ne max

iTrader: (4)

quick question, when you switch off the overdrive button on an auto tranny, does it make the engine rev higher in 3rd gear (since it can't go into 4th) or does it make the engine rev higher in all 3 gears? just wondering if this is why everyone says to turn OD off to get a better launch.

Vyrus

iTrader: (4)

Revs higher in all 3 gears.

ne max

iTrader: (4)

NICE

Chris91SE

iTrader: (1)

umm...it doesn't rev higher in all 3...it just prevents the tranny from shifting into 4th...

Vyrus

iTrader: (4)

Yes it does. You are correct it does disable 4th gear, and in doing so moves up the shift points of the other 3. Atleast that's how it is for my 4th gen.
-Cyrus

Chris91SE

iTrader: (1)

it must be your imagination then...overdrive is only related to the final gear. it has absolutely nothing to do with 1st or 2nd on ANY A/T car...

95emeraldgxe

it doesnt rev higher......it just unlocks the torque convertor and locks up the 4th gear

Vyrus

iTrader: (4)

They why does the car sound so much louder and rev up quicker?
-Cyrus

SteVTEC

It's your imagination, rice boy

j/k

All that little button does is just lockout 4th gear, as Chris has already stated. It doesn't change shift programming or gear ratios or anything like that.

mattattax

so where is everyone getting that it is faster to launch with OD off

Chris91SE

iTrader: (1)

i'm telling you...it's your imagination...

leave OD on and give it gas through all the gears...then take OD off and give it the "same" amount of gas and it will be the same except for 3rd as you can take it to redline. if you give it more then obviously your car will be louder and possibly rev faster because you'll hit a different part of the power band

Vyrus

iTrader: (4)

Go ride in an auto Max with and without overdrive and come back and say that...and please don't call me a rice boy, you're the one with a Honda . j/k
-Cyrus

Vyrus

iTrader: (4)

It is undoubably louder through the 1st and 2nd gears. Maybe it does only go to the same point, but I swear its louder. Faster? I don't really think so, but definitely louder. Maybe unlocking the torque converter?
-Cyrus

SteVTEC

What Honduh?

I drive a Maliboo

Chris91SE

iTrader: (1)

sorry..

here is a link that tells you EVERYTHING OD does and what it's for...

http://www.cars.com/carsapp/national...ry/full_o.tmpl

Vyrus

iTrader: (4)

Ouch, sorry about that, didn't read your sig carefully enough...I know the Malibu wan't out of choice.
-Cyrus

Vyrus

iTrader: (4)

And I quote from your site. "An overdrive gear lets the engine run at a lower rpm to maintain the vehicle’s cruising speed." So overdrive off makes the car run at a higher RPM = more noise. Right?
-Cyrus

Chris91SE

iTrader: (1)

no...overdrive gear referrs essentially to 4th gear...so say the tranny is in third and your cruising at 4k rpm...turn OD back on and you shift into 4th and the rpms fall back down. so overdrive makes the car run at a higher rpm ONLY in 3rd gear

Vyrus

iTrader: (4)

So in conclusion it DOES rev higher in only 3rd.
-Cyrus

SteVTEC

Turning overdrive off will not effect the RPM vs speed relationship in any gear whatsoever. All it does is lockout the 4th gear.

So if you're running at a speed of xx at RPM yyyy in 3rd gear and you turn the overdrive button off nothing will change. You'll still be at a speed of xx and RPM yyyy.

All overdrive On/Off does is tell the transmission whether it can go to 4th gear or not. If so, it will upshift to 4th gear once you get up to speed. If not, the highest gear it will go to is 3rd.

Chris91SE

iTrader: (1)

Yes.

SteVTEC

1 = 1st Gear
2 = 2nd Gear
D (O/D OFF) = 3rd Gear
D (O/D ON) = 4th Gear

The gear ratios don't change, so speed vs. RPM will always remain the same in each gear.

Vyrus

iTrader: (4)

And what you initally said?
So it DOES rev higher in 3rd...
-Cyrus

Chris91SE

iTrader: (1)

grrr...i said "in all 3" which is what you said originally...

Vyrus

iTrader: (4)

mzmtg

iTrader: (11)

No. The transmission will not shift past thr ed line in any gear, regardless of O/D off or not.

Floor it all the way through 3rd with O/D on and it will shift into 4th and you keep going. Floor it all the way through 3rd with O/D off wnd you will bounce off the rev limiter around 128 mph all day...

DA-MAX

iTrader: (10)

I think I know what Vyrus is saying...yeasterday I was using this method to test if my friction plate is still functioning.....to do that drive ~50mph with the O/D on, then push the O/D button(O/D off) and the car surges a little and the RPM jumps up on the tach a few ticks....is this what you are talking about?? but as far as it affecting gear ratios I gotta say you're wrong on that!

Synki

OD on allows 4th gear to be used and this drops to lower rpms. Ex: Drive with OD Off @40mph and drive with OD On @40mph and you will notice the rpms are lower (liek the atricle mentioned).

OD allows you to stay in 3rd gear longer; gives more control.

I leave OD Off when i drive local, the only time it goes on is for highway use.

I have been told my almost every transmission shop to keep OD Off to keep wear & tear down on the shifting when driving local. To me, gas is cheaper then a new transmission rebuild.

Greg's2kGLE

It isn't reving higher in 3rd, that's just the RPM it should be at, at the speed. O/D off doesn't change the RPM at that same speed. Does that make sense?

AndyXXL

yeah right, dream on.

The Max

That is wrong, at least for the 3rd gen. Looking in the service manual for the 3rd gens, the torque convertor locks up in 3rd and 4th gear. If it didn't lock up when overdrive was on, you'd wind up with a very hot gearbox on those long highway/freeway trips.

SECONDLY (and I have the documentation to prove it), under NO circumstances does the shift schedule/pattern change with respect to the overdrive button. This ONLY changes under 2 conditions:

1) Power/Comfort switch setting
2) Throttle position

So for those of you who are suggesting/thinking that the overdrive button changes the shifting pattern in all 3 gears when it's off, you're dead wrong. It only switches on/off the capability for the car to shift into 4th gear when it's desired. It has NO, repeat, NO influence over the shifting patterns, nor the torque convertor, in the off position.

Greg's2kGLE

Well that isn't entirely "correct." You can go past redline in 3rd gear with the O/D off.

CalsonicSE

iTrader: (3)

But anyway, here's my $0.02 -

The O/D button does ONLY TWO THINGS!!! (It does not affect 1st and 2nd gear in any way!!!)

1) Like everyone says, having O/D off will eliminate 4th gear. Your max speed will be whatever your rev limit is in 3rd gear.

2) NOT EVERYONE MAY KNOW THIS -

O/D OFF will LOCK the torque converter in 3rd gear. Therefore, your car will shift like this with O/D OFF: unlocked 1st -> unlocked 2nd -> locked 3rd

O/D ON will UNLOCK the torque converter in 3rd gear. Therefore, your car will shift like this with O/D ON: unlocked 1st -> unlocked 2nd -> unlocked 3rd -> unlocked 4th -> then if you ease off the gas, the tranny will drop to a LOCKED 4th & the RPMs will drop a bit.

(Your transmission will always lock the torque converter in the highest gear for better fuel efficiency.)

If you don't believe me, try this. With O/D OFF, go WOT on the freeway making sure the car is in 3rd gear (anything above 70mph will suffice). With your foot still mashed to the ground in 3rd gear, turn O/D ON while looking at your RPMs. You WILL see your RPMs jump a few hundred RPMS & it'll feel like a lil' boost. THIS IS YOUR TORQUE CONVERTER UNLOCKING.

To me, it seems that the engine revs faster in 3rd with the torque converter unlocked (O/D on); however, others feel that 3rd gear with a locked torque converter (O/D off) is faster. I guess the only way to really tell which one is faster is to do timed 3rd gear runs with O/D on & off.

The Max

Now that's just plain pedanticism. No doubt it will go to redline, since you've taken 4th gear out of the picture. I don't think I need to tell you that, it should be a given, should it not?

The point is, the shifting patterns themselves do NOT change. That's what I meant in my statement and I'm sticking by it.

The Max

True that, I should've been more specific in my explanation, but you've taken care of that.

Thanks!!

Synki

Very well put Cal & very true.

You guys may notice that when you are driving in 4th gear and give it some gas and see rpms jump a little but not drop the gear. (As another example).

Bags

iTrader: (3)

Ben, Are you talking about leaving it in "D" ?

I can take my 1st & 2nd shift passed redline when manually shifting.

I can get to just passed 130, idicated on the speedometer, in 3rd with O/D off.

I am just curious how you came to this conclusion? Are you talking indicated on the TACH ?

I am not the sharpest tool in the shed... so I am trying to better understand what your saying.

Thank you

Bman

Where's the "This Thread Sucks" guy at??

Never has so little been asked of so many for so long....