[boboftherockies]

I just put a new Moser rear end assy in my 69 and had to put new hard lines in from the distribution block at the top of the pumpkin out to the point where they connect to the SS flex lines. It's rear disc.

Everything connected fine and after doing a few leak checks, which uncovered 2 minor leaks: one at the dist block and one of the connections to the flex lines, I fixed the leaks and pressure bled the entire system - all four corners. Lines run clean with no bubbles. Pedal holds firm with the engine off. No visible leaks at any connections.

When I start the engine and press on the brake pedal, it goes to the floor and doesn't pump up until I stop the engine. Then it pumps up again and stays up. I didn't touch the master cylinder in the work I did on the rear end. It's a near new MC and booster that has been working great for several years.

What am I missing? Could the flex line with the distribution block have gone bad in all the moving around? It's not showing any leaks

Thanks
Bob

 

[Everett#2390]

Did the brakes work before the swap? If I read your post, the system did work before.
Engine off, can you pedal bleed all four corners? You should be able to do this.
With engine running, can you pedal bleed any corner?

 

[Steptoe]

When I start the engine and press on the brake pedal, it goes to the floor and doesn't pump up until I stop the engine. Then it pumps up again and stays up.

Now w2hat do u mean "goes top the floor" ?
It is normal for the brakes to be very hard with the engine off...and with the engine on, the pedal to drop a bit and be a little 'spongee'
The brake pedal should still be higher... slightly , than the accerator pedal....IF the accerator pedal is correct height and the brake pedal is in the right hole.

 

[boboftherockies]

Everett;

Yup. Brakes were fine before the swap and, with the engine off I can bleed all 4 corners. Haven't tried it with the engine on. Should I try that?

Bob

 

[boboftherockies]

Now w2hat do u mean "goes top the floor" ?
It is normal for the brakes to be very hard with the engine off...and with the engine on, the pedal to drop a bit and be a little 'spongee'
The brake pedal should still be higher... slightly , than the accerator pedal....IF the accerator pedal is correct height and the brake pedal is in the right hole.

With the engine off, the pedal is at the top of it's travel and can only be depressed an inch or so. When the engine is on and you press the brake pedal, it compresses to the bottom of it's travel and pumping it does not bring it up significantly.

Bob

 

[Steptoe]

With the engine off, the pedal is at the top of it's travel and can only be depressed an inch or so.

Normal

When the engine is on and you press the brake pedal, it compresses to the bottom of it's travel and pumping it does not bring it up significantly

Right down to the floor....?
Now that is a weird one....if brakes are hard no vac, no fade, then should all be ok...
u havent touched the pedals, booster or mc right?
Checked that all wheels spin free... no drag.? asnd pads do lock up when applied?
Have u tried clamping off individual wheels? and/or just fronts then rears?

Bleeding engine on or off makes no difference.

 

[400bird]

How hard are you pushing the pedal with the engine off?

 

[boboftherockies]

Normal
Right down to the floor....?
Now that is a weird one....if brakes are hard no vac, no fade, then should all be ok...
u havent touched the pedals, booster or mc right?
Checked that all wheels spin free... no drag.? asnd pads do lock up when applied?
Have u tried clamping off individual wheels? and/or just fronts then rears?

Bleeding engine on or off makes no difference.

I'll do some checking on the things you mention this weekend. I haven't touched the MC or booster and all the wheels spin without drag. I need to check on the other things

Bob

 

[boboftherockies]

How hard are you pushing the pedal with the engine off?

I'm pushing it pretty hard but not throwing all my weight at it

 

[Matt 69]

Did you swap rear drums for rear discs? You may need two swap your proportioning valve and or master cylinder for dedicated 4 wheel disc pieces.I believe a caliper will have a greater volume than a wheel cylinder,and that my be part of your problem.I know factory JL8 systems did not use a proportioning valve.I am not sure what system your car has.Also the residual pressure valve located on the driver's side frame rail keeps the fluid from backflowing into the master cylinder.I don't know what effect it would have going from rear drums to rear discs.Just some things to consider.If your brakes worked fine before the swap,and all you did is reconnect and bleed the lines,than it might be a component issue.