Well I've been working on doing the brake change over and ran into another problem. The car I took the proportioning valve from doesn't line up with the lines in the car. It doesn't even bolt on in the same postion. Is this the norm with this change over? I looked for a how to but can't find anything on this part of the subject. Thanks for any help.
ward- somewhere along the line maybe 73 or 74 the prop valve went up and down instead of front to back. for what is worth, many i have talked to said no need to change the prop valve. i DID change mine in my 72 disc swap. for whatever reason, when i did the swap with my 70, i didn't change it. i've had to slam on the brakes (life in the great garden state of new jersey) with no ill effects. my advice, don't change it, test the brakes hard and decide from there. all those lil brake lines can be a pain. good luck!
Easiest way is just to bolt the disc on and use your existing brake lines and master cylinder. After its on, go out and haul ass and lock them up. If the rear lock up before the front, get an adjustable proportioning valve from Summit and put it inline on the line going to the rear brakes and adjust it to prevent rear wheel lock up. I've been running disc this way for more than 20 years with no proportioning valve and never had a problem. If you drive the car alot keep an eye on the fluid level in the front reservoir because as the pads wear down, the fluid takes up the slack. Thats why disc brake master cylinders have a large reservoir for the front.
Thanks here also guys. I already have a disc brake master cylinder, so Dennis I guess that is a plus to begin with? Have you ever run it with just the drum brake prop valve and it work like scott was talking about? That would be the easiest way by far, if it worked. Thank you for your time.
I'll probably get some argument here but from what I remember from brake school back in the 70's an all drum brake set up does not have a proportioning valve. That block is just a distrubution block along with a switch to turn on the brake light if you should loose pressure in either the front system or rear. There may be a built in flow restrictor just by varing the size of the orifice going to the rear wheels to reduce pressure to them but I'm only guessing. Thats probably why Ford rotated the block on the disc brake cars 90 degrees so people wont try to interchange them. I believe they use different sized fittings too. I could never figure out why a proportioning valve is needed when converting to disc because they have even better stopping power than the drums. So they should lock up even faster. All the disc conversions I've done, I've always kept the stock brake system that came on the car and I have never had a problem with rear wheel lock up.
On our 70, with the stock prop valve, the front used to lock up first. In the rain, a truck pulled out in front of me and with my whole six months of driving experience I slammed on the brakes, and only the fronts locked up. -Todd
Yer perfectly correct Mr Mavaholic . That is a big misconception that a lot of people have ,escpecially ones that drive chevies (go figure). I have also converted from drums to brakes with out putting a proportioning valve in . It only works reasonably well on light cars I have found . Big boats or trucks not so good .
