Saturday, June 18, 2011

I'm no engineer, but….

I guess I fall more under the artist category than engineer, fabricator or builder - but though I often only have to draw finished ideas of the outside, I think it's a healthy exercise to be able to show some real, practical thought into how things are actually going to built. Ignore my 10 minute sketch/doodle lines and such… this was really for my brain to relax.

Taking a break on the body assembly while I wait for the cowl to come back from the media blasters, I got to thinking about my rear end and how it will sit.
When I purchased the rear end I was told it came from a 1948 Ford truck. It's a banjo rear, so will go with that for the example sake. Now, I know I want to do a bit of a kick up on the rear so it's not completely looking like a cat in heat with the buggy spring.

I picked up a medium arch buggy spring for a model A which if memory serves it has a 10" rise. With the stock model A frame it would probably look a little goofy with the rear high up so I know a kick up is in order. Whether it will be 4" or 6" I don't know just yet. I have to see the way things sit before moving too far along.

In this blurry cell phone shot you can see the rear cross member sits directly centered over the wheel well of the rear quarter panel. Knowing the mounts on the '48 Ford rear end are sitting 7" off the center, toward the rear, it means I have to move/add/raise the rear of the frame. The other option that I've read about is to make the mounts sit top dead nuts over the axle itself which sounds like many folks do. My fear in doing this is actually a couple of factors: welding to the old tubes on the axle can warp them or ruin them completely, then it's back to the parts hunt. Secondly, I'll have to still do the kick up in the rear, probably higher as the weld on spring perches are now on top of the axle, making the damn thing sit even higher yet, where the stock perches of the '48 axle sit level with the tubes themselves. I'm estimating the difference being 4-5"s overall in height.

So my mental plan is to keep the stock perches in use (unless someone has some logic that I can see that changes my mind) and while doing the kick up, also lengthen the chassis by 7" so the wheels/tires sit right in the middle of the rear quarter panels so it looks just right. My diagram that's at the top is sloppy, but I drew it up quick before my 2 year old got ahold of it and destroyed it or drew on top. I think the general idea should work. The only thing I now see that I didn't doodle in are the radius rods which should help with the offset of the spring location and of course the shocks too.

If the plan goes well, the rear cross member should be sitting right in front of the rearward trunk braces so the body will sit still looking stock with only big mods happening to the sub rails/trunk scoop area to compensate for the kick up and movement from the stock location.

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