89 formula firebird , it had a 10 bolt drum rear when I got the car , I swapped to a 9 bolt disk ( from an 89 ) and the brakes still sucked .
I purchased a disk/disk proportioning valve from the boards , I specifically asked if it was from an 89 formula and speedysalvage reassured me it was , tonight I started the swap and all the brake lines have different threads than the proportioning valve ????? what the f*** I thought it was a direct swap ...
Anyone ever run into this before ???????

 

yes. it sucks. stripped my p-valve, got a new one, disk disc, diff year though, lines didnt fit. there is coarse and fine threads, figure out which ones run into the chassis, get a p-valve from the bone yard thats disc/disc with the matching threads on the bottom, and then find 2 lines from the master to the p-valve that will work, the yard wants like $2 for each short line from the master to the p-valve. im sure there is some logic to the threads/years/brake types, but i dont know it, and that is how i sovled my problem

 

Without any other option I just gave up and put the old one back on , now I've rounded the first bleeder I touched , sometimes it's hard to be loyal to something that treats you so bad ( I think I got the beginning of a country song ) .

 

i bought my car, brakes went our on the way home, spent tons of money on them to fix um, because i kept breaking crap when i was "fixing it". took 2 weeks working everyday to replace the front right hard line. "fixed" it 3 time,s then found leaks where i had bad flares. quoting 1bad91z, "thats hot rodding, something's always breaking, and you've gotta fix it." it frustrated me too, but hey, now i know what not to do, and i am way happier than if i had takin it to a shop, also the car feels like its more mine

 

From Dan Burke's write-up:

1LE Combo Valve (proportioning valve)
14089496 1989 1st design: M1.0 tube nut threads (For 1982 - early 1989 applications)
10136840 1989 2nd design: M1.5 tube nut threads (Late 1989)
10136840 1990-'92: M1.5 tube nut threads.
Measure your existing brake line tube nut threads before ordering. The Master cylinder tubes have one that is M1.5 and one that is M1.0 so don't worry about them. Worry about your existing brake lines to the calipers and rear axle.
I used the 14089496 1st design because my car was built in 1984.

Mine required some relocating of the rear disk brake line: My old combo valve had the line coming in the front, whereas the 1LE piece had it coming in from the bottom of the valve. My existing line bent with no problems. Be prepared to replace that line if it's at all corroded. It might crack.

JamesC