Rear end gear decisions

[MustangChuck]

Hey folks. I recently did a 6 speed swap in my 08 Mustang GT at Cincy Speed (thanks again guys for a wonderful job! I love it and I havent fried the clutch yet lol!) and I am probably gonna do a rear end gear swap at some point. It came with the factory option of the 3.55. However, the choices I am considering are 3.73, 3.90, and 4.10. Can anyone give me any advice or facts about these or ya'lls opinion on which I should do?

Here is some info on how the car is used:

I usually only drive it on the weekends (friday thru sunday on a normal weekend, thursday thru monday on a long holiday weekend)

I use drag radials when I go to the track (Mickey Thompson ET Street radial 305s on the rear), but for daily driving I use BF Goodrich KDW2s (265 rear tire width).

Clutch is a McLeoud twin disc

I do drive it long distances from time to time to go to a car show or to come home on leave (I gotta have my toy to go to cruise ins and such when im home! lol).

Any help or advice would be appreciated (i.e. street drivability, gas mileage affect if any, major loss of top end speed, etc.)

[Pitbull1052]

are you going to leave it na or power adder?

[Kevin1989]

i say 3.73 or 3.90

[MustangChuck]

I plan on going forced induction eventually.

[Pitbull1052]

I'm not sure but I think urs is similar to the 2v and like a lot of gear..... NA i'd do something in the 4's with you doing a 6 speed i'd consider the 4:30's but with the forced induction depending on if you turbo or sc it i'd do like Kevin said.....

[MustangChuck]

I'm not sure but I think urs is similar to the 2v and like a lot of gear..... NA i'd do something in the 4's with you doing a 6 speed i'd consider the 4:30's but with the forced induction depending on if you turbo or sc it i'd do like Kevin said.....

Yeah im thinking i'll do a procharger eventually. But thats a while down the road. I may get the 3.90s so I can have a little more pep than the 3.73s, but not the tire-shredding torque that a 4-"level" gear will give. Anyone else got any advice?

[2Fast4You]

I will add that the higher gears (3.90 vs 4.10 +) will keep the gas mileage a little more reasonable as well. Just don't forget to correct the speedometer with the gear change,

[Pitbull1052]

I've had both 3:73's with a 5 speed and now 4:10's with a 6 speed and I know there's a difference in drive ratio's but i hardly notice a difference maybe a few hundred rpm with the 4:10's

[MustangChuck]

I will add that the higher gears (3.90 vs 4.10 +) will keep the gas mileage a little more reasonable as well. Just don't forget to correct the speedometer with the gear change,

You mean with the higher gears it would hurt the gas mileage, right? I know I would probably lose some MPG. Im just looking for a ballpark figure.

[5.0calypso93lx]

I haven't seen anyone ask, but what are the gear ratios in the trans?

[Pitbull1052]

You mean with the higher gears it would hurt the gas mileage, right? I know I would probably lose some MPG. Im just looking for a ballpark figure.




I dunno i don't think about gas milage it needs gas i fill it up lol i've got a 347 with a 6 speed and 4:10's...... I want to say in my 91 LX with 3:73's I got about 16 MPG and that was driving from Amelia to downtown everyday so a little city a lil highway...... in the 6 speed with 4:10's I have no clue I can't say I let up off the skinny pedal enough to figure it out lol

[MustangChuck]

I haven't seen anyone ask, but what are the gear ratios in the trans?

Not sure. But i know its the tremec TR-6060 (the same transmission in the GT 500s).

[boostanggt]

With your setup, at 60 mph you would be 2000rpm. I think that's just about perfect

[MustangChuck]

With your setup, at 60 mph you would be 2000rpm. I think that's just about perfect

Thanks man much appreciated. That 6th gear really helps out more so than people think, huh? Plus i think its logical to assume i wouldnt loose nearly as much top end as I would if it were still a 5 speed seeing as I have that extra gear now.