patrickboyle

Dave1, U & I are on the same page...I have an 03 A4 3.15 & will be going with 3.73's & T/C GHL/headers & down the road H/C. These cars seem to respond well to gears & T/C from what I've seen & heard. I'm looking for a reliable 12.xx street car that sounds nice Good luck to you !

Phil97SVT

I would say at least .4 - .5 in the 1/4
Phil

IMQUIK

Do it you will love it. See sig for my results.

NICK YOSKIN

425 mellow, i dont think so with h/c

i have patriot stage ii and tsp 231/231 and i made 417 locked so........

jhiiidoc

Can you simply swap the ring and pinion or do you have to swap the entire differential?

LS1LT1

Yes do the stall and gears at the same time, you will save a nice amount labor/time by doing it that way.

LS1LT1

Depends on what rear you currently have, a 2.73 geared car generally cannot use the same ring and pinion as the 3.15/3.42 geared cars.
Call Cartek (www.cartek.net) for some assistance there, they do a lot of rear work on C5s/C6s and can ship them as well.

Face

I find that hard to believe. I went from 3.15's with a SY3500 to 3.73's with the SY3500. The 3.73's maybe took another tenth off my E.T. With a stock converter the gains would be more, but no way .4-.5 tenths, that's converter territory.

Eric Fischer

Many guys are cutting great 60' times with a performance converter and the stock 3.15 gears. Converter technology has improved greatly over the last few years. If I had to choose between the two, I would choose a converter over gears.

Dave1

Hmmm..........Why is that?....
I thought gears were a bigger deal. I don't know so, please explain the value of the T/C over 3.73's........

Eric Fischer

I don't claim to be a converter expert, but I will try to give an explanation.

It's all about torque multiplication, often rated as STR (stall torque ratio). A performance converter is going to have an STR increase of around 34% (stock STR is around 1.9, performance converter STR is around 2.55). Compare that to the gear change of 3.15 -> 3.73 where the torque multiplication goes up by 18%. So when simply comparing torque multiplication the edge is given to the performance converter by a factor of almost two (34% increase for the converter, 18% for the gear change). So in theory, a performance converter with 3.15 gears should yield excellent 60' times at the track while retaining the good street manners of the 3.15 gear (low highway RPM).

Here's some additional reading on STR from Precision Industries:

http://www.converter.com/torqueratio.htm

Also for drag racing, low 60' times are essential to getting a low ET. The stock converter is not well suited for drag racing. It stalls too low and it takes too long to get in the powerband. 3.73 gears will help some, but not as effectively as a high stall performance converter that gets you in to the powerband quickly.

In the post above Face's real world data supports what I am saying. DaveT on this forum is in the process of installing a converter and cam on his car while keeping the 3.15 gears. It will be interesting to see his results.

Dave1

Thanks for the info......Very interesting....I'll be looking forward to the T/C cam results ...........

DTE Powertrain

LT1LS1-
FYI~ Yes it can.... We've been building/converting the 2-series differentials to accept ANY other gear ratio for nearly three years now with outstanding success. Many on this board have them.

Alfcarguy

The C5 97 Vette that I work on from time to time, he installed a TCI 3800 convert or I should have I installed for him after pulling his tranny out many many times for him and a few months ago he got installed big cam ( when he got engine rebuilt and had head job done and computer work done with the 315 rear gears in it. But before all this, I believe with a new 3800 converter and no cam yet but was running some Mods to many to say about and the 315 gears. I ran the car down the road and pulled 3 runs and the best I had done on the car at that time was 12.99 @ 115 with street tires

I told the owner what I ran and he looked at me and laugh and said the car is much faster than that. He hadn't seen those numbers in along time. Which I believed him cause I was running on street tires, where he uses slicks and about 150 shot of NOS.

But haven't really tried the car out much with 1/4 mile times to really see what it can do. But with everything the guy has done to it with the engine build, he said he was racing a guy from the local drag strip that runs 10.34 ( so the guy told him )and still left him 2,3,4,5 car lengths.

But right now I am setting him up with a guy that runs 10's, if he beats this guy I will let you people know. That with his set up that he has now its really a fast street driven C5.

Note: on bigger gears your going to lose MPH top ends ( I am believing thats right, getting late here. ) Do the other Mods you want to do to it before you do the rear gears cause once you start reving out on your MPHs than you will know its time to change the rear gears. But get a Converter there worth it. And NOS you can't beat it. Easy install and the set up is worth it if you want to run fast. But I saw the invoice when Vettman had his gears changed at local dealership before I knew him and it says on the ticket back in 99 it looks like 1,767.99 total, labor was $540.00 also was for reprogramming computer I believe. The part by themselves where $1,122. And notes this was a 97 C5 corvette with automatic. Good luck.

LS1LT1

I know, that's why I said "generally cannot".
What I should've specified is that you cannot use the same exact gears from a 3.15/3.42 carrier in a 2.73 geared car (that is correct right?)....I knew you guys did swaps/upgrades for the 2.73 carriers but I didn't want to confuse matters more LOL.

LSK

Do the convertor.

Mitch C

doubledeuce

Yeah, I would, but I heard that there is A LOT of labor involved with installing a convertor, is that true, and how much does the labor cost?

Tru_Ice

I'm thinking of doing the same that will be interesting to see.

Eric Fischer

Dave-T's results are in from last weeks Corvette Challenge. With mods of a mild cam, Vigilante 3600, LT tube headers, and Drag Radials he went 11.85 @ 115 with a 1.68 short time with the 3.15 gears I think his best 60' of the day was a 1.65. Pretty good for his first time out with the new set-up.

Maybe he will chime in with more details....