There are two distinct types of hydraulic brake systems in use on karts.
Type 1, almost universal today, has a master cylinder with afluid reservoir and a self adjusting caliper.
These systems can be bled by pumping the master cylinder as on a road car.
Fluid can return to the reservoir if a pad is pushed back or the fluid expands.
Type 2 , used to be almost universal, but rare today , has a master cylinder with no reservoir and is normally used with a spring pad return caliper. Once bled the system is sealed.
These systems are bled using a bleed tower to run fluid through the system with no pumping.
A Type 1 system can be replenished in the event of fluid loss by pumping the pedal ,at least until the reservoir is empty.
With a Type 2 system any fluid loss is permanent ,the pedal goes to the floor and isn’t coming back without a rebleed.
Pad knock back due to axle shift will push some fluid back into the reservoir on a Type 1 giving a long pedal restored to normal by pumping.
On a Type 2 sealed system if one pad is knocked back the fluid will push the other pad out as it has nowhere else to go. The pedal will stay the same.
I am guessing type 2 then. I also recall complaining about the brakes to the director and him saying they weren’t brakes like the owner karts. Thanks.
I think we solved the problem. When I took apart the old master I found a chuck of what appears to be plastic inside. My theory is this plastic was floating around in the master then occasionally blocked the outlet to the brake line. So the pedal felt normal but no pressure was getting to to the calipers. This would explain the intermittent complete loss of braking. What I thought was the pedal bottoming out was really just the master pressure building when this piece of plastic decided to block the outlet. All the seals on the master look good and there was no signs of fluid leaking past the master piston. I assume the plastic it is a broken off piece of a bleeding system or something. I’ve seen junk in a fuel tank, but never anything like this. Crazy! New master is installed and we have good braking.
Thanks for all the feedback from everyone!
Glad you figured it out! Enjoy.
Glad to hear you found the culprit. I would suggest a thorough cleaning and replacement of the seals anyway. Seal it in a plastic bag and set aside as a backup in the future. Always nice to have spares on hand.