I've been doing lots of figuring and fab'ing, but 90% of it is pretty mundane stuff like brackets, flanges, etc. I am working on routing issues for the wiring bundle that runs to the rear, fuel lines, rear brake line and the (trunk) battery cable. Due to the small size of my tunnel at rear, and the large size of my live rear axle, I'm just not happy with the idea of running everything out the back of the tunnel. It provides too many opportunities for Mr. Murphy to step in unexpectedly if there is a failure of the driveshaft or U-joint at the pinion housing, or if the Panhard rod breaks and I loose lateral control of the axle.
Here's what the end of the tunnel looks like:
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The orange electrical cable is my mock-up piece for the battery cable. It's about half the diameter of the actual battery cable, but very flexible, so easy to play with. The battery will be in the boot on the right side of the car. The fuel tank will be slightly offset to the driver's side, but go over the centerline onto the passengers' side also. I have more clearance above the differential pumpkin and the pinion housing than below it.
You can see the notch cut out in the rear crossmember to clear the bottom of the pinion housing. The pinion is offset on my Ford 7.5" axle. The rear U-joint will run in the clear space just ahead of the notched crossmember. The potential vulnerability of the cable is larger than I'd like. The fuel supply line and EFI return lines will run fairly high, emerging on the left side of the tunnel, and running to the left. The wiring bundle will be top most on the drivers side and run over the middle of the chassis. The brake line run is still up in the air, but will probably run at the lower left, protected by the larger gap between the pinion housing notch and the 1" x 1" RHS vertical at the end of the tunnel.
I spent a lot of time today looking for a more satisfactory solution from a safety point of view. I don't have a perfect one, but I like this setup better.
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The colored circles represent the battery cable (red), wiring bundle (green) and fuel lines (blue) penetrate the bulkheads, represented by the cardboard pieces. This would avoid everything running in an area where a runaway axle could pinch them off or shear them, or an exploding U-joint would be most dangerous.
Of course, if they ran unprotected through the cabin, we'd be going from the frying pan into the fire. So, I came up with this simple way to isolate and seal them off from the cockpit:
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It will be behind your shoulder when sitting in either seat, so won't be a problem for driver or passenger. I know I can seal it up tightly, so nor worries about leaking. This should get the runs high up and forward of the pinion U-joint, pinion housing and differential pumpkin. If the drive shaft lets go, there should be some limited protection provided by the tunnel structure itself.
For the brake line, I think I'm going to run it along the undertray in armor until it's behind the transmission mount, then put it along the bottom of the tunnel on the driver's side. Going under the transmission mount means being exposed below the undertray anyway, and going above it make it easy to damage the brake line inadvertently when the engine/transmission are installed. They go in in together in my build and you have to fiddle them about quite a bit to get everything to line up.
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As I near (about 3 weeks away) a certain, very significant age milestone, I was wondering if my remaining brain cells were sufficient to make an elementary pattern freehand with a compass, ruler, straight edge and Xacto knife. I haven't done one since my Engineering Origami (descriptive geometry) class about 45 years ago. It was pretty simple, but worked out well. I am now reassured.
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Cheers.