We lost Internet last Saturday so I have been burning through my phone data trying to keep up with my web comics and watching my unread e-mail count
approach sail by 1K. I have also been thinking about the T-bucket rear suspension. Thinking may be the most dangerous thing I do, especially when it comes to building things, like cars. But in this case I was thinking about reducing costs by using parts I bought when I was thinking I was going to use a V8 engine in front of the passenger compartment instead of a V6 behind it. Specifically I was thinking about the swingarm links I bought to locate the rear axle fore and aft. They were also designed to use as the lower mounts for coilovers which would mean the only thing the de Dion beam would have to do is hold the knuckles upright and the same distance apart all the time, since the weight of the car would be supported by the swing arms connected to the knuckles and the lateral links from the Watts link would also connect to the knuckles.
What got me thinking about this was seeing if I could mount the brake disks to the outputs from the differential and the calipers to brackets attached to the transaxle. I can’t because there is not enough room for the disk next to the transaxle, but while I was thinking about mounting the disks and calipers there the thought came to mind that all the forces that had been going through the de Dion beam were going elsewhere leaving the beam with pretty much nothing to do except keep the wheels apart. Then the swingarm links came to mind for removing the weight of the car from the beam, and the rest just snowballed from there. Unfortunately I wasn’t able to put the brakes on the transaxle, so I will still need two fore and aft links per side, one to keep the axle from climbing inside the passenger compartment, and a second lighter link to keep the brakes from spinning the beam around the half shafts. The swingarm link is very strong and will be attached to the knuckle on the bracket that holds the knuckle, in line with the horizontal axle centerline to transfer the weight and the thrust from the tires. This lets the bracket be lighter because it doesn’t have to move the weight into the beam, and the adjusting links that change the camber and toe can also be lighter because that are not taking bending forces from supporting the weight of the car. The second link can be much smaller and lighter because all it will need to take is the brake reactive force and prevent the beam and knuckle from rotating when the brakes are applied. It will attach to the same bracket that holds the ball joint that transfers the lateral forces into the beam and also that takes the lateral forces from the ball joint into the lateral locating link from the Watts link. So that piece will have the ball joint in the center with the lateral links to the rear of the car next to the ball joint and the link that controls reaction to the braking force in line with the ball joint and also the support members that hold the knuckle to the beam on either side above the brackets that connect the links.
Something else I was thinking about was where to put the gas tank, and also how much of a riser I would need to be able to see out of the car and endure sitting for 4 hours at a stretch. Then I saw where the gas tank was on the original model T, under the seat. Now most people think this was not a good idea, and given the gas tank technology of the era it was a very bad idea. But in this day and age we have fuel cell technology that can withstand massive amounts of impact force without rupturing and leaking gas, to the point that if you are sitting on the gas tank and something hits you hard enough to cause the tank to leak you won’t have to worry about the gas catching fire and burning you to death because you’ll be dead from the impact first. This has many serendipitous effects, including making the car shorter because I don’t have to leave room behind the transaxle for the tank, and reducing the change in car attitude with change of load because the lever arm for the gas tank is in front of the rear axle so that some of the load is carried on the front axle instead of coming off the front and getting added to the rear. There is another technical benefit from moving the tank forward from the far rear of the car and putting it in the middle, a reduced polar moment. Without getting too technical about it think of it as reducing the length of the dumbbell that is the weight and balance of the car because all the masses are closer together in the center of the car. Also the fuel cell gas tank guarantees at least a 9″ riser for the seats so I’ll be able to see out the front of the car. But how will I put gas in the car, you might ask if you really cared. Easy, just unlatch the seat riser top/seat base and tilt it forward then open the gas cap.
And I also got better information about the power and torque peaks on my engine, and it is even worse than I thought before. The 1996-7 3.8 l engine has a power peak of 166 @ 4300 RPM (!) on a 6000 RPM redline, and a torque peak of 227 @ 3100 RPM. This means there is tons of untapped potential in this engine if I can just unlock it. As I posted earlier since I’m going to have to make tube headers to install this engine in the bucket I might as well make them as racy as I can to try to tune as much power across the band as I can get with (relatively) large tube diameter for a higher torque peak from exhaust tuning combined with very long primary tubes to get as much power at the low end of the range. The Jeep cam for this engine has a lot more power at the top of the RPM range (205 @ 5200) and more torque higher in the RPM range (240 @ 4000). The RPM numbers I posted earlier were for a car version of the engine with much better exhaust with the HP and torque numbers for my van version.
And as you probably noticed we now have internet back. Now I have 1.2K emails to catch up on. And the web comics I couldn’t remember the URLs for which was most of them.
Billed @€0.02, Opus the Unkillable Badass