I can’t, it’s part of my condition. I have the frame almost complete in design phase, so what do I do? That’s right, I change everything forward of the firewall.
I’m trying to get unsprung weight down so the tires will be easier to keep on the road over bumps. This means making everything between the frame and the road lighter, and one way to do that is indirect springing AKA push/pullrod suspension. The thinking is that the connecting bits between where the push or pull rod attach to the moving part of the suspension are : a. lighter than the spring/shock unit, and : b. more sprung than unsprung weight. The coilovers on a rod-activated suspension are believed to be 75% sprung weight with the same said for the rocker. The rod is 100% unsprung, but the total of the rod, unsprung weight of the rocker and unsprung weight of the coilover is (hopefully) less than the unsprung weight of the direct-acting coilover. Another thing is the motion ratio, or the ratio between how much the wheel moves to how much the end of the shock that moves the spring moves. With the rocker arms the effective wheel rate can be anything just by drilling the hole where the shock bolts to the rocker a different distance from the pivot, and a long travel softly sprung shock can be used on a very stiffly suspended car.
Now what this does is change everything that connects the front axle to the frame. There are no spring mounts hanging out in the breeze and everything is tucked up tight. Google a shot of a modern F1 front end as an example. This means the parts of the frame that would have interfered with the tires when they were steered aren’t there any more, but it also means that I don’t have the same radius of gyration to work with as I would with direct springing. And since torsional stiffness is proportional to the 4th power of the radius of gyration that’s kinda important. Like this is going to make the front a whole lot less stiff unless I add a lot of bracing to reduce the average length between pivots or whatever the technical term is for bracing the heck out of the structure. It has been more than 40 years since my last structures class, the one where we built a scale model bridge with 1/16” square balsa and a piece of Bristol board for the road deck, so my terminology is a little fuzzy. Anyway, major loads would be carried by the .060″ wall tubes, and also the braces since I could use the cut-offs from making the major pieces of the frame.
Another thing on my mind has been replacing the heavy steel tube axle and steel spindles with a carbon fiber axle and aluminum spindles. I have even been heavy thinking about how to construct said CF axle. What brought this on is I have had to move the steel axle I bought back when I thought I was going to be using the minivan engine and drivetrain, every time I needed to go in or out of the office, because Mrs the Poet didn’t like where she put something and insisted it belonged in my office. So because leaving the axle on the floor was a tripping hazard and because it blocks access to the door when leaning against the wall, the axle has to be moved every time I go in or out of the office. And I have come to realize that it is freaking heavy and detrimental to handling because it is 100% unsprung weight, and will work to get the car built but needs to be replaced at the earliest opportunity. Between the axle and the forged steel spindles we are talking about 80 pounds (+/-) of unsprung weight on a 1450 pound car. And replacing it with a 16 pound axle carrying 2 7 pound spindles. So replace 80 pounds of unsprung with 30 and the hubs that fit those spindles are lighter than the ones that fit the spindles I have now, by about a pound.
And final note, I screwed up again in my last correction. I used an old value for the rollover hoops of 16 feet back from when I didn’t have a good idea as to how far the rollover structure had to be over my head. The actual value is about 11 feet which takes a metric buttload of weight off the frame. Well a little bit because 5 feet times 1.75 pounds per foot isn’t much, about 9 pounds per hoop, or 17.5 pounds total. But every pound, every gram, adds up, and the fewer there are to add the lower the total will be at the end of the project. Also the less metal I have to buy, the less money I need to spend. Also important.
On top of only getting a little over 2 hours of sleep yesterday I had to spend a lot of time running around. I had a check to deposit to pay my property taxes, and also deposit a return check for something Mrs. the Poet bought mail-order that was sold out when they filled the order, I had to pick up my pull from the Local Comics Store (Unbeatable Squirrel Girl if you must know), and then I had to get my toes done. There was a line to get my toes done so I had to wait about 45 minutes waiting for a tech to get my toenails shortened. With this new pair of shoes (well, the most recent pair I bought) I have to get my toes done more frequently because there is a seam across the toebox just in the right place to snag the tallest nails and pull them away from the nailbed. Trust me, that gets old really fast. So I hit the road just after 1500 after taking care of getting the internet and cable fixed semi-permanently, and didn’t get home until about 1900 and never got more than 3 miles from my house.
Other things, I put the word out locally I need an engine and transmission for the Sprint-T, but TBH I’m not holding much hope at finding them at a price I can afford. But, the local junkyards and auto dismantlers know I’m looking for a RWD engine/trans combo cheap because I don’t have any money, and they say they’ll call if one comes up. Fingers crossed someone calls.
Outside of my little world, here in the US we had another High School mass shooting. Another mass shooting, this time in KY, a day after the last one over in Italy TX. I only found out about the one in Italy because it was brought up in the local news as “color” for the KY shooting. Italy TX is on my route to Waco and the CMA land by bicycle. I used to have a friend living in Waco who I would visit by bike, and I would also stop and overnight there when I rode my bicycle to CMA. So Italy is there and back by lunch by bike from Casa de El Poeta. And was the location of first high school mass shooting of the week, which is a phrase nobody should ever use. We know what causes these high school mass shootings, easy availability of semi-auto guns of all types. And we all know why that is. And we all know who is responsible for the easy availability of semi-automatic firearms so that emotionally fraught high schoolers can shoot up their schools. It’s like nobody learned anything from Columbine.
Getting away from stuff I have no control over to other stuff I have no control over, I have really stiffened up the frame on the Sprint-T. As part of the bolt-in frame that allows the body to be installed after the frame I’m bracing from the torque arm pickup to the upper corners of the roll cage, except for that bothersome corner where the driver sits blocking the upper left rear corner of the cage with his (fat) head. I’m thinking that just bracing against the right corners may not work as well as that inverted pyramid as far as chassis rigidity is concerned, but it’s a heck of a lot better for being able to see and drive. And it does make the chassis more torsionally rigid, just not to the same degree as the inverted pyramid. This is a place where I have to decide if this is a frame part or a roll cage part. If it’s frame then I can make it from 0.060″ wall like the rest of the frame, but if it’s roll cage then by the rules I have to use 1½ diameter by 0.120″ wall like the rest of the roll cage, which is much heavier, but “much” is relative. The brace weighs 9.23 pounds +/- as a frame part, and 17.69 as a roll cage part or 8.46 pounds saved as frame over roll cage just for those 2 tubes. And I have to go through this decision process for just about every tube in the frame aside from the roll hoops and braces between the hoops.
While I was walking Monday evening a pretty girl drove beside me, rolled down her window and shouted out how sexy my body was “WHOO!” And I’m just vain enough to appreciate it. I was wearing a pair of my “just loose enough to let me walk” shorts and a shirt that wasn’t skin tight, but very much “not baggy”. I may be old and died once, but I’m not still dead. I like it when
a woman someone tells me I’m sexy, even if I’m not interested in them.
The catcalls had the effect of causing my tension about the TGS2 to ease somewhat so that I’m not stressing about the build any more. I’m sure that if Mrs. the Poet had been the one doing the catcalling I wouldn’t be stressing about anything.
Anywho I did some looking up to find out how much the RWD version of the transmission in the donor vehicle weighed for a possible front engine RWD bucket and it looks like 100 pounds even. So that stuff to move the output from the end of the transmission to the other end and connect to the front wheels is either extremely heavy, or the previous reported weight for my transmission was way over reality. TBH I would be overjoyed if the 41te was in the 125-150 pound range, that would be 50-75 pounds off the rear axle. I tried to find another source for the 41te weight but all I found was another referral to the link with the 200 pound shipping weight with pallet less fluids. And the link to the 62te weight of 220 in same condition. What I really need is to have the donor vehicle in my drive with a hoist and a scale. Then I could stop looking for information on the web that might not even be there. Looking up the weight of a standard shipping pallet (bare) gives a range of 33 to 48 pounds which gives my transaxle a possible weight range of 152-167 pounds. 🙂 And the fill chart adds 65 pounds of fluids to that empty weight. 😦
So now I’m back to looking at odd tire combinations like 245/45R17 front and 315/35R17 rear Mickey Thompson Street Comps . The fronts are about right for the total weight of the car while the rears would be suited for a car much heavier than the TGS2, so I’m not giving up front grip, just going to extremes for rear grip. Welp, you gotta do what you gotta do. And I could totally drive around with those tires and just swap springs/shocks for Goodguys. They have the same diameter as the 255/60R15 Radial TA tires I was looking at for the street back when this project had a SBC in front of the firewall instead of a Chrysler V6 in front of the rear axle. So I can use the design ride height from all the way back to the beginning of this project back when it was the Sprint-T.
And my arm and neck are tingling and working wonky, so I’m putting this one to bed right now.
Yes, I’m still thinking about the rear suspension on the Mid-Bucket, mainly how to make it lighter. And simpler if I can. One way I can do both is to eliminate the adjustability and just weld the adaptor plate directly to the truss. I hate to do that, both because of all the time and brain processing cycles that went into the adjustable adaptor, and because throwing a little negative camber for racing is a great way to increase total grip and reduce oversteer a tad. I would probably do that for street, too. But I can do that in the jig while welding the truss, probably holding to a half degree precision if the jig is stout enough. That is a mighty big IF.
Which brings me to the other reason for adjustability, correcting for floppy welding jigs for the de Dion truss. And for weld joints that move from thermal stress during construction. I don’t know about how floppy the welding jig is going to be, I mean it’s not like I’m building this to make production runs. I just want the ability to make crash repairs when and if necessary.
And while I was on my walk I was thinking about upgrading to the Pentastar and the 62TE after I get a bit more bucks up. Again I forgot to save the engine and transmission mount picture and now I can’t find it again so I can’t show you how similar the mounting points are between the two generations of minivan. But without having one of each side by side to compare I can’t say for sure it’s a drop-in swap. It’s pretty damn close.
Moment of levity, Amazon apparently thinks I eat enough fancy Italian Provolone cheese to justify buying it in $1K chunks at a time. I have no idea how they got that idea since I get that kind of cheese in the $5 shaker bottle at the deli counter mixed with parmesan. Not that I don’t know what to do with a good Provolone, I do have a Sicilian grandmother and Mrs. the Poet is adopted Sicilian, and I did spend a couple of years working for pizza places helping make the pies.
I got to use the high-precision scale when we were shopping today and I was sure not to rest against the rail on the back that is part of the machine but not part of the scale. Anywho I came in under 210 even after a big breakfast, so progress is being made on destroying the heart-clogging fat monster. I don’t know that I will ever reach 160 while still alive and also still be able to get around on my own, unlike last time, but dangit I’m trying.
Billed @€0.02, Opus the fat but still Unkillable