[rogueelite]

Anyone ever try the gravity bleed method? I've heard that it works really well but I cant find much about it on the interwebs.

 

[twowheeladdict]

I picked up a vacuum device from Harbor Freight for just a few $. Does a great job changing out the brake fluid.

 

[rubix777]

gravity pulls the flush straight out, so I didn't use any special devices for my last brake flush.

 

[rogueelite]

I've heard that if you use gravity bleeding it doesn't remove all the brake fluid from the caliper like using a vacuum device and that there is a still a chance that air could be in the lines? I'm assuming that it would get rid of all the air just as well, because the air bubble will get pulled out with the fluid.

 

[rogueelite]

I picked up a vacuum device from Harbor Freight for just a few $. Does a great job changing out the brake fluid.

yeah im trying to avoid spending much money for brake jobs. what do you do with the vacuum just attach to the nipple and pull out all the fluid? Do you add fluid at the same time?

 

[Roadstergal]

"Gravity bleeding"? What's wrong with the good ol' pump-and-bleed? Even a shortie like me can reach the bleed screw and lever at the same time.

When I change out lines and there's a lot of air in the system, I inject brake fluid in at the bleed screw with a plastic syringe I got at OSH, then bleed it fully the conventional way.

 

[BugMeNot1]

As long as you're simply trying to flush the brake fluid, you want to avoid air entering the lines and calipers. So yes, keep adding fresh fluid to the resorvoir while draining at the calipers; no matter if gravity, vacuum or pump'n'bleed is your choice.
Can't imagine any of the three will make a significant difference in how efficiently/quickly the old fluid is being replaced...

 

[rogueelite]

As long as you're simply trying to flush the brake fluid, you want to avoid air entering the lines and calipers. So yes, keep adding fresh fluid to the resorvoir while draining at the calipers; no matter if gravity, vacuum or pump'n'bleed is your choice.
Can't imagine any of the three will make a significant difference in how efficiently/quickly the old fluid is being replaced...

Well... I got essentially blasted on another forum for suggesting it as a method. so I was just checking here, where people are slightly more reasonable in their reasoning and opinions.

 

[Roadstergal]

If you're talking about tying the lever and opening the bleed screw, it's an unreliable method; the fluid can take a while to get moving, and once it does, it comes out fast, and you can end up with a dry system. Pump 'n bleed ensures the pressure is always going the right way and that the amount is always in your control; plus, it's fast and requires no special tools, which I like.

Again, for large air pockets, like when I put on new lines, I find that injecting in from the bleed screw is the quickest and most controlled way to fill those pockets with fluid. You just have to make sure that the reservoir is open and not over-full (since you'll be pushing air and some fluid into it), and that you start the pressure before you open the screw and only relieve the pressure once it's closed. Then top off the reservoir and bleed conventionally.

 

[rogueelite]

If you're talking about tying the lever and opening the bleed screw, it's an unreliable method; the fluid can take a while to get moving, and once it does, it comes out fast, and you can end up with a dry system. Pump 'n bleed ensures the pressure is always going the right way and that the amount is always in your control; plus, it's fast and requires no special tools, which I like.

Again, for large air pockets, like when I put on new lines, I find that injecting in from the bleed screw is the quickest and most controlled way to fill those pockets with fluid. You just have to make sure that the reservoir is open and not over-full (since you'll be pushing air and some fluid into it), and that you start the pressure before you open the screw and only relieve the pressure once it's closed. Then top off the reservoir and bleed conventionally.

when I did a gravity bleed I didn't even move the lever. I just opened the cap to the master cylinder and unscrew the bleed nipple to get a steady flow and then I fill as fluid drains out. Once its all clear I put my thumb over the nipple and pull off the hose then tighten the nipple so fluid cant come out. Then I pull the lever as hard as I can and hold it while I put the cap back on the master cylinder. Does that sound okay or do you see any problems with that method? Last time I changed my fluid it lasted over 6000 miles before getting brownish as it was before I changed it.

 

[JonF]

I use the gravity method but before I remove the master cylinder cap I open the bleeder screw with a piece of vacuum hose on it with the free end in a container. Make sure your bike and paint is protected in case any fluid tries to come out the vent in the master cylinder. Then I start by squeezing the caliper pistons back in to expell fluid from the calipers. Then I remove the master cylinder cap and keeping an eye on the fluid level I gravity bleed the lines. Once the fluid is clear I close the bleeder, nearly fill the master cylinder, and slowly pumnp the lever untill the pads meet the rotor and the lever is firm. You will need to keep adding fluid. Dont let it run dry! If the fluid has been neglected any moisture will have collected in the calipers. So I would repeat the whole process to expel as much nastiness from the calipers as possible.

As with any work you do on your bike make sure everything is tightened and everything is functional before you go back on the street!

 

[electjohn]

Gravity system works just fine, it just takes a little longer is all.

 

[JustAJ]

For normal bleeding I just do the normal pump and release. Over and done in less than 10 minutes. When installing a new line, I use the vacuum. If you've got the time to do it that way, then good on ya. As long as your brakes work at the end, who cares how you got there? Really.