My truck is an 83....before antilocks (ABS).

In later years Ford went to ABS on one end of the truck, non-ABS on the other end. I don't get it. It's my understanding, when you have ABS, you can slam the pedal til it goes thru the firewall, and you needn't worry about the brakes locking up.
So if two wheels are protected and two aren't....how's that work?

 

I don't think it was ABS but more of a load control they had a control valve on the rear axle and the more weight that was in the truck the more stopping force was applied to the rear brakes,somebody can correct me if I am wrong.

 

I don't remember what years, but Ford did put rear wheel ABS on pickups and vans for a while. The theory as I understood it is like Glenn stated above, that the rear brakes can contribute more to the stopping force as more weight is added to the back of the vehicle. My 86 F250 has the control valve that Glenn mentions, which mechanically adjusts the brake bias as the bed sags under load. The rear ABS system did the same thing electronically. I had a 92 Aerostar with the RABS, never really noticed that it did much for stopping distance but it did prevent rear wheel lockup, which can lead to spinning/loss of control in a panic stop. However, since the front wheels did not have ABS, they would lock up on slippery surfaces and then you had no steering control, so it didn't really matter at that point if the rears were locked or not. Basically, you still had to drive as though you had conventional non-ABS brakes.

 

it was used in the later 80's trucks in an attempt to control rear wheel lock up when the truck was unloaded. Just for giggles do a panic stop with your truck unloaded see how fast the rear end locks up and trys to come around.

 

it was to prevent the rear from locking up under hard braking with no load.