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Discussion Starter #1
I may have two separate unrelated issues, but they may also be connected, I'm not sure....

Got the new handlebar master cylinder/lever on, it was moving the front caliper pistons when they were off the bike, no resistance, y'know. But now that all new pads are in both front calipers, it won't build up any pressure.

Both front calipers are bled and the fluid level drops when I crack the bleeders, so I believe it's moving fluid, it just doesn't ever give any feedback, it always sinks straight to the handgrip.

I can crack the bleeder on the rear master cylinder and shoot brake fluid out of it by squeezing the lever, but working alone, it's kinda hard to see what the front calipers are doing if I do the same.

Now- the rear caliper was removed, and the line blocked off, and that's fine by me, it appears the rear master cylinder is shot, it doesn't move any fluid by the brake pedal, the rear reservoir level never drops, and the brake light switch is stuck on, if that helps clarify anything.

Question I've got, is knowing the lever will move fluid at least through the rear master cylinder, why won't it pump up the front calipers? Is it because the rear master cylinder is, what? bypassing internally? There are no external leaks anywhere.
 

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Get a cheap universal windshield washer pump and use it to push your fluid from the brake fluid container through the caliper up to master
start with the rear brake
Reverse bleed the system
Master cylinders are a d^ck to bleed sometimes
 

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If it was a truck youre working on my automatic first thought would be master cylinder...

Im just not familiar enough with this system to say a bad rear master would affect the front like this.

More coffee is needed...
 

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Not saying you didnt get all the air out of the system but bluenozers reverse bleed suggestion is always relevant on the tough ones.

I have large syringes and clear tubing for just such an occasion.

Never thought of this but...genius.
Hands free and less mess.

Couple of comments you might not have tried that caught my eye that have also worked in the past...
98189

98190


Im sure you'll get it.
Im still betting on rear mc...following for outcome.

Good luck
 

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Discussion Starter #8
Can you remove the line from the rear master, plug it, and pump up the front?

Eliminating the rear system altogether.
I'd like to do just that, but I wouldn't mind retaining the brake light operation. Gotta figure out how to do that..
 

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Discussion Starter #9
Not saying you didnt get all the air out of the system but bluenozers reverse bleed suggestion is always relevant on the tough ones.

I have large syringes and clear tubing for just such an occasion.

Never thought of this but...genius.
Hands free and less mess.

Couple of comments you might not have tried that caught my eye that have also worked in the past...
View attachment 98189
View attachment 98190

Im sure you'll get it.
Im still betting on rear mc...following for outcome.

Good luck
I'm really getting to the point where I'm ready to stop throwing money at this thing tho :rolleyes: but those are solid ideas, can't hurt to try

U still have air...

Sent from my SM-G950W using Tapatalk
That wouldn't surprise me, but I'm out of brake fluid for now, lol. I'm still just scratching my head as to how I can push fluid through the rear MC using the handlebar lever, but not ever get any pressure anywhere in the system.

Any thoughts as to why/how the brake light switch is stuck on? Rear MC maybe seized/stuck, in "brake" mode? Is that even possible? The brake light switch appears to be a hydro/electric combination....pressure must move a plunger, maybe? that grounds the brake light circuit?
 

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Pretty sure when u use the hand brake it uses the fluid from the rear for the rear brake... iv always had great luck with just cracking the bleeder and let gravity do its job...

Sent from my SM-G950W using Tapatalk
 

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Here's what I would do .
1 disconnect the longest front brake line .
2 make sure M/C is full
3 hold the end of the line high and slowly squeeze lever until it's all fluid , reattach.
4 disconnect other front line and repeat .
Then re bleed both fronts .
 

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Discussion Starter #12
Yeah I gotta hit up the parts store, grab some more Dot4.

Now that my little helper is back, and can give me a hand on the levers and the bleeders, I'll get back on it and get it sorted.

I wonder if I could relocate my rear MC brake light switch, to the handlebar lever MC, to retain the brake light function, while blocking off the rear MC essentially removing it from the system..... :unsure::unsure::unsure:
 

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Discussion Starter #13
Pretty sure when u use the hand brake it uses the fluid from the rear for the rear brake... iv always had great luck with just cracking the bleeder and let gravity do its job...

Sent from my SM-G950W using Tapatalk
FWIW, my rear reservoir never dropped level at all, the pedal did nothing. I'm almost certain the rear MC is either seized or bypassing internally, tho the seized angle lends more credence to why the brake light is stuck on.

When I hit the lever, its reservoir level dropped accordingly, never anything from the rear
 

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while blocking off the rear MC essentially removing it from the system..... :unsure::unsure::unsure:
Thats all I meant, for diagnosis.
Until you throw a rebuild kit into the rear master.

Seems to me like the hand lever is basically another input like the foot lever moving fluid thru the whole system including the rear master.

There 2 vids I found, guy had the same issue but he never said if he fixed it completely.
Just that he had a siezed rear caliper, replaced that and running with spongy brakes was the last comment I saw.

Once bled properly movin on...

Glad you have your helper back.
Much easier with two people.

Unless its one of my brothers,,,,
Once I get pressure I turn my helper loose and my new helper is a black bungie on the hand lever and a weight on the foot lever.

These kids nowadays...no patience haha
 

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Discussion Starter #16
Yeah lol, my clone was at a friends house, and I didn't really intend to get as far into it as I did (isn't that how it always works?)

But yeah, I think I can remove the brake switch banjo bolt and use it for the lever line connection. That should retain the brake light feature. I'd just block the brake line leading to the rear MC entirely, that should seal the system and restore my front brakes.

Guessing I'd still want to purge all the air out of that length of line, huh. Dang I was just at wally world, too, forgot to grab a turkey baster :rolleyes:

I'm just not at all interested in replacing the rear MC, seeing as how the rear caliper is awol anyway. There's just no sense in throwing money at this aspect of the bike, imo.
 

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Just grab the one out of the kitchen drawer lol
Im sure the wife wont mind.

Whatever your into.
Thatll work.
Super steep chit here. Id throw a rebuild in the mc and a caliper on it, but I could see how it wouldnt be a priority for flat ground mudding.

Its not like its a mc and the fronts gonna wash out on you.

With everything else you have going on I get it.
You can always throw a rebuild in the mc and a caliper on it later if you decide not to keep it.
 

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I may have two separate unrelated issues, but they may also be connected, I'm not sure....

Got the new handlebar master cylinder/lever on, it was moving the front caliper pistons when they were off the bike, no resistance, y'know. But now that all new pads are in both front calipers, it won't build up any pressure.

Both front calipers are bled and the fluid level drops when I crack the bleeders, so I believe it's moving fluid, it just doesn't ever give any feedback, it always sinks straight to the handgrip.

I can crack the bleeder on the rear master cylinder and shoot brake fluid out of it by squeezing the lever, but working alone, it's kinda hard to see what the front calipers are doing if I do the same.

Now- the rear caliper was removed, and the line blocked off, and that's fine by me, it appears the rear master cylinder is shot, it doesn't move any fluid by the brake pedal, the rear reservoir level never drops, and the brake light switch is stuck on, if that helps clarify anything.

Question I've got, is knowing the lever will move fluid at least through the rear master cylinder, why won't it pump up the front calipers? Is it because the rear master cylinder is, what? bypassing internally? There are no external leaks anywhere.
Not an expert but could there still be possibly an air pocket still
 

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Discussion Starter #20
Yeah that's quite possible, I picked up a big ole jug of Dot4 the other day, I'll spend some time on it this weekend and hopefully sort it all out. I liked that washer pump idea, ain't but like $18 at the parts house, might grab one and throw it in the mix
 
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