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Discussion Starter #1
The spring inside my 1995 Magnum 425 master brake cylinder that attaches to the piston broke in half and Polaris no longer makes that part (7041311). I haven't been able to find one anywhere online either. Is it possible to use a master cylinder from a later ATV in place of the obsolete one? There is no connection (electrical or otherwise) to the cylinder other than the brake line. I would rather adapt to a newer style that I can find parts for than buy another used part that may be worn out or broken. Any help would be appreciated.

Note: I did buy a replacement washer kit for it recently when it stopped working (this was how I found the broken spring) so I already had that installed before I realized I couldn't buy a new spring.
 

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Can you find a spring at a hardware store that is close to the broken one and make it work? What are rough dimensions of the broken spring?
 

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You didn't include which master cylinder...handlebar or foot brake. 2X4 or 4X4 shouldn't make a difference. I looked up the handlebar unit. The Polaris cross reference shows that master cylinder was only used from 94-96...The spring was used on snowmobiles 98 and 99. But that only references the part number. If there was a change to the master cylinder, no matter how minor, the part number would change.

They should all operate the same. The handlebar units on both my '01 and '04 machines look identical. The '07 just has a different reservoir style. My opinion is that you could take a master cylinder from a later machine and put in on without a problem. As long as the handlebar size is the same and you have the same overall braking system. All brakes operate with the handlebar master and just the rear from the foot brake.
 

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Discussion Starter #4
It is the main one on the left side of the handlebar and it's just the usual 7/8 inch handlebar size like the original. Any of the later master brake cylinders should fit the bar. I was just making sure that the pressure would be appropriate (not too much to lock it up or too little to not have stopping power) to operate the brakes safely.

I took the rear brake apart and replaced the seals, piston, and pads. It will work with the foot pedal (it manually presses the piston) but there is no pressure to the piston (via brake fluid pressure) without the master cylinder working.

I also ordered a set of 100 various sizes compression springs to try to match the old one. It was approximately .5 OD and 1.5 inches long. The set had a .48 and a .52 OD that should hopefully work. If I can't make the spring work I will try a different main brake cylinder setup and see if it works (at very low speed). I will keep everyone posted and take some pics later. Thanks for the suggestions and
 

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Discussion Starter #5
Here are a few pics of the replacement spring and how it fits. It compresses to the same size in the cylinder as the old one and has close to the same compression poundage. Hopefully it will work when I get it all back together.
 

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Don't know if this post is still active, but thought I would ask if the replacement spring worked? Mine is also broke.
Also does anyone have a real picture of a 1996 Magnum 425 master cylinder piston assembly?
Mine was in pieces when I got it and I want to make sure I assemble it correctly.
Thanks, Scott
 

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I wish I had now, I’m already $25 into the kit.
Might need to eat the $25 and go the other route.
Thanks for the reply.
 
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