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Old 12-17-2005, 10:38 AM
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Rear axle positioning

I recently replaced the rear axle in my '39 Stude Cmdr with a GM 10-bolt posi. New spring perches, etc. The problem is that is seems my new axle is about 1" or so forward of the place the old axle was in the wheel wells. Also, there is a forward lean in the U-bolts. I am considering modifying the spring perches to move the axle rearwards but am confused as to why this happened and if that is the best solution. What's up here, guys?

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Old 12-17-2005, 12:06 PM
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Never had a 39 Studebaker.........but some of the early 50's Chevrolet had a offset axle mount. Maybe the Studebaker did too....

You might consider redrilling the spring to move the locating bolt.....OR maybe swapping the front of the spring to the rear....I have seen that reposition the bolt to the correct place.......


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Old 12-17-2005, 02:09 PM
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You can also redrill the hole in the spring perch on the axle to move it. That seems to me to be the easiest thing in your case.

When these cars were built many years ago, the sat much higher, and had larger diameter tires. So they built them to look OK the way they were. When you use shorter tires, and lower it, the misalignment becomes noticeable. This is true of many makes, some Fords, some Chevys, and others. Also, particularly in the later 40's, quality control went out the window. So some of the fenders were really off. I have seen as much as 2" difference from side to side on rear wheel openings on 46 to 48 Fords. Build a square chassis, and you have to move a wheel opening to make it look right.
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Old 12-17-2005, 04:56 PM
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Redrilling spring perches

Thanks for the input. That is what I was going to do. I don't need much change so that might be the best thing to do. Amazingly, the Stude is pretty much right as to fit side-to-side. We'll see as I go further.
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Old 12-28-2005, 11:05 AM
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Just something to think about. You can rotate the perches all you want but when you tighten up the ubolts the rear end MAY rotate to the "flat spot" on the springs. the springs aren't going to move to meet the perch, so this MAY change pinion angle. Maybe you are thinking of stretching the perches rather than just "rotating" them around the axle tube.
Make sure you are measuring the WB correctly. You need someone to help. Even if you have to stick the old axle back on, BE SURE YOU MEASURE CAREFULLY WITH BOTH OLD AND NEW AXLES. MAYBE, JUST MAYBE IT'S NOT ONE INCH OFF. AND AS I SAID WATCH OUT FOR PINION ANGLE. I swapped axles on a 56 GMC, but in my case I was redoing the hangers also. All the above is info for leaf springs only, I'm assuming leaf springs here.
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