3.42 or 3.73

[AcId]

Any real gains in going from a 3.23 to a 3.42 rear end or is 3.73 the way to go? I'm asking because the pinion seal is leaking and figured while I was there I'd lower the gear but don't want to go to a 4.10 for highway reasons. Would it be worth the $200 ?

[funkedup]

I prefer a 36-24-36 rear end.

[GtoRA2]

Give us more info on the car, and the motor.

My GTO now has 3.55s in it, I would like to go to 3.90s, but I am already at 3200 RPM on the highway.

[AcId]

'98 Trans Am 5.7L (LS1) ......Automatic.....

oops, double checking my numbers, my current gear ratio is 3.23 how da hell did I miss that. ohwell, hrmm so should I go with 3.42 or all the way with 3.73. I think im right around 1,500-2,000rpm on the highway.

[GtoRA2]

Would get you off the line quicker if you can get treaction, but will prolly put you in the mid to high 2000 RPM range.

Does it bog of the line at all now?

[AcId]

no, it doesn't bog at all I just figured while I was down there that maybe I could give it more jump. But since there is occasional highway driving I don't want to go too far.

[nuchpatrick]

3.55 is a good mid gear..

I have a 4.10 in my Miata.. and I can drop it to a lower gearing...but 80 in 2nd gear..I just love eating those rice rockets up..while their still shifting for 3 more gears...

[crowMAW]

Acid,

GearClac is a great little proggie that can help you decide.  You can see what your rpm and speeds in a specific gear will be.  Here is a link to the freeware:

http://locost7.info/gearcalc.php

From my point of view, if you have the manual 6sp LS1, 3.42 gears would be nice.  Are you on the LS1 forum?  You might see what folks there think.

[AcId]

I've got the automatic, they come stock with the 3.23
I've been looking through the forums there at ls1.com and registered, besides, most of the time it just gives me a 'server load to high try again later' message.

Thanks for the link to that proggie, it will help in my decision.

[TPIguy]

Acid, check out http://www.modernmusclecars.net there are a tons of LS1 owners there. Most of em are deep in the 12's or high 11's. I'm sure someone can give you some good advice.

[Thorns]

3.73 was a good competitive street gear, and it still allowed you to go somewhere.  As for my preference, make it a 4.88!  I always had a small block chevy(hmm, can't get 18436572 out of my head, and it been a loooooooooong time).  I just loved the scream of that engine 327/350 at 6800 rpms.  And, of course I never missed a weekend of pouring money into it.  Those were the days, now they are daze.

Thorns

[eagl]

Acid,

You might have to adjust your redline if you have any engine mods and compete in the 1/4 mile, as you might top out the usual final gear in the 1/4 mile.  You'll also lose up to 5 mpg on the highway.  I did some experiments in my '98 TA 6 spd manual, and at 70mph I get 32 mpg and at 75 I get 27.  That's one mile per gallon for every mile per hour over 70, not a very good tradeoff.  The fuel burn stabilizes a bit at 80-85 dropping to only about 22-25 mpg, but the point is that even a few hundred rpm difference at freeway speeds in 6th gear makes a huge difference in gas mileage.

[lazs2]

depends... I have a 6 speed with 3.31 gears and a .76 final (1:1 in fifth)  this is a richmond box not a t56 with 2 overdrives.   I run 2200 at 70 which is about right but.. I end up in 5th a lot.  With a 4 speed auto you will need some lower gears like 3.70 to notice much of a difference since you have so few gears up to 1:1 (3rd).  You won't notice much diff in top speed in the 1/4 since you will be far from redline even with 4.11 gears but.. you will have better et's.. you will accelerate noticeably quicker.. the car will pull harder through the gears and shift/rev sooner.   I don't know about milage.. my car isn't going to get much over 15 no matter what.
lazs

[AcId]

Thanks for the replies fellas, I appreciate it. Due to the type of rear end I have now, all I need to go to a 3.73 are the gears and associated seals/gaskets/fluids for installation so I think thats what I'm gonna do. W000H000ooooo.....

[udet]

wtf are you all talking about? I don't know anything about cars and I hate mechanics.
Does anybody know of a good site that teaches you about engines and cars and greasy stuff like that?