bleeding brake lines

Brenan225 · Post by **Brenan225** » Mon Mar 27, 2006 7:49 pm

I am about to install a braided steel line for my front brakes and was wondering if anyone had any tips on the procedure for bleeding the line.

I can never remember if you should squeeze the lever and then open the valve or open the valve and then squeeze the lever all while trying to keep the resevoir full etc etc......

Shibby! · Post by **Shibby!** » Mon Mar 27, 2006 8:36 pm

Your trying to put brake fluid through the line. The brake lever is connected to a piston type cylinder pump. Squeeze while the valve is open, close the valve, slowly release the lever and keep an eye on fluid level so it doesn't bottom out and suck air in the line.

Continue till the fluid coming out of the valve is clear and free of all air.

Use a rubber hose stretched over the nipple to see if air is in the fluid.

cedric · Post by **cedric** » Mon Mar 27, 2006 9:17 pm

Sounds different than the way I've always done it. I would pump up the lever, then hold it down/on. While still holding it, release the valve for a split second till the lever drops all the way. Immediately close the valve. Repeat this process a few times and you should be done. If you are worried about air bubbles (if it feels squishy/spongy), you can force the caliper piston in, forcing the fluid (and the bubbles in it) up to the reservoir, then pump the lever enough to bring the piston back into position. The air bubbles should now be on the top of your fluid in the reservoir.

I know there are more fancy/efficient ways of doing this, but this automotive type method requires no special tools and has always worked for me. Flame away...

Post by **Rackman** » Mon Mar 27, 2006 9:32 pm

Check out this site, Someone on the forumn directed me to it an it was of use to me. My brakes are spongy and I am going to give this a go. I was told that there can be pockets of air that can hide and that bench bleeding will solve this.

http://www.john-stichnoth.com/BackBleed.html

Hope this helps,
Jamie

Post by **dirtyboy** » Mon Mar 27, 2006 10:02 pm

cedric wrote:you can force the caliper piston in, forcing the fluid (and the bubbles in it) up to the reservoir, then pump the lever enough to bring the piston back into position.

First time I'm heard of this technique but it makes perfect sense to me. I gotta try it sometime.

The addition would be to take the lever off the bar and raise it up if you have a brake line with a big curve in it at the top like a WR or XCW. That way the bubble can't hide at the top of the curve.

Nice one cedric.

Jamie, that's an interesting site too. Back bleeding.

Post by **fryguy** » Tue Mar 28, 2006 8:15 am

Often the trouble with normal bleeding procedures is that you are pushing air down and thats not its natural behavior. Some auto stores should ahve them too, but Vet clinics have all sorts of disposable syringes. When you ask, be prepared for the grill, in the city they don't like to sell them, ie drug use. Its a simple procedure, fill the syringe with fluid, use a hose to attach it to the caliper. Bleed the air out of the line so you don't push more air into the brakes. Now simply squeeze fluid up into the brake system. Using this technique 'pushes' the air with it. Its messy, but I always find a mess is always easier to clean up than trying to drink enough to calm my nerves.... not that a beer or two is a bad thing, ...oh you know.

As well, pushing your caliper through does work wonders. You can get that extra life out of your fluid. It will get spongy more often indicating that your fluid is pooched.

fry

WR_Dave · Post by **WR_Dave** » Tue Mar 28, 2006 4:39 pm

You can get the huge syringes at UFA. I use them for setting the fork oil level. I've never had any problem getting them there. WR Dave.

Post by **Dakota_c69** » Tue Mar 28, 2006 6:44 pm

Setting the fork oil level...sure!! Dave, You're such a junkie!!!

Glenn.

Post by **dirtyboy** » Tue Mar 28, 2006 7:14 pm

Dakota_c69 wrote:Setting the fork oil level...sure!! Dave, You're such a junkie!!!

Glenn.

Isn't you talking about junkies, the same as me talking about guns at the airport? Just doesn't seem right.

WR_Dave · Post by **WR_Dave** » Tue Mar 28, 2006 10:02 pm

Junky !!!! Is that some sort of KTM rider talk,,,bashing the bike choice of us lowly Blue bike riders???? Careful Glenn, there's no need to go all ENFORCEMENT on us, remember, I have a ransom item of yours $$$$$$. WR Dave

Post by **Dakota_c69** » Wed Mar 29, 2006 5:07 pm

Oh Yeah, right!! Forgot about that! Dave...No Dave isn't a junkie! He's a junkie for perfomance and he feeds his habit with Yamaha Power! He's really nice too!

Glenn.

DIRTTV · Post by **DIRTTV** » Fri Mar 31, 2006 6:20 pm

some of the F1 teams that run brembo brakes use the reverse bleed method. The only thing they do different is hang the calipers from the ceiling overnight so all bubbles that are left rise to the top. On steel braided brake lines they tap them with wrenches for five to ten minutes to un attach any bubbles that may be present. Bubbles like to stick to rough surfaces.

buggo · Post by **buggo** » Sat Apr 01, 2006 12:53 pm

An old trick we used on "British" cars / landrovers (they where notorious for bad brakes)
Was to drill and tap a old master cylinder cap, apply a bit of pressure. Or leave it overnight with a vacuum applied if it was stubborn. Worked well.
I typically use the reverse syringe method, and tap all your compoents.
Something to remember though, you should slightly move your master cylinder piston off its rested position, pull in the lever with a zip ty

.

TrialsPaul · Post by **TrialsPaul** » Mon Apr 03, 2006 7:30 am

Here is another good reference for brake/clutch bleeding.

www.shercousa.com/content2.cfm?action=9
(shercousa website, select service info, select service manual & other info)

now click on "Sherco Brake and Clutch System Bleeding Manual"

The manual include the gravity method, pressure method, and the syringe method. It goes through each of the procedures step by step.

Brenan225 · Post by **Brenan225** » Mon Apr 03, 2006 11:14 am

That's great! just what I needed - pictures!

Thank you