Bought a 2002 325 Trail Boss recently needing minor repairs. It now runs and drives great but doesn't stop. Since its for the wife I thought about leaving it that way...just kidding. Front brakes worked great, rear pedal had nothing. So I bought new rear pads and a caliper rebuild kit. Put it all back together and can not get it to bleed out. No matter what I do it takes three pumps on the front brake (since its tied into the rear) to get a firm feel. Nothing on the rear pedal. Here is where it gets weird to me . Fill all reservoirs and close it up, start pumping the front brake and you will hear a squishing sound for one or two pumps and then it starts pumping fluid out of the rear reservoir (Seals are good, just to much pressure?) . If you try pushing both levers at the same time you can feel them fighting against each other. I figure maybe a seal is bad in the rear master cylinder and have ordered a new one. When it gets here I will start all over again, anything I am missing or overlooked that I need to do to this thing? Thanks for any and all help!

 

Make sure the caliper pistons aren't stuck.Use a mity vac and you don't have to fight brake bleeding.As far as bleeding the pedal brake,if it's been sitting up,the seals on the small master cylinder can dry up and suck air. You might get lucky with the mity vac,but if the rear can't get a firm pedal either replace the seals,POLARIS TRAIL BOSS REAR BRAKE MASTER CYLINDER SEAL REPAIR KIT OS145 | eBay or for 3 bucks more get a new master cylinder and ship the hassle on seal replacemt.New Rear Brake Master Cylinder For Polaris Trail Boss 325 330 2000-2009 | eBay Plus another common problem is the two small seals in the rear caliper than can cause problems when they leak like you mentioned when you pull the hand brake and pedal at the same time. You have to split the caliper to replace these plus the kits come with piston seals also. http://www.ebay.com/itm/Polaris-Scra...ZXl6zU&vxp=mtr

 

I went ahead and ordered a new master cylinder. Didn't want to take a chance of it having internal damage and have to still order a master cylinder. I have one of the mighty vac, so after new parts get here I will start over and hope for the best. Any tips I need to know about? Does the new master need to be bench bled like one for a car/truck?

Thanks!

 

I just took a new one out of the package,filled the reservoir with dot 4 and pumped it up with shop towels and finger over the end.Once it was primed I just installed it on the bars and hooked up the line.Then bled the system with a mity vac. On brake repair/pad replacement with the old master cylinder still installed,I just clamped off the rubber brake line a tad to be able to prime the old master cylinder back up,then released the vice grips. Some people shutter at the thought of doing this but no big deal on these old rubber line models and a quick way of priming the master cylinder without removing it.

 

Ok I think you lost me on the prime the caliper for pad replacement? How does compressing the line help the caliper re prime itself ? Unless you mean it stops the flow leaking at the caliper as in you don't lose as much fluid and makes bleeding quicker?

 

Was talking about the main master cylinder on the bars on priming. On the small rear master cylinder I just hooked it up and pushed the pedal several times fast to see if it could prime up on it own.If it couldn't I just used the mityvac and the pedal together along with keeping the small reservoir filled.Usually a couple minutes you could pull the mityvac off. If the caliper is seeping fluid and pulsing when you use both the hand and pedal brake usually this is because the small 0-rings between the caliper halves are seeping or the caliper piston seals themselves are. Both seals and o-rings are in the kit I listed.Polaris Scrambler TrailBlazer Trail Boss Rear Brake Caliper Seal Rebuild Kit 123 | eBay

 

Put the new master cylinder on and bled it out and no change. Has to be something to do with the caliper? If you clamp off one or the other line (front or rear) they will work fine separately but soon as you unclasp the line they don't work. You can put a weight on the rear brake peddle and press the front and it will lift the rear brake lever with the weight.

 

The seals in this split caliper is allowing fluid to back flow to the assist brake system as I mentioned earlier as one of the problem areas also. Just get the kit and rebuild the rear caliper.The two small o-rings are the main culprit. Plus the kit has new piston seals.Polaris Scrambler TrailBlazer Trail Boss Rear Brake Caliper Seal Rebuild Kit 123 | eBay

 

I rebuilt it once already but that doesn't mean I didn't mess something up putting it back together. I will pick up another one and start again.

 

A little seal grease or regular grease can help keep these little o-rings in place when you mount the caliper halves.