DanADaMan

OK, I know this will be a dumb question, but here it goes.

Just got my 90 vert with auto transmission. This is my first sports/performance car with an auto. In my other cars, trucks, and RV with auto tranny, I just put it in drive (or OD if it has it), and drive normally. I've had other performance cars in the past with manual tranny, and I know how to drive those depending on how I feel. But with the vette with an auto, not sure what most guys do.

Do most just put it in OD (over drive) and leave it there all the time. Is this recommended if I want to take off fast from a red light? Is the OD good if I want to leave some rubber behind?? Or do most guys drive there auto tranny like a manual, in that you manually put it into 1st for takeoff, then shift to 2nd, etc, etc.

Thanks

I had

Klondike

Your choice. It's OK to leave it in the OD position all the time cause the OverDrive portion of the trans doesn't do anything till you are up to highway speed anyway. It will run up through the other gears first before it gets to OD. If you are in OD cruising and squash the go pedal it will go out of OD and shift down. If you want to play and not want the constant shifting in and out of the OD, play with it in D.

Joe C

(my 2-cents, FWIW) -- while it may or may not hurt anything, automatic transmissions were not designed for "manual" shifting. both my C4's are automatics, and personally, i put them in "OD" and drive. with the roads and traffic conditions, especially having to drive defensively, shifting gears is one less thing I have to worry about. if you want to just shift gears, my suggestion, buy a manual.

Churchkey

Early 700 OD transmissions are not as stout as the later years they were redesigned around 1988 = stronger.

Stand on the gas, shift it if you like, if it fails it was headed south anyway.

Urban drives below 45 mph suggest "D" for throttle response/drive-ability. If left in OD during 40-45 mph cruise there will be throttle lag when trying to accelerate the converter needs to unlock + the trans needs to downshift.

Maintenance tip: When changing motor oil change some trans fluid with a device like this:
http://www.jmsonline.net/sea-dog-lin...FYEZgQodlhMCvA

Luck with your new ride.

SmokinBlack

I agree. Mine likes to hang in OD with the converter locked in those slow speed situations. Beyond that, my car has a very annoying low rpm slow speed buzz/vibration that goes away if you pull it in to 3rd.

All other times I just leave it in OD and forget about it.

89dd

I leave in OD all the time. The only time I use D is when I'm on some hilly twisties.

1993C4LT1

D in the city. OD for highway.

confab

"OD" is fine for all normal driving conditions.

The Trans is the 4L60 and in "1" it is a little stronger on a hard launch because you bring on the coast clutch to back up the forward sprag and forward clutch, which bears the weight of your entire vehicle.

You also bring on the boost system and get a line pressure bump. Transmission line pressure is the pressure that holds the clutches on, so it helps prevent slippage and it is beneficial in that way.

Selecting "1" permits you to override the governor and the controls which would normally shift you up, and hold first longer.

confab

This is true, and it is important to people spending 1500 bucks on a transmission for their early vette.

When you are having an early Corvette transmission rebuilt, the later parts, and even some of the better parts from the 4L60E, will retro into the older transmission.

Some (actually many) transmission shops don't seem to know or understand this. So, since you are spending the money anyway, it is good to look around and find a shop that won't just rebuild your early trans, but upgrade it with the heavier parts. As the 700R4 wasn't a very good transmission in stock form.

We do this all the time here and it doesn't add a lot of expense. It is definitely worth your time to look and find someone willing to rebuild it right and make it better than it was when you broke it.

the kid C6

Judging from the answers, not a dumb question.

cv67

Another vote for D in town OD on the highway;will extend the life of your trans guaranteed
Noticed 0 mileage difference up til about 60mph and not using the 3-4 clutches which always seem to be a sore spot on these cars. Dont care for the "lugging" sound around town either motor seems happier

confab

The 3/4 clutch is engaged in both third and fourth gear.

The 3/4 shift is a band apply. The clutch is holding and doesn't move.

A Peter C4

I drive my 94 auto like its a manual all the time upshifts and downshifts ,don't overrev engine follow owners manual for max shift points and have fun,no clutch to worry about slipping or replaceing ,if tranny goes just rebuild but they are pretty strong with common sense, use keep fluid clean.I have been useing castrol full synthetic multi vehicle for GM specs with recent filter change,no problems don't be afraid of it,was built to have fun.Look at what they put them thru at the race track.Also saves brakes when downshifting.

tlong

Downshifting a 4l60E often without a manual shift kit installed is going to kill it prematurely. I broke mine that way. The rebuilt version is equipped with modern heavy duty parts and a shift kit.

The manual shifts are brutal at WOT with downshifting allowed. It's wonderful to have the auto turn into a clutchless manual chirping tires into 4th. The difference is amazing and transformed the car with all the right sounds and G Forces. Lower speeds in auto have lower pressures and shift so smoothly you can 't feel it.

My buddy drove it and worked the stick up and down. He didn't say much. 2 weeks later he sold his Porsche Cayman and bought a new C7R Z06. He said if a 20 year old car ran like that a new one must be great. Welcome to the family! What a way to start out in Vettes.

confab

Downshifting to third brings on the coast clutch (Which you will notice as engine brake. It is two friction elements in the forward drum.)

It will bump the line pressure and (within reasonable limits) otherwise has no negative effects on your transmission whatsoever.

BLUDICE

How does the OD operate - electric, pressure, module, or?? Can it be adjusted?? If it is not operating correctly - such as when at speed dropping out when you let off the gas slightly.

confab

Well, it is hydraulic in both the 700/4L60 and the 4L60E types. (In the "E" it is technically a binary solenoid combination, but you have no control over it. You move the manual valve in the VB and the computer takes it from there.)

You can pull it into third or you can reprogram the E with a chip, or whatever they use. A really diligent person could probably swap springs in the 700/4L60 trans, but I've never met anyone who wanted to.

Are you sure we are talking about 4th gear, and not the lockup clutch in the converter?

A 4 speed transmission shifts 3 times because it starts off in first. People get fooled here sometimes because the converter clutch comes on and feels like a (very soft) 4th shift, but it isn't.

The TCC clutch is computer controlled. You can play chip games with it on all models. The 700/4L60's have pressure switches on the VB that affect apply time, and delay switches are available. I have seen guys use those to hold it off. I have seen people use a switch to turn it off while in town. (You should never use a switch to turn it on.)

If you want to test this, in most older GM vehicles you can roll down the highway at speed and leave your foot steady on the gas while taking your left foot and touching the brake just hard enough to turn the brake lights on, and this will disengage the converter clutch. You will (or should) notice the RPM's jump. Remove your foot from the brake and it will re-engage. (It is wired into the brake light switch to help prevent bind ups.)

If that is what you are feeling, that is the TCC clutch and not 4th gear.

Since it is wired to the brake light switch, problems with the switch or its adjustment can cause an otherwise healthy transmission to cycle the TCC on and off unexpectedly. With the E, engine controls will affect the shift schedule and converter apply. So, if there is a problem there you may get TCC cycling or strange shift schedule issues.

BLUDICE

I think it's the "lockup" - if I let off the gas slightly (over 55 mph) feels like it is downshifting - gave it a little gas and I can feel it lockup again.

leadfoot33

if im just cruising around i leave it in drive (not OD) but most times i shift it from 1-2-d and back down

confab

Not sure what year yours is, but the PCM may be commanding it and it may be fine.

You can put a scanner on it while you drive and the data stream feature will show you the PCM command to lock/unlock.

It may be perfectly normal.

Most of them (mine do, anyway?) data stream the brake switch and engine sensors also to help diagnose a problem with lockup. This is important because it is very complicated. There's a giant hydraulic circuit to put it on and hold it off, and electronic controls in the trans. (solenoid, pressure switches on the older ones. Thermistor.) AND the PCM, and the engine sensors, brake switch all affecting the shift schedule and lockup.

It may be fine but if it bothers you of you think something is amiss, you can confirm this with a test drive and a scan tool.