I'm putting Granada discs on the front of my '72 Comet and wondered if the original combo valve can be used or do I need one off a Granada or later Comet/Maverick with discs?I was just going to use a new manual disc brake master cylinder with the existing plumbing. My Comet came with a 250 6 which per the manuals and parts books was supposed to have 10 inch brakes like a V8 car but only has the small 9 inch drum brakes. Is this normal? Thanks.
Some people have used the original distribution block from the drum brakes. Others have replaced it with a proportioning valve from the donor car with front disc/rear drum. I chose to use a proportioning valve so the front disc brakes get more pressure than the rear drums. I figure if Ford used a prop valve they did it for a reason.
brakes Use the one from the donor car. the valve is different from disc to drum brakes. The react differently and require different valves.
the only difference is it divides the fluid amounts going to each brake set back or front one takes less volume of fluid to apply braking pressure than the other because the pistons are different sizes. thats the main reason for the metering block. if you dont change it it will still stop your car, it wont fail on you or anything like that. the biggest difference you will have is the fact that the front or rear brakes will wear faster than the other
I noticed you have a morris minor, my brother has 14 of them, he has a pickup,convertible,panel,traveraler(woody) plus several 2 and 4 doors. My dad worked for Over Seas Motors when I was growing up and we always had at least 1 morris in the drive, He has several parts cars so if you need anything give me a shout
Thanks for the info. I'm going to install the combo valve off a Granada with disc/drums.If the rear tires lock up under hard braking then I'll use an adjustable prop valve. When I put Granada brakes on my Falcon I used a Granada combo valve but the rears still lock from a panic stop.Guess it could use the prop valve also? quickvic: Yeah,I have a 289 Morris Minor which is mostly a 1/8 mile(6.85/99.6) drag car. It looks street legal but with huge stock 7 inch drum brakes in the front it isn't something to be driven in rush hour traffic. I'll contact you about parts if I need any,thanks.
With changes it is important to get the front to rear bias as close as you can. The pressure applied is the thing you control. The fluid is all ready there, it's the pressure applied. The other thing to be awhere of is the fluid volume the disc calipers require over the small cylinders of drum brakes.
prop valve Just so you know, all prop valves are NOT created equal. They have different springs that CONTROL the pressure changes. They are different due to car weight, brake type including power or manual, disc or manual. One thing is the Granda is heavier, and so a different prop valve. If you have a SAFE road that you can do some testing on, use the one you have now and then the other one. But do it at different speeds and stopping conditions. I can tell you on my son's 72 Grabber, 302, AOD with factory rear drum brakes and 76 Maverick discs we used the 76 prop valve. We changed it from factory power drums around, to manual discs/drums. Stops on a dime now, wet or dry roads.
i am sure that you referring to "prop" is actually that you mean poportioning valve right? i agree with what you say that porportining valves are not created equal, but you have been mislead on the fact. the fact is porportioning valves are different because of different piston sizes in calipers and rear brake cylinders. the weight of the car doesnt make a difference on porportioning valves however, weight distribution does.i.e. if you brake normal compared to braking hard the porportioning valve works differently. here is a better explaination...... A Proportioning Valve is only found on cars with disc brakes. It is spliced in the brake line running from the master cylinder to the rear wheels(and Disc on newer cars). Its purpose is to dampen and reduce brake pressure going to the rear brakes. Because front disc brakes are not self-energizing like drum brakes, they require more pressure to work properly. Also, front brakes do most of the stopping and thus require more pressure. Without a Proportioning Valve in the system, both the front and rear brakes receive the same pressure. This will cause the rear brakes to lock up long before the front brakes are engaged enough to stop the car. The Proportioning Valve allows full pressure to the front brakes and dampens the pressure to the rear brakes, allowing the correct pressure so both can stop equally. The valve is adjustable to allow for differences in front-to-rear brake pressure due to variations of weight distribution, tire size and compounds, brake pad/shoe material and brake fade. porportioning valves are not 50%/50% like most people believe they are, most common ones are around 64% front/36% back
The "prop' valve I was refering to is a proportioning valve. The factory combo valve for a disc/drum car has the prob valve built into it ,the drum brake combo valve doesn't .My original question was if anyone has had good results using the original drumbrake combo valve when doing a disc swap. I guess the original could be used but for the brakes to work properly the addition an adjustable prob valve would allow balancing out of the system.The different calibrations of the valve to match the weight of the car is probably why the Granada combo valve with built in prob valve I used on my Falcon doesn't stop the rear brakes from locking up in a panic stop.
Why the big debates? Ford put the disc brake Prop valve there for a reason. To stop better and safer. Put the right valve in. Are you really ready to almost compromise the well being of you rmaverick just because you dont want to do the full job? Sorry if I got on anybody's nerves. -Todd
that is what i am trying to explain to you........ the drum/drum block is not a metering block of any kind it is just a distribution block, works the same way as a cable splitter on you tv. thats all it is. the reason the porportioning valve you are using is because it was set up with the rear brake cylinder for the granada. more than likely the falcon has a smaller piston bore than the granada did. i assume what you are saying is you also did the disc brake swap on the falcon. so all you need to do to solve your brakes lock up problem is put rear brake cylinders from that year granada into your falcon, as goes with your comet,with the porportioning valve. and yes the cylinders will fit in the backing plates. the cylinders arent that expensive
the only thing that may be different would be the line fitting i did forget to mention that, but if you have a double flare tool it isnt that hard of a fix and some napa's will do them for you
Thanks for all the replies.Quite a welcome for a new guy. Sorry if I got anybody's knickers in a knot over a brake question.I'll try to be less controversial next time. Since Maverick/Comets are hard to find in the local Pic A Part I'm going to use a Granada combo valve that I have. I'll add an adjustable prop valve if the rears lock up in a panic stop.When I did the swap on my Falcon 15 + years ago I did use the rear cylinders and combo valve for a Granada but the rears still lock under real hard braking. Not bad though.
Conversation is what this board is for. A couple of people jumping up and down trying to be the "rightest" happens all the time. That's just what happens when you get a bunch of people with a lot of skill, but different philosophies together and show them all the same problem. My opinion.
