Installed two pot calipers on my OBS and while i was bleeding the system i ran the MC dry....twice, goober. "suck, suck"....OH CRAP.

 

I tried bleeding the front brakes and it doesn't seem like I'm getting all the air out. So I probably need to bleed the entire system now.

 

Sequence is?:

FR - RL - FL - RR

 

How does ABS affect this process? I bled a ton of fluid out the fronts and still no dice. I'll do it again tomorrow and bleed the rears as well this time.

I've always done it in order of distance from the master: RR, LR, RF, LF.

 

If you suspect air in the ABS, bleed that first.

If you suspect air in the ABS, bleed that first.

that's a special process? hmm...didn't know that!?

Not all that special. . . Take a look at it and you will see bleed screws on it as well. I would just bleed that first so as to be sure that all of the air was out of the system "north" of it.

I couldn't find the ABS unit bleeding directions in the FSM, but sounds simple enough. There's more than one screw?

thanks for the help gnuman. good to see you around more lately!

You may even have to start bleeding at the mc. Crack the lines and have someone push the pedal to the floor, tighten the lines, then let off the pedal. Repeat until you don't get anymore air out of the mc.

See these:

http://endwrench.com/images/pdfs/BrakeFluidSumm02.pdf

http://endwrench.com/images/pdfs/BrakeSystemWin01.pdf

sequence control? that's ridiculous - it doesn't even tell you why that insane amount of tinkering is necessary.

 

i still can't find anywhere that says how to bleed the ABS unit itself.

and what's all this talk about "secondary blah blah blah first"...why not just TELL ME. spit it out you goobs?!? tell me the bleed order, don't talk about it.

 

i'm starting to hate ABS even more than i do in the winter!

sequence control? that's ridiculous - it doesn't even tell you why that insane amount of tinkering is necessary.

 

i still can't find anywhere that says how to bleed the ABS unit itself.

and what's all this talk about "secondary blah blah blah first"...why not just TELL ME. spit it out you goobs?!? tell me the bleed order, don't talk about it.

The info is there, Gary, just not as nicely presented as it could be.

 

For the bleeding order, see the diagram labeled "Brake fluid replacement sequence" in either of the End Wrench PDFs. (The order shown is: front right, rear left, front left, rear right.)

 

Before doing the ABS sequencing, check for a sufficiently hard pedal. If it's okay, find a place you can safely verify the ABS operation (gravel road?), and then recheck for a hard enough pedal. If it's still okay, you're done.

 

If the pedal remains spongy, there might be air trapped in the ABS hydraulic control unit. The ABS HCU sequencing is done to open and close valves in it and "agitate" the fluid a bit to free the air. Once it's sequenced, you'd need to rebleed at the wheels.

 

By the way, the reason some procedures have you do the ABS sequencing before bleeding is in the hope that you'd only have to bleed the system once.

 

i'm starting to hate ABS even more than i do in the winter!

I can't help you with that.

If you have trouble bleeding, a sneak-attack trick that sometimes works is to loosen the MC cover, loosen the bleeder of choice (usually furthest one) and just walk away and do a slow gravity flush. Let that bleeder run for awhile, then close it and go to the next furthest one, and repeat...

 

Keep the MC topped off to ensure the most head pressure.

 

Dave

Well I properly bled the system today and the brakes are still spongy. Better but spongy, still really bad. Didnt' really see any air coming out of the lines though?

 

If I pump the brakes it stops noticeably better, much better. Is that a sign of MC failure or bubbles still?

 

That makes sense now about sequencing the hydraulic unit. The article should say that if a rocket scientist can't figure it out on first glance. I tried cracking the lines on it since there's no actual bleed screw for it, but that's obvious not how to do it.

on the ABS unit - Nipper says they're a pass through design and shouldn't require bleeding or hold air?

 

but of course i saw the endwrench article.

Gary,

 

Why don't you pressure bleed the system? You can build your own rig if need be using an old cap to a master cylinder, a bottle, some hoses, a source of compressed air (which could even be a tire.) Works great.

 

 

Nathan

i have compressed air, but i'm going to go ahead and buy a unit to do that pressure bleeding. dave PM'ed me about one and said they're great.

 

they're that much better i suppose? for $50 i can't go wrong if it'll be easier to do myself.

Is this a Mighty Vac that you are looking at?

Is this a Mighty Vac that you are looking at?

dave said something about a "Motive" product, but i haven't looked or ordered yet. i know there's a few out there. i think they're on ebay.

Pressure bleeding is the way to go. I usually do the farthest slave cylinder first and the nearest last.

 

As far a checking the condition of the master cylinder- just depress the peddle to 3/4 travel with the engine off. If you feel the pedal gradually sink further with the same leg force, the M/C is bad. If it stays put, it's probably air in the system.