Sorry bro, need to lay off the chuckle juice... Ford has been using them for years as well. The 6R family of transmissions began life as a ZF design in the Navigator several years back, '06 or 8 I believe.. Anyhow, they have no 1:1 at all and absolutely do use a double overdrive.. In fact, they turn at .86:1 for 5th and .69:1 for a true 6th..


General train of thought for more gears is to keep the engine in its power band rather than make it work back to its peak power on every shift.. In fact, that's the real reason for the CVT's.. By going to a double OD with sufficient Tq, the engine will certainly get better fuel economy.. But, as you illustrated with your bike, it takes power to maintain it..

 

I guess I should have made my statement more detailed in order for a auto trans to go double overdrive it has to lock up in 5th. the 6R is a good example because I have one in my POS explorer It wont lock In 5th gear at all. not until it hits 50 mph in 6th then the rpm will drop when its locked
almost 1000rpm so 5th gear is not really an OD since the motor is spinning faster than the input shaft of the transmission and with a final drive of 3.73 in 6th that's not much of an overdrive my old 76 gutless
had the same final drive with only 3 gears


almost forgot yes 5th gear will lockup if you turn the pulling mode on but you lose 6th gear so its back to a single overdrive
the mx-5 has a manual transmission with 2 overdrive gears but they tweaked the final drive so much to make it work I dont consider it a double overdrive either

 

Well, I'm not going to get in a pissing match over semantics.. I was merely trying to point out that you were spreading false info.. Its really irrelevant what you interpret OD to be, based on what may be a broken Explorer in your driveway.. While the converter is a large component in the equation, the fact is, that OD is used to lower the engine RPM below the output shaft speed. If you monitor the turbine shaft speed to output shaft speed, you can easily see the ratios and lockup.. It can only do so when the load is low enough for the engine to maintain speed.. However, due to fuel economy and emissions, calibrations are becoming more and more aggressive every year... The latest version of the 6r140 in the Super Duty will hold lockup down to about 1k RPM, pretty deep into lug territory.. For reference, your transmission should lock the converter in 3rd as well.. Might even do it in 2nd, I forget, but the converter should be on more than its off..

 

what you say is very true except the broken truck part its fixed again and there is one thing I like about the 6R if I get on it hard in 1st and 2nd
and let off it will jump right to 6th without jerking

 

From Jasper86's shifting issue thread, this sounds interesting:

"had a chat with Baker. depends on winter OT/budget...but a DD5 with a stretched out 1st/2nd and an OD (.88 or .86 i forget now) would be REAL fun..."

 

I seen that. I hope he does it. im curious how well that will work

 

He's got plenty of power to spin it, I think he'd be pleased... I'd love it too, my bagger lives on the highway.. Like Schex and D pointed out, it is a great mod, if you run up in the 80's or have a lot of surplus torque..

 

Also read that the gears have more contact area to hold the abuse from the larger ponies and the catsazz for large cubes, I believe they are all helical cut gears to achieve the larger contact.