First, let me introduce myself. I am a professional mechanic specializing in drive lines who apparently can’t get enough car stuff. I realize that transmissions are a complicated topic. I understand most people are perfectly fine with the two sliders provided, and don’t know or care what a final drive is. Here are some suggestions for the overly technical minded people who would enjoy this feature. I think it would be wise to maintain a radio button for “simple mode.”
I would like to describe, hopefully in brief, a transmission designer.
Case material (like block/head):
This will apply to both automatics (auto) and manual transmissions (man). You would have four options:
Cast steel - cheapest and lowest manufacturing cost. Strong but heavy.
Milled steel - more expensive to make, but faster to mass produce. A bit lighter, and stronger.
Cast aluminum - relatively cheap to make, light and strong enough for most applications.
Milled aluminum - quiet expensive, but very light and strong.
Cast steel could handle high Torque (TQ), but low RPM. Milled steel can do the same TQ, but higher input speeds. Aluminum would handle less TQ but higher RPM and cools better. Milled aluminum is back to near steel TQ numbers, but still much lighter.
Just some for instance numbers, the cast steel Eaton ES-(series) can hold over 1000 Ft/Lbs, the milled aluminum GM/Ford 6R140 can handle around 800 Ft/Lbs. Do remember these are commercial transmissions selected for being the extremes.
Gear material (like piston/con rod):
Cast steel - cheap but rough. Low(ish) torque, low speed only (4000?).
Machined steel - costs more, but way stronger and higher speeds.
Lightweight steel - TQ between cast and machined, much higher RPM.
Treated steel - Very expensive, very strong.
The higher torque a transmission is built for, the higher percentage of engine power it consumes due to its own weight. Those two selection would be mandatory so to speak, when you went to advanced mode you get the following options:
For all transmissions:
Integral or detachable bell housing. Integrated bell housing means the trans is stronger, but is you assign it to an inline engine it cannot be fitter to a boxer, or either V style, and you must make a new variant. Detachable you can bolt it to whatever by changing the bell housing at a comparably low cost.
For manuals only:
Counter shaft number:
Single - basic compact 2-6 speed transmission. (Like a Aisin-Warner AX15)
Dual - Nearly double the input torque, much larger, heavier and more expensive. 4-10 speeds (Like a Semi/Lorry). The old GM SM420/465 pickup manuals also ran an over-under counter shaft (really tall).
Synchronizes - Increase costs, but hugely improve driveability. Available from the 50’s on.
For automatics only:
Conventional planetary - basic working part of an automatic.
Ravigneaux set - More compact (lighter), but slightly weaker. Available from the 50’s on.
Stall speed - lower is more efficient, higher is more drive-able. Too low, and the engine may lug/stall, to high and you wont move.
Bands or clutches - Bands are cheaper to make, but consume much more engine power to work. Also increases maintenance costs. Clutches cost more to produce, but improve efficiency and reduce maintenance. Clutches available from 90’s up.
PCM/TCM controls. An automatic with a transmission control module can be connected to any engine without additional development costs. The powertrain control module is more fuel efficient and driveable, but needs engineering time to match that transmission to that engine.
Advanced mode also allows manual entry of gear ratios, and naming of gears. For example the SM465 was a four speed, but only three were for on road. The pattern was L-1-2-D (Low-first-second-direct), but the T-56 pattern is 1-2-3-4-5-6 (first-second-third-direct-overdrive1-overdrive2).
I have not touched on DCT, or CVTs. In short a DCT is a dual countershaft manual that must use an integral bellhousing, and TCM. Much better efficiency than a conventional automatic, but much higher maintenance costs. I do not have a working knowledge of CVTs.
I have attempted to make the transmission designer similar on form and function to the engine builder. Transmission specs would include things like:
Max input torque
Max input speed
Weight
Efficiency (the percent of engine horsepower consumed during operation)
Size (being similar in metric to engine bay fullness)
Of note, trans-axle AWD systems would require a different variant than FWD due to casting requirements of the case half (I’m a mechanic, trust me on this). In addition trans-axles cannot use detachable bell housings. Longitudinal builds require a minimum wheel base (more gears or heavier case means longer transmission). Also the addition of a transfer case/transfer box needs even more wheel base. For example, the AX15 only can handle 300TQ, but is under 3 feet long and weighs about 100 Lbs, the 6R140 is closer to 5 feet long, and weighs over 350 Lbs.
Hopefully this has been thorough, but not too long winded. I look forward to additional thought, and suggestions. Happy crafting.
