Master Cylinder Bad, is this one rebuildable? - Polaris ATV Forum
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post #1 of 8 (permalink) Old 03-25-2010, 12:15 PM Thread Starter
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Master Cylinder Bad, is this one rebuildable?

Hello all, I just joined up after finding the site while looking for information for my ATV.

I have a 1994 Polaris 400L(liquid cooled) 2x4 that I'm getting back into shape after years of storage.

The master cylinder seems to be bad. I tore it down on the bench and depressing the piston pushes no fluid out the exit port.

After reading a few of the posts about non-rebuildable units I'm wondering if mine is one of them since I can't figure how to get the piston out with using a drift punch through the exit port. See the picture below.




I was pretty much thinking about replacing the whole unit if i can find a replacement. Can anyone tell me what I can replace it with? It has the screw in style brake hose not the banjo style brake line.

Also, if anyone knows of a parts house that has good pricing. I'm just starting the project and know I'm going to need other parts. At minimum a carburetor rebuild kit and a few other odds and end parts.

I'm also trying to find a online or downloadable service manual for it, if anyone can help with that it would be much appreciated.

*Picture Fixing
-blueline15

Last edited by blueline15; 03-25-2010 at 07:45 PM.
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post #2 of 8 (permalink) Old 03-25-2010, 04:05 PM
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this is the master cylinder on the handlebars?
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post #3 of 8 (permalink) Old 03-25-2010, 06:55 PM
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It depends on the condition if the chamber has deep metal scratch better to replace the whole accessory.
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post #4 of 8 (permalink) Old 03-27-2010, 05:42 PM Thread Starter
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Quote:
Originally Posted by elmerkit View Post
It depends on the condition if the chamber has deep metal scratch better to replace the whole accessory.
Yes, if I could figure out how to remove the piston. I had asked if the unit I have is one of the types that is "non-rebuildable". From what I was able to grasp from a few of the threads on the forum there are some that are not that fall into the same era mine was made.

Anyone able to answer yea or neh on this?
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post #5 of 8 (permalink) Old 03-27-2010, 06:01 PM
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yes, your MC is rebuildable. although there isnt really a kit to purchase, you can buy all the parts individually. and it looks like everything is still available from polaris too
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post #6 of 8 (permalink) Old 04-11-2010, 05:13 AM
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You can use a master cyl off alot of polaris quads and sleds. They used the same master cyl for alot of different applications. You will want to use your lever because the sleds have a shorter lever and its pretty hard to get the bike stopped with a short lever.
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post #7 of 8 (permalink) Old 04-22-2010, 06:05 PM Thread Starter
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Well I ordered parts to rebuild the one I had and received seals that don't fit the piston my unit has.

I've decided to just buy a whole replacement master cylinder. But don't want to buy the same unit due to the high cost. My unit uses a 1/8 NPT (pipe thread) line to connect to the master cylinder.

Can anyone tell me what will fit with the hose line I have (1/8" NPT)? Even If I have to use an adapter similar to this Auto Meter.

I've looked at these units. But they call out a connection that is a inverted double flair, like what you find on steel brake lines.
Wilwood Disc Brakes - Master Cylinders

Now... I don't mean to sound rude, but please if you answer be specific. I've spent weeks waiting for parts, looking for alternatives etc... My nerves are frayed trying to do what should be a simple fix.


And to spare anyone the pains I've already went through. The u-cup seal Polaris part#5410164 will NOT work if you have a 94-95 Polaris ATV master cylinder. the original part is 5410784 that superseded to 5410994. Both of which aren't made anymore. If anyone has NOS stock of those seals please let me know. I would like to buy one.
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post #8 of 8 (permalink) Old 04-23-2010, 04:17 PM Thread Starter
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UPDATE:

Well, after reading about a few people with the exact problem on various forums I decided to get a vacuum bleeder and try that. I bled the system twice until I couldn't extract anymore air. The brake now works, but is pretty spongy. It pulls almost to the handlebar but does apply some force to the brakes. I can still turn the rotors using hand strength but it requires some strength to do so.

Bench bleeding the master cylinder the brake was much firmer. I can only suspect part of the problem is the master cylinder and part of it is the rubber lines allowing expansion. If there is air left if the system it is trace amounts so I am assuming it isn't the larger issue.

So the question is, for those that have had experience with this master cylinder, is this spongy feel normal for this older unit? I ask because my newer 2000 era Polaris has excellent brake force with no spongy feel.
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