My friend and i noticed this the other day, but when im cruising along on the highway or accelerating onto it, i can hear the car shifting from 1,2,3, then to OD, the odd thing is that it goes from od @ 2250 rpm to what sounds like an even lower gear and it settles to about 1700 rpm at about 55-60 mph. I do get power at both, so its not like any spooling or anything, but it has made me extremely curious as of to whats up?

 

It's 1,2,3, OD then the torque convertor locks.

 

So the torque converter becomes almoat like a second OD gear kinda?

 

That makes since, I told him when comes to trannys, I has no I dear

 

Yeaup.

 

Interesting...im gonna have to read into that but thanks!

 

I always thought it was 1, 2, 3, t-convert lockup, OD

 

The tc can lock in 3rd or od. The tps and tcu decide when.

 

I go by 1,2,3,4, then OD or torque converter lockup or whatever the guys call it. To me, overdrive is a separate gear from the others since it drops the rpm's so low. Manuals don't have overdrive, its just the last gear. To me, auto should be categorized the same.

 

overdrive refers to the ratio of the gear. if it is greater than 1:1 then it is an overdrive gear. AW4s have 1-2-3-4(which is overdrive). manuals have an overdrive as well. its 5th gear.

 

Actually manual trans do have overdrive. OD was originally created to help prolong engine life, by letting the engine rev at a lower rpm while cruising. OD gear is anything numerically lower than 1:1 . In Drive (1:1) the engine and trans are spinning at the same RPM. When you go into OD, say for example AW4 has a OD gear of .74:1 the trans output is running 25% faster.

 

Too bad things don't get catagorized by you, eh?

 

It's 1-2-3-OD-Lock on your 89.
In 87 it was 1-2-3-Lock-ODUnlock-Lock

 

The AW4 is 4 speed auto in which the final geat ratio is .70:1 or .75:1. On any tranny, when the ratio drops lower numerically than 1:1 it's considered OD. Some trannys have double ODs. The sensation/feeling that the AW4 shifts a 4th time is just the torque converting locking up. Under light throttle, the torque converter will lock-up in either 3rd or 4th gear. This has been the case on most vehicles since the late 80's, early 90's.

 

this is spot on, for example my Trans Am WS6 has a 6-speed manual with double overdrive. 4th gear is 1:1, 5th gear is .79 and 6th gear is .50