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For those of you that have ever needed to weld a pair of leaf spring perches on a rear end housing, this tip could save you some aggravation. I use a perch jig to weld the perches on rear end housings at my shop. It probably sounds expensive or complicated, but it is not. All it is, is a piece of steel that you can bolt two pieces of 2" x 4" rectangular tubing to that will locate the perch centers. A piece of 5' long x 4" channel iron works well as it allows you to access the bolt that will hold the rectangular tubing in place. You will need to drill two holes in the channel at the exact center to center distance of your leaf spring perches. Mustangs have a 42 3/4" center to center distance. You will need to cut two pieces of rectangular tubing 5" long. You also need to accurately drill a two 3/8" holes right in the middle of the tubing on each side (the narrow side) A 3/8" allen head bolt is inserted through one hole, and a nut will hold it in place. The allen head portion will simulate the center bolt of the leaf spring. (you may need to grind the head down slightly to fit some perches) The other side will bolt to the channel iron.

Here is the rectangular tubing bolted to the channel iron. The channel has a slot as I use this jig for any kind of perch distance, so all I have to do is slide the rectangular tubing pieces to whatever center to center distance I desire, make sure they are square to the channel, and lock them down.


You place each perch on each side of the jig and level the jig each way.



You then place the housing on the jig on top of each spring perch. You measure from the edge of the housing to the edge of each perch until both measurements are exactly the same. With the jig level, rotate the housing so that if it had a centersection in it, the pinion would be pointing up 5 degrees on your angle finder. I know some of you are thinking that 5 degrees up is wrong, but trust me, ALL leaf spring equipped Fords are 5 degrees up, matter of fact, so are almost all leaf equipped vehicles, regardless of make. Once the housing is bolted in the car, the pinion will usually point down. If you are building a race car, now is the time to adjust the pinion angle, I usually point it up to 2 degrees.



Once the angle is set, re-check the side to side measurements, and tack weld the perches on. Weld half of each side of each perch, and then go to the other perch so that you will not concentrate too much heat in one area at one time and warp the housing. This is an easy method that will really pay off especially if you are going to do more than one housing. It sure beats bolting everything in the car, tack welding the perches on, and then un-bolting it all so you can weld everything. I do dozens of housings each year, and it is foolproof. Sorry the pictures came out so large.

 
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