User 113021

I've heard things about both gears and wasn't sure which one would be better suited for my car. I have an automatic transmission, and heard that 4.10s are good for it. Any thoughts?

hamidlmt

I have an auto too... I went with 3.73's because I didn't want such high rpm's at cruising speeds. The 3.73's have certainly woken my launches!

tomsa55

I'd go with the 3.73's. The 4.11's will drop your top end some and increased rpms at hiway speeds and will cost you in gas miliage. I put the 3.73's on my auto w/ a ford traction lock diff. Some increase in drivetrain noise, and higher rpms around 2300rpm at 65mph. My gas mileage is about 19.7 mpg. Thats a mix of highway and city driving, with a heavy foot You will need a tuner to adjust your speedo and help the transmission hit it's shift points properly. Have fun driving

scrming

4.10's are blast around town... LOL! Now the question is what type of driving do you do? And what are you willing to tolerate?

Try this... turn your overdrive off (the button is on the shifter). Drive your car for a week without out using overdrive... if you can survive that than you can survive 4.10s.

Now if you have a power adder in your future plans you may want to hold off on the 4.10s...

LX200

I am kinda clueless on the gears thing... when you say 3.73 or 4.10, is this a set of gears, or just one of the gears? If it's one, which one? What gear do we have stock? Any good links to a thread describing all this gear stuff?

Also, If I was looking for better low end torque, which gear would I use.... even if I end up giving up top speed, which is not too much of a consideration for me?

Torch_Vert

It's a set of two gears. A ring gear and a pinion. Basically the pinion is connected to the driveshaft and meshes with the ring gear, which drives the wheels. Both of the gears reside inside the differential housing (that big pumpkin looking thing in the middle of the rear axle)

Stock gears on a new V6 are 3.31

3.73's will give you better low end torque

4.10's will give you even more but may be a little too much for highway use

There are other gear ratios too, but the 3.73's and 4.10's are the most popular for 'stangs

ranebowcyxx

scrming gave me this tip a couple of weeks ago, it works, I'm going with the 3.73's especially since I do a fair amount of highway driving.

BTW John, thanks for the idea.

LX200

Well, the 3.73's must have a negative effect on the highway as well, or is it only when you try to go 70+ or 80+.

And, when we say more torque at the low end, is it subtle, or really noticable increase in torque.

Lastly, how difficult is the install? Is it best done by a pro, or can any decent garage monkey do it?

ranebowcyxx

The 3.73 will have less impact at highway speeds.

To see how your launch will be impacted simply multiply first gear (3.22 I believe) by the rearend ratio (3.31 is stock) = 10.6 to 1. Used to be anything over 10 to 1 was great for the street, but the way motors are setup today (they make more power on the top end but sacrifice a low end torque) you need more gear to get off the line.
So 3.73 x 3.22 = 12 to 1, which is a great number for a street/strip car. Any more than that and you probably should have a little more cam than what is stock.
But the bottom line still comes back to how you will use your car on a daily basis.

The plus side of overdrive transmissions is the last gear, which in the case of the Auto is .71. By having a number less than 1 means in effect it only takes .71 revolutions of the engine to get a full turn from the drive shaft, also the effect of going to lower gears (higher numerically) will only impact your final RPM's at cruising speed by 12 percent

Example 3.31 x .71 = 2.35 final drive ratio where as 3.73 x .71 = 2.65. You will only see a twelve percent increase on the tach.

SO if you cruise at 60 and see 2000 RPM, going to 3.73 should turn the motor at 2240.

Now a 4.10 will give you a final drive of 2.91 to 1, that is a twenty percent increase, now you would be turning 2400 RPM.

Keep in mind, we're dealing with percentages here, if you cruise at a speed that currently gives you say 2500 RPM, your difference won't be 400 RPM as in the last example but 500, so now you'll be turning 3000 RPM.

As far as installing gears? I have never done it. I have built a dozen or so of engines over the years but never tackled a rear. For that kind of work I would rather pay someone. I was quoted 150 to setup my gears and Tloc.

Stewart

I just had 4.10's installed in my manual. I love them, yes crusing rpm's are a bit higher but very tolerable, no gear whine, and I'm about to drive across the country with them so I'll see if the highway driving gets to me by the end of the trip. If anything the higher rpm's bring you closer to the peak of the powerband in 5th. After having the 4.10's in it seems if ford had put in a 6th gear with 4.10's the gearing would be perfect.