4.10 vs 3.73 gears.... AGAIN.....Road Courses

[smokin5ohhh]

The decision is slowly killing me....

I have read like 50-100 posts on this.....

Manual 2006 GT. Probably keep it N/A, but if I ever get enough money I possibly could add a supercharger in the distant future. It is primarily a weekend car, not a DD. I do use it on the highway at times. I would like to use it for road course racing.

I have read for road course racing 3.73's are recommended, because you will be losing time shifting so much with 4.10's. I was all set on the 3.73's after running all the RPM calculations. Just so happened to mention it to a guy I know who has an older Cobra with the 4.10's. He thinks I should get the 4.10's. But, he is primarily a straight line guy. He tried to talk me out of it, so now I am up in the air again. His theory is that since I am already 3.55, I am not going to get that much of an increase and it wouldn't be worth it.

I had originally thought that 3.90 would be the perfect gear, but I have read many stories about them whining/ noisy after installation (motive). Is this still true?

So that brings me back to the endless 3.73 vs 4.10 debate. Looking for guys who run road courses. Is it better to have the 3.73 or the 4.10's? Do you lose time ultimately shifting so much? Also, I also don't want it to be too buzzy on the highway if I do take a trip with it. I have the GTA axle backs.

Looks like I will be at 2375 at 70 mph in the 4.10s
2125 at 70 mph in the 3.73s
2550 at 75 mph in the 4.10s
2350 at 75 mph in the 3.73s

To test the relative sound, I down shifted into 4th and ran the car at the RPM to see how bad it would sound. Anything above 2400 was kind of annoying. Even my Cobra guy whos car is a daily driver claims it does get annoying with the RPMS. That is why I am leaning away from 4.10s

Anyway, any thoughts appreciated.

 

[GreyDiesel]

I think.... your overthinking it.

You are right, that 3.73 are "best" for road courses, but it will vary depending on the exact road course your running. In some cases, the 3.55s may actually be better. You'll want to avoid going into that long fifth gear at all costs, so if there is a long straight, you'll get more speed topping out 4th with 3.55s. than with 3.73s going into 5th*. And, I agree with the man in the Cobra, changing from a 3.55 to a 3.73 is hardly worth the effort.

*course, that may never happen. I have only ever gotten midway into 4th. That is with 3.31s.

Are you sure you have the 3.55? I thought I had it, but checked my rear diff and it says 3.31 right on it.

I would say, save your money and put it into suspension and brakes first. Once that is all set, you may want to add forced induction. Gears are probably fine unless your going to the drag strip.

You may want to upgrade to a T6060 trans and then get some 4.10s.

But... I am no expert, just flapping my gums here. I would be curious what others would say.

 

[sonnier]

I have to agree, it all depends on the road course. I have 3.55s on mine and they are fine. If I ever need to rebuild the rearend I may go to 3.73s but 3.55s work just fine. After all, you have to weigh your options and unless you are actually doing wheel to wheel racing or timed events how much will it actually improve your enjoyment/experience. I've put off many mods that I thought I needed before and instead spent it on more seat time in HPDEs as I feel that allows a much better gain in performance than spending that money in mods. Still there a few things I'd like to do but I know for a fact that the capabilities of my car are still above my skill...and I'm in a fairly advanced running group.

 

[smokin5ohhh]

Pretty sure I have the 3.55 set. Axle code of "CD". Right now I just have a C&L intake with a tune and axle backs. Looking for a bit of a speed improvement, but wanted some road course opinions

 

[orange 07]

If there are long straights switching to 4.10s will probably drop your top speed because of 5th gear. I like my 3.31s for Road America. I use only 3rd and 4th gears, except turn 5 gets 2nd gear. Shifting less does make you faster and so does staying out of 5th gear.
Now if you prefer a short track without any high speed areas 3.55 or 3.73s may be better but you will be working the shifter more.

 

[orange 07]

Heres another way to get the revs up with quicker with your stock gears. Install an aluminum driveshaft and flywheel along with underdrive pullies. It will rev quicker like having higher gears without shifting an extra 5 times per lap.

 

[o0Dan0o]

It depends on a few things. First, while your cars top speed is probably in the 155 range, even on a longest of straits you probably would only push 130 (if that). In which case, with the stock tire size, you'd probably be ok with 4.10s, though you would have to push over 6500 rpm to get there in 4th. Of course if you get a blower in the future you will run out of RPM in fourth.

The next thing is on any give road course a gear change is probably going to help you on a few corners and hurt you on a few others, making it more or less a wash in terms of improvement.

Third, if you do any auto-x (which I highly suggest, as it is an excellent way to learn how to drive your car while being safer than HPDE) you're going to want a gear that will get you between 35-60 mph in second, which with the stock tire size is 4.10, though 3.73 is really just as good and 3.55 aren't much worse.

Here's my bottom line suggestion. First thing, if you do true road course events, get a big brake kit, doesn't have to be a $2k kit, the gt500 brembos or the saleen kit off ebay, both about $1k. Then, before you do any other mods, run your car at a few events, HPDE and auto-x. It is much easier to learn on the stock car, much less likely to bite you. Then slowly mod the car, start with some tires (you will likely need some new wheels and tires for the BBK, but go with some fairly tame tires because they are easier to learn on), then maybe some suspension to limit the body roll and brake dive. Then when you start getting really good add power. THEN, when you know your car and the tracks you frequent really well, decide which gear you believe would suit you best.
Dan