There was a Can-Am car that Jim Hall built with a 2 speed Chevy Powerglide based transmission.
There was another sports racer built by a Canadian engineer, Bill Sadler, that made his own 2 speed out of a Halibrand quick-change axle by adding a second set of spur-gears. The car was super light and had a Chevy 327 V8 so he didn’t really need and more ratios.
Good point. The spacing of the sub overdrive gears would matter as well. 0 - 60 might not need to go beyond 2nd out of 4(D) gears in some cars. It might be better if 3rd gear topped out just above 60 in that case. But if 0 - 60 is done in 5 seconds, the added time needed to shift in to another gear might slow you down.
Top fuel drag racers only have one speed!
No it isn’t, because what I call the overdrive gears are never used in a performance application. 1 2 3 4(D) 5 6. Only 1 to 4(D) are going to be used. 5 and 6 are overdrives which are used to save fuel. If more overdrive gears are added it won’t affect performance, since the non overdrive gears should remain the same.
Whether they are used in a “performance application” or not, it is still only about total spread. Many sports cars used 5th as a “performance” gear (in your terms). First was left and down, NOT inline with 2nd on many sports cars. 1st was not a “performance” gear, in your vernacular, as it was not used to enhance the performance of that car only to launch it.
Not always true. But, if there ARE more overdrive gears added, the final drive can be increased numerically to gain performance. I.e. If I add a 7th gear (3rd overdrive) and drop the final drive from 3.55 to 4.56 I can stay at the same RPM at highway speeds but accelerate off the line MUCH faster. Proving this point…
Then it wouldn’t be called a 3rd overdrive. You adjusted your final drive so that 5th out of 7 is now drive, instead of 4th out of 6, so you still have only 2 overdrives. Overdrive as I am calling them are gear ratios above which the vehicle can reach top speed, not which speed is a 1:1 ratio in the transmission.
Now that you have a 5 speed manual transmission, can you shift through all those gears fast enough to not lose speed, compared to 4 speeds, when going from 0 to 120?
If it was all about which speed is 1:1, then 1st gear could be drive, and all the other gears could be overdrives, with a 12:1 reduction in your rear end instead of 3.55.
This discussion is completely about semantics as stated by the late writer, L.J.K. Setright, the major reference for the Wikipedia link you shared. With all due respect to Setright, the argument is semantics, not reality.
How would you define overdrive on a front wheel drive vehicle?
Now you are just being ridiculous and argumentative . The very same things that earn you your time outs/
I’ve been test driving some low mileage (under 15k miles) C7 Corvettes. I only want a manual, so the C8 is out. They have 7-speed manuals. 7th gear is really only used on the highway over 65. Below that you really lose torque. Friend who owns a C7 has gotten 30mpg on a long trip cruising at 75 in 7th in Eco mode. That’s better MPG then my 2014 highlander.
Remembering my early 70’s nova, 2 speed automatic!
GMs 2-speed power-glide. It was in a lot of GM vehicles back then.
Powerglide to TH350 swaps are possible in the 67-69 Camaro and early 70’s Nova’s. Reportedly an easy bolt in change.
They were in the Chevelles also.
The Glide (Powerglide) is still widely used in Drag racing today in light weight big torque (mostly big blocks due to there long torque curve) cars, and they can be found behind ALL the big 3 OE’s engines… That in itself should tell you that rear gears, weight of the vehicle, and the torque curve are the main thing that determines how many gears… You also have to be able to control your traction not only on launch, but also down the track…
A recent poll showed 9 out of 10 BBC engines prefer the TH400 
I have numerous TH400 (and M21/22) laying around. The Powerglides were kicked to the curb years ago…
I missed something here somehow, what are y’all calling OD on a transmission??
Anytime the output shaft in the transmission is turning faster then the input shaft, it is in OD (overdrive), that is what overdriven is, same thing with Supercharger pulleys, the crankshaft being the input shaft and the blower being the output shaft…The more overdriven the faster the output shaft or boost with a supercharger (blower)…
Yep, that’s the definition 99% of folks follow. The other definition tossed out here is any set of gears that don’t allow the vehicle to achieve a higher speed than the next lower gear is an overdrive.
There you go again, confusing people with the facts😁
Really, you are concerned about 0-60 times with a Ford 300 ci in-line six?
In that case, I can take almost any given vehicle with a N/A engine and add 50% more boost (more HP/torque) to it without changing any gear ratio in the vehicle and the OD gear now changes to a different gear???..???
That would mean that the OD now becomes a floating OD depending on power output…
According to that, I had a Nissan Sentra 4 speed, that 3rd and 4th gears were both OD even though 4th was a 1:1 ratio… Yeah, OK 
In a world of front wheel drive vehicles with integrated differentials, how do you define overdrive now?
Overdrive is more accurately defined as any gear above which the vehicle can reach its top speed. It exists for economy and reduced wear. When overdrive was added on to traditional drive trains, the highest not overdrive gear in the transmission was always 1:1, and the overdrive went beyond that. To maintain tradition and compatibilty, it has been kept this way. So a transmission that has a less than 1:1 gear ratio can be called an overdrive transmission, and this works for traditional rear wheel drive vehicles. Had overdrive existed from the beginning, it would probably have been designed as 1:1 ratio in the transmission, and a lower gear ratio rear end would have been used. This is what happened when front wheel drive transmissions were created.
Keeping Drive as the 1:1 ratio offers a silght performance boost since a 1:1 ratio has less loss. So your top speed is maybe 1 MPH faster than if the overdrive was the 1:1 ratio. The trade off is a slight decrease in fuel economy for highway cruising by not having the overdrive as the 1:1 ratio.