3:73 gears, what do you think about this?

upstate · Dec 1, 2004

I have heard so many positive things regarding putting 3:73 gears in my automatic Mustang. I was going to by some and have my garage install them. This is the description of the ones I was looking at. Are these what I should buy? Is $159. a good price? Here's the description:

3.73 Genuine Ford Racing Mustang 8.8" Rear End Gears Ford Racing # M-4209-F373N

Replaces M-4209-F373. New manufacturing technology utilizing a Face Hob Process which features a single pass pinion tooth machining operation compared to a conventional three pass process for machining. CNC cut and lapped gear teeth. Higher strength and better quality gears are produced with the Face Hob Process. Note: These new gears look a little different, the gear teeth are cut on a different angle and the ring gear has a bevel on the back of the gear.

This kit comes complete with the Following:

- 3.73 Ring & Pinion Gears M-4209-F373N
- Ford Pinion Shim Kit
- Ford Pinion Nut
- Ford Crush Sleeve

These will fit any Ford Vehicle with a 8.8" Rear end.

These Are brand New and in the Box!!!

Thanks

Darkhorse845 · Dec 3, 2004

There is nothing wrong with 3.73's in a auto!

J666Z · Dec 3, 2004

3.73's are a great gear for the auto. I know for the 5-speed manual I am loving the 4.10's

SuperchargedSix · Dec 4, 2004

Go with the 3.73's. You'll love them.

Wsmatau · Dec 5, 2004

DON'T do it! Yes the 3.73s will fit in any 8.8. But, I would wait a while if you are putting these in a 2005. Ford may come up with some better form of calibrating the speedo. I had those gears in my old cobra and they were fun, but they will throw your speedometer off even if you use the correct speedo gear (21 tooth). This is just my opinion based on my experience, but I didn't think it was worth the hassle.

2005RedGT · Dec 5, 2004

A computer flash can fix that speedo issue.

SRMobile · Dec 11, 2004

2005RedGT said:
A computer flash can fix that speedo issue.

Computer flash or wait until chips become available if they arent already. You can never go wrong with a little fine tunning while your at it as well.

95snoozer · Dec 13, 2004

SRMobile said:
Computer flash or wait until chips become available if they arent already. You can never go wrong with a little fine tunning while your at it as well.

i would go 4.10s if you think that is too much i would go 3.90s

i wouldnt go with 3.73s if i had the car... a higher geared auto will rip out of the hole.

fast01gt · Dec 20, 2004

Wsmatau said:
DON'T do it! Yes the 3.73s will fit in any 8.8. But, I would wait a while if you are putting these in a 2005. Ford may come up with some better form of calibrating the speedo. I had those gears in my old cobra and they were fun, but they will throw your speedometer off even if you use the correct speedo gear (21 tooth). This is just my opinion based on my experience, but I didn't think it was worth the hassle.

You're ****ing kidding me. right?

AzSnake · Dec 22, 2004

Wsmatau said:
DON'T do it! Yes the 3.73s will fit in any 8.8. But, I would wait a while if you are putting these in a 2005. Ford may come up with some better form of calibrating the speedo. I had those gears in my old cobra and they were fun, but they will throw your speedometer off even if you use the correct speedo gear (21 tooth). This is just my opinion based on my experience, but I didn't think it was worth the hassle.

WTF?????
I had 3:73 in my 98 for a LONG time and my speedo was right dead on with the speedo gear swap. Anything over 4:10 and you will need a speedcal which is a cheap 80 bucks (great unit because you can adjust for different size rims and tires and gears to make your speedo dead on) or get a chip or reflash on the newer cars.

gilmoujr · Dec 22, 2004

3.73's are a waste of money. You are already starting at 3.55's. that is only a 5% change. To really feel anything, you will need to go 10% or higher. The reason that there are so many that say 3.73's are great is because they probably started out with 3.27 gears (a la the 04 down Mustangs - except the Mach 1 - and the auto trannies). Now that these cars have 3.55's then you should AT LEAST go 3.90's but I would personally go with a 4.10 gears. I have done 3.73's and 4.10's and the 4.10's are MUCH better IMO and the gas milage does not really change that much - you stay in higher gears instead of having to downshift to pass.

Meat496 · Dec 22, 2004

gilmoujr said:
3.73's are a waste of money. You are already starting at 3.55's. that is only a 5% change. To really feel anything, you will need to go 10% or higher. The reason that there are so many that say 3.73's are great is because they probably started out with 3.27 gears (a la the 04 down Mustangs - except the Mach 1 - and the auto trannies). Now that these cars have 3.55's then you should AT LEAST go 3.90's but I would personally go with a 4.10 gears. I have done 3.73's and 4.10's and the 4.10's are MUCH better IMO and the gas milage does not really change that much - you stay in higher gears instead of having to downshift to pass.

I thought the auto 05's came with 3.31 gears?

gilmoujr · Dec 22, 2004

Not sure. I know the Manual comes with 3.55 so with the auto tranny generating more LOSS, I would suspect that they would come with the 3.55's as well. Can anyone with an auto confirm/refute this?

exc911ence · Dec 22, 2004

V8 Auto: 3.31
V8 Manual: 3.55
All V6 cars: 3.31

My 89 LX: 3.73... I love 'em!

04torchredgt · Dec 23, 2004

I say don't waste your time with 3.73s,I had 4.10s put in my mach the other day and can't keep from plus when you take someone for a ride that has 3.73s or lower in their car,they will get out of your car going :worship:

Darkhorse845 · Dec 23, 2004

Yes go with the 3.73's!

Zedoc · Dec 23, 2004

In My Honest Opinion, 3.73 is the absolute MAX unless you wish to degrde the practical use of the car. Gas milage and drivability will decrease above that. Engine wear will increase. Also, unless one is actually drag racing, the higher the gear the more you lose the feel of the engine torque and feel the gear multiplication torque instead. It's less like driving a freight train and more like driving an axle ratio. You lose the feel of the engine, which is what V-8s are about, anyway, and you spend more time shifting because you can't stay as long in each gear. In a new GT, that 3.55 is just fine, for all practical use. I wouldn't mess with it.

CatmanJJ · Dec 23, 2004

Zedoc said:
In My Honest Opinion, 3.73 is the absolute MAX unless you wish to degrde the practical use of the car. Gas milage and drivability will decrease above that. Engine wear will increase. Also, unless one is actually drag racing, the higher the gear the more you lose the feel of the engine torque and feel the gear multiplication torque instead. It's less like driving a freight train and more like driving an axle ratio. You lose the feel of the engine, which is what V-8s are about, anyway, and you spend more time shifting because you can't stay as long in each gear.

4.10s are awesome, don't fear the gear!! I don't think you'd even really feel a change between 3.55s and 3.73s.

Had 4.10s in my daily driven '02 GT (plan on going 4.10s or 4.30s in my Mach for the future) and gas mileage went up!! Fun factor is simply awesome, these 4.6s are built to rev!!

DJsZincGT · Dec 23, 2004

Zedoc said:
In My Honest Opinion, 3.73 is the absolute MAX unless you wish to degrde the practical use of the car. Gas milage and drivability will decrease above that. Engine wear will increase. Also, unless one is actually drag racing, the higher the gear the more you lose the feel of the engine torque and feel the gear multiplication torque instead. It's less like driving a freight train and more like driving an axle ratio. You lose the feel of the engine, which is what V-8s are about, anyway, and you spend more time shifting because you can't stay as long in each gear. In a new GT, that 3.55 is just fine, for all practical use. I wouldn't mess with it.

No offense man, but what you just typed makes it sound like you are either scared of the gear or you are just pulling info. from your @$$ and haven't actually experienced a car with a tall gear.

The point of putting a steeper gear in the car is to get from point A to point B quicker. Noone cares about gear multiplication when they are trying to make their car quicker.

351CJ · Dec 23, 2004

Go with 3.73's if you have an auto.

If you have a manual, go with 4.10s.

3.31 to 3.73 = 12.7% increase
3.55 to 4.10 = 15.5% increase
So the % increase will be similar.

Also keep in mind the OD ratio on the Auto is .71, while the manual has a .62 OD ratio.

3.73 x .71 = 2.65
4.10 x .62 = 2.54

So an auto with 3.73s will be pulling more RPMs on the highway than a manual with 4.10s

3:73 gears, what do you think about this?

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