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Front drum brakes - fluid lines

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P

PHulst

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While inspecting parts of the car yesterday I looked at the front brake lines. What I noticed is that the current (previous owner installed) layout or direction of flow doesn't seem logical.

Currently the soft hose enters the bottom of the first wheel cylinder, and a hard line then goes from the upper port to the second wheel cylinder. It enters this in the top port, and the bleeder is on the bottom.
Is this correct, or should the hard line enter the bottom port of the second cylinder and then the upper one be used as the bleeder? Just wondering, as it seems using the lower to bleed the system would make it difficult to remove all of the trapped air, if present. I Googled pictures of AH brakes, and they seem to agree with my second description, not the actual layout I see on the car.

Thanks for your assistance again.

Patrick
 
Bleeder on the bottom side of cyclinder - this was the setup on my BN6 before converting to disc brakes:
FrontDrumPipe.JPG
 
Interesting. That's how the car is currently set up, at least with respect to the second cylinder.

How can you be sure to get out the air? That would seem to me to be a bit of a challenge.
 
PHulst said:
Excellent! I knew there was a reason I needed a rotisserie!
Now if you could call my wife and explain it to her...
Click to expand...
Plug the vent hole in the reservoir cap, or you'll have to start all over...

BN6L/942's been swapped to 3000 discs since about 1987, so I really couldn't imagine what the layout was, but I know I had bled the front drums in the years leading up to that. I do recall the "2nd" cylinder in the circuit had a tiny, tiny ball behind the bleed screw__I expect that most have been long lost by now__that may have facilitated bleeding that unconventional arrangement.
 
steveg said:
When you attach a clear hose to the bleed screw and depress the brake pedal, you can see the air bubbles move downhill into the jar. They just need a little push.
Click to expand...
Which is when I suspect the check-ball in the bleeder orifice comes into play; as the pedal is lifted, the ball prevents the air in the tube from re-entering the cylinder, in preparation for another stroke of the pedal.

If the check-ball is missing, closing the path by tightening the screw should accomplish the same thing.

Should the fluid not flow out the 2nd cylinder, a closer inspection to verify that the check-ball hasn't been OVER TIGHTENED and jammed into the fluid port is warranted.

As the memory returns: I can remember on one side of my car (or maybe another 100 or 100/6 I worked on?) not being able to get the fluid to flow out the bleed screw(s), so simply loosening the steel tube fittings will also allow the air to be purged out. On a fresh rebuild, with mostly empty circuits, bleeding the 1st cylinder by cracking open the steel tube fitting will expel the bulk of the air, rather than trying to get it all out from the lowest point in the circuit__the bleed screw.

A manual bleeder that forces fluid back to the master cylinder would seem to render the point moot.
 
Yes, I'm quite familiar with brake bleeding. Doing so on a C3 Corvette and getting a firm pedal can be quite the chore.

Anyone ever adapt a Motive pressure bleeder to work on a Healey? I have in mind a way to try, but if someone already has done it with success I'd like to know.
 
That is set up exactly the same as my BN2. Nothing fancy needed to bleed other than a clear tube that reaches the bottom of a bottle that already has enough fluid in it to submerge end of tube. Just pump the pedal til air bubbles stop and you're done. No need to close bleeder between pumps. Do check level in reservoir every so often.
 
The previous owner tried for years to get a good pedal on this car, and currently only the right front brake works. So, the brake system will be the focus of some effort on this car.
I've read several years worth of "difficult to get a firm pedal" threads on this board, and wanted to be sure that the brake lines weren't a part of the problem.
 
For what it's worth, I have 30+ years in the auto repair world. I have bled hundreds of cars using the same method above. I am extremely picky about the brakes in my Healey and I settle for nothing less than a rock solid pedal. Just replaced all my front brake hydraulics early this year and bled them as described. End result was a rock solid pedal.

By the way, having one brake that doesn't work is more likely a blockage in a line or frozen wheel cylinders, although having both go bad on one side would be a bit unusual.
 
My suspicion is that he has the brakes adjusted improperly. Both close scrutiny of the adjustments as well as a good bleeding are part of the plan.
I also have the braided lines on order from Moss.
 
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