Did you rebuild the master cylinder or the brake caliper?
If you are not leaking fluid anywhere then you have air in the system...otherwise make sure the master cylinder is put together correctly and make sure your brake pedal is connected to the master cylinder -sometimes the pin falls out?

 

Thank you for the reply.

I rebuilt the master cylinder. I just wasnt sure if thats what its called on a quad (Its tiny compared to a car). Nevertheless, I assembled it the same way the old one came out, making sure not to rip the top or bottom rubber seals. The first time I put it together, the top seal wouldnt lubricate and it was causing the piston inside to lock at fully closed. I ended up taking it apart and putting an old seal in there. I think connected the reservoir to the mater cylinder, poured some fluid in the end, and pushed the pedal. It seals and pushes it out the line-end ok, but when I start to bleed the line, I get lots of tiny bits of air and thats it. 30 minutes of pumping the pedal, holding, cracking bleed screw, repeat, and it still isnt pressurizing. Finally I took the vacuum pump and proceeded to pump until I saw the fluid. Im using SuperBlue Racing fluid, so when it started to change to blue, I knew I was seeing new fluid from the reservoir. No leaks anywhere else, pedal is securely attached to the master cylinder with the pin. Is there a possibility that the brake fluid is the culprit? Ive never heard of such a thing, but I havent done a lot of work on quads either. Picture and link to fluid:

http://www.tirerack.com/brakes/accessoryDetail.jsp?ID=21

 

could be the caliper

 

Do you have any suggestions for things I could check on the caliper that would cause a lack of pressure and no leaking?

 

I think others when bleeding the rear brakes put the caliper above the reservoir and master cylinder to let the air go up, try this and see how that works for you.

 

Yea, I'm sort of with Limited660 on this one....If you don't have a leak then you still have air. I would try to get someone else to help pump the pedal while you work on pushing or pulling the fluid through. I really can't figure out how the caliper would cause this problem. Stick with it, these small brake systems can be a pain to bleed especially when you're alone in the shop.

 

When you say theres no pressure, Can you push the pedal all the way down to the metal? If you can i doubt that its air in the lines

 

Lift the caliper above the rest and it should pump right up for you.

 

so when you press the pedal the pad doesent move at all?

 

I was wondering if you ever figured out the problem with your brakes, mine are doing the same thing. I, like you, have already rebuilt the master cylinder and it still has not pressure.

 

i had same problem so i took caliper apart and took the handbrake side of the caliper apart and replaced a "O" ring in the caliper.... put it back together took about 5 mins of bleeding etc and never had a prob since.

maybe this helps
justin

 

Make sure to check the caliper slide pins!
My rear brake quit working recently and it was just the slide pins sticking and not letting the caliper move. I just removed the pins, cleaned them, lubed them, then all was fine!!!

 

Unfortunately I havent had a moment to get back to the garage. Have a new house and new baby that has been keeping me 100% occupied for the last couple months now. However, these new postings have re-established my urge to grab a 6-pack and a wrench and fix this raptor. Its riding season already. Will tackle this on Thursday or Friday and let you all know. Im going to start by disassembling the rear caliper and cleaning the pins, give it a good once over, and elevate the rear above the reservoir.

 

Dont forget to bleed the Master Cylinder first. I did this when i added my SS Brake Lines.

 

Sorry for the delay, just now put the back above the reservoir and bled it, took about 5 minutes and bled correctly. Thanks for all the info! Time to go ride.

 

I am having the same problem. I noticed that the piston in the calliper is on a thread. U can turn it all the way down or all the way out. What is the correct position for the piston.

 

That is for adjusting the parking brake.