BN2 Master Cylinder

[mezy]

If you clamp the cylinders so they cannot expand and then check if it improves your pedal, if it does not then you're barking up the wrong tree.

 

[bighealeysource]

If you clamp the cylinders so they cannot expand and then check if it improves your pedal, if it does not then you're barking up the wrong tree.

So, clamp them closed with a C clamp and if the pedal does improve, then my problem could be with that cylinder ?

 

[mezy]

So, clamp them closed with a C clamp and if the pedal does improve, then my problem could be with that cylinder ?

correct bud, if you clamp both cylinders closed with c clamps and the pedal does not improve then the problem is not inside the drums.
then do the same with the front brakes.
You can replace both rear drums on the back, tighten the adjusters all the way solid, this will keep the rear cylinders closed while you test the fronts.

 

[bighealeysource]

Thanks Mezy, I'll try it tomorrow and report back !
Regards,
Mike

 

[bighealeysource]

Hey Mezy,
Can you do one side at a time on the rear brakes or do you need to do both at same time ? I've replaced both rear brake cylinders so if got a bad one could be either side. Same on front side, both at once or one at a time ?
Thanks,
Mike

 

[mezy]

Hey Mezy,
Can you do one side at a time on the rear brakes or do you need to do both at same time ? I've replaced both rear brake cylinders so if got a bad one could be either side. Same on front side, both at once or one at a time ?
Thanks,
Mike

Hi MIke, I realy dont think your problem is with the wheel cylinders, but you need to clamp them both so they cannot expand when you put your foot on the brake, I have a feeling the pedal will still need pumping, and if that is the case it will prove your cylinders are not at fault. or any other part of the rear brakes.
if you clamp only one of them, the other can still expand and give you a soft pedal, so clamp them both and try your pedal first.

 

[bighealeysource]

Hi MIke, I realy dont think your problem is with the wheel cylinders, but you need to clamp them both so they cannot expand when you put your foot on the brake, I have a feeling the pedal will still need pumping, and if that is the case it will prove your cylinders are not at fault. or any other part of the rear brakes.
if you clamp only one of them, the other can still expand and give you a soft pedal, so clamp them both and try your pedal first.

Thanks Mezy ! I'll let you and all who have been reading this saga know what I find out. BTW, what's your guess on the problem ???

 

[mezy]

Thanks Mezy ! I'll let you and all who have been reading this saga know what I find out. BTW, what's your guess on the problem

My guess is you still have air in the system somewhere, If you have a long vertical drop on a brake pipe usualy straight off the master
down to the chassis this is probably where the air is trapped, gentle bleading will not shift it, the bubble will move down and up when you pump the pedal. but just do the clamping thing first and take it from there.
If when all the cylinders are clamped you still need to pump the pedal, and if when pumped up the pedal will hold there and not creep
it cant be the master either, it can only be air.

 

[bighealeysource]

Interesting, fluid reservoir is remote on a BN2 and line from it to master cylinder is about 18 inches pretty much straight down ! I’ll try the wheel cylinders but wonder if I put pressure on the reservoir and broke that connection to MC could dislodge an air bubble ?

 

[mezy]

Interesting, fluid reservoir is remote on a BN2 and line from it to master cylinder is about 18 inches pretty much straight down ! I’ll try the wheel cylinders but wonder if I put pressure on the reservoir and broke that connection to MC could dislodge an air bubble ?

Air in the feed line from the reservoir will not give you a soft pedal and it will float its way up.
It will be somewhere in the brake lines.
Go through the system sytematicaly. Eliminate the cylinders by clamping them up and see if it makes a difference to the pedal.

 

[bighealeysource]

Air in the feed line from the reservoir will not give you a soft pedal and it will float its way up.
It will be somewhere in the brake lines.
Go through the system sytematicaly. Eliminate the cylinders by clamping them up and see if it makes a difference to the pedal.

That makes sense. I’ll start with the cylinders and proceed to hard brake lines

 

[bighealeysource]

Well, think I might have found the problem. Clamped down rear brakes and pedal did not improve. Clamped down front brakes
and pedal improved ! So checking out the cylinders and connections and have a very minor leak at left wheel cylinder on the left side.
Apparently not enough to show any fluid leakage when everything together, but enough that wet along edge of the rubber boot on
the cylinder and upon looking closely can see where the metal side of the shoe has evidence of past fluid leaking onto it ! So assuming this is where I am losing pressure and need to double pump. This an aftermarket cylinder, not sure who from but not a Girling. I have
a Girling from the right side that I replaced with a Moss cylinder so might try to rebuild the Girling to see if that works. Did close up the
right side front brake and left other side clamped and poor pedal.

 

[mezy]

Well, think I might have found the problem. Clamped down rear brakes and pedal did not improve. Clamped down front brakes
and pedal improved ! So checking out the cylinders and connections and have a very minor leak at left wheel cylinder on the left side.
Apparently not enough to show any fluid leakage when everything together, but enough that wet along edge of the rubber boot on
the cylinder and upon looking closely can see where the metal side of the shoe has evidence of past fluid leaking onto it ! So assuming this is where I am losing pressure and need to double pump. This an aftermarket cylinder, not sure who from but not a Girling. I have
a Girling from the right side that I replaced with a Moss cylinder so might try to rebuild the Girling to see if that works. Did close up the
right side front brake and left other side clamped and poor pedal.

nice one, now your getting somewhere, but i would replace wheel cylinder, i have never trusted resealing them. never seem to last

 

[kodpkd]

I am afraid a tiny little leak wouldn't cause the double pump issue. I don't even think, that small of leak would cause a spongy pedal. I do think you have limited it to the front. The double pump still should be the adjustment of the front.

 

[bighealeysource]

Hey Mezy and Kodpkd,
Well, changed out that wheel cylinder just to err on the side of caution and now have a weird situation when I adjust the front
brakes to have a slight drag. Come back a little later and wheel spins freely, like the adjustment went away ? My snail cam adjusters
are working properly and do engage the post on the back side of the brake shoe. Drum off you can clearly see the shoes move
with turning the snail adjusters. Same on both wheels or for right now, drums - wheels not on. So I tighten things up, come back
later and no longer tight. Any ideas on this one ?

These brakes are going to be the death of me. Feel like Chevy Chase from the Vacation movie going to Wally world - this is a ............................... quest - and going to keep trying to get it right.
Thanks,
Mike

 

[kodpkd]

When you adjust both adjusters tight and test the pedal, then come back and test the pedal again,,,, how does it feel? How many times can you keep tightening the adjusters and not lock the drums?
Are the shoes bending to take the arch of the drums?

 

[mezy]

When you adjust the brakes on the front leave the spanner on the nut pointing straight up. Where is it when you go back. If the spanner has moved. Adjusters are slipping

 

[bighealeysource]

When you adjust both adjusters tight and test the pedal, then come back and test the pedal again,,,, how does it feel? How many times can you keep tightening the adjusters and not lock the drums?
Are the shoes bending to take the arch of the drums?

Hey Kevin,
Shoes are good to the drum and haven't been changed in some time as probably drive it less than 2500 miles per year. I would say they are 10 years old. I'll try your idea above.
Thanks
Mike

 

[bighealeysource]

When you adjust the brakes on the front leave the spanner on the nut pointing straight up. Where is it when you go back. If the spanner has moved. Adjusters are slipping

Good idea, I'll see what is going on. I have not taken the snail cam adjusters apart, only lubricated, which may be the problem. Before I try the wrench idea, I will clean them off with brake cleaner.

 

[kodpkd]

OK,,,, I think you do have gremlins in the system.
Are the surfaces of the drums refinished and flat? Another thought, if there is a ridge on the inside edge of the drums, this might be messing things up.