# Daily Archives: March 22, 2017

## Still thinking about the rear suspension on the Mid-Bucket

Yes I was being dangerous again, thinking and all. Basically I’m thinking about details now, how to arrange the heim joints on the plate so they don’t interfere with other bits and are still adjustable for what needs to be adjusted.

My first thoughts were they needed to be set up in an equilateral triangle with one located center bottom. Then I ran some adjustments in my mental model in that configuration and there too many interactions in that configuration. What it came down to was every adjustment would change another parameter that did not need changing (or maybe it did but not at the same time and maybe not in that direction). So, change to a right triangle with the sides adjacent to the right angle located vertical and horizontal. Changing the camber will change the toe slightly but changing the toe doesn’t affect the camber. The longer the distance between the vertical pair of heims and the toe heim the less a camber change would change the toe. Thinking about it more putting the toe heim on the horizontal centerline of the rear axle with the camber heims equally spaced in relation to that line would give the least toe change with camber adjustments, especially if the camber heims were adjusted in equal and opposite directions. So, maybe not equilateral, but isosceles with the point on the horizontal center of the axle and the short side vertical.

Now that that part is decided how to connect it to the de Dion truss? The reason the equilateral triangle first suggested itself was using the horizontal part of the truss to support two of the joints and a side support off the vertical for the third. And as I think about it I can get zero interaction with the right triangle by leaving one joint fixed, and adjusting the other two for toe or camber, depending on which axis they are on. Which tells me that the horizontal pair mount to the horizontal truss, and the vertical pair the vertical, and the heim that is on both axis is the fixed one.

See how problems can be solved if you just put them in words while thinking in 3 dimensions? I know, not everyone can do that, I have what amounts to a 3D CAD program in my head. What frustrates me is I can’t just copy and paste from my head to my computer like I do when I write stuff on my phone. I mean I can see it perfectly, but I can’t reach in and pull what I see in my head out where everyone else can see it, and I lack the skills to enter what I see into a real CAD program, and the patience to learn how. I know, that last one is on me, my problem. But I can even see how the flanges for the various heims interact to add support to the mount for the hub bearing with minimal added weight. Just connect them around the bolt pattern for the hub bearing and they have enough vertical depth to keep the mount from flexing. I just need to leave enough room for the bolt heads and a socket to drive them into the holes on the flange on the hub bearing. All the major forces go directly into that hub mount, bypassing the de Dion truss which has been reduced to keeping the wheels pointed in the right directions on two axis and the same distance apart all the time.

Speaking of the same distance apart, it looks like this is gonna be a very wide bucket, about 6′ 3″. The front axle is going to be 56.5″ wide compared to the usual 48″. That’s because the hub-to-hub width on the donor vehicle is right at 65″± compared to 56″± for the usual hot rod axles. This solves a lot of problems with the suspension, while introducing others. But mostly it solves problems or makes them tiny. And tiny problems are either easily solved or ignored.

And on that note it’s time to say buh-bye until next time. Opus the Unkillable