I discovered something new about my car tonight. I had O/D off going WOT around 80 - 85 mph which means I was definitely already in 3rd gear. With the accelerator still floored, I pressed the O/D button turning it on and the revs instantly jumped 300-500 rpm (I'm still in 3rd gear) and the car really seemed to accelerate faster than with the O/D off. Just to make sure, I did the same thing a couple more times and the outcome was the same every single time. What gives? It's quite strange 'cuz I actually see the revs jump & I feel a kick in the pants whenever I turn O/D back on. It is not my imagination.

Thoughts? Opinions? I am very puzzled since I thought turning O/D off is just to lock out 4th gear. If so, then why would the revs jump when I'm already going WOT?

BTW, I have a 97 Max with a Protorque high-stall TC. Would this have to do anything with it? I dunno...probably not...seems to be tranny program related...

Anyone else ever notice this?

 

Sounds like you're talking about the upshift... sometimes if the differential is in the right place it feels like the car is climbing into the next gear, giving you a little boost. You can do this easily if you have a stick, but it depends on how you play with the accelerator on automagic.

i think

 

The jump in revs is the torque converter unlocking....

 

Melanthius - I know it's definitely not upshifting from 3rd to 4th. The jump in revs starts in 3rd and ends up in 3rd.

UMD - Why would the TC unlock itself if I'm already at WOT to begin with? I mean, the O/D button is just to allow the tranny 4th gear, correct? Shouldn't 3rd gear just wind out smoothly regardless if I press the O/D button or not? Instead, I get a jump in revs and a kick in the pant.

 

we had this discussion over on the 5th gen forum a while back also... The O/D button does control when it shifts into 4th, but the TC is still locked in 3rd gear at WOT past 3200 rpm or so. I have tried on mine before, it does the exact same thing

 

The shift is a neat mini-boost in my opinion. Pretty cool.

Jeff: Can you send the pics that you took at the school with Kev, Matthel, yourself, and me? Thanks.

 

i remeber that particular discussion...

 

so according you, when I'm WOT in 3rd gear with:

O/D off -> torque converter locked in 3rd = slower accel
O/D on -> torque converter unlocked in 3rd = quicker accel

right? it sure feels like it...

 

yeah... i think so, and it seems that way from both our experiences.... but if you want to take it to redline, keep it in O/D... and then let it go into 4th.... I think 3rd gear is good up to 115 or 120...

 

so say in the 1/4th, if you go off the line with the OD "off" and after a certain MPH(say 55-65+), switch the OD "on" would you see a better or slightly improved time?? hehehe...I guess I'm showing a little 5spd envy.

 

I don't think so. Cuzz it's only a lil jult and you would be near done anyways. I turn o/d off on the highway and it jumps and my engine sounds louder revs louder, and is a cool lil' boost.

BTW, How do you guys feel about manually shifting an automatic !?

I have a 95. I start in 1st (major power baby) then eventually shift into second, then into drive...Is this bad for my transmission!?!?? Everyone says it is, but my sis does it and its soo much more fun (and quicker!).

 

shifting an auto manually is just telling it when to shift. You aren't doing any shifting. You are just telling the computer when you want to shift. The only way you could hurt the tranny is if you made it so all your shifts were at redline or really high rpms.... then you are putting the same stress on the tranny as you would when you are flooring it.

 

Sweet bro, becuase I can start out in 1st, and get FAST acceleration, then when the car stops "moving" and the rpm's start goin up, I shift into second, and then I shift into drive.

Makes sense. My dad told me "well, thats great but if you screw your tranny up, your payin for it" ...

""hmm...manually shifting a VB upgraded auto..Mmmmmmmmmm""

 

well, of course you and I know it's not really a boost when you turn O/D off while cruising on the freeway...it's just you downshifting from 4th to 3rd.

What UMD and I were saying is that 3rd gear winds out quicker when the O/D button is on. If this is really the case, then I dunno why people manually shift from 1 to 2 to D(O/D off) to D(O/D on). The quickest way to get from zero to your top speed is to leave the O/D on.

 

Hey guys,

I know exactly what UMD is saying, but I feel you will accel faster in 3rd with the O/D off than just being WOT in 3rd. The O/D off will lock out 4th.....and make third the last possible gear in the eyes of the tranny computer. It will lock the t/c. If anything I think the 300 rpm just would be misleading and you would accel SLOWER. When the tranny tc is locked it puts down more power to the wheels b/c there is no slip in the converter. SO>>>>>.......clicking the o/d back on.....unlocking the t/c is going to put the car at a higher rpm.....but not at a better part of the rev band(the vq makes flat torque from 2k-5K)....so there is no power advantage to being 300rpm higher. The t/c will no be unlocked and therefore transfering LESS power to the wheels.

Make sense?
I should sticky this!

 

you will get a more efficient transfer of power when the TC is locked like Mike S. said... so I don't know if the jump in revs makes a large difference in acceleration. Sure the revs climb higher and you feel it, but you may not be getting the best transfer of power....

 

Just get a 5 speed

 

I was waiting for someone to post something like this

 

...but 3rd gear does wind out a lot quicker with O/D on...meaning you get to 115 mph (or wherever 3rd gear ends) quicker as well...

i think with the TC being locked it's just saves you gas when you're at your top gear...why wouldn't 1st and 2nd gear always be locked during acceleration as well, right? it's unlocked for torque multiplication which means faster accel..................i think.

uh, i think i better go do some timed 3rd gear runs with O/D on and off.

 

yeah.... that is the only way to get the definitive answer... I'll play around with it also