I just bought an '84 L69 TransAm with the 3.73 rearend and the 700r4 transmission. I've been driving it in drive only, and overdirve when I get on the highway. I know the RPMs aren't high when driving in drive, so it doesn't seem like a problem. I only have experience with a 2004r Cutlass, a 3 speed 350TH '77 transam, and manual transmissions. I don't want to wear this one out, so should I be leaving it in overdrive all the time instead? My worry is that with slower driving it will be shifting in and out of overdrive like my 2004r does. What do you all do?

Also, what is the shift pattern in drive v. overdrive? Since the 3rd and 4th gears are so close, I figured it would be 1-2-3 for drive, 1-2-4 for overdrive and 1-2-3-4 for overdrive at WOT. Like I said, I am not familiar with the 700r4.

 

"automatic" shifting on the 700r4, when the stick is in overdrive, is 1-2-3-4. It'd probably be less stressful on the trans if you leave it in overdrive, since the trans will stay cooler.

Any "shifting in/out of overdrive" is probably your TCC - torque convertor clutch. You can do a <a href="search.php?s="><img src="images/top_search.gif" alt="Search" border="0"></a> for "TCC lockup" and you'll find a ton of messages explaining it. This in/out "shifting" (which isn't really shifting) will probably be most noticible if you're climbing a hill, using light throttle, between 35-45 MPH. If it annoys you, use your left foot to lightly press the brake- not enough to slow the car down, but enough to turn the brake lights on. This will disengage the TCC. (TCC can't be in lockup when you press the brakes.)

 

The shift pattern in normal driving is 1-2-3 (TCC apply during 3rd) - 4.

It won't hurt anything to leave it in OD. You'll get used to the converter clutch and you'll learn how to coax it into staying in one state or the other; alot like how after driving a stick car for a while, you develop a feel for what gear to shift it into as you go around a corner or something, to make it engage as smoothly as possible and be prepared for acceleration or parking or whatever.

 

Thanks very much. That's exactly what I needed to know.