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Johnny @ May 8th 2008 4:48PM
This is good news. I like 6 speed transmissions as long as it is a true 6 speed and not a 4 with two overdrive gears.
This one seems to have 6 distinct gears so its all good.
Simon @ May 8th 2008 4:50PM
Anyone know the gear ratios from old 4 speed and new 6 speed?
Dan @ May 8th 2008 5:38PM
How are overdrives different from distinct gears?
A transmission could have 6 overdrives and no 'regular' gears at all and do just fine, so long as it was matched with a suitable axle.
EXP Jawa @ May 8th 2008 6:41PM
@ Dan
Sometimes the overdrive is simply another "regular" gearset in the transmission, like all of the other ratios, which I think is what you're thinking of.
What I think Johnny is referring to, though, is a secondary (inline) planetary gear speed multiplier that is used in combination with another "regular" gear set in the transmission. A good example of that are the overdrive units that where popular in '60s on British sports cars and such.
On an electronically controlled transmission, you can easily command it to engage the OD unit with more then one transmission ratio. Ford did that with the 5R55 family of transmissions - instead of running OD only with the 3rd gear (as in the 4R55), they operated it with 1st also, giving it "fake" second, which they could turn around and market as a 5-speed. If you combine it with 2nd as well, then you could call it a 6-speed.
Another way to do it, though, is like what Getrag did for the SVT Focus/Mini Cooper S: have 4 primary ratios and 2 final drive ratios. If you combine enough of them, you can make 6 effective gears. Maybe that's what he's thinking of...
AMcA @ May 8th 2008 9:20PM
Ford's getting its act together.
- Kirk K
jordan @ May 9th 2008 12:44AM
@StickShift
Oh AX4S/N (which ever came w/the Vulcan), how I hate thee...
MikeW @ May 9th 2008 5:54PM
http://www.ford.com/about-ford/news-announcements/press-releases/press-releases-detail/pr-ford-accelerates-shift-to-28198
{hey that is just like GM's 6t40 & 45. Primary axis, chain drive to secondary axis, and then axle ratio (helical bevel gear) to differential axis}
Look up GM's 6t45 gear ratios
http://en.wikipedia.org/wiki/GM_6T40_transmission
6t70 (no chain drive)
http://wardsauto.com/ar/ford_gm_automatic/
The dual countershaft manual transmission does not work that way.
You are not just switching axle ratios to get 6 gears, you actually have 6 gears, it just happens that 3rd/4th drive gears do double duty, driving 3/4 & 5/6.
You are not being specific enough. You should not call your transmission a 4 speed automatic, it should be called a 3 speed + overdrive.
There are wholly integral 4 speed automatics vs 3 speed + overdrive