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Discussion Starter #1
I have an A- body 8 3/4 rear end, but the perches are missing.
I have bought new ones to weld on.
I can figure out the center to center measurements easy enough, but the leveling has me stumped.
Can I just level up were the center section bolt or should I install the center section and then level it.
Does the center section need to a degree off from the transmission in the opposite deprecation?
 

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According to an older Chrysler performance book, the center section should be installed at 2-6 degrees down from level. Installing at level causes damaging vibration in the drive line. Perhaps a call to the guys at Mopar can verify this info for you.
 

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I looked at the A-body 8.75 housing I have and if you position it with the center section level the spring perches are angled back and down a little bit. It seems consistant to what tazdevil says.
 

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Correct. When the rear end winds up, the wheels turn and the axle will then twist upwards, which is why there is a rubber bumper and bracket that attaches to the top of the rear end third member and can touch the floorboard to prevent it from twisting even more. 2-6 degrees is a good measurement.
 

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KOG
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If you want to be really accurate you would need to have the car on the springs at normal ride height and set the driveline angles per the shop manual.
 

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Discussion Starter #6
I thought about settling the ride height and then adding the perches. I think this would be the most accurate way. I was told that I could use the angle of the still in place 7 1/4 rear end. Once I removed the existing rear, I could line the old up to the new. The angle would work.
I'm not sure of this do to the off set motor mounts and the small block I'm going to use. I think the perch angles could change.
What do you guy think?
 

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Get it bolted in, set the angle with the weight on the axle, tack weld them, then pull them out and weld them completely. Do small welds so as not to warp the axle. Isn't as easy to warp as sheetmetal, but care should be taken.
 

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Axles and oil should probably be out of the housing before you weld on it. The housing tube's wall is fairly thick so you are going to put some heat in those welds to get good penetration. TIG will give you the best results.
 
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