2.93's to 3.29's?

[Daveliz99]

I have a 99 GTP with a bad transmission. I'm planning to have it rebuilt soon, and then some engine mods after that. I've been reading up a little and trying to learn about these transmissions without making new threads because I'm sure all of my questions have been covered before. This one too I'm sure.

Here is a link to a guy with doing his own rebuild of a 1998 4T65E-HD from a 98 Regal GS.

Illustrated 4T65E Rebuild : General Chat

Since the thread is so long, here is the quote I'm asking about:

Drive Sprocket, Driven Sprocket and Drive Link Removal:

The turbine shaft looks good, and with my anticipated power level I do not see the need for a high-dollar aftermarket upgrade. Sprockets look good, too; but I'm going to replace the 37 drive / 33 driven with 35/35 stockers (like from a GPGT or n/a H-Body) to wind up with 3.29's. I expect to spend $75 to $100 for these sprockets; and I don't see the need to spend big $$$ on a single-chain "race" setup here.

So, my question is this: Since I have to rebuild my trans anyway, have any of you ever swapped in 3.29's in place of the 2.93's? I was thinking if I did that, maybe it would give the effect of more power, though it actually isn't making any more, and then I wouldn't have to do as many engine mods later to get the desired performance result. It may save some money over engine mods too.

I know muscle car guys do it all the time with 4.11's etc, and it's effective.

So if that's a good option, does anybody know about the impact to gas mileage? Going to taller gears like that will make it go down, but most engine mods will too, is there any way to speculate the best option gas wise?

My planned engine mods were basic 3.4 set up, headers, tune, intake....3.4. Possibly 1.9's or a VS cam, but probably neither.

BTW, I've searched for keywords stock transmission, engine mods; stock transmission, 3.4, etc, and haven't found exactly what I was looking for, or maybe I just didn't understand it. Whatever; does anyone have good links about engine mods and when they require transmission upgrades? That will be important to me in the future.

Thanks.

[Daveliz99]

To put my question another way:

If a basic 3.4 set up provides xxx performance level, and adding rockers or a cam provides an additional xxx performance level, can I short cut to those same performance levels by changing to 3.29's and save some money?

[FordMan77]

If you change to the GT gears you will have to tune the ECM. As far as shortcutting adding cam, rockers, 3.4 setup I doubt it. All the gears really do is let you get into the powerband more quickly. It doesn't change the existing amount of HP you have available (as you noted), just gets you there quicker. You would get off the line better, but hit top end sooner than someone with the 2.93's.

Search for "gear swap" or "gear change" and see what comes up. I know it's been talked about before.

And for modding info, give this thread a read--> http://www.grandprixforums.net/safel...0-a-67580.html

[Bio248]

gearing will net you some better ETs at the track, but i always liked the 2.93 ratios for driving around in the street.

[231FUN]

But you won't gain any E.T. spinning the wheels out of the whole quicker with a 3.29 gear set... depending on your setup, I prefer the 2.93 myself.

[Daveliz99]

So maybe it would be better to just stay with 2.93's then. It was just a thought, especially since the guy in that thread I linked to says it only costs $100 or so. So I'll keep reading. Just thought that might be a way to cheat a little, since it is said that these transmissions are somewhat weak, with different gears it may feel to the driver that there is more power but to the trans it still feels stock from the motor. so then, once you start to mod, you wouldn't have to mod as far to get the desired feel (not ET in my case), so your engine wouldn't have to make as much power, and the trans wouldn't have to handle as much extra power. But the driver never knows the difference.

It will be a daily driver, and I tend to value low end torque more than high end HP, so that's another reason I thought it may be a good idea. Bio, why do you and 231 prefer the 2.93's for the street?

I have read the thread about modding your 3800 a few times, but it doesn't talk about trans upgrades until way down near the end. At the same time, lots of people talk about them being weak, so I've been looking for some more clarification. But I will be checking off the upgrades on that thread as I mod the engine.

[gtpsleeper]

I agree with the 2.93s for the street aswell. Honestly, if you have access to a gtp with 3.29s see if you can drive it and get a feel for them. Personally, I liked the stock gears, cuz with the 3.29s i couldn get traction for ****. Some guys hate driving one that dont have the 3.29s. My overall opinion really though is these things have a hard enough time getting traction, so why make it worse? But each his own...

[Daveliz99]

Thanks for the reply sleeper. I guess it would be really bad in the rain then. Thanks again to everyone.