One of the first things I noticed after I purchased my truck is that it took a fair amount of brake effort to get the truck to stop. I also found through testing that the rear brakes did very little to help slow the truck down. I estimate that about 90% of the work was done by the front breaks and only about 10% was done by the rear.
Later on I lifted the truck and was careful to add a drop bracket to the proportioning valve rod to make sure I kept the brakes working correctly. The brake arm is a device that tells the proportion valve how much weight the truck is carrying with the idea that the heavier the rear end of the truck the more rear braking you need. The arm effectively measures the weight of the truck by measuring the amount of rear spring compression. One end of the arm is mounted to a valve on the frame of the truck. The other end is attached to the axle. The more weight you put in the truck the closer the frame is to the axle so the proportioning valve sends more of the braking effort to the rear brakes. When you lift a truck and don't include a drop bracket for the sensing arm you tricking it into thinking the rear of you truck weighs less then it does and proportioning valve responds by sending more brake effort to the front so at the very least you must raise the arm with a bracket the same amount as the lift you are installing. Another problem I found is that when setting up my rear axle for more articulation the valve is given false information about the weight of the truck. When the left rear wheel is compressed the rear brakes are doing their job But when the left wheel drops and the right wheel is compressed such as when driving over a rock the valve responds by releasing the rear brakes. That is a bad thing. After much testing I found that on my truck that the rear brakes work best if the arm is always in the full up position. This simulates a full load at all times and the proportion valve always sends ample pressure to the rear breaks. This works so well that it eliminated any ideas I had about converting to rear disks brakes. I ended up cutting the arm off at the valve and tying it up with a large wire tie. Some day I may replace the proportion valve all together with an after market race unit, but it's working real well for me now. It's very important to have more work done by the front brakes than the rear. If the rear brakes lock up before the front the truck becomes unstable and spin out of control. During testing I removed the rear valve altogether and replumbed the rear brake to work with out a proportioning valve at all. I found that on wet pavement that the rear end of the truck would slide and cause an unrecoverable spin to occur. I did this test several times in a large parking lot, sure was fun! I would suggest extensive testing on wet pavement after any adjustment of the brake arm to make sure that the front breaks lockup first and the rear breaks don't lock up unless you continue to press on the peddle. You may find that placing the valve arm all the way to the top may provide too much brake pressure to the rear brakes and a lesser adjust may be ideal especially for lighter in the rear pickup trucks. An alternative to cutting off the arm is to disconnect it from the axle and use a drop down bracket to attach the arm to the frame of the truck, adjusting the position of the arm for the desired amount of rear brake pressure. Follow us on Twitter at www.twitter.com/OffRoadDotCom
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