[cweagle]

I am in the middle of a complete refit of my 81's brake system. New calipers, new hoses, new hard lines, new master cylinder, all that stuff is pretty straight-forward, and Napa or Autozone has what I need.

I can't find the Brake Pressure Differential Valve anywhere for reasonable $$ though. I mean, if I can get an entire master cylinder from Autozone for less than $30, I'd figure that the BPDV would be about that much too. They don't even have one! Neither does Napa, and I looked though their entire Brakes book. Bronco Graveyard has them, new OEM, for a couple hundred. WTF?

Basically, everything on the whole truck is so rusty that if you want to replace one bit, you have to do everything attached to it at the same time. All the connections (and body) to the BPDV are rusty and let grit fall into the compression fittings, meaning I can't get good seal. My only other option is to remove it and beadblast it (or something), and hope it all goes back together.

 

[jmorriss]

A proportioning valve?

 

[Fireguy50]

$190 :shocked
http://broncograveyard.com/bronco/i-32519_oem_proportioning_valve.htm
JBG used the wrong name, but it's what most people call it

Search steve83 he has an exploded view of it, try to clean it up :shrug

A proportioning valve?

no :twak
prop valve just limits flow/pressure to 1 line

BPDV blocks flow to 1 line if a leak causes a differential in preswsure.
It also turns on the brake light

 

[jmorriss]

$190 :shocked
http://broncograveyard.com/bronco/i-32519_oem_proportioning_valve.htm
JBG used the wrong name, but it's what most people call it

no :twak
prop valve just limits flow/pressure to 1 line

BPDV blocks flow to 1 line if a leak causes a differential in preswsure.
It also turns on the brake light

ouch...give the newb a break :cry

 

[Fireguy50]

not cheap here either
http://www.lmctruck.com/icatalog/fd/0127.asp

ouch...give the newb a break :cry

broken teeth? :toothless

:drinkbud

 

[jmorriss]

lol...about my soft top....

 

[cweagle]

Search steve83 he has an exploded view of it, try to clean it up :shrug

Can't seem to find it with a wide variety of search terms...

I guess I'll pull it and see what I can do. Too snowy to go to work today anyway (winter's back in Boston!) Maybe I can free up the actual switch part too, while I'm at it!

 

[Apache0715]

yea they are expensive, I had bought one for my bronco when I first had it,never installed it, I think i bought it from Advanced automotive. If you can wait 5 months I may be able to find it in my parts, or it may have been left at the shop when I joined the army and is lost forever... Damn I wish I never bought that thing...

 

[cweagle]

OK, it's all back together. The switch still seems to not work, but I freed up the valve (apparantly - I had to make a little thing to hold the pin in the front OUT while bleeding the front brakes, otherwise the valve seemed to shut them off >90% of the way and I could not effectively bleed them). I took it out, sealed the ports VERY well, beadblasted it, and then cleaned the threads and seats with paper towels and brake cleaner.

So even though the Haynes book says that you only have to do that if you are using a 'pressure bleeder', that's not true, at least on my '81!

By the way, I ended up replacing:

master
2 hard lines from master to diff valve
2 hard lines from valve to front hoses
front hoses
front calipers
2/3 of hard line from valve to rear hose
rear hose (had integrated manifold, from Napa)
both rear hard lines
all bleeder screws

And all I wanted to do was bleed the system! Every time I built up enough pressure that I thought it was getting bled, something else would leak. At least I'm not driving a deathtrap anymore :twotu: