Hey Guys,

I am visiting a friend this weekend up in the mountains and he developed a brake problem with his ATV and I am trying to help him out before I have to leave.

Originally the rear reservoir cap became loose and he lost his brakes, he attempted to refill/bleed the system with no luck, I tried the same but want to make sure everything is doing what it should before I spend my afternoon bleeding some more.

Currently the individual brakes (handle or foot) are pretty much non-functional, however using them both at the same time will give you a hard lever/pedal and will operate the brakes. The rear caliper obviously has two lines to it, and two bleed screws, what I don't exactly understand is why. If its a single cylinder I can't understand how you could have a separate system and if they are separate, I don't understand why they are affecting each other.

I tried to bleed the two bleeder screws, the rear reservoir never changes level through the bleeding process. Is there something I am missing? I cant say I understand how this system works. Thanks for any help!

 

Caliper has two chambers that push fluid at the back of the caliper piston. One from the front master cylinder,one for the rear. Best on something like this to bleed the front master cylinder first with a mity vac to purge air from the system. You may have to bleed the front calipers also.Have someone keep the master cylinder topped off at all times.Once you have a reasonably firm handle,use the mity vac on the rear brake bleeder and keep the reservoir filled. May have to go back and forth on this a couple times depending on how much air is in the system.

 

What I don't understand is why when I squeeze the handle lever, why fluid comes back to the foot master cylinder, obviously they aren't completely independent or something is wrong with the caliper, that is what I am having trouble with.

I have bled the main/handle system quite a lot an have not been able to get anything like a firm handle. If I step on the foot brake while I squeeze the handle it feels good.

 

Also, I can't seem to get the foot reservoir level down, I know it hardly moves any fluid, but if I use the mityvac on the foot bleeder I get plenty of fluid out, but not from the foot reservoir, it comes from the handle reservoir.

 

No they're not independent,they work hand in hand with each other, but just have separate areas behind the rear caliper piston that push fluid. Any air in the rear caliper,front calipers,brake lines just pushes trapped air and you can feel it in the rear pedal when you pull the hand brake or when you push the pedal you can feel it in the hand brake lever. Common thing for this to happen. You just have to get all the air out of the lines and calipers and sometimes takes a while. That's where the mityvac helps rather than trying to hand bleed.

 

I appreciate the insight, I just feel like I am completely out of ideas. I am a mechanic by trade and am simply stumped by this brake system.

- If I have both reservoir caps off, if I fill the handle reservoir it will all push through to and overflow the foot reservoir.

- If I have both caps off and try to bleed the front brake calipers, it wants to pull fluid from the foot reservoir.

Tried bleeding one system at a time with no real results either.

 

Not unusual if the rear master cylinder sucks air also and may cause problems your having.Most people don't ever use the foot brake and seals can get hard and brittle. Seal kits are available rather than spending 90 bucks for a new one.You might want to consider this also.http://www.ebay.com/itm/1998-2009-POLARIS-SPORTSMAN-REAR-FOOT-BRAKE-MASTER-CYLINDER-SEAL-REPAIR-KIT-DR16-/281708309365?hash=item41971fab75&vxp=mtr

 

I forgot to mention the soft line that terminates at the foot brake cylinder seems to weep a noticable amount of fluid if I try to apply the brake. Perhaps the seals in that cylinder are just shot. I would imagine the reservoir is not supposed to come under pressure.

 

No it's not,just supplies fluid to that small master cylinder,probably bleeding past into the reservoir.I'd get the seal kit then still bleed the devil out of it all the way around. I've had a bunch like this where I thought I could never get all the air out when this happens. Just have a couple bottles of dot 4 handy as it may take a while and may go through a lot of fluid before you can have firm brakes. That's where the old mechanical foot brake was so much better,no small master cylinder to mess with and could lock the rear wheels down by itself.