Ok here's something that's been wracking my brain for a while, I have a 4pot TR auto and it's giving me the impression it is a 5 speed.. If i'm right overdrive locks the trans into 1st and 3rd, when I'm cruising about 100kph I often notice the rev gauge flick from around 2k rpm to 2.5k and it feels as though the car changes gears, so after some time I decided to see what was going on and just after it flicked to 2.5k I pressed overdrive and the needle flew up to around 3-3.5k rpm.. So if 3k rpm is 3rd gear and 2.5k is 4th.. what on earth is 2k rpm!?! 5th? :nuts:

Ok here's something that's been wracking my brain for a while, I have a 4pot TR auto and it's giving me the impression it is a 5 speed.. If i'm right overdrive locks the trans into 1st and 3rd, when I'm cruising about 100kph I often notice the rev gauge flick from around 2k rpm to 2.5k and it feels as though the car changes gears, so after some time I decided to see what was going on and just after it flicked to 2.5k I pressed overdrive and the needle flew up to around 3-3.5k rpm.. So if 3k rpm is 3rd gear and 2.5k is 4th.. what on earth is 2k rpm!?! 5th? :nuts:

That is the torque converter locking/unlocking. With the OD on, that is, in 4th gear, when the car reaches certain speed, 60 - 70kph, the torque converter fully engages and the revs drop to give better efficiency. When you attempt to accelerate, the torque converter unlicks and the rev rises. Do a google search on torque converters to see how they work or visit www.howstuffworks.com (http://www.howstuffworks.com)

thanks for clarifying that, I know what torque converters are, I've just never noticed another auto doing it so noticeably :shifty:

Yer most cars are a bit more subtle, like my 3rd gen if u watch the revs they drop gradually when u are cruising.

its the same on my KR...

Interesting.... Noticed this on my old mans TJ. Now I know!

Note, too, that Magna autos, 2nd gen and 3rd gen, which have the lock-up torque converter in 4th, will not lock up if the transmission is cold.

It usually takes about 30-40 minutes before the lock-up engages.

For example, I had a KS (auto, obviously) which would sit at 2400rpm at 100km/h with the converter "unlocked", ie. press the throttle a bit more and the revs rise first, then the speed increases. Like a slipping clutch, kind of.

But once warm enough, the torque converter locked up at at 100km/h, the cruising rpm was more like 2200rpm, and the fact that it was "locked-up" meant that when you pressed the throttle, it would accelerate like a manual car in gear, ie. no extra revs, just direct progress. Of course, if you floored it or accelerated hard, the torque converter would unlock and/or it would drop back to 3rd.

Same in the 3.5 4-speed auto, when 'unlocked' at 100km/h they hover at 2200rpm, but when locked up, it drops to 2000rpm exactly.

So much for my useless trivia


I also remember reading that the EF/EL Fords had a lockup torque converter only in 3rd gear, but not in 4th. I wonder why, possibly because 4th was so tall anyway....something like 1700rpm at 100km/h

Heh, I had to explain to my mother that this was not an extra gear, nor was it a 4.5 speed....