Moving me forward of the original firewall really changes the frame design. And I’m not just talking about swapping the seat and gas tank around, either. The original frame could be considered an exoskeleton as almost every part was outside of the body to some degree in order to increase torsional stiffness. Well the new frame is much smaller, only 27″ wide to fit the firewall on the body, up to the point the engine and drive bits mount which will have to be wider because of the transverse mounting.
Basically the part of the frame forward of the firewall are going to be like a ’50s Indy roadster. This is still going to be hella stout and light, but the frame members are going to be different than the Sprint-T derived frame. This frame is going to be designed for a mid engine from the get-go instead of trying to cram a mid mounted engine in a front engine frame. The other major change is all of the frame is going to be round tube, most 1.5″ diameter and most 0.060″ wall thickness except for the bits around me that have to be 0.120 by SCCA rules. This will lighten the frame by a few pounds, but nothing spectacular. What will do the most to lighten the frame is tucking everything inside the body and doing the engine and transmission mounts first instead of making them fit what was already there. Also the Sprint-T was designed around a roll cage that won’t be there because the driver isn’t where the roll cage is designed to protect.
I can make this frame as stiff and light as the Sprint-T, it will just take a bit more brain work to do so. Instead of spreading the frame as far apart as possible I’ll have to concentrate on using internal structure for stiffness. It can be done, and I’m the guy who’s crazy enough to do it. Incidentally, the changes move the fuel tank right over the center of gravity of the car so the balance doesn’t change at all between full and no gas. The Princes of Serendip are victorious again! (Look it up)
On other fronts I need to get that brake hone this evening so my walk will be extended to the auto parts store. And tomorrow’s walk will be by the pharmacy to pick up more not-sad pills for my brain. Tonight I’ll be walking about 3 miles to get some bonus check-ins on my mobile game. I haven’t been able to walk as a workout for 2 days now and I need to stretch out a bit.
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.
One thing I have been thinking about is the rear suspension. Well two things actually. The first thing was it saves less than $40 for me to use the steel swingarm/spring mount in the Mid-Bucket suspension, and it seriously complicates the rear frame. The second thing was that putting the rear spring that far out on the suspension complicates the roll stiffness bias. Putting enough spring to give the right rate for a 2 wheel bump over the end of the axle just makes the roll rate too high for the light front end even with the front springs almost on the kingpins. Seriously I’m going to mount a spindle with the steering arm on the axle and put the side of a pencil against the steering arm with the point against the axle and turn the spindle back and forth and watch the mark on the axle. The point that is furthest away from the kingpin boss is the closest point of the lower spring mount on the axle. That will give me the most front roll stiffness I can get with just the springs. It still won’t be enough to balance the car with the springs mounted on the trailing arm or to the rear upright. So I either have to use a front anti-roll bar, or I have to mount the rear springs closer to the centerline.
Mounting the rear springs closer to the centerline means making the de Dion truss strong enough to handle vertical forces. I have been thinking about that, and if my sums are right putting a truss of 1″ square tubing with 0.5″ round verticals and diagonals on top of the 0.5″ round tube truss would support the rear of the car with adequate safety margin. “Adequate” in this context means no damage if I hit a few pot holes or slide off the track during a time attack run, it doesn’t mean taking the car off-roading in the desert.
The other thing I have been thinking about is how light I could get a front-engine bucket like the Sprint-T. By adapting an A-904 Torqueflight to a Pentastar V6 with a steel 9″ Ford rear axle I could get 1450 pounds without even trying hard. Start swapping out an all-steel 9″ for an aluminum and magnesium quick change in the rear axle and carbon fiber in the driveshaft and we are looking at a 1400 pound bucket with 305 HP on 87 octane regular without changing anything in the engine or calibration. Get serious about making the frame lighter with aluminum instead of steel and a space frame instead of a ladder and maybe 1375 pounds. About 4.5 pounds per HP. That’s like a 750 HP Corvette or Viper running on Regular gas. As in car*√-1, imaginary. Even with the frame from the Speedway kit we are talking a hot rod that could give anything short of a Hellcat or Z06 a run for its money 0-60 MPH, on 87 octane regular gas. There are 2 ways to make a fast car, 1) lots of power and 2) no weight. 1) is fast in a straight line, 2) is fast everywhere. I think I like 2) better.
Incidentally, did I ever say how I figured out that I needed to use different size tires and how different they had to be? The book Chassis Engineering has a graph of grip over load for a typical race or passenger car tire. The problem here is it’s a graph for just one size of tire, and has to be scaled for a different size of tire. The way I did it was to leave the shape of the graph pretty much alone for the big tire and then scale the grip by dividing the load and grip by the ratio of the squares of the widths between the tires. F’rinstance the street and street tire autocross will use 195/50 fronts and 245/40 rear tires so the graph was scaled down by a factor of 1.58. This is not perfect, but it is close enough that I can come close to getting the balance right with just the springs and a light anti-roll bar to make up the difference of not having the perfect spring rate. For street and highway driving I will need slight understeer for stability, but for the autocross I need a slight oversteer for better turn-in and rotation through the middle of the corner. I’ll be able to do this with just a swap of shocks and springs which I have to do anyway because I need a lower ride height for autocross than for the street. Theoretically I could do that without changing springs and shocks but that would require carrying around a slew of scales and platforms and adjusting before and after the competition, or I could just do that once and pull those shocks off and put them in a case with labels as to which one goes on which spot on the car. Instead of spending time adjusting and re-adjusting the spring seats to lower or raise the ride height and move the weight around to balance the car in turns, I do it once at a test track and then just swap the coilover shock/spring units at the race from street to race and back to street in just a few minutes instead of the hour or so (if I get lucky) each way adjusting the spring perches.
And I have wandered around the verbal landscape long enough, time to wrap it up and do something else.
Opus the Unkillable
I was getting used to the idea that Mrs. the Poet was not going to be riding in the Mid-Bucket, but I just found out that unless I took all of the bracing out of the halo my BFF would never be able to get in, and also that my grandson was not going to ride with me either (his mother remembers my driving her and friends in a 2-seat sports racer from before I quit driving back in the mid-’90s). So I’m going to go Monoposto with this car. That means I’m only putting in the one seat in the center of the car. This will make getting in and out much easier as the escape route will be unobstructed, there will be a place to sit on top of the cage and swing my legs over, and I can put my feet on either side of the seat instead of standing on the cushion.
Going Monoposto will make racing easier by letting me see both front wheels going past the cones, and make driving between events easier by putting the snacks and drinks in easy reach on each side of the seat. There will also be room for a day bag on either side of the seat down by the pedals with a cargo net to keep them from interfering with the pedals. It will also let me move the seat forward because I have the whole width of the firewall to use as a foot box all the way up to the firewall, about 26″ of inside width. Compared to the Sprint-T this is like having the whole state of TX to spread out in after living in RI.
This will also require some changes to the steering column and steering box mounting which then feeds back into changes in the gas tank. The steering box will have to go in the middle of the nose with an access trench through the top of the gas tank instead of down the side when the driver sits on the left. The trench is also needed to give the master cylinders a place to go on the firewall. The alternative to the trench is just restricting the height of the fuel tank to what clears the steering box and column.
And now it’s very late and I need to go to bed. I will think about the Mid-Bucket some more tomorrow when I go get a latte at my local Starbucks with the cards I have been generously donated and earn 150 bonus stars and a free drink.
Billed @€0.02 and a Starbucks card, Opus the Unkillable
Mrs. the Poet has been complaining about how I’m “not helping” her throw away my stuff when she does it during the part of the day when I’m still asleep. I don’t understand this. I don’t complain that she’s not helping me write when I start composing stuff at 0300 when the Internet is fastest locally and I can get to reference materials most quickly.
So we reached a compromise, in that Mrs. the Poet will not start throwing my stuff away until I get up, and because we both have things to do over the weekend I will start helping her on Monday afternoon after I have had coffee. There is something in the garage that she calls a “box full of rusty metal stuff” that I’m almost afraid to open. Then we don’t go into the garage again until after I get up Friday.
On other things I’m playing some more Shadowrun tomorrow, and there is a late race on Sunday, the Las Vegas race for the Monster Energy NASCAR Cup. And now that I have a new tube of GOOP™ I can continue to mock up the Mini Sprint-T street version. I haven’t found a model kit that has the Pentastar V6 as an option so kitbashing is right out. But I have that first wheel glued up and ready to test fit to the tire when the glue dries. I’ll probably do that Sunday while I’m watching the race during commercials.
Billed @€0.02 Opus the Unkillable
Posted in Daily Feed, Department of DIY
Tagged conflict, Life, making model cars, Mini Sprint-T, model cars seldom kill people, Monster Energy NASCAR Cup, Mrs. the Poet, Pentastar V6, race, Sprint-T, unkillable badass
I was on a long walk to get some stuff at the hardware, and well, my mind also wandered. Specifically it wandered around the Sprint-T. What I was thinking about was what it could be like with the Pentastar 3.6l V6 DOHC aluminum block and heads engine that weighs a factory-claimed 326 pounds (as compared to the 545 claimed for the SBC and the 413 for the 3.8 pushrod engine out of the minivan) and delivers 305 HP in stock form. As a comparison the “performance” SBC in the first-gen Camaro was rated at 290 HP. In the Sprint T with the SBC and a TH 350 transmission I was looking at just over 1700 pounds empty, with the Pentastar V6 and the 42RE transmission coming in at 1450 pounds but that 42RE transmission would be dicey for racing use. The later models used 6 and 8 speed slush boxen that would survive racing but also weigh considerably more, the 8-speed being strong enough for the legendary Hemi. The transverse version of the 3.6 would bolt to the 41TE transaxle in the mid-Bucket and take 87 pounds off the weight and rear axle, while adding more than 200 HP over the engine as it sits in the minivan. Do I want one? Not if I had to buy it from the dealer with a car around it. Would I take a similar deal as I got on the 3.8l pushrod engine, remove a derelict vehicle to remove the stuff I needed to make a car for free? Hell I would even pay for a car that got wrecked in the back as long as it wasn’t more than $1K to get the 305 HP version of the engine and then swap the FEAD (Front End Accessory Drive) for the transverse installation. I mean 200 HP more and 87 pounds less would I take that? Hell Yes I Would Take That!
So the reason for the walk was to get the 7/32” drill bit and the small tube of GOOP for the bike and Mini Sprint-T respectively. I logged 3.93 miles and 25 checkins on Map My Walk and M Plus Places respectively and burned a lot of calories in the process. The weather was perfect, just warm enough and just breezy enough with a high overcast so that it was bright but not blinding.
And I have to get the rest of the stuff I do offline done so I can go to bed, so I’m putting this post to bed first, then me.
Billed @€0.02, Opus the Unkillable
Yeah I wanted to use another word starting with the letter “F” but that would make for a bad headline.
I have decided that since I can’t do the hot rod the way I wanted, or the alternative way that was offered, that doesn’t mean I can’t continue working on either one. I will work on BOTH switching back and forth as my interest waxes and wanes. It would not be the first time I have built something in my head I couldn’t make IRL. There is a lot of cross-pollination already between the two projects in frame design. And the good thing about building in your head is there are no budget restrictions unless you decide there are. That’s kinda what I was doing with the LS7 version of the Sprint-T. And for the Fantasy version of the mid-Bucket what should I use? There is a DOHC 4-valve per cylinder 3.6L Mopar V-6 in the current minivans that puts out 283 HP through a 6 speed OD transmission to motivate 4500 pounds of minivan, supercharge that to 350 and drop it in a 1500 pound bucket… But there are other transverse mounted V-6 and V-8 options out there I should be considering…
And recent events have me pondering if something or someone is trying to tell me something. I have been trying to ride this bike since early fall of last year and I still haven’t ridden it since I got it home and fell off trying to get off the bike when I got home. I have been trying to build a hot rod since the 1970s, and you can see how well that’s going. It’s like the things I want are the football, the universe is Lucy, and I’m Charley Brown… D:
Well I need to go pay for my phone and get a bit of exercise so I’ll cut this off before I get to crying in my Shiner White Wing.
Billed @€0.02, Opus the Unkillable
I feel accomplished today. I went for a walk and picked up something for Mrs. the Poet, then got some tools (files) from the hardware for working on the mid-bucket and the Mini Sprint-T, got a present for the B-Day party I was invited to on Saturday, and fitted one of the steering arms to the spindle all by 2100. I had to walk 4.2 miles to get all of the stuff done that I had to leave the house to do, and then spend about 2 hours filing tiny amounts of metal off the steering arm until it fit flat against the spindle registers. It’s a snug fit, almost an interference fit, but fit it does. The material is so hard that there were no actual filings, just a dark powder that got my hands dirty but didn’t actually spread anywhere. I used a mill bastard file that was designed for precision work by the captive brand for Lowe’s, Kobalt. It worked very well. Tomorrow I will take some pictures of the arm I didn’t work on and the one I did work on and show the difference in fit on the spindle.
I also used the walk to rack up check-ins on my phone game that pays me money to play. I hit my limit again. I may not be racking up the big points, but I’m still racking up points to get more gift cards. And then next month I start selling plasma to make up for the gigs I lost in 2016. So Yay! me.
PSA, Opus the Unkillable
I need to go to the hardware and get a file or 3 to fix the steering arms so they fit the spindles, but right now my foot still hurts, so I’m sitting tight and just chilling and reading Twitter and web comics on separate devices. I prefer to use my phone for Twitter, and my laptop for webcomics, so until just now I was bouncing back and forth between the two like some kind of screen addict. Now I just have the laptop active while I do the blog post. The weather forecast is that tomorrow and Wednesday will be much warmer so I’ll do my walk then and get the files. Actually I’ll probably go to Harbor Freight on the bus and get a whole set of files. And I can also use these to make the Mini Sprint-T, files are useful tools.
So I just finished my walk to get the $$ for tomorrow’s shopping trip and it was about the same temp outside as it was in my office when I left, but now my foot hurts again. Tomorrow should be better.
Instead of a merry Yule I went on a 4.22 mile walk to pick up the car cover I ordered last week so my parts car doesn’t get stolen by Codes. I’m not allowed to have an unregistered/inspected vehicle on property but as long as they can’t tell it’s unregistered I’m good. In TX current registration/inspection status is indicated by windshield stickers so if they can’t see the windshield they can’t tow the car out of my driveway. This car cover is supposed to go all the way down to the rocker panels on the bottom of the car, so to see the windshield they would have to come onto my property (legal) and remove the car cover (not legal) to uncover the windshield.
The weather was slightly above normal temperature for the date, which meant I could walk in shorts and a t-shirt to the parts store to get my stuff. Of course I can do that down to about 55°F, but colder than that and I have to start throwing on layers toot sweet. If I keep moving and there is no wind chill 55° is uncomfortable but not excessively so, but the conditions were 60°F and light winds while I was out. On the up side with all the walking I’m doing I’m burning a lot of calories. Not as many as when I was riding my bike everywhere, but lots more than sitting at my laptop.
On the Mini Sprint-T front some of the changes I’m making on the mid T-Bucket will transfer over to the Sprint-T and because the one is supposed to be the other only smaller it will show in the Mini Sprint-T as well. TBH I see the changes as an improvement for frame stiffness and ease of assembly for the full-size version of the car. For the model, it’s ehhh 6 of one half-a-dozen of the other.
Time to hit the hay.
Opus the Unkillable Badass