[nonsequitur]

Maximum input shaft speed is 6000rpm (the reason why the 6000rpm redline).
Variator (pulley) ratios can vary continuously between 2.416:1 to 0.443:1.
Final drive ratio has been displayed as 4.10:1 in magazine sources.

I just learned that the "constant ratio" of the gearbox is 5.76:1, and variator ratios used for the Steptronic "gears" are 2.416:1 (1st), 1.622:1 (2nd), 1.117:1 (3rd), 0.847:1 (4th), 0.675:1 (5th), and 0.562:1 (6th). Overdrive in D can reach the 0.443:1.

Depending on the speed from which kickdown is activated in SD, these same ratios are where the "shift" occurs at 6000rpm. The first "shift" will be at a unique ratio, and then the next one and subsequent shifts will occur at the next logical "gear" above. As an example, if you stomp on it to pass in SD at 30mph the gearbox will find a ratio that works to bring up engine rpm and get moving. The first "shift" at 6000rpm may not be any of these fixed ratios (say between 3rd and 4th), but the next one after that will be the next higher in the range (4th, then 5th, then 6th).

I'm not entirely sure I know how all these numbers relate to each other. How is 5.76:1 related to the quoted Final Drive of 4.10:1 (or 3.82:1 in some publications)? There is also a 2.68:1 Reverse drive ratio quoted.

[Spookyfish]

Interesting values! I read a bit here http://www.team-fate.net/reports/1998TechReport.pdf and maybe the 5:76:1 is the ratio that drives the fluid pump or the reverse gear?

[nonsequitur]

I think it's a ratio derived in combination with the Final Drive, but I'm still having trouble making the math flow through to the road speeds and engine rpm observed. I was having even more trouble before I was given these fixed ratios!

Reverse is another situation entirely. I'm fairly certain that the Low ratio is used (2.416:1), with other gearing brought into the torque flow trace.

The published numbers of 4.10:1 (Final Drive) and 2.68:1 (Reverse) don't seem to fit into the any of charts I've done. So ... I'm doing them incorrectly, but I don't know how or why!

[Spookyfish]

To calculate your theoretical road speed (SPEED in KM/H), you need:
- engine RPM, given in, well, revolutions per minute , example: 5500rpm
- your current gear ratio (RATIO), example 2.416
- your tire circumflex (TIRE in METERS), for 175/65R15 this is 1.912m
- Final drive (FINAL) of 4.100

SPEED (km/h) = RPM / (RATIO * FINAL) * TIRE(m)/60*3.6

5500 / ( 2.416 * 4.100 ) * 1.912 / 60 * 3.6 = 63,7 km/h

[nonsequitur]

I'm going to buy your math because I've used a very similar approach, but those are the numbers that I can't make work. I've even steel-tape measured the circumference of the mounted tires (74.875 inches; 846.2 revs/mile; Continental ContiTouring 175/65R15).

With these fixed ratios, it should be possible to go onto the freeway measured mile (to eliminate speedo error) and observe a Tachometer rpm that matches the calculated rpm (or speed).

The math is off, and it must be something basic and stupid that I'm doing wrong, or we still don't understand the gear reductions in the Final Drive and on the Gearbox case.

Why (as one example) would Road&Track and MINI2 quote a CVT Final Drive of 4.100:1 or 2.680:1 Reverse, if it is really 5.76:1?