Brake Master Cylinder

[bighealeysource]

Quick question/s - just finished replacing the brake wheel cylinders on my 56 100M and did an initial bleed using a pressure bleeder. Did not get good
results even though I got a good seal on the power bleeder plastic cap to the brake reservoir. No apparent leaks from brake master cylinder and it was
replaced about 15 years ago. I will admit I did not check it when system under 15 pounds of pressure so if I do not see any fluid leaks should I
assume it is okay ?

Also, any recommendations on using the power bleeder ( Motive brand) on a 100 ? I have read about everything out there from past postings but
could not find one specifically about using a Motive pressure bleeder.

Thanks,
Mike

 

[kodpkd]

I have the Motive pressure bleeder and love it. The directions say to put brake fluid in the tank. This can make a big mess. When you remove the cap the reservoir will be over full. I normally don't put fluid in the tank. I am very careful to not let the reservoir run dry. That being said when you bleed the clutch on the AH, there is so little fluid in the clutch, it will run dry very easily. I do put fluid in the tank when I bleed the clutch. I use 10 lbs.
If the bleeder cap doesn't seal, I use the rubber seal from the reservoir lid to help seal it.

 

[kodpkd]

I also had issues getting a solid pedal after installing a new MC. I had to do the double pump on the pedal to get it solid. I tried the Motive bleeder, pedal method, tilt the car trick, still had to do the double pump.
I installed new semi-metallic pads. During that install, I opened the bleeder screws to push the pistons back and noticed a few air bubbles. I am not 100% sure but it seems like I have a solid pedal now. I am still breaking in the new pads.

 

[prb51]

Having the same pedal issue on my 100-6,,,I am doing the Motive thing and get no air coming out of the lines but still a pedal to the floor. I replaced the master cylinder. If I pump it up solid...then let it sit for a bit and back down.
The 'double pump' is what...multiple little pumps while you bleed the fronts?
This is still with drums up front and the goofy layout of the one slave higher than the other.

I am going to try a Phoenix pressure bleeder that forces fluid up from the bleed nipple. See how that goes.

 

[kodpkd]

The "double pump" is when you have to pump the pedal more than once to get it hard. You might try opening the bleeders while forcing the cylinders at the wheels full closed to push the fluid out the bleeders.

 

[prb51]

Thanks.... this is the most bass akward system I've ever seen on a brake system (drums) designed by idiots. If I let the system sit for a bit it takes multiple pumps to get pressure but nothing but fluid comes out of the lines...no air.
If the reverse pressure deal does not work I'll remove the pads and put C clamps on the depressed wheel cylinders.

 

[kodpkd]

May the force be with you Luke. I have disc brakes in the front and it isn't much better. I think there are two cylinders on a each wheel, I would do both at the same time. Reverse bleeding might work. If you look how the two cylinders are hooked together, if you use reverse bleeding you are pushing the air bubbles up.

 

[mezy]

What i have found with bleeding brakes in the past, if you are having trouble getting the air out of the system,
collapse the wheel cylinder pistons closed. collapse the caliper pistons and clamp them in.
Then bleed the brakes as normal, this stop air getting trapped in the cylinders and calipers.

 

[bighealeysource]

Thanks.... this is the most bass akward system I've ever seen on a brake system (drums) designed by idiots. If I let the system sit for a bit it takes multiple pumps to get pressure but nothing but fluid comes out of the lines...no air.
If the reverse pressure deal does not work I'll remove the pads and put C clamps on the depressed wheel cylinders.

I would agree about the design !!! Had a BN6 and same issues trying to get those brakes bled properly as with my BN2/100M. But going to take some of the suggestions from everyone that replied-much appreciated - and see if I can get a good pedal on it.

 

[prb51]

Misery loves company....will try the reverse here today or tomorrow. One plus, def new fluid!.

I was surprised to hear the disc front style can have similar problems.... I thought that conversion fixed that.

 

[Legal Bill]

Healeys can be tough to bleed. I only use the two person pump and hold method. If I have a third person available, I station them at the reservoir. If I am bleeding after a major hydraulics overhaul with new cylinders, master, booster, brake lines or calipers, I bleed at ever pipe union. I use rags below and to wrap under the Union to protect painted surfaces. I bleed each junction just like a bleeder screw.
Also, I adjust the brake shoes until they are tight against the drums and can’t be tightened any further and then back the adjuster off one click.

 

[prb51]

Bill I may have to go that route.... what a pita.

 

[Bob_Spidell]

I'm not sure it makes a huge difference--I usually forget to do it--but when installing a new or repaired M/C 'bench bleeding' is recommended. It should, in theory at least, make the initial bleeding a little easier and use less BF.

 

[BobHaskell]

I guess that I've been lucky using Gunson's Eezibleed to bleed the brakes on our tri-carb.

 

[kodpkd]

I guess that I've been lucky using Gunson's Eezibleed to bleed the brakes on our tri-carb.

That's a cool bleeder, basically the same reservoir pressure bleeder as the Motive.

 

[prb51]

well, the reverse bleed did not work either altho it did fill the master reservoir so 'was working'. Same result.....pedal to the floor and no leaks.
So, will take off the drums and depress the wheel cylinders/foot pump and if that does not work replace the master again and start all over.

I know some of the master cylinders have been known to be bad out of the box....all I could find were the 3/4 bore Moss one (made by whom) and will now try the 5/8th one. No one has the TRW for the 100-6 or early BN7 unless someone knows of a source.

 

[kodpkd]

I would just hook the Motive up to the MC,,,, 10 psi,,,, squeeze the cylinders and watch for air. I wouldn't pump the pedal at first.
When you push the pedal the MC rod, closes of fluid and pressure from the reservoir.

 

[prb51]

Heck, I'll try anything and that is doable... tonight I'm putting chicken bones under the car. Try some Voodoo

 

[kodpkd]

Like Mezy said, If you can hold both cylinders closed at the same time, bleeding would be good with the Motive or with pushing the pedal. Just make sure the pressure isn't released when the bleeder is open.

 

[red57]

prb51,
There are probably other sources but here is a link to Pegasus Racing supplies - these are more expensive but are Genuine Girling, not some off shore unknown manufacturer using unknown materials like most sources sell. They have both the remote reservoir and integral reservoir versions in several bore sizes. > Girling Remote Reservoir Master Cylinder - Pegasus Auto Racing Supplies <