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Brake Bleed Screws

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K

Klepper

Senior Member
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I am in the process of putting new flex hoses on my brakes. I ordered the new hoses, and also ordered brake bleed screws as well. I received my package today, but the bleed screws look quite different than the one I took out of the car. I took one out of a front wheel on my BN6, and the bottom of the screw is flat with a small "dimple". The new ones I received have a tapered bottom, but the threads appear identical. Would the rear bleed screws be different?Are there different bleed screws on different cars? The Moss website shows the same part number for all drum brake bleed screws.

Can I use the new ones I got?
 
[ QUOTE ]
...I took one out of a front wheel on my BN6, and the bottom of the screw is flat with a small "dimple". The new ones I received have a tapered bottom...

[/ QUOTE ]

60 hours w/o a response -- maybe others are as mystified as I am.

I recognize the replacement part as a common or garden variety bleed screw. The one you removed is outside my experience and from the description I can't even imagine how it would work.

Is there any chance the tip has broken off the one you removed?
 
I'll make a guess,
The Healey Hundreds had a ball bearing under the bleed screw that pinched down on a seat in the wheel cylinder. Your car may very well have the same arrangement. If so, you should remove the ball bearings from the cylinder inlet hole before trying the new screws. Hopefully, the new screws will seat in the old ball bearing seats. For that matter, if your old screws are usable, stay with the old ball system. It sort of makes a one way bleed screw arrangement if the screw is only opened a little bit. Kind of handy, actually.
D
 
Did the 100's just have this arrangement on the front, or on all 4 wheels?

My two front bleed screws are near unusable. I just barely got them loosened using the vice-grip method. "If" I could get them tightened up, I am sure in 2 years time there would be no way to get them loose.

If I wanted to keep the ball bearings in, does anyone see any reason why I couldn't just grind the new bleed screws flat to match the old ones?
 
[ QUOTE ]
..."If" I could get them tightened up, I am sure in 2 years time there would be no way to get them loose...

[/ QUOTE ]

FWIW -- I routinely use teflon tape on bleed screws (cutting the tape lengthwise to make it narrow). Mainly this simplifies bleeding as you do not get air leaking back in around the threads while pumping, but it also makes it unlikely those guys will seize up.

That said -- if it took vise-grips to remove them then you probably don't want that chewed up thing staring at you everytime you look there.

Interesting thought on the ball-bearing -- I'm out of my element on that one other than to say that if it is in there it might be coaxed out with a slim magnetized screwdriver.

There are replacement check-valve type bleeders but those are a modern design and would require everything be out of the bleed hole (if in fact there is anything else there).
 
If the thread fits -try them. Either they will bleed and not leak, bleed and leak, not bleed and not leak.

If they bleed and not leak that should be OK.
 
Took me a while to figure out what you were describing, however, I now remember the types of bleed screw you are talking about. The seal is made by the flat edge of the taper, not the point (or lack of). If your origonals had a 'dimple' then I would grind off a similar amount so that you guarentee that the seal is made on the edge, rather than the point jamming into the hole. To check where the seal is being made, tighten a new bleed screw, remeove it, and check for scoring on the edges. If the seal is being made solely on the tip, then you may want to take some of that off, although I believe that there should be enough clearance. To my knowlege, there were no ball bearings in there (nor have I ever seen them on a Brit brake system).
 
[ QUOTE ]
Did the 100's just have this arrangement on the front, or on all 4 wheels?

My two front bleed screws are near unusable. I just barely got them loosened using the vice-grip method. "If" I could get them tightened up, I am sure in 2 years time there would be no way to get them loose.

If I wanted to keep the ball bearings in, does anyone see any reason why I couldn't just grind the new bleed screws flat to match the old ones?

[/ QUOTE ]
As you originally said,
"and the bottom of the screw is flat with a small "dimple"."
I think you also need the small dimple to help keep the ball centered.
The Teflon tape will prevent future freezing. They were found on the back & front brakes.
--------------------
Bob,
"To my knowlege, there were no ball bearings in there (nor have I ever seen them on a Brit brake system)."

Believe me, they do exist on the early big Healeys & work very well.
---------------------
Whether the new screws will seal to the original bottom dimple, ball removed, is a matter of trial & error. See what works. The last word would come from Doug Reid of 18G motorworks spannerman@prodigy.net
Contact him.
D
 
Dave - just goes to show we can always learn somthing. Was it a steel ball or what? I know that when I was in the UK and ordered bleed screws there were 2 kinds, one with a point and one with the 'dimple' but I never came acress any balls! If you know what I mean! /ubbthreads/images/graemlins/nonono.gif
 
Just a small free floating steel ball, maybe 1/8" diameter. Sometimes they stay in the wheel cylinder when the bleed screw is removed, sometimes they drop out, roll to unknown places & are never noticed. One of the most interesting things that I ran across was that the balls somehow ended up in the inlet hose fitting end of the cylinder & effectively shut off all fluid flow into the cylinder.
D
 
I just wanted to let everyone know that the the new brake bleed screws (tapered kind) worked fine in my brakes. I simply removed the ball bearings from the cylinders and screwed in the new tappered screws. They tightened up and sealed without a problem. I have been driving with them for a couple of weeks now and all is well.
 
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