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Discussion Starter #1
I have proven to myself that there is no air in my brake lines. I have a 1986 TRX200SX. I got it used. It is possible the MC and teh brake cylinders are not original to the quad. My cylinders were frozen up and I HEARD that I could use cylinders from a 2013 Recon. SO I bought them. They fit OK with some modification. The hand brake goes to the handlebar, and you can't lock up the front wheels even on gravel. So, I put two C-clamps directly on the wheel cylinders, just enough to hold them in. The hand brake is hard and only goes back an inch or so. So, we know the system is completely air free.

What I noticed is that my MC has an OT cast into it. ONE of my cylinders had OT cast into it as well. So, are the casting numbers and marks meaningful? Is it possible that my MC and cylinders are not matched and something about the new wheel cylinders requires more travel to activate the brakes, which my MC cannot achieve? Even with the adjusters locked up, there is still a ton of travel in the brake handle.
 

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Master cylinders are matched to their respective slave cylinders. Dirt bikes only operate one slave cylinder where as four wheelers operate 2 to 4 slave cylinders (depending on the brand) However I think you should be getting better feel than this especially since it was replaced with one from a similar machine.
 

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I'd try and source a good second hand MC from a larger machine and try it out. I bet a pound to a dollar you'll get a good lever
 
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Discussion Starter #4 (Edited)
But even that doesnt make complete sense. I have the adjusters LOCKED TO THE DRUM. I've locked up the front drums when testing. So that means the TOP of the pads should be touching the drum too. And after you pump it, ANY movement of that cylinder should immediately firm up. It just isn't adding up. Something is up.

If I have C-clamped the cylinders closed, and I get a decent hand brake feel, then that means:

MC is good
Hoses are good
No internal leaks on wheel cylinders


It essentially clears all malfunctions of the system.

SO how in the hell can it not work?


One thing that I find odd is that my cylinders will retract when the hand brake is released when they are disconnected from everything. There are no springs pushing the cylinders back in. I did not think they should do that. They should push OUT and stay OUT....at least on a car, that's why you have to compress the cylinder before you can get anything apart. Even if you open the adjusters on the BOTTOM so far out that they lock, the TOP of the brake is still a FAR way away from teh drum, because the cylinders retract completely.


The springs on my TRX200SX and the ones for the Recon are completely different. The fourtrax uses two different springs, the recon uses two of the same.....neither of the part number sets are interchangeable. Could that be it? Brake cylinders should NOT retract. They should simply relax. The shoes always 'drag' lightly on the drum. That's the whole point.
 

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Have you tried checking your part numbers against part numbers from a TRX250A at all? Both ATV's are from the same era and may well share many parts.
 

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Discussion Starter #6
Brake cylinders are different numbers, MC is a different number, springs are a different number.

Pads, adjusters are the same.

Like I said....I'm wondering if springs are teh issue. If they are TOO STRONG, then they will simply push the cylinder back in as you release the handle. Which means you will always have teh FULL distance to travel, no matter how tight your bottom adjusters are. The top will ALWAYS start from cylinders that are completely compressed. If I understand correctly, you should pump the handle, so the brakes expand, touch the drum, and the cylinder remain in the extended position, when you release the handle, the pressure is gone, but the pad should touch or lightly touch the drum. Then the MC has retracted and refilled its cylinder with fluid....at that point, all you are doing is applying a little pressure.

I should be able to test this theory by removing the top springs and re-installing everything.
 

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Discussion Starter #7
That theory did not help.

Im just going to have to accept the fact that this quad won't lock the front wheels even if yanked back to the handle bars and rely on the rear brakes for the heavy stopping. Nothing I can do any longer. Maybe the drums are actually out of spec but my micrometer can't measure it around the lip as well as I thought it could. Either way, drums aren't available, so it is what it is.

Im still not a fan of how the cylinders will retract. I dont think they should do that. But they do, and the MC cups are brand new, and it holds when clamped near it so....


I got nothing guys. I don't think a new MC will solve this problem. I have no idea how that could matter. The other guy that used these is having no issue.
 

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That's a more modern MC but yes it will fit. If you want one to fit the era of your machine it would be trx250a, trx300, trx350D Etc
 

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Discussion Starter #10 (Edited)
I was thinking I should get the MC that goes with the machine that calls for the wheel cylinders I got.

I'm looking at the parts for the Recon TRX250TM. This is the model I have my cylinders from. The brake shoes are different, the brake panel is different. And on the trx250, the pads, with a different number, are oriented upside down from what the trx200sx are. Why would this be? I have both IPL's open, and the two sets of pads are flipped. I dont know if the 250 pads will work in my 200 or not.

Also, Mine has two different colored springs. Online, other people's 200sx brake panels have pads upside down, right side up, springs are flipped either way....does it matter?
 

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... Brake cylinders should NOT retract. They should simply relax. The shoes always 'drag' lightly on the drum. That's the whole point.
This explains the normal behavior of a disc brake system... not a drum brake system. Huge difference!

The disc brake caliper piston will stay put after pressure is released allowing pads to drag lightly, because it has a square cut piston seal on it that only allows the caliper piston to return.... only as far as the square cut seal has stretched from its relaxed position due to its grip on the piston. The square cut seal design provides for that behavior.

A drum brake system has a cup shaped piston seal on the inner end of the piston. This design provides a seal for pushing the piston only. A cup designed seal cannot pull that piston back... it will suck air in around the cup long before it will be able to exert a pull on the piston.

To make a cupped piston return, requires a spring or other force... pushing on the piston. That is why drum brakes must have return springs.
 

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Also, maybe its these cheap ass pads I bought? I see some made by EPI and EBC and they look CONSIDERABLY thicker at the top. They are TAPERED to the bottom. The one's I have are the same thickness all the way around.
If the brake shoes' radius (they are NOT pads, they are shoes) don't match the brake drum diameter nothing will make the brakes work... Different friction material thicknesses or differing design (leading + trailing shoe or leading + leading shoe) matter little... UNLESS you put a trailing shoe in the leading shoe location on the backer plate, which on your machine means the trailing shoe goes toward the rear of the vehicle. I doubt you have that issue though (a leading + trailing design installed wrong) unless you bought chinese made brake shoes... they are dumber than rocks!

EDIT:
If you have thicker friction material at one end of the shoe tapering off in thickness toward the opposite end of the shoe.... you got useless china made garbage that will never work in any application. Period.

You got two front brake threads going for the same machine and the same issue...
 

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Discussion Starter #13
OK. According to your explanation, the brakes are operating as they should be. My cheap chinese pads do have the same thickness pad all the way around and they match the diameter of the drum perfectly.

One thing I did not account for is that the pads have not bedded yet. Even after several miles of riding, there are clear areas on the pad that are not contacting the drum yet. Maybe 50% of the pad at the most is actually touching....you can see spots where they are contacting and clean spots where they are not. I'm going to leave it alone for now. It's as good as its going to get. There is no air in the system, and they at least stop some.
 

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At least they work a little, just remember they're drum brakes, they'll never stop you on a dime.
 

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Discussion Starter #15
Yep. The handle feel is better than it was. I'm going to ride it, and keep adjusting the brakes to touch the drum, but still be able to roll to speed up the bedding process. After they seat, it should be pretty obvious.
 
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