C5 Forever

I haven't been able to find conclusive evidence which is better through using the search. I'm leaning towards 3.90's, but I want to make sure my A4 can handle them. I'm going to be running a TSP 231/237, PP Stage II heads, LGM Longtubes, and underdive pulley. I'm not sure on my stall yet. The gears will probably go in before the stall. I do a lot of city driving and occassionally a long one. I think the difference between the two is a 200 rpm's at 70 mph. Doesn't sound bad. With the power I'll be putting out, would I just be better off with the 3.73's as far as traction goes, would they be faster?

Dave00C5

iTrader: (4)

Unless your a dedicated drag racer the 3.73's will be your best bet. Traction will be iffy no matter what.

Blktie8

iTrader: (1)

I have the 3.73 and the Vigilante 3800 TC
Love it
Might have liked the ypt 4200 better but was right when all the move of Yank was going on and didn't want my car tied up.
3.73 spinn up around 25-2700 on the freeway at 75 or 80 real torquey there.
Check out this websight for a good comparison of gears for rpm range at different speeds.
http://www.smokemup.com/auto_math/mph_range2.php
Don't forget about the extra exhaust note at higher rpm

Good Luck
John blktie8

XTrooper

The performance between 3.73s and 3.90s is negligible. The only thing you'll really gain is decreased full mileage and higher engine speeds. I went over this thoroughly myself and feel good about my decision. Also, our sponsors, East Coast Supercharging, well-respected tuners that they are, recommend 3.73s to the majority of their A4 customers.

Lost

iTrader: (2)

I assume you are going to be putting a drag radial on the car, as my kumhos wont handle a full throttle launch with my basically stock car with 3.15s. best 60s Ive gotten were in the 2.0, 2.1 range and that is with quick roll into the throttle, if I bust em loose 60s go up accordingly...

H-5-L

On another forum,some folks (the drag racers) break 3:73s,more teeth=less mass on each tooth.In my old T.A...A4, i had 3:23s and put in 3:73s and hated them,no more than 3:45s for me,but even with that said,i'm sticking with my 3:15s and adding power and a convertor.I have traction issues even now,3:73s would require a E.T. street to get the full launch (and breakage) potential.If your doing it yourself,the tools that work on a 10 or 12 bolt won't work,rear end/transaxle tools for the Getrag are more expensive than a rebuilt transaxle from a catalog.
I came very close to just bolting in a 3:42 transaxle from a z06.But i like the 3:15s.Have fun which ever way you go..

fastbasser

iTrader: (1)

If you are gonna swap the gears, do the convertor at the same time..

Makes no sense to pay labor to do the job twice! Trust me, I listened to a local installer and could kick myself!! The money saved will pay for a hardened output shaft..

JMHO

XTrooper

This was without doubt concerning F-body rears. Apples versus oranges comparison. The fact is, the Getrag gears just don't break. Get a hardened output shaft and you're good to go all the way up to those super-high hp applications.

I agree regarding the converter. During the gear swap would be the best time to get a new one. :yesnod:

H-5-L

No f-body forums here,and not corvette forum either,there all c5s with getrags,mostly 4:10s breakage,they had less breakage with 3:73s,but still a some.The ring gear just doesn't have the mass of a 3:42,that said,iv'e never seen a getrag apart.But these folks don't lie.A couple guys don't even have hardend shafts,and broke the teeth right off the ring gear.

XTrooper

First I've heard of this and I spend a fair amount of time on the Corvetteforum.

H-5-L

Thats ok i won't hold that against you.. j/k

XTrooper

Well, I can't say it's my favorite hangout either, but most of the C5 "big dogs" do spend their time there.

REDGAR

First I hear of breaking rears also. I made many many passes on my A4 with 4.10 and did not break any gears. Wore them out but did not break them.

On the original question, look at your dyno too. You want to maximize rpm for your power band on the quarter mile. This is what lead me to the 4.10 rear.

Mileage sucks but then I did not buy the car for mileage. It spends more time on the strip.

It is matched to a 4400 stall converter.

I don't notice it much on street driving but highway driving will be at higher rpm and if you have loud exhaust it will be louder with the lower (higher number) gears

nick y

iTrader: (1)

i have 03 with same damm azz mods!!
i have 3.73 w/tci3800 11.17 @123mph
remember that the tranny when not locked-up, rpms @70 can be 2950!
its funny cause it can unlock on highway but then 1 or 2 miles later it locks up. dont get me wrong its not all the time its random. i guess load on the motor.

i would definately go w/3.73!!!


3.73
70mph locked =2350


go with tci3800 you wont be sorry neither will your wallet!

C5 Forever

11.17, damn! that's what I'm talking about. I'm actually going to have a fast car, yes!
what do you have on that thing for rear tires?