1975 CJ-5 Brake proportioning valve

Quick question...on my proportioning valve I no longer have the metering valve off the top. The PO just put a bolt in this spot. Question is...will this work of do I need the metering valve and, if so, would on from a later model (ie 76+) work as I can not locate one for the 75. Also, when I bleed the brakes, should I just take the bolt out and bleed them as normal? BTW, its all drums. Thanks for your help.

 

Front Drum brakes do not use a metering valve normally. A metering valve holds off pressure to the front disc brakes until pressure rises to a certain point in the rear drum brake hydraulic system for even braking. Otherwise the fronts could lock up prematurely, especially on slick surfaces.
A proportioning valve simply limits hydraulic pressure to the rear brakes to help control lockup as compared to the front. A combination valve has two or more components in one unit.

A 4 wheel drum brake system like you have may or may not have a proportioning valve stock. Sometimes this is controlled by different diameter wheel cylinders front to rear. There is a third component commonly used that might look like a valve but is actually a pressure differential switch that closes, grounds a circuit, and turns on a brake warning light on the dash when hydraulic pressure is lost in one circuit. I wonder if that is what has been removed?

 

I believe that may be what was once there. So can I just leave it out and keep a bolt in that spot?

 

The brake differential pressure warning switch plugs into the top of the combination valve. This is clearly shown in the '75 FSM. The '76 FSM is online at www.oljeep.com, and should have similar content. As I recall, the other section of the valve is a proportioning valve, and holds off the rear brakes under severe braking.

I suggest you get and read the FSM for your year. There is much more detail about this topic that is covered there.

 

Regarding the combination valve, the '74-75 and '76-77 valves are different. Functionally, they are the same AFAIK. However, even if you bought the '76 valve, it would not come with the plug for the warning light.

 

Thanks for the info. So back to one of the original questions...since I dont have the switch and cant seem to find one for my year, can I just place a bolt in it?

 

Depends on what you consider to be acceptable performance.

There is supposed to be a warning light connection in that hole. The warning light will not work if there is a bolt in there.

Like this, but likely not this one - http://www.ebay.com/itm/like/200877774614?lpid=82