I have all the info I need on a disc brake swap and know where a couple of donors are but I need to know where the proportioning valve is and what it looks like?
Its about 2 inchins in length its mounted on the fender all the brake lines go to it from the master cylinder then to the brakes, its useally a brass color if its stock. It is held on by two bolts that can be accesed from the wheel well. I suggest taking the brake lines if possible, i didnt and i have bend and reflare the lines, and take your time removing the braking system the brake booster and master cylinder MUST be separated to take the system out I learnt this the hard way and wrecked the housing on my booster.
not for nuthin....when we did the swap, we didn't change the prop valve. we did keep the disc brake prop valve on hand just in case. anyhow we purposely took the car through a nice big wet piece of open road at 50 mph and stood on the brakes with no ill effects. i am not convinced you need to change the prop valve. by the way... if we were justlucky and somebody else darn near killed themself by not changing it, changed it and found a big difference, please let me know.
I've seen this a couple of times and stayed out of the conversation. The block on the Maverick is a pressure differental switch/distribution block. On the old cars they used the mastercylinder to set the proportion. Most master cylinders are around 60% front and 40% rear, sometime in the late 70's to early 80's they started using that block as a proportioning valve by restricting line for the rear brakes. If you tear one of these blocks apart the holes are the same size front and rear so that means there is no restriction AKA no pressure differental. I have taken apart one from a 90 mustang and it has a small replacable restrictor on the rear brake side. I machined a new one that didn't block the hole as much for my buddy and it fixed his spongey brakes on his mustang with 4 disc swap. With a disc/drum master cylinder you will probly not be able to lock the rear wheels because you don't have enough fluid movement to fully actuate the caliper. On our car we have a disc/disc master cylinder from an 85 SVO mustang and it locks the rear wheels pretty easy. I got a proportioning valve from summit that was pretty cheap, around $40. I plumed it in on the rear brake line before the distribution block. My 2 sence
The old valve is 50 frount 50 back the new one is 70 frount 30 back if you dont put the new one on it will be harder to brake and the back wheel have a chance at locking up before the frount WHICH IS NOT GOOD well unless you wana have fun on a icy surface Change the valve, might as well if your doing the brakes anyway never know when that extra power to the frount may help anyway Just my 2 cents also
tom... it is late so let me ask you in "third grade english" you uhhhhh HACKED (sorry i had to) a disc/drum prop valve in half and found no difference with the drum/drum valve? thanks
If the old one is 50/50 (i never changed mine either, but my brakes suck)....would that be the better one to use on a disc/disc setup? I'm going to be doing the explorer rear discs sometime soon here.....
On a radical brake system change, the front to back brake bias should be checked by doing low speed panic stops on smoothe pavement a few times to see what the rear wheels are doing. It is a danger to have the rears lock up making it harder to control the car. In addition, poor stopping and brake pad/shoe life could be the result of improper bias. At min. if the rear tends to over brake, an adjustable valve can be inserted into the line to the rear and dialed in until the lockup goes away and stopping feels much better. It's a saftey item for which the law can be pretty hard on if an accident ocurrs and braking is found to be lacking.
As I have stated many times, I have been running disc on the front with the original drum system for years. I tried to lock the rear wheels and even had to slam on the brakes in a real life situation. The rear never locked up. Put your discs on and try it out. You can change it all if you want to, but, you probably dont have to. By the way, I'm Not slamming on you , just curious where you find this type of information:
Ooops my mistake I thought we were talking about putting 4 wheel disc...........bad tom bad................I'll be in the corner with the cone hat on When I first up graded Tammy's it was just front dics with a power booster I never changed the block either and had no problems. I will say that it didn't stay disc/drum for long. Hey dennis, one way to check the old blocks is to put a drill bit in the holes and check the difference in the drill sizes. Like a number 30 drill in front and rear would be 50/50. Say it is 30 (.1285) in front and 40 (.098) in the rear would be 56.8/43.2 percent bias
I agree with Mavaholic 100% You really only need the prop valve if you have power brakes because they are more "touchy". I also converted my '73 to front disc/rear drum and have the stock distribution block and it works great...in fact it is the SAME set-up that came on '74 Mavericks with disc OR drum ('74 used different calipers though). And just in case anyone is skeptical, I ALSO tried the prop valve from a '75 (same car my discs & everything came off of) and there really wasn't much difference, except I think the brakes have a slightly better feel with the original distribution block...
I would also like to say that since changing over to a prop valve is a hassle anyway, IF you need to change it, definitely go with an aftermarket adjustable unit. It will perform far better than a stock unit and will make all that hard work worth it...
dennis are you still using the drum/drum master as well? our finally gave up the ghost and we switched to a MANUAL disc brake master. a LOT less pedal is needed. todd found an article on power masters vs. manual masters. the "innerds" of the manual are smaller, making less pedal pressure required. uhhhh if you have a disc/drum master, disregard
