power brake conversion question

Power brake conversion: has anyone used the single diaphragm booster from morris? does it just bolt up and work? http://www.jeep4x4center.com/9-slim-...bm-pb9002.html

 

Link doesn't work for me.

 

A dual chamber is always better.........more stored vacuum for maybe another stop if your motor died or a line broke.......better in high elevation use and for motors that don't put out much vacuum.......you do need about 19-20 inches for the system to work properly.
One last thing if you have manual brakes now on a swing pedal setup the pedal ratio will be greater than you need to stop with a Booster system.

 

thanks, what can i do about the pedal ratio? what problem will it cause?

 

GM accounts for that by tipping the booster. Then when the rod contacts the pedal it is at a point a couple of inches closer to your foot which reduces the lever arm. Never had a jeep with a power booster so not sure how AMC handled that.

 

thanks, Mike C. maybe the pedal pivot is changeable….

 

i just added a yj booster/master to an existing manual brake pedal on the wifes 76 . I haven't noticed any problem with the leverage difference between the two.

 

Not sure what year you have............could be two holes or one.............I have seen some that had one hole and then others that had two.............Go figure?.......Sometimes the linkage adapter on the outside of the firewall bolted between the firewall and booster corrects that...........one thing ...........whatever position you put it in the push rod has to be straight and level so it does not bind.......that in itself with the booster not having allot of room under the hood without the use of an adapter will almost tell you where it needs to attache on the brake pedal.........Normal ratio for Jeep pedals.............manual brakes about 6.4:1 and power about 4.5:1 mechanical advantage.........that means from the fulcrum point where the pedal swings from to where the push-rod is attached take that length .............and then the length of the pedal from the same fulcrum point to the foot pad. Divide the large number by the small and that is your ratio.

Correctly Calculating Brake Pedal Ratio

Pedal Ratio is one of the most overlooked parts of a brake system. One of the main reasons and causes of a hard brake pedal is simply due to incorrect pedal ratio. When a brake pedal gets modified to “fit” in a vehicle or a booster/master cylinder gets installed where it “fits” in the car, the pedal ratio is rarely taken into consideration. Proper pedal ratio is a must when installing and operating a brake system. Below is a diagram to show how to properly figure pedal ratio:

Pedal Ratio = X divided by Y​

In a manual brake system, the pedal ratio will be between 5:1 and 6:1 and a power system will be between 4:1 and 5:1. In the above illustration of the hanging pedal on the left, let’s assume the overall length of “X” is 12” and the “Y” measures 3”. That puts the pedal ratio at 4:1 which is perfect for a power system. To make this function as a manual system, the “Y” measurement would need to change to 2” giving a 6:1 ratio.
If the correct pedal ratio is not achieved, the pedal will be extremely sensitive due to too much pressure being applied too quickly.
As you can see, if you don’t take pedal ratio into account, you are not getting the most from your brakes.

 

Thanks all of you! I will post pics after I do this.