DPE

So I tracked my 2010 GT a number of times, and it had the 3.73 which I would almost consider mandatory given that motor doesn't have tons of torque down low and you've only got 5 gears to play with. However, I'm looking at buying a plain 5.0, perhaps at the end of this year, and am curious what folks think of the gearing on track.

From looking at the gear/mph splits, it sure looks like a 3.73 would mean a whole lot of shifting and quite a bit of 'throttle management' in the lower gears to keep from lighting the tires. I won't be on R-comps; probably tweeners like NT-05s or just plain summer tires. I know lower is typically equated with faster, and it may well be, but it kinda seemed like a 3.55 would give the car a little more range in each gear and on the tracks I run reduce the number of shifts by a few per lap. I'm not afraid of shifting or having to manage the throttle, don't get me wrong, it just seems like a 3.73 might be overkill for a car with that much engine and not exactly an overabundance of traction. I dare say a 3.31 may even be just fine, as that retains essentially the same mph at redline in each gear through the first two gears and then goes slightly lower than my 2010 GT did in 3rd and 4th. And that car worked fine with 100hp less....

So for those who have tracked their 5.0s, anyone on anything other than a 3.73 have comments? Any 3.73 guys feel like it's perhaps a bit too low? Anyone think I'd be a dumbass to get anything other than a 3.73?

The car will be used on track several times per year, but will also go on long road trips etc. All purpose car, not a track toy. But I'm more interested in track impressions right now, just to get a feel for it.

tigercrazy718

this is a good question and im interested in the responses. i know i run 3.73s in my car, but obviously that doesnt apply here since i have half the HP of a 5.0 lol. what kind of track do you run at? that could possibly make a difference as well.

Andy13186

depends on the track

with 3.31's 2nd gear ends at about 70 mph, 3rd about 100 mph i think

traction is an issue in temps below 70 for me (depending on the surface) with stock 3.31 gears stock hp and michelin pilot supersports in 295 width

Id say anything would be fine, youd probably stay in 2nd for quite a bit on most road courses i would think

tigercrazy718

hmm didnt know the top of 2nd was 70 on the 3.31s. i would say that would be pretty decent gearing then because youll hardly ever have to shift, mostly only if you come into a hair pin or youre on a straight.

DPE

The tracks I run are Heartland Park, Mid America Motorplex and Hallett. HPT and MAM are relatively fast, open tracks (both around 2.2 miles long with 120mph+ straights), while Hallett is more technical and 'slower' in the sense that the whole track is only 1.6 miles long and being a 'square' track it doesn't have any long straights. It's also the most fun of the three . On any given track I'm in third most of the time in the 2010 (down to 2nd a few times, up to 4th a couple times), whereas it looks like with a 3.73 in a 5.0 I'd be between 3rd and 4th quite a lot and occasionally into 5th. And again, I don't object to that, but it does kinda seem like overkill. I had an STI several years ago and they are geared entirely too low; just felt like I was shifting a lot in that car when slightly taller gearing would have reduced the number of shifts and given the car more time in gear to put its power down.

I don't recall on any of the tracks I run feeling like I was in a bad spot gearing-wise in my 2010, and with an extra 100hp and notably broader powerband it's hard to imagine wanting/needing the gearing to be lower. However, I have not driven a 5.0 or Boss on track, and though I haven't searched for it I have not seen anyone complain about their 3.73 gear on track, so it may be the right way to go regardless of what I think from looking at the numbers. Just wanting to get a feel from folks with experience what they think.

moochman4life

It really depends on the overall diameter of your tires, too. Going from the stock 27" tires down to about a 25.5" effectively changed my gear ratio to a 3.90 or something. I can't do the math, but there are calculators out there that can do it for you.

Actually, here you go, a top speed calc:

http://www.catherineandken.co.uk/sti/tyres.html

Basically, with the stock 3.55s on 275/35zr18 race slicks and a 6750 redline (yep, my car makes power all the way up there), my 4th gear will wind out at like 144mph. 3rd gear is 109, 2nd 72 and 1st is 43.

I think that's right where I want it for smaller tracks, but I've gotten to 144 in a hurry at VIR...meaning 5th gear or stay pat. =/

So, if someone has 3.73s and a shorter tire on a 5 speed transmission, they might be a little limited at faster tracks like VIR. 3.73s in the new fav-ohs with their 6 speeds are killer, though. Just right, imo.

moochman4life

Double post.

Norm Peterson

The speeds from that application are probably 3%, maybe 3.5% optimistic. Not that you'd notice out on the track.


Norm

moochman4life

Engineers are so specific.

DPE

Thanks for the responses. I've got my spreadsheet all dialed in with the gearing, tire size (I'll always be on 275/40/18s), etc; all the more reason I'm not sure a 3.73 will be 'right' given the overall diameter of those is slightly smaller than OEM whether you have the Brembo wheels/tires or the regular 19s or 18s that come from the factory.

So again, by the numbers a 3.73 seems a little too low and ultimately unnecessary given how much engine the car has vs. how much traction is available, but I would still like to hear from some 5.0 track guys with any of the available gears to see what they think....