King TChalla (wakanada forever) got me thinking about why they haven’t put the Toyota 8 speed, what toyota calls the worlds first 8 speed auto, into the tacoma where 8 and 10 speed autos are the norm. They even already have a version that mates up to the tacoma engine in the AA81...so why don’t they? I think I figured out why.
The 8 speed has a strange ratio spread. here
4.596 - .685 vs the 6 speed 3.52 - .586
The key takeaway is the overdrive ratios, .685 being the tallest vs .586 being the tallest.
Toyota uses this transmission in the land cruiser alone right now for 4wd applications and in that application it uses a 3.3:1 axle ratio which is way low for a Toyota truck. Normally they are in the 3.9-4.3:1 ratio I think because their transmissions give them very tall overdrives and big ratios mean strong gears and less transmission strain.
The Tacoma has a 3.909:1 axle for example in auto form (4.3:1 in manual)
If you took the Tacoma axle ratio and put the 8 speed in front of it it would have amazing low end torque, nearly 18:1 first gear crawl alone is nutty and it would take off like a rocket...but...at .686:1 and 3.909 its only 2.67:1 vs 2.29 for the 6 speed. So it would get worse economy both on the highway and city cycles because it would be in shorter ratios pretty much all the time.
Im guessing they don’t have a 3.3:1 ring that can fit the Tacoma’s carrier. Seems like a problem they can and NEED to solve. if you had a 3.3:1 ratio in the Tacoma like the land cruiser with the same transmission you would get better acceleration in all ratios and SLIGHTLY better overdriver at 2.27:1 It would actually make that high strung 3.5 feel pretty perky and they could relax the shift logic a little to allow it to stay in gear longer.
I personally wouldn’t mind the overdrive penalty on the Tacoma as it would be a killer towing machine even with that 3.5 and it would crawl like nobodies business.
Granted Toyota also has a new FR - 10 speed that is supposed to solve that issue
So...GET ON TOYOTA!
UPDATE: found the ratios for the AGA0 (10 speed) here is a comparison
Good gads that 10 speed 1st gear ratio is hot. Too bad overdriver is still less than the 6 speed. Still, with the new transmission you could easily get a 3.73 ring on that axle and be perfect.
Okay, thats pretty great. Even with the wimpy 3.5 I think the 10 speed would transform the Tacoma. DO IT!