brakes

i have read alot of threads on here and am confused i have a 74 mav with drum drum i put a 77 granada front end under this 74 including springs and upper and lower a frames spindels and calipers i am now trying ( and i do mean trying) to get the brakes going found out the hard way the booster won't work and am wondering which master cylender to use i think some one posted that in 74 the mc was allready disc/drum and manual so do i use this mc ??? and which prop.. valve do i use hope this does not sound like a dumb question but i reall would like to ease my mind


and by the way i have a geo and took the booster off to try to use it and just don't get all the hype about using a geo booster any help would be nice

 

The master is not different between disc and drum.
You can use your stock master with discs.
You should, however, use the proportioning block off the Granada.
You should not switch power master for manual master though.
If you don't mind manual brakes, just stay with your master.
A manual master on power brakes will be WAY touchy, and a power master used for manual brakes can require a lot of pressure to function.
This is the way it works on most cars.
I know the Mavs though, have a different fulcrum placement on the pedal arm for power and manual brakes. This might be the only difference on our cars...
It's the same theory though.
The power brake fulcrum location is engineered for LESS leverage on the master, so the brakes are not overly touchy. Then the fulcrum on the manual brakes is positioned to give more leverage, so braking is easier without power assist. To mix the position of the pins in the pedal arm gives a similar problem as mixing the masters.
Hope this helps some.
The Geo unit is swapped in so you can fit a booster/master all behind the shock tower, instead of over it, like stock. This way you don't need the big-ugly PDB tower brace.
Good luck
Dave

 

Here is what you should consider.
The Chilton's book on MAV/COMET page 228 has a chart on the master bore size differences, the wheel cylinder bore size differences, the drum/disc sizes.
Once you mix and match brake parts like this, you have completly left an engineered and balanced system.
Unless you have some understanding of what needs to be done, you will have quite a time getting what you feel is satifactory brake operation.
There are many areas that need consideration.
The disc fronts now have higher fluid capacity affecting master cylinder fluid reservor capacity as opposed to drum system.
The balance between front and rear is now upset.
If tire size, width and grip have been changed, this throws another issue in the mix.
Some make changes and just happen to come out with a final result they think works for them but this is never a gaurenteed result.
Generally in a near stock parts swap, the MAV disc master has a smaller bore size especially in manuel operation. This results in higher pressure applied to the front disc calipers.
Good luck with your brake setup.

 

'74 used the same master cylinder (large front reservoir) for both disc and drum brakes, and did not use a prop valve, but rather a distribution block. If you want power brakes, you'll need the master cylinder, booster, prop-valve, brake pedal & bracket assembly, lines & fittings, and spring-tower brace from a '75-'77 Maverick. It's that simple. People who tell you different don't know what they're talking about...

 

Correct if I am wrong, but I thought the only difference is the location of the pin in the pedal arm.
IF that is the only difference, you can just reposition your manual pin for the proper placement. The move was only to give your foot less leverage so the pedal won't be touchy with the power assist.
If there are other differences, then so be it. However I have seen articles and web pages with instructions on how to mod the pin in the pedal arm for power brake swaps.
Dave