Third or OD??
Thread Starter
Instructor
Joined: Apr 2013
Posts: 178
Likes: 0
Third or OD??
I have an 88 auto and I'm curious driving around local roads where the speed limit is say 35-45 mph , should I keep my car in D or let it go into OD? It just seems like it is way too low of RPM at these speeds. When I had an early 90's Tahoe I used to drive around in D and when I got on the highway I would shift into OD. Just some thoughts please?
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Our '88s don't upshift into OD untill ~43mph. I mostly cruize in a 40mph zone so take her up to 43mph so I can cruize the speed limit at 1,000rpm==great local mileage.
If the motor starts to lug the A4 will down-shift into 3rd==no worries.
If the motor starts to lug the A4 will down-shift into 3rd==no worries.
Safety Car
Joined: Aug 2009
Posts: 3,745
Likes: 275
From: Melbourne, Victoria, Australia
Just leave her in OD and let the transmission decide what gear to use.
The D is mainly for if you are going up a long steep hill, OD is for normal use.
Safety Car
Joined: Jan 2014
Posts: 4,017
Likes: 492
From: Poughkeepsie New York
I have an 88 auto and I'm curious driving around local roads where the speed limit is say 35-45 mph , should I keep my car in D or let it go into OD? It just seems like it is way too low of RPM at these speeds. When I had an early 90's Tahoe I used to drive around in D and when I got on the highway I would shift into OD. Just some thoughts please?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The problem with OD is that the trans will shift into OD at ridiculously low speeds. Mine will shift into OD as low as 20 MPH (I have a '89 700r4 in my car, but the original one did the same).
I never shift into OD unless I'm going over 50 MPH. With the TCC locking and unlocking and the OD going in and out around town it drives me crazy.
Since I'm always shifting into D instead of OD when I start my car, I did this:
http://forums.corvetteforum.com/c4-t...ification.html
I never shift into OD unless I'm going over 50 MPH. With the TCC locking and unlocking and the OD going in and out around town it drives me crazy.
Since I'm always shifting into D instead of OD when I start my car, I did this:
http://forums.corvetteforum.com/c4-t...ification.html
Safety Car
Joined: Jan 2014
Posts: 4,017
Likes: 492
From: Poughkeepsie New York
The problem with OD is that the trans will shift into OD at ridiculously low speeds. Mine will shift into OD as low as 20 MPH (I have a '89 700r4 in my car, but the original one did the same). I never shift into OD unless I'm going over 50 MPH. With the TCC locking and unlocking and the OD going in and out around town it drives me crazy. Since I'm always shifting into D instead of OD when I start my car, I did this: http://forums.corvetteforum.com/c4-t...ification.html
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Burning Brakes
Joined: Jun 2000
Posts: 865
Likes: 6
From: Auburn Michigan
I'm not too worried about a mile a gallon less I may be getting.
Racer
Joined: Nov 2008
Posts: 321
Likes: 2
From: Auburndale FL
If I am driving between 30 - 40 for an extended period of time my tranny will shift into OD. This may be good for fuel economy but my engine will start lugging and the car will surge forward and back, so I drop it into drive and the rpm's go up and the car is happy.
I probably need to take it back to tranny shop and get them to adjust the shift points a little more but I was thinking my problem was gearing until I read this post.
I probably need to take it back to tranny shop and get them to adjust the shift points a little more but I was thinking my problem was gearing until I read this post.
Burning Brakes
Joined: Apr 2012
Posts: 888
Likes: 4
From: Ridgecrest Ca
Around town where the speeds are predominantly 35-40 I use D. When I intend to drive faster than that like heading out of town I put it in OD. Mine upshifts to OD at 40 and can be annoying around town. 1990 700r4.
Navigator
Joined: Oct 2008
Posts: 9
Likes: 0
From: San Jose CA
I almost always leave it in OD unless I am going for a very spirited drive. I dont notice any gear hunting, car pretty much only drops into OD at ~37mph and will stay there unless I decrease speed significantly or punch it. Even when climbing hills, the L98 has plenty of power and I usually pass cars up the hill in OD. '89 btw
Pro
Joined: Mar 2013
Posts: 628
Likes: 13
From: Indiana
For the first 15 years I owned my 96' I always put it in OD and never thought about it. Last year I was testing out a new exhaust system and jumped in, put it in gear, and took off. I'm thinking WOW this thing is really peppy. Tight shifts, quick revs, and lots of torque. I get too a long stretch and the engine is starting to rev up. I realize its not kicking into overdrive. I look down and I'm in D. From that point on I only use OD when on the highway and only for extended trips. I just love how aggressive this car is when in D.
I posted the same question you did and got about the same response from everyone.
http://forums.corvetteforum.com/c4-g...overdrive.html
It doesn't hurt anything to play around in D and its a lot more fun. Your car, drive it your way.
I posted the same question you did and got about the same response from everyone.
http://forums.corvetteforum.com/c4-g...overdrive.html
It doesn't hurt anything to play around in D and its a lot more fun. Your car, drive it your way.
Last edited by Klyde; Apr 15, 2014 at 05:55 PM.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,062
From: altered state
St. Jude Donor '05
Always drove it around in OD
Learned that over time it slowly wears the clutches going up...then down over and over. So I buy a lot of trans over the yrs
Now I leave it in 3 no matter what til Im on the fwy mileage is the same actually.
Learned that over time it slowly wears the clutches going up...then down over and over. So I buy a lot of trans over the yrs
Now I leave it in 3 no matter what til Im on the fwy mileage is the same actually.
Team Owner
Joined: Dec 2000
Posts: 21,094
Likes: 282
From: Phila., PA burbs
My car never sees OD unless I'm on the highway for an extended period. One reason is the lugging while in OD at low speed. The second reason is, on my car, the trans makes a downshift "clunk" if I coming to a stop in OD. In D the trans is quiet while downshifting. I'm not sure of the cause, but IIRC its common to 90-91.
Racer
Joined: Nov 2008
Posts: 321
Likes: 2
From: Auburndale FL
Not looking to thread hi-jack but a follow up question.
Do any of you that use OD down shift to D when coming to a redlight? I do from time to time as I love the sound of my exhaust as the engine is slowing down.
I even found in the 87 owners manual that doing this is recommended for extra stopping power. I thought that was funny but I guess the idea of engine braking make sense.
Just curious, if yall do it or am I the only one???
LOL
Do any of you that use OD down shift to D when coming to a redlight? I do from time to time as I love the sound of my exhaust as the engine is slowing down.
I even found in the 87 owners manual that doing this is recommended for extra stopping power. I thought that was funny but I guess the idea of engine braking make sense.
Just curious, if yall do it or am I the only one???
LOL
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
The TCC in the 77r4 is designed to run in D for city driving where there is stop & go or hills.
The OD is for cruising above 50 mph ONLY. You will cause excess wear internally if you lug the trans in 4th at slow/low speeds, even tho it seems to handle it ! You WILL be doing a rebuild a lot sooner than had you allowed it to spin freely. Lugging is also bad for the engine.
TCC lets the D selector feel like a stick. OD lets it feel more like an auto.
Engine braking IS advised for added stopping power. IF your trans is in good shape, learn how to do this with throttle so the drive-line shock is minimized. Reciprocating forces on u-joints ID the weak ones pretty quick...
IF the OD selector allows OD at under 50 mph...(25mph) the TV cable is WAYYYYYYYYYY out of adjustment and needs to be set. OD should never engage until 50-60 mph under normal throttle.
The OD is for cruising above 50 mph ONLY. You will cause excess wear internally if you lug the trans in 4th at slow/low speeds, even tho it seems to handle it ! You WILL be doing a rebuild a lot sooner than had you allowed it to spin freely. Lugging is also bad for the engine.
TCC lets the D selector feel like a stick. OD lets it feel more like an auto.
Engine braking IS advised for added stopping power. IF your trans is in good shape, learn how to do this with throttle so the drive-line shock is minimized. Reciprocating forces on u-joints ID the weak ones pretty quick...
IF the OD selector allows OD at under 50 mph...(25mph) the TV cable is WAYYYYYYYYYY out of adjustment and needs to be set. OD should never engage until 50-60 mph under normal throttle.