[Cupra R, Brembo] Weak brakes

[Equalizer]

Hello.

I have a big problem with my MK1 Cupra R with Brembo calipers. Since I bought my LCR I had some doubts about my braking system- it didn't worked as good as I could expect. Simply- it was (and still is) very weak. Recently my friend gave me his cupra for a ride and his brakes were better than mine by about 50% (or even more)

I gave my all four calipers for total regeneration (new paint, pistons, seals etc.), replaced the braking fluid to Motul RBF600, mounted new braking pads and removed all air from whole braking system. Disc are still good, so I left them as they was. It all helped only a little bit.

After some tests I think that servo is good.


So, after my description mixed with my poor English, can you help me even just a little bit? What could be the cause of weak brakes?

 

[irf]

What pads are you using?

 

[Bouncerbeater]

I thought Cupra R in Europe didn't have Brembos ? Sure I read it somewhere

 

[Equalizer]

I thought Cupra R in Europe didn't have Brembos ? Sure I read it somewhere

It seems you have wrong info Everywhere in Europe buyers had two options- one piston 312mm brakes or Brembo 4-piston 323mm set.


I use ATE pads.

Maybe I use wrong brake fluid. What brand of fluids do you use?

 

[Bouncerbeater]

Not wrong info, you just proved me partly correct haha. Brembos were optional
Perhaps your discs are the problem as they are the only bit not changed ?

 

[Equalizer]

Rear discs are like new and front seems to be only a little bit used.

I'll add, that the brake pedal, when pressing is similar to what you feel when trying to squeeze syringe with stoppered top.

 

[hendo#1]

When I bought my Cupra R, the brakes were awfull. Turns out it had the wrong size discs on the front (too small, possibly from a standard Cupra?)

Replaced all 4 corners, disks, pads and rear calipers and all is well now.

Check your disk sizes.

 

[Bouncerbeater]

Rear discs are like new and front seems to be only a little bit used.

I'll add, that the brake pedal, when pressing is similar to what you feel when trying to squeeze syringe with stoppered top.

Sounds like you're not getting any servo assistance. Certainly when I had a Manta years ago the pedal would intermittently go hard and have no power. Turned out to be a split in servo pipe

 

[Equalizer]

Maybe that's it.

I've read about simple servo test: while engine is turned off, press/pump brake pedal a couple of times to make it hard and hold it down. While holding the pedal, turn on the engine- pedal has to drop a couple centimeters down.

Anything from this list worked for me :/

@hendo#1

I have 323mm at front and 256 at rear, so everything is all right here.

 

[Gaz7]

Very much sounds like a servo problem, start by looking for collapsed vac pipes and check non return valves

 

[Equalizer]

Please tell me: the vacuum line for the servo consists of pipes, that I have highlighted in yellow in the picture below?

If so, does this line end with a non return valve and a plastic hose going straight to the servo?

 

[the parrot]

it also sounds like a sezied caliper some where. have you rebuilt the rear calipers. as this can cause the solid feeling as well.
check the pads are moving freely in the calipers themselves.

 

[Equalizer]

All four calipers have been totally rebuilt.

I have another trail. On other site, they advised me to rinse the whole system two times then refill it with a new fluid. I have this car for two years and before I thought about changing the brake fluid, it was there for at least four years (earlier owner didn't care about that). Imagine how it looked like when I removed it (colour of an old tea with something floating in it).

 

[the parrot]

that would make the brakes feel spongy.
and over heat quickly.
it is a strange one.

 

[Muttley]

I gave my all four calipers for total regeneration (new paint, pistons, seals etc.), replaced the braking fluid to Motul RBF600, mounted new braking pads and removed all air from whole braking system.

Did you replace the fluid by putting the new fluid in using a pressure bleeder while draining the old stuff out, or did you drain the system completely and then refill?

If you drained the system you will have got air in the ABS pump, which is extremely difficult to get out, and for which it is said that VCDS or a dealers diagnostic computer is required.

 

[Equalizer]

Unfortunately the fluid was changed by the mechanic, so I didn't seen the whole process.

 

[Born2bwild]

Exactly the reason I prefer to do my own work. I'm with Muttley on using a pressure bleeder. Cant the ABS pump be purged manually by engaging the ABS?

 

[Equalizer]

Perfecto! I have my trail I'll buy about 2-3 litres of braking fluid (Maybe Motul DOT 3&4), and clean the whole system. Then we will see.