Rear Axle Ratio on 2008 GT
 

I am ordering a manual transmission 2008 GT and I presume the standard axle ratio on it will be 3.31.. is that right?

Any advantages on upgrading to the optional 3.55 axle ratio.. launch?? top end?? is it worthy to upgrade alone without adding any other mod??

Thanks.. :)

Do you plan on modding the car? If you are going to mod just order the car with the stock gears and then have some 3:73's or 4:10's installed later, I prefer the 4:10's. Rob

At the moment.. no modification.. but in the future their might be some :grin:

My concern was to order it with 3.31 or 3.55.. I am going today to my agent as he already placed the order and I wan to see what did they ordered (and change if possible).. The car is arriving in here by Jul/Aug :(

I have the 3.55 from the factory in mine.

With the 3.71, have you had the chance to test the launch (from 0) with a 3.31 or a 3.55 car?? and what is the difference??

My Cal Special came with 3:55 If I had ordered the car like you I would have the 4:10s from the factory.You get the full factory warranty and if you are going to add a CAI or power adder later your just going to add them anyway.

There is no factory option for 3.73's, or 4.10's. 3.31 is standard, 3.55 is optional...and that is your only choices. I don't know what you guys are talking about having "factory gears" that are other sizes than 3.31 or 3.55.

GT automatics only get 3.31's from the factory, so I had 4.10's DEALER installed right after delivery. However, they are not covered by the factory warranty.

Hani - as you won't be modding much, I suggest that you get the 3.55's. You'll get a better launch, and higher top end, as well (gotta love overdrive transmissions!). 3.73's and 4.10's would offer even stronger launch, and higher top end, too.

yeah you are right, I dont know why I was thinking i had the 3.73...brain fart.

Why didn't they offer 3.55 for the autos? Is a 3.55/3.73 bad for the automatic transmission?

3.31's give you better gas mileage. Since prices are going up I would think about it seriously. :D

I don't know if I should be laughing or whining, when an American tells me something about rising gas prices. I used to live in Germany - € 1,45 per liter.

So is it just mileage or are there also worries about the tranny?

No worries about the tranny, it doesn't make the tranny any difference what the rear end gear ratio is. The tranny is the same either way, and a little higher rpm won't affect it. The engine on the other hand, will be running at a higher rpm for the same speed....and will in theory, wear out sooner than a car with lower gear ratios.

That said, I don't think you would need to worry about wearing out your engine for many many years no matter what gears you get.

I just ordered a new 2008 GT with the 3.55. It is the correct gear ratio for the manual. Correct your order if you still can. The reason Ford changed the stock to 3.31 is that you get about 0.1 MPG more.

yeah.. I am going tomorrow to check what was the final order..

I am not sure if I can change any spec at the moment.. I hardly convinced them to order me a manual transmission one!!!

I ordered my 07 with 3.55s (TR-3650) as a $87 option. In retrospect, I should have stuck with the factory 3.31s for better fuel economy.

I went today and checked.. they ordered the standard 3.31 one :banghead:

Sorry to hear that you have the 3.31. The Bullitt is being equipped with the 3.73 now, which is an excellent performance compromise, but will cost about 0.5 MPG over the 3.31. I am planning upon pulling my ring out to install a Detroit True Trac after the car arrives. It really is a great invention. If you were planning other work on your differential, you could change out the ratio then. No matter what, the car will be a blast, so enjoy it.

I snapped off all of the side cap bolts on my Detroit TrueTrac. It turns out it was a problem with ALL Ford 8.8" 2-pinion units but they refused to do anything about it for at least 3-4 years. I now have a $300 paper weight.

The Traction-Lok is simply one of the most effective limited slip differentials and they are cheap and easy to rebuild. Our S197 Traction-Loks are equipped with carbon fiber clutches and I am appalled at how quickly and easily TMS members are to throw these things out. If you are autocrossing or road racing, I could understand the need for a torque biasing differential such as a Torsen or TrueTrac. If it is a daily driver, leave it alone.

Okay, My 2 cents...
If I had a choice of any ratio on my 2006 I still would have chosen the 3.55 gears.
In my opinion it is the perfect ratio for the car. It works very nicely on the road.
4.10s or more are great for drag racing but...
With the 3.55 you only shift twice if you want.
Shifting takes time. (Not much,but it is time without power.)
My last car had 2.41 gears, great for gas mileage and top end was aero drag limited only.
Of course for me, gas mileage is never a concern.:p