bleeding brakes

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ir3333

ir3333

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..has anybody had trouble bleeding Kelsy Hayes 4 piston discs?
those transfer tubes are higher than the bleeders?
remove calipers and gravity bleed?
 
If the bleeders are on the bottom they need to be swapped side to side. Bleeders up, always.
 
The bleeder is after the cross over tube so any air would be pushed through the caliper just like it is throughout the complete system.
 

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ntsqd said:
If the bleeders are on the bottom they need to be swapped side to side. Bleeders up, always.
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in the stock position the transfer tubes are a little higher than the bleeders.
just wondering if they are a little harder to bleed out.Gravity might not be enough?
 
ir3333 said:
..............Gravity...............
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I've said this before and stick by it

I do NOT believe in "vacuum" or "gravity" bleeding.

I believe in PRESSURE bleeding, either by pressurizing the system or by simple two- person "pump the pedal." Keep positive pressure on the system at all times. Bleed with pressure, and close the bleeder before the pedal stroke "runs out" of pressure, thus preventing "suckage"
 
If you've got a high spot that can't be eliminated then odds are that gravity won't work. Some vehicles gravity bleed perfectly, others are a pain no matter what you use.

I use a glass peanut butter jar, some 1/8" copper tube, and a roll of vacuum hose.
IMG_0984.jpg

Short hose is long enough to reach the bleeder while the jar is sitting on the ground. Long hose is long enough to reach a vacuum nipple on the intake manifold. Short hose is connected to a piece of copper tubing epoxied into the lid that nearly reaches the bottom of the jar and definitely below the fluid level in the jar. Long hose is connected to a short piece of copper tubing epoxied into the lid that does not extend very far down into the jar.

Remove bleed nipples, coat threads with brake system assembly lube, and re-install. Make hose connections & start engine. Crack nipple open and hold until no bubbles or enough volume to cause you to check the reservoir fluid level.
 
^^^ and this is eXACTly what I'm against. This puts NEGATIVE pressure on the system. If you have something restrictive in line from the master to the wheel cylinders, and this includes the master residual valves, the prop valve, metering valves, or even a little 'gum' in the warning switch, this vaccum may very well pull air PAST THE CUPS in the wheel cylinders.
 
I'm OK with your being against it. I think you're over-thinking this, it's been working just fine for me for about a decade, but I'm not going to force anyone to use this method. I recently noticed that rust let the epoxy loose, so a new peanut butter jar is needed.

Even with assembly lube in the bleeder threads it still will pull air past them if there is a serious problem upstream somewhere.
FWIW there is no such thing as "negative pressure". There is only pressure and the absence or partial absence of it. So the all-out absolute most lack of pressure that can be applied to the system is zero psi, down from the atmospheric 14.7 psi. Not like we can get a couple hundred psi on this thing. Assuming that the average car idles at 15" of Mercury that translates into being 7.4 psi. Not a lot of pressure possible.

Is pulling air past the wheel cylinder cups so horrible? My time in designing racing disc brake stuff never exposed me to drums.

FWIW I didn't use this method on my Valiant after putting new SS hoses on it and assembling the AR brackets with wilwood DynaPro's on the OE rotors. The engine wasn't running then and the system gravity bled almost perfectly.
 
I've worked at an OEM brake place for years.

We use the pump up/open bleeder, floor, then close bleeder pressure bleeding technique. They do have the vacuum bleeder (a store bought one) and they may use that with a nearly empty system to save time, but we have ALWAYS pressure bled for the final part. Use clear tubing and bleed until you no longer see bubbles coming out.
 
I used that same peanut butter jar to pressure bleed after gravity bleeding. Can see the bubbles in the fluid in the jar. With fluid in the jar can just slowly pump the pedal with a cracked bleeder and not suck air back in up the up-stroke. Not good for final bleeding, but good for refills or flushing prior to final pressure bleeding.
 
ntsqd said:
FWIW there is no such thing as "negative pressure". ................Is pulling air past the wheel cylinder cups so horrible? .
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"Negative pressure" might be slang but it IS a term that is used. What I mean is you are generating a VACUUM as opposed to atmospheric pressure.

Is pulling air past the cups bad? Why would it NOT be bad. You are trying to get RID of air and if you are pulling it INTO the cylinders..............I...........just...........don't..........get how this could be what you want

As an old guy "I know what works" I never heard of vacuum bleeders or gravity bleeding until a few years ago. There seems to be a number of folks on here who have trouble bleeding brakes.

I'm going to guess that all this "came along" about the time that plastic master cylinders did---which cannot be easily pressure bled.
 
LOL, a hose all the way to the bottom of a pop can still works for a 1 man show, I don't know why y'all are getting fancy for these cars.
 
Wasn't implying that pulling air in past the cylinder seals was a good thing, just not sure that it's bad beyond now having more air to get out of the system.

I don't use pressure bleeders and won't allow their use on my own stuff, even when available. The reason is simple and has little to do with pressure bleeding itself. It has to do with the brake fluid in the unit. How long has it been out of the bottle absorbing atmospheric moisture? I'm not going to guess or take a chance. I want the fluid going in to have the highest boiling point possible, and that isn't going to happen with fluid coming out of a pressure bleeder.
 
67Dart273 said:
I've said this before and stick by it

I do NOT believe in "vacuum" or "gravity" bleeding.

I believe in PRESSURE bleeding, either by pressurizing the system or by simple two- person "pump the pedal." Keep positive pressure on the system at all times. Bleed with pressure, and close the bleeder before the pedal stroke "runs out" of pressure, thus preventing "suckage"
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THIS...Non a.b.s. systems.Anything else,follow the F.S.M.....
 
Abodybomber said:
THIS...Non a.b.s. systems.Anything else,follow the F.S.M.....
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Not for me, for reasons stated above.

Don't mess with ABS, nor have any intention of doing so. I kill it on any vehicle of mine. Vehicles that I'm likely to buy with it will be useless off of pavement, which is where I'm going with vehicles likely to have it.
 
ntsqd said:
Wasn't implying that pulling air in past the cylinder seals was a good thing, just not sure that it's bad beyond now having more air to get out of the system..
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Ya know when I used to drive up into Mom and Dad's house I did NOT come driving in through the back woods, which is what you are arguing here. If pulling air in "is not good," then it "must be bad" Air is either good or bad, in this case bad. So don't get this twisted around in some sort of alternative logic.

ntsqd said:
I don't use pressure bleeders and won't allow their use on my own stuff, even when available. The reason is simple and has little to do with pressure bleeding itself. It has to do with the brake fluid in the unit. How long has it been out of the bottle absorbing atmospheric moisture? I'm not going to guess or take a chance. I want the fluid going in to have the highest boiling point possible, and that isn't going to happen with fluid coming out of a pressure bleeder.
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There is NO reason to assume that just because you are pressure bleeding a system you are using contaminated fluid. Bleeding by pumping the pedal IS pressure bleeding. What, you have a 55 gallon pressure bleeder? I sure as hell don't. Mine holds about a quart of fluid


This is quickly getting to be the silliest argument I've seen lately. I have a suggestion. Go ahead. Get out the vacuum pump. Pull a Great Big vacuum on YOUR system if that's what makes you happy. Hell I've got at least two pumps sitting here from my HVAC /R days. I sure as hell don't use 'em on brake systems.
 
I'm not twisting anything. I was wondering if there was something beyond what I thought that you were implying about allowing air to be pulled into the system. Turns out that there wasn't but I'm open to learning from anywhere.

I don't own a pressure bleeder, therefor I have no idea how long the fluid it has been exposed to air and absorbing atmospheric moisture. When I'm working on brakes I want that new fluid to start out with the highest possible boiling point, so it is always from a new, sealed container. The pumping method is what I ALWAYS finish bleeding with, no matter how I mostly filled the system.
 
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