[VasileiosG]

Hello again guys,
I'm fiddling around with my brakes in order to optimise them but i'm far from it.
My setup currently is:
Brembo Rcs19 master cylinder
Venhill Braided lines
Motul Rbf 700 brake fluid
Tokico standard brake calipers
Suzuki standard brake rotors
Brembo SR pads.

My issues are:
A) Too much of empty space before the brake lever begin to grab. It's almost 1/3 of the full length (If needed i will provide photos)
B)Almost none initial bite.What i mean is that when i press the lever (2/3 of the length due to problem 1) i can feel that the brakes grab but i don't slow down. In order to slow down i will have to put a lot of force (not 3 fingers force, still 2 but u get the point) and then they work as expected. There are no brake stucks, no sudden changes in the grabing force, they work as expected. Also temperature doesn't play any role, i have the same situation with cold brakes and hot brakes.Also there are weird patterns on the brake disc, like "white dots".(Can provide photos if needed).

What i have done/ checked.
A)Already done multiple bleedings-Seems to work for a couple of kms then its the same
B)Cleaned my calipers without putting out the pistons, checked for leaks, no sign of leaks,the pistons move freely and no issues with different pressure from side to side.
C) Cleaned my brake discs with scotch bride and brake cleaner,also cleaned (kind of) the brake floaters (i don't know the name)- the thing that keep the outer part conected with the inner part, like small discs.
D)Checked if pads are touching the discs, i have over 1,5 turn of the rim, no issue there.
E)Checked for leaks in the system, nothing
F)My mechanic didn't find anything unusual
G)Used both settings in the master cylinder (20/19?), none worked as i would like to.
I'm out of ideas, and the issue is that with that much of a traveling distance in the lever, i have to "prime"my brakes before each corner.
What can i do more?

 

[mikemanzo213]

How were the brakes before you changed everything ? My guess it’s the calipers, it is a little expensive but I would upgrade to the brembo calipers, also I heard if you don’t use brembo calipers with the brembo mater cylinder you can damage the calipers, and I though the Rcs19 was for the 1000cc and the rcs17 is for the 600/750 that may have something to do with it also

 

[Mb1500]

The fact that you say bleeding helps but then goes back after a few KM’s makes me think you have an air pocket or the system isn’t closed. Try reverse bleeding and lightly tap on calipers, lines, etc while you’re doing it. Triple check for any possible leaks.

 

[nick49]

The piston in the master cylinder is too large. For the stock calipers, you need the stock size piston in the master cyl. Too large a piston requires too much effort, too small a piston is little effort and too much travel.

 

[VasileiosG]

I have run this setup for over a year now, and im quite positive that it's not the master cylinder diameter, because it used to work better that now. The issues i mentioned arrived around 2-3 months before but i can't pin point what changed because they were gradually. As for the air pocket, i have tapped everything my line again and again. I can't seem to find the issue.

 

[alexei]

Sounds like the RCS19 kit might have a leak.

 

[alexei]

Is it the RCS19 CorsaCorta?

 

[Bat-1]

Are the brake lines secured all along their path? You don't want any movement.

 

[BillV]

Your "floaters" are more commonly referred to as "bobbins".

"Seems to work for a couple of kms then its the same" I'm suspicious of the caliper seals. Suggest that you disassemble the calipers, clean the pistons & caliper seal grooves, and install new seals.

The 19RCS is a bit large for a 1000 calipers in terms of the caliper-to-MC area ratio (ratio is too low). I gather that the 600 caliper has a smaller trailing piston diameter, which will lower the ratio even more. I haven't done the calc but a 17RCS might give you a ratio that's closer to the ideal of 27.