I am in the midst of a project car build that is utilizing all C5 suspension and drivetrain components and was wondering what the difference in both gearings are? In other words what is the performance gains that a 3.73 would have over a 3.42 or are there any?

Thanks!

John

 

If you are talking about a manual tranny, don't bother with 373s unless you will be doing alot of track racing. For the street, 3.90s or 4.10s are the way to go if HP stays below 450 or so. Above 450-500, traction becomes an issue.

Dave

 

Really? I was told that 3.42 was the standard issue in most 'vettes but then again they may be talking for an automatic. Mine will be manual(T-56) so you feel a 3.90 or 4.10 would be best? It will be mostly cruised on the street but will probably see a few open track days. I'll be running a modded LS2 which, hopefully will be able to dyno around 570 hp at the crank. Do you still think the 3.90 or 4.10 would be best in this situation?

 

3.42 is standard on most M6 vettes, 2.73 or 3.23 or so on auto trans. A 3.73 makes a very noticeable difference in the 1/4 mile on a stock vette, but even that makes it noisier around town (higher revs).

I do not favor higher gears than 3.73, or even that, for highly modified vettes, because they bring down the speed at revs so much you have another shift to make in the 1/4 mile: my vette tops out in 4th at about 140 (3.42 gears) and does 135+ in the quarter. If I went to 3.42s it would mean I would have to shift into 5th before the end of the quarter. I am actually thinking of going to 3.23 as I add even more power - 1st and 2nd are just wheelspin anyway.

 

Lee is right - 3.42 is the OEM rar end for 6-speed C5s. Below 450 HP, the 390s and 410s are a blast to drive and will lower 1/4-mile times significantly. However, if you are planning to get up to 570 HP, you might want to re-think swapping gears.

Dave

 

So which do you think would be better with the horsepower that I plan on making 3.42 or 3.23?

 

570 at the crank . . . thats about 500 at the rear wheels. I'd leave it at the stock 3.42, or go to 3.73 if you have upped the rev range of the engine to 7000 and want the very best 1/4 mile time at the expense of higher revs on the street.

 

Gentlemen!

Thank you for your input, time and knowledge! Lee I think I will take your advice and go with the stock 3.42.

Thanks again Guys!

John

 

Sorry, one last question! I have heard that the corvette diffs have a tendency to leak out of the left side. If this is true would you suggest I take the new diff I am going to use and have it gone over by someone like, say, DTE? Maybe even have them beef up some of the internals while its apart with their stage 1 or 2 kit? Any suggestions as to where I can get a good deal on a new diff? And while we're on the subject of drivetrain components.......Since I am buying these components new, would it be best to use an M6 or M12 manual tranny? Oh Crap! That was more than one question! Sorry!

 

Just for the record on C5 6 speeds, they come with 3.42 gears, an auto's base rear gear is 2.73 and the performance axle for a auto is 3.15