I have an '06 rubicon with about 2,000 miles on it. It recently flipped once at low speed. After fixing everything, I still have one issue: front brakes intermittenly disappear. I tried bleeding them as I thought maybe some air got in there. I cracked each side about 4 times to bleed out the air.

The brake lever is nice and stiff, then when I ride for a short bit or move it, the brake lever goes all the way to the handlebar, and i have no front brakes. It's quite scary for rides. I'm always tapping it to see where I stand.

I NEVER seen or heard of master cylinder issues with these. Mine seems way too new. I'm not losing any fluid from the resevoir, and I don't see any leaks anywhere. When the brakes work, they're great. When the lever goes down, it's like they're dead.

Do I maybe have debris in the system that needs to be flushed? Fluid looks clean. The master cylinder has a good scrape/gouge in it from the flip over. Is this related somehow? (the dealer thinks it is). The dealer also thinks it must be a caliper problem, because they don't ever have problems with the master cylinder. I'm highly doubting it's got anything to do with the calipers.

Your expert advice would be appreciated.

 

what do the drums look like? or does this have disc on the front?

 

they are discs on the front. they seem fine. I can't see even a severely warped disc causing the brake lever to sink to the handlebar and not work at all.

 

You may have to dissassemble the brake system and bleed the master cylinder first, then the rest of the lines and calipers. While replacing the brake line on a freinds skidoo the master cylinder ran dry and caused a similar problem. after bleeding the tiny air bubbles out of the master cylinder first then reattaching the lines, and bleeding them (being very careful not to run the MC dry) the problem was cured.

 

how do you bleed the MC first? I thought you pump lever, hold it down, and release air though bleeder screw on caliper. MAYBE the MC took on some air in the roll over??it was upside down for several seconds before it got righted.

 

Yes, there is air trapped in the master cylinder. Blead it a few times by loosening the bolt that holds the brake line to the master cylinder. Blead it like you would a bleeder on a caliper. Break the bolt loose, hold the lever, tighten the bolt and release the lever. Repeat until no air is noted coming from the brake line where you loosen the bolt.
I suggest a grease rag below the line to keep brake fluid off the bodywork

----- Gimpster -----

 

great, thanks, I'll try that. why wouldn't that air in the MC push out to the caliper?

also, do i need to bleed both calipers again after that?

 

1. I dont know why it doesnt push through, I think it floats back up in between pumping the brake and loosening the bleeder on the caliper.

2. Yes you will have to bleed the brakes at the calipers again.

 

THANKS...a little brake fluid to fix this frustrating problem is no big deal!! ANd I'll post if this fixes it, so hopefully someone else can learn from my frustration.

 

well, we tried bleeding the master cylinder about 4 times, then bled both calipers 3-4 times each. Same problem, BUT, we did find that jerking the handlebars back and forth seems to make the brake lever collapse. It's way more noticeable when we turn hard to the left. Checked the brake lines and there are no obvious pinches or wet spots or leaks. The master cyclinder piston seems to slide in and out okay.

The only part of the brake line that actually moves when you crank the brakes back and forth is the last 3-4" where it goes into the caliper.

Could the calipers be the problem? What would i check for?