Polaris 4 wheeler brake help

[Cuz]

I have a 2003 Polaris magnum 330 4x4. The front/grip brake works fine but the rear/pedal brake does nothing. I've bled and bled the line (there is not air in it) but the brake still doesn't do anything. I'm thinking/hoping it's the master cylinder instead of the caliper (big price difference). My question is; how can I tell if it is the master cylinder not working? Is there a line I can pull and push the brake pedal to see if the cylinder is doing it's job or something along those lines?

Thanks for ANY input!

[Philip-TX]

Did you only bleed/fill the reservoir on the handle bars?

On my 2003 sportsman 500 there is a MC down by the footrest (on the right), and a little fill cup under the seat.



The rear caliper has two cylinder bores (large & small). The large one is activated by the hand brake and the small one by the foot brake.

[Cuz]

^^^ Yes sir, mine is the same way. When I was referring to my master cylinder I was talking about the one you posted a pic of. It's right behind the foot pedal.
I didn't do anything with the handle bar as far as bleeding it. I just bled the "cup" that's above the foot brake. I didn't realize the handle bar worked the front AND back brakes until reading that this morning...


With all that said, now, when I push the brake pedal, the cylinder/bore in the caliper does not move. If I squeeze the handle bar brake the cylinder/bore DOES move. So maybe it is that master cylinder above the pedal? There's also slowly leaking brake fluid coming out from around the bore, where it comes out of the caliper when you push the brake. Not sure what that's about...

[Philip-TX]

Bleed both chambers of the rear caliper, while filling the appropriate reservoir.

The rubber boot and seal for the caliper is leaking. This happens when pads get worn ALL THE WAY down and the caliper cup comes out too far. They have caliper kits for the seal/boot. Hopefully the caliper cup hasn't pushed too far out and worn off or you'll need a new cup too.

Do you know how to get the caliper cup out with compressed air to replace that seal? (You can probably google it.)

[Cuz]

No sir, never done it before but I bet I can figure it out.
So, since there's fluid leaking out around the cylinder boot (not sure if that's proper terminology) does that mean it's a bad seal or just that the cylinder extended too far and is ok now that it's back in place?

Thanks for your help, Phill.

[Philip-TX]

You'll have to take it apart to see if the seal is bad/worn or just out of place and to get it back in place.

When putting it bad together used a little brake fluid (or grease) to get things to sliiiiiide together a little easier. Probably brake fluid since it will be all over everything anyways,
Good Luck,

[Cuz]

[Philip-TX]

Yea you have a seal problem.

Take off that rubber boot (carefully pry a little on the outer edge with small screwdriver to get it started), pull it out of it's groove, and blow the caliper piston out (with air), there is a seal (sq. side oring) on the piston. If I remember it fits in a groove.

[Cuz]

I'll give it a shot!

[Cuz]

Well, I tried but the rubber is just too old and there's brake fluid leaking from within, somehow. I gave in and ordered a used caliper and master cylinder, and pads. Hopefully that'll do the trick.

[Philip-TX]

At least you didn't give in to $80-$90/hr labor at the shop.

You got this....

[Cuz]

At least you didn't give in to $80-$90/hr labor at the shop.

You got this....

True story. Thanks again!

[kmitchl]

Where did you find the used parts? I have a similar issue with a 2000 Polaris Expedition.

Also, I've found that reverse brake bleeding works best on ATV's. Here is a youtube video of this method. Works better that the traditional method.

https://www.youtube.com/watch?v=GV78az6yyYg

[Cuz]

Where did you find the used parts? I have a similar issue with a 2000 Polaris Expedition.

Also, I've found that reverse brake bleeding works best on ATV's. Here is a youtube video of this method. Works better that the traditional method.

https://www.youtube.com/watch?v=GV78az6yyYg

I'll check that out.
I bought the parts off ebay.

[Cuz]

Where did you find the used parts? I have a similar issue with a 2000 Polaris Expedition.

Also, I've found that reverse brake bleeding works best on ATV's. Here is a youtube video of this method. Works better that the traditional method.

https://www.youtube.com/watch?v=GV78az6yyYg

So you open the bleeder some and the fluid from the hanging bottle, by gravity only, pushes the air up and out of the reservoirs. Is that the idea?