Brembo M/C issue

**Baddie** · 22-08-2013, 08:58 PM

Hello Boys and Girls.

Ok spent all day installing and trying to get less travel in my new RCS 18-20 brembo master cylinder.

I'm current using Castrol DOT4 brake fluid but I have way to much travel in the lever after bleeding (both calipers and M/C) at least half a bottle of fluid.

http://www.youtube.com/watch?v=tkxcQzhgJLU

Any idea Why?

My girlfriend (Senator8)..Did mention to check the pistons are not sticking which I will do tomorrow.

Attach picture showing travel distance of the lever to off the full on.

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**Marshy** · 23-08-2013, 04:30 AM

It must be a bleeding problem. The only thing that gives a long lever (while the bike is stationary) is fluid (or air in the fluid). If the bike is moving, it could be warped discs, sticking pistons, warped pad backing plates, out-of-round wheel, collapsed wheel bearings etc. But sitting still, there's air in the system somewhere, and it's almost certainly in the master cylinder. The Brembo RCS is difficult to bleed properly.

First question - was is a new bottle of fluid? What's the date on the bottle? Does the fluid look brand new? Maybe the fluid has contaminated in the bottle.

Then, move the M/C around (ie take it off the handlebar and physically turn it around in the air) to release any air bubbles, and allow them to travel up to the bleed nipple. Move it in such a way that you eventually end up with the bleed nipple at the highest point. Bleed again (a small amount of fluid is fine. Putting heaps of fluid through it with no air coming out is just a waste of fluid).

Then cable-tie the lever to the handlebar so the brakes are on. Don't go overboard with the pressure; just a moderate squeeze is fine. Leave overnight.

Check the lever in the morning.

**Baddie** · 23-08-2013, 04:56 AM

Cable-tie was attached last night and I'm up early to attack this problem..

Brake fluid is brand new (care of Supercheap)

The Girls on the Honda forum did mention to try and bleed directly from the banjo fitting first.

Also mentioned Bloody Brembo are hard to bleed but are worth they weight in gold.

**senator8** · 23-08-2013, 04:57 AM

Sorry Baddie, when you called me yesterday I was in the middle of something. On top of what Marshy said. I have often found air trapped in the m/c banjo itself. So now when ever I bleed the system, I just automatically bleed the banjo by cracking it open and bleeding the bolt itself with a rag wrapped around it as part of my process.

**Stu23** · 23-08-2013, 07:03 AM

IF its still a problem, you could always take the entire brake system off the bike, then you can get the air to move as you bleed by moving the calipers / m cyl up and around etc

**Marty** · 23-08-2013, 11:26 AM

Just don't let the resovior starve otherwise you'll be starting over. The first time I bled my RCS it was mint, I was doing something else on the bike and let the res tip over (didn't have enough hands) and rebled it but it wasn't as good since.

One trick I found is hang onto an old bottle. If you've got fully flushed fluid in your system there's no point dumping it when bleeding, bled it into the spare bottle and recycle it, that way you can spend ages bleeding into it without wasting expensive race fluid.

**Marshy** · 23-08-2013, 06:06 PM

Originally Posted by Marty

One trick I found is hang onto an old bottle. If you've got fully flushed fluid in your system there's no point dumping it when bleeding, bled it into the spare bottle and recycle it, that way you can spend ages bleeding into it without wasting expensive race fluid.

Good tip!