• There has been a recent cluster of spammers accessing BARFer accounts and posting spam. To safeguard your account, please consider changing your password. It would be even better to take the additional step of enabling 2 Factor Authentication (2FA) on your BARF account. Read more here.

Bleeding brakes. MC vs. Caliper order?

jraice

jraice

New member
Joined
Aug 19, 2008
Location
Los Gatos, CA
Moto(s)
2009 Buell XB12Ss
Name
Jordan
It makes sense to bleed the caliper first because air rises, but if the MC has air trapped in it and the caliper bleeder valve is open I could see air filled fluid getting pushed from the MC down the lines.

I did a bit of google searching and didn't find too much but saw one person say to do the caliper, then leave the lever pulled overnight (to make the air bubbles as small as possible, I had heard of this technique but never the explanation, makes sense) and finish the process with a MC bleed.

So what do you do?
 
i'd bleed the MC before i install it onto the bike. it's a lot easier that way. did you drain the entire system or suspect air in the MC?
 
How do you bleed the MC before installing it onto the bike?

I haven't done any of the work yet just trying to figure it all out. I bought a radial MC for my Buell.

Any advice on how to do the swap would be great, do I just empty the stock MC reservoir and pump a bit of fluid to empty out the top of the brake line, then swap MC's and bleed?
 
My general attitude is that brake fluid is cheap and air bubbles are not. Besides, a good line flush is probably due. Anyways when I put radials on mine I just went back and forth a couple times after filling and pumping to get it started. MC then caliper then MC then caliper... until no more air bubbles and nice clean fluid. This is KISS and suits me fine. Your going to love the radial. They rock.
 
JimE said:
My general attitude is that brake fluid is cheap and air bubbles are not. Besides, a good line flush is probably due. Anyways when I put radials on mine I just went back and forth a couple times after filling and pumping to get it started. MC then caliper then MC then caliper... until no more air bubbles and nice clean fluid. This is KISS and suits me fine. Your going to love the radial. They rock.
Click to expand...

Yeah I am really excited to try it out. My brakes have been the weak link bike wise at the track, and even a bit on the street.

I usually have a ton of brake fluid go to waste anyways (I never reuse bottles) so I guess I'll do the same.
 
jraice said:
Yeah I am really excited to try it out. My brakes have been the weak link bike wise at the track, and even a bit on the street.

I usually have a ton of brake fluid go to waste anyways (I never reuse bottles) so I guess I'll do the same.
Click to expand...

I rotate through all the bleeders several times but finish with the mc, thats the way I was taught. +1 on fluid is cheap. I just used the like 1 liter bottle of the castrol fluid on a dry rebuilt front brake system and rear flush yesterday.
 
jraice said:
How do you bleed the MC before installing it onto the bike?

I haven't done any of the work yet just trying to figure it all out. I bought a radial MC for my Buell.

Any advice on how to do the swap would be great, do I just empty the stock MC reservoir and pump a bit of fluid to empty out the top of the brake line, then swap MC's and bleed?
Click to expand...

it's called bench bleeding... i couldnt find a decent DIY, but here:
http://autorepair.about.com/od/fixityourself/ss/MC_bench-bleed.htm
 
Might try that if I have trouble getting things to bleed.

So what is the best way to do the swap? How much fluid do I need to drain from the system etc...
 
I'm going to paste something that was posted over on the GSXR forum. I tried it and it *does* work, teflon tape and all.

Fail proof bleeding. ........... TRUST ME

Get some teflon tape.
Get some clear aquarium hose.
Get a catch bottle for the fluid
Get a wrench to fit bleeders (8mm on most)
Get a phillips screw driver to remove reservoir lid
Get a NEW UNOPENED BOTTLE of QUALITY brake fluid. IMPORTANT!!.
Only takes one person

Put tape on the threads of the bleeders, being careful not to get it so low on the bleeders as to get under them. The teflon tape is important to keep air from seeping past the threads on the bleeders and into the system, as well as keeping the bleeder in place while you pump the lever.

Forget the "Pump pump pump, crack.... close... repeat" method. It sucks.

Attach the hose to the bleeders. Run that hose to a catch bottle well above the nipple you are bleeding, so you keep a column of fluid in the hose on top of the bleeder. This column of fluid in the hose on top of the nipples is very important to keep air from going back in the system

Crack the master cylinder bleeder, just enough that you still have some pressure on the lever as you pull it, but fluid is coming out of it also. pump until you get clean clear fluid out of the MC bleeder. I usually run one entire reservoir of fluid through the bleeder. Re-fill reservoir and move to lower right caliper.

Tap lines lightly with something.

Crack bleeder on lower right caliper (with teflon tape on it) again just enough that fluid will pass out of it, but there is some effort at the lever. Run an entire reservoir through it. Close bleeder.

Tap on lines again.

Repeat with left caliper.

Repeat at all three bleeders, (meaning do this TWICE at EACH bleeder) using about one full reservoir at each bleeder.

Remove all hoses and catch bottles. Clean up and ride.

Trust me, you will thank me later. Assuming you dont have a mechanical issue, you will now have the most firm lever you have ever felt in your life.

Some people argue going through that much fluid is "a waste". Truth is once a bottle of fluid is opened it is garbage anyway. So with that said, might as well run it through the system to flush out old fluid and bubbles before you throw the bottle away. Once it is opened it has started absorbing water from the atmosphere and is GARBAGE.
Click to expand...
 
Very similar to the youtube link but thanks!

I have a speed bleeder on the caliper, perhaps I'll order one for the master.
 
^ can you attach a picture of the teflon tape + threads + hose thing that's mentioned in that post? i'm having a hard time visualizing what it's supposed to look like
 
Teflon tape is put onto the threads so that air bubbles don't go back into the system via the threads. The tube is just put over the nipple normally.

I'd buy this over teflon tape.

http://speedbleeder.zoovy.com/product/THREADSEALANT/Sealant.html

Or better yet spend $7 per nipple and just buy the speed bleeders. They come with enough of the sealant on them for several uses and they will make your bleeding ten times easier. You simply open the nipple and pump the lever until the fluid is clean. No tighten/loosen routine or worrying about how well the tube seals on the nipple (probably not well) because the only way air can get in thanks to the one way valve is through the threads.
 
Last time I suggested teflon tape on the bleeders on this board I was chastised by the purists for introducing "contaminants" into the braking system. :rolleyes

Speed bleeders are cool but if you run through bikes quickly it's not really worth the hassle of ordering them.. and they only really seem useful when you can't reach the bleeder and pump the brakes easily (meaning a car), on a bike it's so easy to bleed the brakes without special bleeders I don't worry about it.

I just use a mityvac with teflon tape or paste (choose your poison) and I can get a super firm lever in about 5 to ten minutes. I always start with the left caliper, then right, then master cyl. Usually do each twice and it's good.
 
Last edited:
aram said:
Last time I suggested teflon tape on the bleeders on this board I was chastised by the purists for introducing "contaminants" into the braking system. :rolleyes

I just use a mityvac with teflon tape or paste (choose your poison) and I can get a super firm lever in about 5 to ten minutes. I always start with the left caliper, then right, then master cyl. Usually do each twice and it's good.
Click to expand...

Opposite order from what I have seen others doing but it sounds like if I do them both twice (Buell single caliper setup) it shouldn't matter. My order just went through for a second speed bleeder so it should be a quick process. I have a mity-vac hiding in the garage somewhere should I need it.

I have always used speed bleeders and been pretty thorough with my bleeds (lever is always good and firm) but have never bled the MC (OEM one didn't have a bleeder), or done the pump/squeeze release method before.
 
jraice said:
Opposite order from what I have seen others doing but it sounds like if I do them both twice (Buell single caliper setup) it shouldn't matter. My order just went through for a second speed bleeder so it should be a quick process. I have a mity-vac hiding in the garage somewhere should I need it.

I have always used speed bleeders and been pretty thorough with my bleeds (lever is always good and firm) but have never bled the MC (OEM one didn't have a bleeder), or done the pump/squeeze release method before.
Click to expand...

It's just a throwback from the old bleed the furthest from the master thing first on cars. Probably doesn't matter if you do it 2 or 3 times. I think you are over-thinking the master cyl bleeder thing. Just think of it as something that makes your bleeding a whole lot easier. :ride
 
Makes sense.

So any advice for how to make the swap? I was thinking empty the OEM reservoir, pump the lever a few times (drain the top of the brake line) then remove OEM MC and install replacement, then bleed.
 
jraice said:
Makes sense.

So any advice for how to make the swap? I was thinking empty the OEM reservoir, pump the lever a few times (drain the top of the brake line) then remove OEM MC and install replacement, then bleed.
Click to expand...


Sounds good to me. Maybe it's bad but I just pull it apart without doing anything. I usually just pull the lines off away from the bike so I don't get any brake fluid on anything.

I also keep a spray bottle of water or soapy water around in case I do spill any fluid to keep it from destroying paint or other surfaces.
 
I don't bother with the tape. I use a mity vac and keep pressure on the bleeder while I close it. That gives me super firm lever every time, and it takes about five minutes to bleed.
 
You must log in or register to reply here.
Back
Top