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Registered
Join Date: Apr 2013
Posts: 14
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How Critical is Rear Longitudinal alignment?
Hi everyone. I've got a '65 that I'm a good way through the metalwork on, but I fear I may have taken off a piece I should have made a jig for first. I've got a new rear longitudinal piece, and I cut off the old panel last week. As an aside, there are some substantial differences in the shape of the new panel, and what's on my car. The panels start and end in the same place, but in between the original Porsche metal has an extra, very pronounced, crease in it where the rear inner wheel well spot welds to it. Anyway...
My torsion tube is in the correct place. But how critical is the alignment of the four cover holes in relation to the torsion bar, both in angle and depth? My driver's side is still intact, so if need be I can use some 80/20 rail to make a jig based on the factory measurements, but I'd like to save myself the trouble if it's not a particularly critical dimension and "eyeballing it" will do. 
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09-06-2024, 07:32 PM
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Registered
Join Date: Dec 2014
Posts: 14,042
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It’s critical as far as camber goes, any error will be multiplied at the hub. Also any error could affect how torsion bar fits into spring plate. Can you insert torsion bar get it centered, support it at end and use it as a guide for fitment ? I’m sure someone with more experience will chime in.
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09-07-2024, 07:46 AM
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The 9 Store
Join Date: Dec 2009
Location: Wilmington, DE
Posts: 5,433
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I would make a jig and make it fit correctly. Anytime you are off on a critical dimension, it tends to cascade to other parts of the car and cause additional issues.
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All used parts sold as is. |
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09-07-2024, 12:53 PM
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Registered
Join Date: Dec 2020
Location: The Swamp and NC
Posts: 457
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On the other hand there are a lot of perfect 911's that are off by more than you can believe..
This question lead to some very angry fights here and this spec is the one that is not in the little technical specification book. This is also why people have problems with doing the "string alignment" and can not get it right and some say it is easy. Some Porsche techs here said the left to right mounting can be off by X mm's. Mine is off by 6mm. Flame on gents..
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I'm not picking my nose..I'm porting my upper intake manifold. |
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09-07-2024, 03:04 PM
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Navin Johnson
Join Date: Mar 2002
Location: Wantagh, NY
Posts: 8,843
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I did the same repair on one of my cars..
Since the torsion tube apparently has not moved, You're pretty good to go, try to orient the plane of the mounting bosses for the spring plate such that they are square to the vertical plane of the tub, and parallel to the centerline of the car.. On the car that I performed this work on I did the front pan, both rear torsion areas, door jambs, kidneys, etc... and I'm able to align it accurately.. its between 1/8-1/4" out of square...Oh yea I did the longitudinals at the same time I can't find pic of when I worked on the torsion tube area... however...   
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09-07-2024, 04:07 PM
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