I spent most of last night staring at my eyelids or looking at my phone. What happened was I stumbled on a website selling upgraded T5 transmissions that could be shifted without using a clutch or lifting throttle.
Now they didn’t give a torque rating on the upgraded clutchless transmission, just “stronger” than the factory 300 foot-pound rating, and reading about the fragility of the transmission proves that’s a hard limit. Since the engines I’m looking at are much higher rated for output than that the stock T5 is never going to work, but this company sells parts and complete transmissions that claim to greatly increase that throughput.
Of course I had to see how this 75 pound transmission would work for my application including figuring out cruise RPM and how fast the car would go with the “40MPH in 1st” final drive gearing in 2nd (about 70). My mind wasn’t working right when I tried to figure “40 MPH in 1st” to “RPM at 70 MPH cruise in 5th”. I mean I know it’s just comparing ratios, except there are several ratios and I couldn’t get the equation to work out. There is the ratio between RPM and speed, the ratio between the street and race tires, and the ratio between 40 race and 70 MPH cruise. When I’m awake, that’s not a problem, but last night my brain was sleepy and did not work to let me calculate that it would cruise at 1850 RPM at 70 MPH in 5th and not being able to figure that out wouldn’t let me sleep.
But as I was looking for upgrade parts from other manufacturers I found this that has been track-tested at 550 ft-pds without breaking on slicks with a significantly heavier vehicle than the Sprint-T.
G-Force upgraded T5
But anywho I was looking for manual transmissions and stumbled on this: Strong 5-speed transmission. The super low 1st gear option only supports 500 foot-pounds but also only weighs 99 pounds (well all of them weigh the same, but the one with the lowest 1st only takes up to 500 foot-pounds without breaking). And that low ratio 1st gear turns 1860 RPM at 70 MPH in 5th with the same final drive that turns 6000 in 1st with the same final drive. Also tops out in 2nd at 66 MPH with the race tires. Obviously strong and light are not cheap at approx $2600 plus freight and taxes.