i race all the time street race and on 95 alot lot lot and i always shifting gears manually i noticed that when completely floored from the beginning while in first gear it only goes to about 30 MPH and i shift to 2nd and it goes to 80MPH at the highest possible RPM then i shift to 3rd and that gets me to 110MPH then obviously D is 4th but while already in fourth i feel the car does a much harder and badass shift but i know its only a 4 speed is it possible that while in 4th going at high speeds the monte automatically shift into overide which is kind like an extra gear no regular driver knows exist?

S.N. i only shift at highest possible RPM in each gear so i wont get drawback speed of shifting to early.

 

Manually shifting our transmissions (4T65E) is pointless and will make you slower.

The point of having 1, 2, D, and OD is so that you can select the proper range for your driving condition, not so that you can manually shift the tranny. In 1 and 2, your tranny will engine break when your foot is off of the gas pedal (which means it will force the engine's rpms down). In D, this makes it so that the tranny will not shift into OD. This is especially useful when hauling trailers. OD is there to give you the best fuel economy possible. This is because first and second gear are accelerating gears, third gear is "direct drive" which is about a 1:1 gear ratio, and fourth gear is your "overdrive" gear due to the fact that it has a smaller gear ratio then 1:1 (IIRC it's 0.70:1). Any gear ratio that has a number higher then 1:1 is accelerating, and any gear ratio number lower then 1:1 gives you a gain in fuel economy.

If you try to manually shift the tranny, you will accelerate slower because the computer can shift faster then you can, everytime. And in fact, it will ignore your upshift until it needs to shift anyways. The only time it won't ignore you is when you shift from low range (1 or 2), to D, because if you keep it in low range it won't shift until you put the gear selector into high range. That's why you will be slower accelerating. I even tried manually shifting at a local drag strip and it was just a mess. You can NEVER shift faster then the computer, and the computer knows the best time to shift anyways, so there's no point in manually shifting the tranny.

Don't allow the tranny to shift into OD at high speeds. What definition of high speeds am I talking about? Honestly, I wouldn't allow it to shift into OD at any speed above 90mph. The 4th gear shaft in our trannys are very weak and MANY 4T65E's have lost fourth gear (OD) because of people allowing the tranny to shift into OD at high speeds.

Lastly, there are no bonus gears that "no regular driver knows exist". The name of the tranny that's in our cars is called the 4T65E. Here's how that name breaks down. The 4 means that it's a 4 spead transmission (4 gears, 1, 2, D, and OD). The "T" means transaxle. The 65 is the strength rating of the transmission. And the "E" means electronic, as in it's an electronically shifted transmission. In Monte Carlo's (and other GM cars) that have the supercharged 3800 (aka the L67), they have what is known as the 4T65E-HD. The main differences between the 4T65E and the 4T65E-HD are the final drive ratios and the 4T65E-HD has a slightly beefier differential.

I hope this helps. The main points of my post are, don't manually shift these trannys, and don't drive in OD at high rates of speed. If you're going to go fast, put the gear selector into "D".

 

Great info!

 

Great reply Zipper, honestley if u wanna shift get a manual, autos are designed to shift themselves

 

Keep on manual shifting it and see how much longer your transmission works

It won't be much longer.

 

How can you prevent your car from shifting into OD at high speeds? Doesn't it do it automatically?

 

Drop it to 3 - then it won't shift up into 4th gear which is OD. I think of it as a gear limiter, wherever you set the shifter, it won't pass. So basically if you set it in 1, it'll stay in first gear. The computer still does the shifting, it just won't go past the gear you have it in. If you leave it in D it'll shift through all 4 gears.

 

Like everyone else has said, I would stop. If you race put it in 3, that way you don't lose 4th next time you race, because that's bound to happen anytime now