Hydraulic Brakes Maintenance

[cuzn246]

My first time working with a buggy/cart; is there anything different about servicing the brake system on a mini buggy vs automobiles? I have either a Blade or Kinroad, GY6 with external reverse, disk brakes on both front wheels and on right rear axle. The front brakes work, but poorly, and the rear one does not appear to work at all.

Questions: Checking for pad wear; bleed sequence; type fluid to use; any other considerations?

Thanks in advance for any assistance.

[bige]

its about the same as a car, the rear caliper has a parking brake adjuster that looks like a bolt. adjust it in by loosening the lock nut and turning the bolt in just until the buggy has resistance, also may check the cable for adjustment.

when there is air in the lines it is a pain to get out

[drillpvt]

I found a one man bleeder kit at the local auto parts store for like 9 dollars ! you crack the bleeder screw and you attach the line that goes to the little bottle. neat little tool.
But the best way to get every air bubble out was to take the caliper off with the line still attach and raise it higher then the fill cap on the buggy and pump and bleed the piss out of it. Making sure to close the fill cap while bleeding and checking it every so often for level of fluid !

[metalstudman1]

IMO-If fluid level in the master is kept full then putting the cap on isn't neccessary- with the cap off you can observe the air bubbles returning from the valve and see the debris that's pushed back up through, to see if the whole system needs flushing. Bench/elevated bleeding is the most effecient way by far to bleed the brakes. It may require some more effort to disassemble but it's quicker in the long run and doesn't require the bleeding tool,or a second person. Brake fluid-Dot 3 unless the system has it labeled for Dot 4. The difference is that Dot 4 will withstand a higher temperature that most karts/buggies will ever never reach.

[Tosser]

Originally Posted by drillpvt

I found a one man bleeder kit at the local auto parts store for like 9 dollars ! you crack the bleeder screw and you attach the line that goes to the little bottle. neat little tool.
But the best way to get every air bubble out was to take the caliper off with the line still attach and raise it higher then the fill cap on the buggy and pump and bleed the piss out of it. Making sure to close the fill cap while bleeding and checking it every so often for level of fluid !

This is probably a dumb question but could you accomplish the same thing by jacking up the rear (then the front) instead of taking the calipers off?

Sorry to revive an old thread but I am having trouble with the brakes on a 150cc buggy. I took the master cylinder off an cleaned it. It looks okay but I was getting no braking in the front or rear. I am thinking it was a problem with air or possibly the caliper pistons. I ordered a bleeder tool so I'll trythat first when it comes.

[metalstudman1]

The whole principle is to get the caliper lower than the master cylinder-Just take the bolts out of the caliper with the bleeder being the highest point and set it on the floor/ground- try and straighten any elevated hose/line to avoid air being trapped in the bends. Gravity is the best tool you own!!!! Put a clear tube on the bleeder and run it up in the air a several inches to see the bubbles being pushed out & the other end of the tube into a catch container. You can do this with one person as you can move the caliper within reaching distance to the pedal.

[Tosser]

Guys, I am confused. I thought the idea was to raise the calipers so the air bubbles would work their way up to the caliper and could be more easily pushed out the bleeder. Am I wrong?

Metalman: You seem to be saying the opposite. If you raise the master cylinder above the calipers the bubbles would go up toward the master cylinder. Is there some kind of valve that will allow the air to pass back though the master cylinder and out?

Thanks guys.

[metalstudman1]

Yes- you're incorrect- there are hundreds of video's about bleeding brakes for you to confirm my method-The system is sealed by fluid-when in a vacuum you need gravity to flow the fluid- the air is pushed thru the system by the fluid and the remaining air is released at the bleeder being pushed out.If there is a higher point in the line the air can get trapped and the fluid will run right past causing spongy pedal. With the reservoir cap off any air in the master will bubble into the reservoir.
Reservoir is the highest item
master cylinder next highest item
down-hill run with the brake lines
caliper is the lowest point with the bleeder screw pointing up-with a clear tube connected to the bleeder nipple that's elevated you keep fluid pressue on the system and allows the air to rise & be viewed when bleeding.

Maybe someone else could chime in and confirm-

[Tosser]

Thanks, I think I understand. So the air will be pulled back into the reservoir?

I took the master cylinder off and cleaned it. I am going to put it back o and try to get the brakes working. I bought a mity vac tool to help bleed the lines. Do you know if I have to prime the master cylinder (bench bleed?) before putting it back on or will the mity vac tool take care of it?

[metalstudman1]

The bubbles that will emerge from the master's reservoir will be tiny (back bleed)- You can bench bleed the master- but usually not needed as the system is very small in fluid volume.By filling the reservoir you've primed the system.Keep it full thru the process. The mighty vac just provides for you to be at the bleeder on the caliper instead of applying pedal pressure. Even when I use my vac I still have to get it finished with pedal pressure for a solid brake pedal.

[x-bird]

if your mity vac kit included the fitting in the pic, completely remove your bleeder screw, turn the black fitting ALL the way into the bleeder hole--until the flange seats against the caliper. Put about an inch of fluid in the mity vac reservoir. With the brake reservoir lid off and the reservoir full, pump the mity vac to build vacuum and keep your bottle of brake fluid ready to top off the brake reservoir.

With a good seal at the bleeder, you should be able to purge all the air from the system in about 2 minutes. When it gets down to the tiny bubbles coming out, begin to flick the brake hoses and lightly tap on the master and caliper with a screwdriver handle etc. When you hit the point of topping up the reservoir 2 or 3 times after that and no bubbles at all are coming out, it's done. apply a little more vacuum, top up the reservoir before the vacuum draws down to zero, put the lid on it, then remove the fitting and install the bleeder screw.

One of the issues with these brakes is that the mity vac hose attached directly to the bleeder nipple WILL suck air around the threads of the bleeder screw, even if it's only loosened a little bit. You can sit there all day watching bubbles appear in the line attached that way--meanwhile it's not drawing any fluid down through the system.

[Tosser]

Thanks guys, I really appreciate it.