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Discussion Starter #1
The brake system on my 04 Sportsman is ridiculous. If you loose one line, you've lost both front and rear. Has anyone tried to separate the front from the rear brake system like a normal set up? I suspect you have to replace the rear caliper if you want to do that right? When you pull the front lever it pushes on one side of the rear caliper and the foot pedal presses the other side. You can't simply block off the front line to the rear caliper right?
 

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I don't know where you are riding, but I have ridden a lot of miles on these machines including a 2004 sportsman 600 and never lost the brakes. This system has been in use since Polaris started making ATVs so I don't see the need to change it. Make sure your brake lines are in good shape and protect them as best you can then go riding!
 

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Discussion Starter #3
I don't know where you are riding, but I have ridden a lot of miles on these machines including a 2004 sportsman 600 and never lost the brakes. This system has been in use since Polaris started making ATVs so I don't see the need to change it. Make sure your brake lines are in good shape and protect them as best you can then go riding!
I'm not just talking from a loss of brake issue, but that is still an issue. I've put many thousands of miles on all sorts of machines. Harleys that I've built from the frame up to a Hayabusa. Camaros, Mercedes, F350 trucks, snowmobiles and more than 30 different dirt bikes over the 40 years that I've actually been ripping up the dirt and pavement. My last off road bike was a KTM 300 2 stroke. This is my first real quad though. I just don't like the Polaris brake system. I want to be able to use the rear brake separate from the front brakes. They should be two separate systems IMO.
 

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The foot brake for the rear is separate. It has its own MC and operates on one side of the caliper stepped piston while the hand brake works on the other side of the piston.
 

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Discussion Starter #5
The foot brake for the rear is separate. It has its own MC and operates on one side of the caliper stepped piston while the hand brake works on the other side of the piston.
The footbrake is not separate. If you bleed the front brakes and rear needs bleeding or vice versa you won't have any brakes. They push against one another. Like you said the rear pedal pushes on one side of the caliper and the front lever pushes on the other side. Goofy ass system IMO. Yes, if the whole system is operating correctly you can use the rear pedal to lock up the rear wheel and not the front.
 

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The front and rear brakes are totally separate systems. It's just that the rear caliper has two separate chambers pushing on the same piston.

The rear caliper has one piston that is stepped - both the hand lever and foot pedal apply pressure to the same piston. If you want to separate the brakes operators, you have to disconnect the line that goes to the front MC and cap it at the junction block - you then need to get a special line line that has a Y fitting on the caliper end so both piston chambers can be connected to the rear MC or find a conventional caliper that will replace the stepped piston design. Viola, problem solved!
 

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The foot brake for the rear is separate. It has its own MC and operates on one side of the caliper stepped piston while the hand brake works on the other side of the piston.
The footbrake is not separate. If you bleed the front brakes and rear needs bleeding or vice versa you won't have any brakes. They push against one another. Like you said the rear pedal pushes on one side of the caliper and the front lever pushes on the other side. Goofy ass system IMO. Yes, if the whole system is operating correctly you can use the rear pedal to lock up the rear wheel and not the front.
No, they don't push against each other. They are separate. Not the greatest system in the world I agree. The foot MC has its own reservoir and separate bleeder and acts on only one step of the piston while the hand lever MC acts only on the other step of the piston. If you use them together you're putting pressure on BOTH stepped sections of the piston. There are two separate bleeders for each system. If the foot and hand lever push against each other the piston seals are bypassing/leaking fluid past them from one section to the other and the caliper needs rebuilt.
 

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Discussion Starter #8 (Edited)
The rear caliper has one piston that is stepped - both the hand lever and foot pedal apply pressure to the same piston. If you want to separate the brakes operators, you have to disconnect the line that goes to the front MC and cap it at the junction block - you then need to get a special line line that has a Y fitting on the caliper end so both piston chambers can be connected to the rear MC or find a conventional caliper that will replace the stepped piston design. Viola, problem solved!
I guess I was wrong about one side or the other pushing. I didn't look close enough at it, but the principle is the same. What you said sounds like a good work around. Don't you think it would also work if you just plugged one of the line ports? It's still pushing with the same amount of force as if you were just pushing on the rear brake pedal. Seems like it should, but I don't know. Might have to find out... We'll see.

No, they don't push against each other. They are separate. Not the greatest system in the world I agree. The foot MC has its own reservoir and separate bleeder and acts on only one step of the piston while the hand lever MC acts only on the other step of the piston. If you use them together you're putting pressure on BOTH stepped sections of the piston. There are two separate bleeders for each system. If the foot and hand lever push against each other the piston seals are bypassing/leaking fluid past them from one section to the other and the caliper needs rebuilt.
That makes sense and might be one of my issues. One of the bleeders was broken off and I didn't notice it until I threw more than a few curse words at it. I've never seen a caliper that has two bleeders. That's when I dug into my service manual to see what made the system tick. Right now I don't have brakes until I apply both the lever and foot brake. I'd say you might be right about the caliper seal. I'm going to replace the broken bleeder and try bleeding that side and see what happens.
Now that I'm thinking about it though, I think the service manual did say they pushed against each other. I'll have to see where I read that. Not saying I don't believe you guys.
 

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Here's the problem with just removing one line and capping the other hole (or leaving it open)

If you cap the line port and close the bleed screw, as you apply the brake, it will draw a vacuum on the closed off side and you will have vacuum working against application. If you leave the ports open, dirt and water will enter the piston bore causing it to lock up. To get full operating pressure, you would have to close off one line port and cap the bleed to the smaller of the two chambers and remove the smaller bore piston seal you could use either line port for pressure while capping the other port, but you would have to bleed the caliper from the bleed port on the larger chamber. If I were to do it, I would use the small chamber line port instead of the large chamber port - reason; with the small piston seal removed, pressure would initially push on the smaller surface area first, push past the piston and enter the larger chamber to push on the surface area there providing 100% of available pressure to the brake pad.

Bleeding would be tricky as air would tend to become trapped in the piston seal groove that the seal was removed from. If I were to do it, I would reverse bleed (push the air to the MC for expulsion). Holding the caliper so the piston bore is vertical, I would fill the caliper with brake fluid - with the cap off the foot pedal MC, push the piston in until it just contacts the piston seal and attach a c-clamp to hold things in place (the c-clamp will be used to push the piston all the way in later) - with the c-clamp holding the piston in place just enough to prevent leaking or spillage, move the caliper to the lowest point possible - put enough fluid in the MC reservoir to cover the bottom of the reservoir and wait for any air to escape naturally (if there is any air bubbles coming up into the reservoir, just add enough fluid to keep the bottom of the reservoir covered) - once all the air that wants to escape has, turn the caliper so the line port is at its highest (caliper at about 45 degree angle with the line port at the apex) - use the c-clamp to push the caliper piston into the caliper body (if it is not straight, you may have to re-position the clamp or use water pump pliers to push down on the high side of the piston) - as the piston is pushed slowly into the caliper body, the fluid in the caliper piston chamber will be pushed through the line to the MC reservoir - push slowly so air will be pushed ahead of the fluid - if the reservoir gets too full, sop out excess with a paper or cloth towel. When the piston is fully seated in the caliper & before removing the c-clamp, operate the MC to see if the system pressurizes - you might have to bleed the MC - turn the caliper so the piston is vertical - push on the foot pedal, hold it down, crack the line bolt to let air out, snug the bolt and let off the pedal - repeat a couple of times - if still not getting normal pressure, loosen the c-clamp about 1/2 inch - pump the pedal - the piston should move out about 1/16 inch - when you let off the pedal, the piston may retract about 1/32 inch - wait about 15 seconds between pedal pushes - when the piston is pushing against the c-clamp, hold the pedal down, tip the caliper so the line fitting is at the apex, loosen the line fitting just enough that fluid escapes and tighten - let off the foot pedal and wait about 15 seconds - press the pedal down & crack the banjo line bolt on the MC just enough that some fluid escapes - continue to hold the pedal down & tighten the c-clamp to force fluid and air out of the fitting then tighten the banjo bolt - let off the foot pedal and check operation - if necessary repeat all the steps - when all the air has been purged, pressing the brake pedal should spread the c-clamp about 1/8 to 1/4 inch and when the pressure is relieved the clamp should push the piston back.

Now remove the c clamp, install the brake pads and caliper - make sure the reservoir is filled to the upper line install the reservoir bladder and cap - pump the pedal until the brake is applied and had normal pressure. Hold pressure on the brake and crack the bleed screw just assure all air has been purged - tighten the bleed screw before letting off the pedal.

Not how much fluid is in the reservoir - this is an indication of how much wear there is on the pads - DO NOT TOP OFF THE RESERVOIR - when the brake pads are worn out, the fluid level in the reservoir will be below the lower line - when you install new pads, the fluid level return to normal when the piston is depressed - with new pads installed, the fluid level may be topped off if necessary - do not add fluid between pad changes unless the has been a leak or other problem.

Have fun - this job should keep you busy for several hours and depending on parts are needed and where you have to get them could stretch into a week of occupation.
 

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Discussion Starter #10
Here's the problem with just removing one line and capping the other hole (or leaving it open)

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Have fun - this job should keep you busy for several hours and depending on parts are needed and where you have to get them could stretch into a week of occupation.
Wow! You put some serious thought into that. Thanks. I see your point about not being able to just cap it. I haven't rebuilt one of the calipers yet, so I couldn't see how they're designed. I would definitely replace the caliper with a standard single bleeder one if possible or just run it factory built.
 

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Discussion Starter #11
I checked things out this weekend on the caliper and ended up ordering a new one. I replaced the broken bleeder (1/4x28 fine) and I couldn't bleed it. Sure enough, the seals must be bad. If you hold half pressure on the front lever or rear pedal and squeeze the other one you can feel them working against each other. That's the only way the brakes work at all right now. I have to pull the front and push the rear pedal.
I'll save separating the two for another day...
 

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Hawk, I looked seriously into separating the F/R brake systems when I first got my 06 800. I too, was a dirt biker since childhood and was used to having that RH front brake lever. I also was less than impressed with the effectiveness of the OEM foot brake. The dual chamber caliper and prone-to-fail little foot MC on the older machines is not very good even when working perfectly. I went so far as to research easily available parts, prices and how to go about doing do it.
Over time, I eventually decided against doing the mod, in part because of the time, effort and expense that would be involved but mainly because I eventually got used to how the OEM system operated. Heck, I even looked at installing a twist throttle when I first started riding atv's because my thumb was hurting so bad but I got used to that too. :grin
The OEM brakes are set up so the LH lever applies roughly 60/40 F/R braking like your car. The foot brake is actually referred to by Polaris as an "auxillary" brake. Just a helper brake or to hold the machine still while your hands are busy. Its not meant to be used as a primary means of stopping the machine. Once you get used to it, machines with a RH front brake lever such as Honda ATV's feel very awkward to use. Having to release the thumb throttle to grab the front brake if you want to get the machine stopped just feels weird after a while. And we all know that the cable operated rear drum brakes on a Honda suck lol!
If you really wanted to try it later, some Polaris machines like the 2004 X2's come with a RH front brake MC or there are other RH MC's that would probably work for the front brakes. That would leave the LH MC for the rears only. The 2008 Touring machines have dual single chamber rear calipers that could be used. Add a LH disc and the calipers and the necessary lines along with a junction for the foot brake and you'd have it. I think I had it all calculated at somewhere around $300-$350 and some garage time to complete the mod before I changed my mind.
Be sure to let us know if you try it.
 

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Discussion Starter #13
Hawk, I looked seriously into separating the F/R brake systems when I first got my 06 800. I too, was a dirt biker since childhood and was used to having that RH front brake lever. I also was less than impressed with the effectiveness of the OEM foot brake. The dual chamber caliper and prone-to-fail little foot MC on the older machines is not very good even when working perfectly. I went so far as to research easily available parts, prices and how to go about doing do it.
Over time, I eventually decided against doing the mod, in part because of the time, effort and expense that would be involved but mainly because I eventually got used to how the OEM system operated. Heck, I even looked at installing a twist throttle when I first started riding atv's because my thumb was hurting so bad but I got used to that too. :grin
The OEM brakes are set up so the LH lever applies roughly 60/40 F/R braking like your car. The foot brake is actually referred to by Polaris as an "auxillary" brake. Just a helper brake or to hold the machine still while your hands are busy. Its not meant to be used as a primary means of stopping the machine. Once you get used to it, machines with a RH front brake lever such as Honda ATV's feel very awkward to use. Having to release the thumb throttle to grab the front brake if you want to get the machine stopped just feels weird after a while. And we all know that the cable operated rear drum brakes on a Honda suck lol!
If you really wanted to try it later, some Polaris machines like the 2004 X2's come with a RH front brake MC or there are other RH MC's that would probably work for the front brakes. That would leave the LH MC for the rears only. The 2008 Touring machines have dual single chamber rear calipers that could be used. Add a LH disc and the calipers and the necessary lines along with a junction for the foot brake and you'd have it. I think I had it all calculated at somewhere around $300-$350 and some garage time to complete the mod before I changed my mind.
Be sure to let us know if you try it.
Definitely sounds familiar lol. I was thinking about the twist throttle too. I used to ride sleds in Mass and NH so I got used to the thumb throttle at least. This isn't a machine that I'll be ripping it up much on so I don't think the juice is going to be worth the squeeze in the end. It's mainly a yard work, exploring and hunting machine for me. Who knows though. If I end up doing it, I'll definitely post it.
 
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