I receintly put a Moser ford 9 inch in my car with 11" ford explorer rear disk brakes. I used my stock hard line to hose set up to the rear end then ran hard lines to new ford explorer brake hoses. I bled the brakes and now it seems the pedel is very soft and spongy. The car has not been started or driven yet, I am in the process of replacing the intake gaskets. But I believe the power brakes will make it even softer, is this correct?

The car is a 87 firebird that had front disks and drum rears, and the proportioning valve is the block one that was machined out of a block. And from what I have read some people get away with this proportioning valve master combo when converting to rear disks.

What do you guys think? Thanks

 

the prop valve should be replaced with one form a disc/disc car.

I sounds to me like you still have air in the system. Did you let the whole system drain when you changed the rear? if you did you could have air in the master cylinder and will have to remove and bench bleed it.

 

ok,maybe a lil off subject here but lets say he did have some air in the master cylinder.
If he were to install self bleeders on all 4 and open them up and pump the crap out of the brake pedal and keep a close eye on the reservoir while doing this,could it clear that air out?

 

No...

The place on the MC that the lines hook up to, isn't the highest point of the MC itself; meaning, if there's air in there, it can go up into the "corner" ABOVE the fitting, and stay there FOREVER, and NEVER EVER come out through the fiiting into the lines and out the far end. He can run 10,000 gallons of fluid through it with any kind of bleeder system there is, and that air will NEVER come out.

The MC needs to be "bench bled". Removed from the car, put into a vise, bled, put back onto the car without letting the fluid come out and air get in. Then the system fully bled again, which could be done by whatever common method is available; gravity, speed bleeders, whatever.

 

Like they all said, get a different prop valve, get the brakes properly bled.

 

I bled the hell out of the brakes, and when I did the swap I just rubber capped the lines at the rear end to keep most of the fluid in. I doubt all of the fluid drained out but the master was almost drained or out I can not remember. I am thinking about buying a summit proportioning block that can be adjusted and keeps the correct front to rear bias. What do you guys think? I really do not want to bench bleed my master if its not needed.

 

the adjustable block would be fine, though you will have to cut and re-flare all you brake lines, unless you can find adapters.

 

Reflaring is not a concern, do you feel replacing the valve will fix all problems?

 

When I did my drum to disc conversion I gutted the prop valve according to Baers directions and installed an adjustable valve.. the spongy pedal was air in the lines and it took ALOT of bleeding to get it right (pressing on the brake, mity-vac repeat).

I would recommend going with a regular disc/disc valve if you can get your hands on one.. with my recent redo I changed over all my lines to metric and went with a 1le valve replacing the other stuff which was a sloppy way to go IMO..

 

The reason it took for ever to bleed is because you most likely have a quick take up master cylinder. You need to wait 15 seconds between pumping the brakes and opening the bleeder valve.