3.73 gear on 98 GT automatic,

[Dave Maple]

Thanks to all who responded to question on headers.
Next question. I was wondering how installing a differant rearend gear (3.73) would effect my automatic transmission? Or would it at all? What else would be effected and how? Would the car be harder to handle on wet roads or snow? Would my wife be more afraid to drive it than she already is?

[surfbeast]

The gears will give you beter acceleration from a stop. With 3:73's you will not really notice any change in gas milage and your RPM's will only increase by a bit. You will be able to spin the tires a bit easier but your wife probably won't know the difference. When you get the gears this is what you need,

Gears : FRPP with pinion nut and pinion bearing and crush collar

gear lube 2-3 quarts, and a bottle of "stink oil" wich is tracktion lock oil from ford for the posi trac unit. About $ 3.00.

A 23 tooth speedo gear to corect the speedo $ 10.00 or the $ 100.00 sped cal unit from Dallas Mustang to correct the speedo to within .2%

Also, have the mech check your inner axel bearings and races, mine needed replacing and a so-so mech would have missed it. That would have cause major damage if left unrepaired!Before my S/C I could actually chirp 2nd, something unheard of before gear swap.

Look around for a good gear installer: Mine charged $ 130.00 for gear change, bearing change and transmission oil change. It took the guy 2.5 hours total to do. Other places wanted $ 225.00 min to do the gears, what a rip off!

Good luck

[95mustanggt]

Regarding the question on difficult driving conditions: If you drive hard, yes you'll get in more trouble, you are increasing the torque to the rear wheels by changing the gears. However, you will have more control (atleast you do with a 5 speed) and will actually have better traction. Just don't step on it!

[ajcolv]

I have also been looking into gears. It has been highly recommended by most people to go with the SpeedCal over the speedo gear. The gear is plastic, and apparently has a tendency to get shredded, meaning it would have to be replaced again.

In regards to it effecting the auto tranny, I have been getting many mixed responses to this. Numerous people have told me that a chip will be required to adjust the shift points, otherwise you'll be bouncing off the rev limiter all the time. However, I have had the same amount of people tell me that a chip is not required, at least with 3.73's, because it's not such a drastic change that it effects the shift points too dramatically.

Hopefully you can get a few more responses that will help us both get that question answered with more of a solid response.

[95mustanggt]

I was under the impression that with a 4.6L stang you had to get a chip with gears. But that is only an impression, I could be out in left field.

[ajcolv]

Not to correct the speedo. Actually the chip won't effect the speedo at all. The speedo isn't connected to the computer, it's mechanical (or something like that) in the 96-98's.

[Hammer]

Go with the speedo gear...

Its cheap, effective, and easy to replace...

I had mine for 50k miles and never had a problem with it...

I would recommend a chip to go along with the gear change to get more aggressive shift points and correct operation of the rev limiter...