Dragging Brembo brakes

Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

All,
I've rebuilt the master cylinders and calipers on my Trackmagic. Still, one front and the rear caliper drag. I know this is a fairly common issue with the Martin master cylinder and Brembo caliper setup on Trackmagics.
Does anyone know how to fix this issue?
Thanks!

Chris Reinhardt · Posted: Mon Jul 30, 2012 9:23 pm Post subject:

What brake fluid are you using, what seals did you use in the master. Did you lube all the seals real good with brake fluid?

The other thing is any type of rust or pitting on the caliper pistons or bore can cause an issue.

Have you tried removing the cap on the top of the master to see if that helps? If there's any pressure build up inside the master cylinder reservoir, the brakes will drag.

We run that setup on the Cobalt kart. We use a regular caliper up front, you most likely have those motor quality calipers which are troublesome. We modify the MCP masters and install the Brembo reservoirs, so they vent a little better.... They never drag, stop on a dime and give you change Very Happy

CR
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Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

Hi Chris.
I'm using DOT 5 because I started with all fresh parts. No DOT 3 or 4 has been introduced. I cleaned all parts very well and replaced all polymer rings and seals. I use MCP master cylinders with vent holes to eliminate pressure build up. I would like to have more travel of the caliper pistons but am not sure how to gain it with the MCP MC's. I think if there was more travel the pads would back out clear of the rotor...
Not sure where to go now.

Chris Reinhardt · Posted: Tue Jul 31, 2012 5:20 pm Post subject:

Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

I researched the change to DOT 5 and was told that either DOT 3/4 or DOT 5 are fine as long as I don't mix DOT 3/4 with DOT 5. That is, if I start with DOT 5, it's fine but I can't add DOT 3/4 to DOT 5, once I initially start with DOT 5 on new MC and caliper o-rings and seals.

Chris Reinhardt · Posted: Wed Aug 01, 2012 9:43 am Post subject:

I don't believe that to be true as far as the Brembo calipers are concerned. There are seals that work with silicone based brake fluid (DOT5) seals that work with glycol based fluids (DOT3/4) and seals that work with both.

I believe the "new" MCP seals work with both so your statement would be true, but I don't think the Brembo calipers are compatible with silicone fluid.

Now there's a DOT 5.1 which is not a silicone base that would work OK.

CR
_________________
East Coast Super Kart Series
"This is how we roll!"
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Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

So, if I understand this right, to change to DOT 3/4 I'll have to rebuild everything and start anew with seals and o-rings. Is this how you understand it?

Chris Reinhardt · Posted: Wed Aug 01, 2012 4:46 pm Post subject:

That would be the best way.... I would have to look at it to see if the seals are swollen, but you might get away with taking everything apart and cleaning it real good. Not sure what seals you used in the masters, but make sure they will work with the DOT3/4.

I'm sorry to say, but using the wrong brake fluid in a system is probably the easiest and biggest mistake made.

Hope that helps...

CR
_________________
East Coast Super Kart Series
"This is how we roll!"
www.eastcoastsuperkart.webs.com

CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com

Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

I spoke with numerous people before going to DOT5 and was confident it would work. Previous experience with MCP/Brembo hybrid brakes was that dragging is a chronic problem and I only had one set that didn't drag at least some...

Chris Reinhardt · Posted: Thu Aug 02, 2012 3:11 pm Post subject:

I have Brembo's on every kart I own and build, none of them drag. Like I said earlier, those Motor Quality calipers had issues, we don't use them. No where have I found that Brembo motorcycle calipers are compatible with silicone brake fluid. In fact, search some of Ducati forums and they all say DOT5 is a big no no...

All of my Cobalt karts use MCP masters with Brembo calipers. The MCP masters use the EP seals and we run DOT4 with no issues. I even have a CRG with stock masters and Brembo's on the front, with DOT4 fluid, no dragging either.

Use what you like, but I don't think the Brembo seals will hold up and they might be swollen already causing your issues.

Good Luck

CR
_________________
East Coast Super Kart Series
"This is how we roll!"
www.eastcoastsuperkart.webs.com

CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com

Chris Reinhardt · Posted: Tue Aug 07, 2012 5:01 am Post subject:

Another bit of information I came across....

Although the EP seals from a DOT 3/4 system may be OK with silicone fluid, silicone fluid lacks the lubricating qualities of glycol based fluids. This lack of lubricating qualities will cause the brakes to drag and not retract smoothly....

I guess it's a very common thing for karts to use silicone fluid, so it's mostly used as a standard, but it may not be the best choice....

CR
_________________
East Coast Super Kart Series
"This is how we roll!"
www.eastcoastsuperkart.webs.com

CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com

Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

Thanks again, Chris.
I'm going to change to DOT 4 when I have time to do so. I just wish I didn't have to replace all the brand new seals...

Chris Reinhardt · Posted: Tue Sep 18, 2012 5:11 pm Post subject:

So what happen?
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Greg Lindahl · Joined: 13 Jan 2011 Posts: 271

Hi Chris.
This problem is still on my to-do list. I'm still in thinking mode on this problem. Rebuilding the entire brake system is not on my "fun" list. The next race is Thanksgiving weekend so I'm working on other more fun projects on the kart at the moment. BTW, experimentally I tried supermagnets on both sides of the piston to pull the piston back. Not enough force. I'm considering machining an o-ring groove in the back side of the calipers and installing a pull rod threaded to the piston to positively pull the piston back. It's unlikely that I'll go to such lengths, but it would be fun to machine and test. I also purchased some new front calipers and may simply install them as replacements for my old units.
What are you working on?

Chris Reinhardt · Posted: Wed Sep 19, 2012 3:21 pm Post subject:

Funny, I was putting together some Brembo's calipers with spacers I built for the 12mm rotors, etc, and I was just wondering what happen with yours...

You could ever put a spring on the bolt that hold the pads on the caliper. Use a compression spring in between the two pads and thread the bolts through it. Personally, I think dot 4 fluid will fix your problem....

CR
_________________
East Coast Super Kart Series
"This is how we roll!"
www.eastcoastsuperkart.webs.com

CR2 Motorsports
"Home of Cobalt Superkarts"
www.CR2MotorSports.webs.com