411 gears or 373 gears

[99 red cobra]

I own a 99 cobra,I am thinking about putting in a set of gears but I dont know which to use 411 or 373. Also what kind of job is this? Can I do it myself? What about the speedometer?Will it damage my half shafts?What kind of rpm will I be running in fifth gear at 100 mph? And finally what kind of torque numbers can I expect with either one of these gears?Where can I buy these? Thanks, 99 red cobra

[Skip Miner]

I think the choice between 3.73 and 4.10 depends upon what you want to do. I just replaced my 3.27 gears with 3.73 because I wanted better response on the road course at Summit point. I understand that if you want to drag the car, 4.10s or lower would be better.

[Greg@SVTOA]

You guys with mod motors have a higher useable RPM range then us old-school pushrod types. I have had 4.10 gears with my windsor motor and loved the feel of the car and the pull in 5th gear. I went back to 3.73's when I installed a blower, but I have since gone to a hi-winding 347, and am thinking I will go back to the 4.10's with that combo...

One thing to consider in your decision, is the gas mileage issue. You will see a drop in gas mileage if you go up to a higher numerical gear ratio. To some folks, this is not an issue, but if this car is your daily driver and you do a lot of city driving, this is something to weigh out in your decision..

[99_Venom]

I have a 99 coupe and I installed the 4.30s. Don't do it yourself. Ask around and find a reputable shop to do it for you. You could always pull the center section out and take it to the shop to avoid some of the cost.

With the 4.30s I am turning ~3k at 80mph and 100 mph is about 3500. If you plan on any 1/4 mile running go with 4.10s or 4.30s. If you plan on opentrack racing go with the 3.73s. That is my two cents worth of smelly opinions.

As for the breakage of parts, I haven't heard of that until you start putting some slicks or drag radials on it then you will be looking for half shafts.

Now for the torque numbers, gears will not actually change your hp or trq numbers. But it will feel like you put a blower on it if you stuff in a set of 4.30s. I haven't been to the strip yet but my 0-60 mph time went from 5.2 to 4.6 with the 4.30s and drag radials, and that was with 28 #s in the DRs. I don't have the Raxle or GKN half shafts yet so I will not drop the tire presure until I do, I want to keep driving it. :bna

[Elapidae]

Originally posted by 99 red cobra
I own a 99 cobra,I am thinking about putting in a set of gears but I dont know which to use 411 or 373.

Most go with 4.10 or even 4.30. I had a 99 Cobra and I went with 3.73's. Not saying it's the right choice. People with 4.10, 4.30, or 4.56 or 4.88 gears could beat me in the 1/4 but mine was a daily driver and 3.73's worked for me.


Originally posted by 99 red cobra
Also what kind of job is this? Can I do it myself?
I paid someone to do it and I'm reasonably handy. I'm sure you could do it yourself but in my case, I didn't want to make the mess and I was concerned about getting a good seal and about the IRS differences from a live axle setup..


Originally posted by 99 red cobra
What about the speedometer?
Your speedometer will be off (read high). You can get a speedo calibrator (black box) to modify the input to reflect the change or I think you can get this adjustment made with an aftermarket chip.


Originally posted by 99 red cobra
Will it damage my half shafts?
It's easier to break a half shaft with a higher gear (and DR's and high rpm launches, etc...) The gear change alone is not the damaging factor, it's how you drive it after the gear change.


Originally posted by 99 red cobra
What kind of rpm will I be running in fifth gear at 100 mph?
Assuming stock tires, wheels and T-45:
With 3.27's you'll be at about 2868 rpms at 100 mph in 5th.
With 3.73's you'll be at about 3271 rpms at 100 mph in 5th.
With 4.10's you'll be at about 3596 rpms at 100 mph in 5th.
With 4.30's you'll be at about 3771 rpms at 100 mph in 5th.
With 4.56's you'll be at about 3999 rpms at 100 mph in 5th.


Originally posted by 99 red cobra
And finally what kind of torque numbers can I expect with either one of these gears?
Same torque numbers you had before the gears. Gears don't increase your torque or hp. They just allow you to stay in your powerband a little better.


Originally posted by 99 red cobra
Where can I buy these? Thanks, 99 red cobra
There are vendor links at the bottom of the forum pages. That's probably a good place to start and you might just want to call some local shops.

It all boils down to what you want to do with the car. Good luck.
:tmb:

[cobra-cane]

I have a 01 and just installed 3.73 (with a diablo chip). I love it! I think it is exactly what I was looking for. I can't say I know what 4.10's are like, but I am very happy.

[BUG]

I have 4:10 gears in my Cobra and like them very much. How often do you drive on the freeway? How aften do you see 145mph+. If you don't speed and see mild freeway then I would suggest the 4:10. The rpm's are great. Once you get thru first you will never be out of power. I have not experienced the major drop in gas mileage when I take it easy. I still get around 23 freeway and 19 city.

Chris

__________________________
99 cobra
22,000 miles
Will be breaking axles soon.

[chrismc1]

I also went with the 4:10. I love it!! I do bounce off the rev limiter now and then, but its great. I pulled out the pumpkin myself and took it to a gear shop. Ask your shop before you buy the gear set. The Ford gears do not come marked for set-up. I returned them and swaped for the Richmond set. It saved me about 1/2 the cost of set-up. Lost about 1 mpg but I do get on it more. I also installed the Steeda bushings, Kenny Brown cross brace, and a Speed-cal at the same time. Was very easy to do.