Brake lever fading after some turns

G

guitarrasa

Registered
Hi guys:

I have a problem on my 2012 Busa that nobody has been able to fix.

I have a Brembo M/C 19/18, Carbon braided lines, Accossato Calipers and Sinter pads.
The thing is: The feel on the lever feels very solid and powerful but after using the brakes a little bit hard (on the street) the lever starts to have like a dead space before it starts to brake. The stopping power is similar but every time the lever fades more and more. After stopping using the brakes for 2 minutes or so the lever feels very solid again. I've kept an eye on the Calipers temperature and It has never gone upper than 100º C which is nothing extreme at all.
I bled the circuit multiple times in some many ways, manually and with a vacuum machine. As you might guess, I'm just about to give up on it.

Any of you guys may have any idea?
Would be really appreciated

Regards
 
well if the lines are free of bubbles and there are no leaks, seems the only thing left is the MC. You might try replacing all of the washers on the banjo bolts and then re bleed. BTW did you bleed at the top? On the RCS you have too bleed the MC too.

next step is to rebuild or replace the MC I guess? Has the system ever worked properly?
 
Another thing. This is a long shot but the RSC can be adjusted to pump the amount of fluid needed for different applications and feels. IS it possible that this can be an adjustment on the MC to the proper ratio to work with those calipers?
 
Hi Fallenarch:

Thank you for your quick reply. Unfortunately I've tried 3 different MC a,d yes, I did bleed on the top. I even raised the calipers up and bled them in case there was some tiny bubble there. I used to have the Brembo RCS but now I've got a Brembo CNC, same issue.
The thing is, the first 5/6 agressive kick on the brakes are fine, and then, progressively the braking point on the lever starts to move backwards more and more, after 2 minutes or so the lever comes back exactly to the same place. I tried with the OEM rotors and it still does it. Regarding if the system ever worked.... I had never had any issues until I upgraded the whole brake system but It's true that I don't think I used to stress it that much.
I'm monitoring the caliper's temperature and everything happens below 110 º C.
 
The only thing to do is totally rebuild the entire system bit by bit, starting at the M/Cyl and then new hoses.
Dunno . . whatever you do, it's gonna cost ya. But all you can do is work through the components systematically and you will eventually nail it.
 
I've already gone through all the components bit by bit, tried 3 different radial MC, 3 different calipers, 2 sets of braided brake lines, several brake pads, sintered and Brembo Z04, I use motul 660, Changed the reservoir.... I don't know what else I can do.
 
Kiwi Rider said:
The only thing to do is totally rebuild the entire system bit by bit, starting at the M/Cyl and then new hoses.
Dunno . . whatever you do, it's gonna cost ya. But all you can do is work through the components systematically and you will eventually nail it.
Click to expand...


I've already gone through all the components bit by bit, tried 3 different radial MC, 3 different calipers, 2 sets of braided brake lines, several brake pads, sintered and Brembo Z04, I use motul 660, Changed the reservoir.... I don't know what else I can do.
 
guitarrasa said:
I've already gone through all the components bit by bit, tried 3 different radial MC, 3 different calipers, 2 sets of braided brake lines, several brake pads, sintered and Brembo Z04, I use motul 660, Changed the reservoir.... I don't know what else I can do.
Click to expand...
Bring in a Priest to perform an exorcism?
Sounds like you've tried everything.
Except different rotors?. ... Does Brembo have a technical advice phone number? Or a tech service centre in your local area? See if they can come up with an answer maybe?
 
Kiwi Rider said:
Bring in a Priest to perform an exorcism?
Sounds like you've tried everything.
Except different rotors?. ... Does Brembo have a technical advice phone number? Or a tech service centre in your local area? See if they can come up with an answer maybe?
Click to expand...

Brembo after sales service is terrible, brembo doesn't even do it itself, the hire a company to do it for them. I asked them, but they don't know. Calipers that I'm using now are a different brand. I did try the original rotors too.
 
guitarrasa said:
Brembo after sales service is terrible, brembo doesn't even do it itself, the hire a company to do it for them. I asked them, but they don't know. Calipers that I'm using now are a different brand. I did try the original rotors too.
Click to expand...
who bled the brakes?
 
ali123 said:
brake lines? i know everyone thinks anything (carbon) fiber is the best.... but u might get lucky and have a compromised line......
Click to expand...
Carbon lines are just a carbon sleeve covering the same inner tube as all other braided lines bro .
As for the brake fade , got me stumped ... swap out the rotors , maybe to ductile iron , or swap out the calipers for Brembo and sell your Accossato .
Not real helpful I know , but you have covered every other angle .
 
As a long shot, only thing I can offer is a possible mixing of different brake fluid types. As in Dot 3/4/5/5.1
As some are glycol-based and others which are silicone-based. Maybe some cross contamination of fluids??
Sorry, that's all I can offer...
 
I was thinking the same thing. But with SO many brake bleeds surely the fluid has been checked by now. My only other out of the box idea is somehow air is getting in with with every pull through a gasket failure in the M/C. I'm stuck otherwise
 
My crappy oem gen 1 res and calipers don’t have any fade. If all else fails you can always trade with me and I can live with your ghost fade :poke::poke:

Just messing with ya, my techs had a similar issue recently with a fuel system on a truck....they bled it, it worked great we roadtested and then delivered. 2 days after, truck stuck on road no fuel pressure. Got it back bled it out sent it back same issue.

What you can do (I think) is maybe try to dry out the system and pull a small vacuum. See if the system can hold that small vacuum. I mean really when you break it down the only thing It can be is a disturbance of flow. It’s just finding the why the where and the how.

Check out what I found on the truck. There was 2 small nicks in the fuel filter housing my guys missed (changing the filter without sufficient lighting, and just not being thorough)

47D2FAF4-C14B-48DC-8AFA-3140CE92D9C6.jpeg


BA88F6C3-2CCD-486F-9E65-3D509360B45C.jpeg
 
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