I am finishing up my granddaddy project. I have the MCP disc brakes installed and bled ( I think). There seems to be good pedal, but I can’t lock up the rear wheels. I am using a fair amount of pressure on the pedal (more than the grandkids will be able to apply) but the wheels will not lock up. The pads are moving. Any suggestions? I assume they should lock with not excessive pedal pressure. Thanks
Disc brake issues
- Thread starter GCC
- Start date
Kent
Member
It sounds like the pads are not squeezing down on the disc far enough. Some calipers have an adjustment bolt to move the pads closer to the disc. I think your pads should be just barely touching the disc when no brake is applied or just barely off the disc. Is the brake system new ? I have read on this forum where some people have bought thicker disc's to get better contact. Maybe the pads are worn down.
Kent
Member
Does the caliper have the adjustment bolt ? Can you watch the pads as someone pushes the brake ? Maybe you can see how much the pads are moving before making contact. Should be very little. Seems like the pads should be okay if the manufacturer supplied them. It could be the disc is to thin. The disc wasn't part of the brake kit was it?
The brake pedal should not be bottoming out after you bled them.
The brake pedal should not be bottoming out after you bled them.
Everything is part of the kit. The pads are almost touching the rotor before the pedal is pushed. The pedal is not bottoming out now, but the wheels don't lock up until I have alot of pressure to the pedal. Maybe this is normal and I am just used to power brakes in the car.
Pictures would help.
I have the MCP ones on my barstool racer with the MCP master on the hand lever and it locks them up everytime. But yes you gotta pull it firmly to do so.
if it stops good then I wouldn’t worry about it.
I have the MCP ones on my barstool racer with the MCP master on the hand lever and it locks them up everytime. But yes you gotta pull it firmly to do so.
if it stops good then I wouldn’t worry about it.
anderkart
Moderator
When the MCP brake kit is fully bleed, it'll easily lock up the brakes on a 125lb racekart with 11" tall rear tires & one 250lb driver using just a medium pedal force.
But this brake kit can't be expected to work nearly as well if you & your Spidercarts GrandDaddy kart end up weighing a LOT more, and especially if your rear tires are a lot taller...
Is your brake pedal designed to give good leverage?
Also, do you have your brake linkage rod connected to the top hole of the master cylinder lever to achieve maximum leverage?
But this brake kit can't be expected to work nearly as well if you & your Spidercarts GrandDaddy kart end up weighing a LOT more, and especially if your rear tires are a lot taller...
Is your brake pedal designed to give good leverage?
Also, do you have your brake linkage rod connected to the top hole of the master cylinder lever to achieve maximum leverage?
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I haven't driven the go cart yet to see how it stops. I have just tried to push it while someone pushes the pedal. If the pedal isn't pushed really hard I can push the cart. My concern is that my 9 yr old grandson won't have the leg strength to push hard enough. The linkage is set up for maximum leverage. Is there a screw to adjust the pad clearance? Photo shows what I have. I also have 18" tires.
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jamyers
Well-known member
When pushing on the pedal, does it go down a bit, then get a LOT harder to push, or does it "squish" on down? If it's squishy, you've still got air in there somewhere. Bleeding can sometimes be a royal pain.
Kent
Member
I'm no expert but to me, given the problem your having, that looks like to much clearance between pads and disc. If the unit has a provision to adjust the pads you should be able to see it on the caliper.
http://mcpbrake.com/default.html
You could try calling MCP and they may have the answer for you.
http://mcpbrake.com/default.html
You could try calling MCP and they may have the answer for you.
madprofessor
"Loose Cannon Creations"
Something nobody ever seems to question is the size of the brake disc. Whether it's part of your problem or not, just remember: The more diameter, the more braking. I have an 8" solid disc on my live axle, with a single cheap Chinese caliper on it. Very little pedal travel on my linkage setup, massive grip on disc. If you use one of those little 5" or 6" discs trying to get more ground clearance, you'll need logarithmically more pressure to the pedal. Discs that are slotted and/or perforated for cooling and weight reduction purposes reduce the square area of contact to the pads to boot.
I had a really hard time initially bleeding the brakes, red beard garage has a good video on youtube about it. if you closely follow the instructions on mcp website and have another adult to help you should be able to get stock setup to work. The hard part is that it is a dual piston caliper and has very specific bleeding instructions. a 1/4" combination wrench (I think that is bleeder screw size) really comes in handy. i have rounded off a few bleeder screws using pliers.