that you maybe have air in the system, the pads may be low or that the calliper(s) are in some way sticking, all of which will contribute toward a terrible brake system.

Mick

 

[percival ian staker]

Thanks Mick - this is my next port of call; brake fluid has been changed as I initially assumed air, wasn't that, this weekend all the callipers are coming off to see if they work properly. Discs are relatively new (fronts sub 20k brembo HCs, and back just standard) will hopefully change the pads at the same time and see what happens.
Hasn't been on a brake tester - having a rear bias valve related headache as well (keeps jamming, buying another) so anything I learn on one at the moment will be of limited use I think

 

[JackD]

What should 172 cups braking force be on the rears? I had 0kgf one side and maybe 50kgf on the other

 

[dan112]

What should 172 cups braking force be on the rears? I had 0kgf one side and maybe 50kgf on the other

I had brake issues on the mot with my cup it failed for having 0kg on one side on the rear a new compensator valve and caliper sorted it and it passed with 50kg both sides on the rear