Ford 9 axle and disc brake conversion?

I just bought a Ford 9 axle that came with disc brakes.  The calipers do not have an emergency brake connection.  Someone told me that a 1976 Cadillac Elderado caliper will work for my 83 CJ7.  Also, I was told that my master cylander will not work and that I will need to get a 79 Corvette master cylander.  

Has anyone made this conversion?  Any suggestions on to best make this conversion?  And other things I'm missing?

Thanks for any help,

Mike  

Many people make the mistake of installing a larger master cylinder and don't upgrade the booster too. They need to work together.

A bigger master is not always better. It needs to be the right size master for the volume of fluid needed for both the front and rear calipers. Calipers need more fluid than drum wheel cylinders for sure.

Keep this equation in mind: Volume * Pressure = Force.

If you increase the volume (bigger master) it will take more force (pedal) to build the same pressure. And ultimately it is the pressure that the system builds that provides the clamping force to stop the vehicle.

If your brake system is bled and the pedal goes to the floor, that usually means there is not enough volume. So, you put on a bigger master. Then the pedal doesn't go to the floor anymore, but you still can't stop. The pedal is firm and feels good but you can't put enough force on the pedal to build the pressure needed to have properly functioning brakes. You need to be able to apply more force on the pedal, that's where the bigger booster comes in. Everything needs to be matched. It's not just about a bigger master.

There are lots of guys who think just putting disc brakes on their rig will give them much improved braking performance. They usually fall short because the braking system components are not matched.

Rear disc brakes will give you better performance than rear drums in wet and muddy situations. But will not make much if any difference on the street. Discs are better, less complicated, and don't require any adjustments, so don't get me wrong. But, a rear disc conversion when not properly matched with the master, booster, and proportioning valve will not even work as well as the properly functioning drums.

If you want to make huge improvements in your braking performance, get bigger front brakes. As much as 70% of braking comes from the front brakes during hard braking. That's why there is a proportioning valve on the rear. If there wasn't a proportioning valve the rear brakes would lock-up.

Proportioning valves have two variables. They allow the same pressure, front and rear, up to a certain point. Then the valve proportionally reduces the pressure to the rear brakes. So when you look at proportioning valves they have a pressure at which they start proportioning and then a percentage of reduction. Both parameters are variable. Deciding what the variable parameters should be depends on the specific setup (brakes, vehicle weight, tire size).

Now I know guys that have used the '79 Corvette/Firebird master on their CJ with rear discs. They were never very happy with the brake performance when weighed with the effort to get rear discs.

My only advice is if you're going to go with the rear discs, look into upgrading the fronts also and then calculate the fluid volume needed to run the calipers that you end up with both front and rear and then get both a master that will provide that volume and a matching booster. Then depending on how the rears work, look into proportioning valves.  

Wow, thanks for the great infomation!  I really appreciate you taking the time to educate me.  I will look at all of your suggestions.

Thanks,

Mike