I'm rebuilding a 94 sportsman out of two broke down units...brakes are the latest problem

had to swap the rear caliper (pin was stuck) and I replaced pads all the way around.

now i can't get any pressure in the brakes - I've bled all three brakes and brake fluid is coming out of all three calipers. But it's not really building any pressure and not moving any pistons. also - the brake light switch is not being activated either (I assume thats a pressure switch there at the junction block that turns on the brake light?)

master cylinder is topped off and doesn't appear to be leaking.

So - is there something in this system I'm missing?

thanks for the help

 

so if you squeeze the brake handle you dont any pressure? you might ned to rebuild your master cyclinder if the seals are bad not letting it build any pressure by bleeding back into the master. just a thought.

 

no real pressure to speak of....fluid comes out the bleeder screws, but not much pressure and no pistons move with the system closed

I thought master cylinder too, so I swapped master cylinders for the one from the donor machine...same problem - I'm pretty sure they are both good (since brake problems is not why they needed work) but I thought maybe I damaged the first one when I compressed the pistons back in to put new pads in.)

when I had the master cylinder off I gave the handle a squeeze and it put out a good stream of brake fluid.

I'm kind of thinking it's still got a ton of air in there, but I can't figure out why it won't bleed out.

 

I found some threads about guys not building pressure and having to rebuild the master cylinder.

I suppose anything is possible, but I still think it's highly unlikely that both M/Cs are bad.

I think it's a lot more likely that there is a bad air pocket in there. The caliper was off for quite a while and the line leaked until the master cylinder was empty.

I think my next try is first to get a small fluid pump (I'm thinking a clean differential fluid hand pump) and back feed brake fluid from the bleeder valve through M/C. Hopefully with a little more volume (pump would move way more brake fluid than the M/C) and with the upward flow I'll be able to get the air out of it.

If that doesn't work I'll try to bench bleed the M/C and see if that makes a difference.

 

well I give up...going to go ahead and rebuild a master cylinder.

I looked on the polaris parts website and can't find a rebuild kit, just individual parts. Is there a kit and where can I get one?

 

did you have brakes that worked on the other bike you took the m/c off? if you let the m/c go completely dry to where it sucked air in the brake system then your right as they are bear to bleed the air all out. if you had a away to plug the m/c off like on the bench and squeeze to see if it would give some kind of pressure then i would guess it wouldnt be rthe m/c as the problem. not sure but seems like you could get a kit but most likely if the pluger was fine you would only need the rubber seals for the rebuild. imo

 

When I got them they were already torn apart so I can't say 100% that they worked.

But I can say that isn't one of the problems that was on the list of needed repairs. and it seems very unlikely to me that both master cylinders on previously running bikes are so bad they build no pressure. If the previous owner hadn't already bought new pads for it I wouldn't have even messed with the brakes.

But I did...and when I got into the brakes I couldn't get one of the rear caliper pins out (corroded in place in a bad way)...so I swapped calipers and that's when the bleeding problems began!

I already tore one of the master cylinders down so I'll just go ahead and get a kit for it. Can't hurt and I'm better off dealing with it now since I'm going to be riding it!

 

ok I have parts now so hopefully will get time to night to work on it...

hopefully I can post good news tomorrow

 

Well I'm still a little baffled, but it's fixed.

I rebuilt it and it was much better - made pressure, brakes worked, etc...but after holding it for 5-10 seconds pressure would bleed off.

After fighting it for a while I took it apart again.

The new u cup seal was ripped...must have happened while I tried to install it.

I reused the old one since it looked fine and put it back together -

success! (so why didn't the old seals work before!?)

My rear brake foot pedal needs some adjustment, but other than that the brake issue is solved...on to the next job. Actually all I have left is tightening chains, greasing everything, installing and sealing the outer clutch cover, mounting the gas tank and the pod, putting plastic and tires on and she's ready for a test ride!

thanks for the help

so far the completed list looks like this
engine swap
synced throttle and oil pump
bled oil pump
tested oil pump
carb swap
fuel tank swap
changed counterbalancer fluid
changed trans fluid
starter swap
recoil swap
new swing arm bushings
new rear chain
taillight swap
installed exhaust
installed and sealed inner clutch cover
installed clutches
adjusted motor mounts for clutch alignment
set belt offset
change hub fluid
speedo swap
new pads all the way around
rear caliper swap
rebuilt master cylinder!!

 

do your self a favor and for get ab[img]i/expressions/face-icon-small-smile.gif[/img]out the foot brake lol. no really these foot brakers on most of the polaris bikes are a joke and half of them loose presssure even afte ryou get them working. glad you got it fixed.