Daily Archives: July 20, 2018

I have internet back!

I am so glad to be back on a full-size (more or less) keyboard. The fix was so annoying, it wasn’t the interface board that was out, the µP controlling the interface board needed a hard reset, as in push a button on the board to send s signal to the µP to do a hardware reset. Now I’ve done some hardware back in the day, but I have never seen a µP that didn’t do a hardware reset when coming back from a power loss, but then again my last work with µP was back when the Zilog Z8 was cutting edge and I connected a TI speach processor to one for a prototype toy for the toy company I was a co-owner for. You could also use the speach processor for sound FX. But anyway for the online tech remote accessing the situation it was impossible to tell the µP stuck in the POST (Power On Self Test) loop from a fried interface board. The return signal is the same, nothing. Unfortunately the reset button is behind a cover fitted with tamper-resistant screws and they have to send a tech out to push the button or replace the fried board.

Anyway, this left me with lots of time to do the most dangerous thing I can do: think without interruptions. And what I thought about was the Sprint T frame, Subaru engine edition. I had previously dismissed using the square front hoop design as ugly but as I had nothing but time these last few days I used the actual body and some 2 by 4s I had lying around to do a mock up of sorts, combined with a little basic math and trig to calculate important stuff like will the tires hit the frame at full bump, full lock, or full droop or any combination of non-conflicting parameters. And it looks a little “off” to have the legs of the front hoop so far away from the body, but it’s something I could get used to because you would not believe how much that increases the torsional stiffness, and it also improves the beaming stiffness slightly.

Anyway, verbal description since I still haven’t figured out how to get the drawings out of my head and into the computer. The front and rear hoops are the same size and profile but have different bracketry hanging off them the diagonal from the top of the rear hoop is straight, but the opposite diagonal from the top of the front hoop to the bottom of the rear hoop isn’t. That diagonal makes a detour to collect the front mount for the swing arm that locates the rear axle and also connects the coilover to the rear suspension. That then continues forward until it intersects with the diagonal from the top of the rear hoop, and the diagonal from the top of the front hoop connects to the intersection of the rear hoop diagonal and the lower half of itself so that everything triangulates. The top of the coilover for the rear axle connects to the rear hoop below where the locating rod from the brake floaters connects, or maybe they are co-located, because I still don’t know how long the reaction arm is on the floater. It might be long enough that it sticks up higher than the coilover, but then again it might not. Moving on, there are two forward-running members from the front hoop per side, one from the top and one from the bottom, to the front spring mount, and another from the bottom to the front crossmember/diaphragm. Now I’m still trying to figure out which way I want the front diaphragm to connect to the rest of the frame. One way would to continue the body mount forward to pick up the engine mounts and steering box mount, which simplifies packaging, but adds weight because I would have basically two frames, one for the body and engine, and the other for carrying the suspension loads. The other way would be to have the front rails go from the lower corners of the front hoop to the center of the front diaphragm, and stretch the engine mounts sideways to meet the rails. Both methods have points that increase weight, in that the longer engine mounts will weigh more by sheer size and may need to be made from thicker material because of that, and extending the body mounts to meet the front diaphragm adds 2 extra chunks of metal that wouldn’t need to be there except to collect the engine and steering box mounts. And speaking of the steering box mount, either way it’s going to be a mess, less of a mess with the two parallel rails from the body mount, more of a mess with the rails that meet at the front, but either way a mess. Looking at it without getting into fine details the two rails that meet at the front diaphragm is lighter basic structure but may be heavier after the mounts and brackets are added in, compared to 4 rails with two parallel spaced the same as the body mounts and two running from the bottom outside corners of the front hoop, and a more complicated front diaphragm. all with more material.

And while I was sitting here thinking about how to describe this frame in words I came up with a simpler and lighter way to mount the body. But it’s getting late and I have a lot of e-mails to catch up on. Not as many as I would if I hadn’t been burning my cell phone data keeping up with it, but enough that I really don’t have the time to pound out another 500 or so words describing what I just came up with.