3.73s are in!

[Husky44]

What else is needed besides the gears to swap them out? Gaskets? Bearings? I've never done it before and want to do it right.

-Gear set (I HIGHLY recommend the Ford Racing gears)
-Small parts kit (comes with shims, which you may or may not need, crush washter, pinion nut--these were in my gear set also, so you may not end up needing the parts kit at all)
-You may need a pinion bearing, if you can't get yours pulled off the shaft without damaging it; same goes for seals and other bearings... on a new car you've got a pretty good chance of not having to swap all of the bearings and seals; on an older car it's a good idea to do them while you're in there
-Loctite
-RTV for your diff cover
-gear oil (and friction modifier, unless you use Royal Purple or others that don't require it)

If you've never done a gear swap before, I would suggest doing a lot of reading before you decide to DIY. It is do-able, but you'll need some special tools and a lot of patience to get it dialed in right. The reason my bud can do it so well is that he's done hundreds of them over 30+ years. If you're not experienced, and don't plan on ever doing it again, you would be better off to pay a pro (or buddy up with a driveline guy).

I'm all for DIY on almost anything, but this is one job that I'd recommend you seriously consider farming out (having done one myself, and watching a pro do my latest).

 

[mike69440]

3.73 gears are waht Ford should have done.

I reaaly do not think it makes any difference in fuel consuption, 3.31 or 3.73 in real world driving if you are just tooling around. After all, 6the gear is a .5 O.D. which is one heck of an O.D. Driveability with 3.73 has to be so much better than the 3.31 when just loping around.

The overall first 4 gears on a 13 with 3.73 grears are damn close to the ratios in my 03 with 3.55 and smaller tire. At 35 mph all 6 gears are useable at light throttle. 6rh in a Temi is .63 O.D. so a 13 with 3.73's is still lugging in 6th at legal speeds.

I'm not sure your 1/4 mile will be that much quicker with the extra shift, but it will feel faster, and t hat is important.

 

[psucobra]

Thread hijack warning!! Has anyone considered 3.55s as a compromise between the stock ratio and the 3.73s? I always liked the way the 3.55s felt in 04 Cobra and the transmission gear ratios with the exception of 6th gear are very similar.

 

[Lethalchem]

Thread hijack warning!! Has anyone considered 3.55s as a compromise between the stock ratio and the 3.73s? I always liked the way the 3.55s felt in 04 Cobra and the transmission gear ratios with the exception of 6th gear are very similar.

Thought I heard someone say 3.73's in the Shelby are similar to the 3.55's in the 03 Cobra. I liked my stock gears in my Cobra too, which is why I was thinking the 3.73's would be perfect.

 

[psucobra]

Thought I heard someone say 3.73's in the Shelby are similar to the 3.55's in the 03 Cobra. I liked my stock gears in my Cobra too, which is why I was thinking the 3.73's would be perfect.

This is what I found:

03/04 Cobra - 2.66, 1.78, 1.30, 1.00, .80, .63

13/14 GT500 - 2.66, 1.82, 1.30, 1.00, .77, .50

 

[Sparko]

I am thinking about installing 3.73's in '13 GT 500. I've seen a lot of parts number being discussed ....could someone answer 3 things for me....

1) what parts# are the correct parts I need to buy and from where
2) What will a dealer charge to install these parts
3) can the dealer to your knowledge reflash to compensate for the gear change

Thanks for any help....you guys always amaze me with the depth of knowledge you have.

 

[SteveWK]

This is what I found:

03/04 Cobra - 2.66, 1.78, 1.30, 1.00, .80, .63

13/14 GT500 - 2.66, 1.82, 1.30, 1.00, .77, .50

Looks like the only major differences between the 03/04 Cobra and the 13/14 GT500 is 6th gear and the 03/04 Cobra having 3.55s.

 

[Lethalchem]

Looks like the only major differences between the 03/04 Cobra and the 13/14 GT500 is 6th gear and the 03/04 Cobra having 3.55s.

And 17" wheels.

 

[SteveWK]

And 17" wheels.

Completely forgot about that. The 03/04 Cobra has 275/40/17 tires which are 25.661" in diameter and the 13/14 GT500 has 285/35/20 tires which are 27.854" diameter.

The equivalent gear ratio from the 03/04 Cobra is:

(27.854/25.661)3.55 = 3.85

The 3.73s are actually a taller overall gear ratio when tire size is taken into account.

 

[psucobra]

Completely forgot about that. The 03/04 Cobra has 275/40/17 tires which are 25.661" in diameter and the 13/14 GT500 has 285/35/20 tires which are 27.854" diameter.

The equivalent gear ratio from the 03/04 Cobra is:

(27.854/25.661)3.55 = 3.85

The 3.73s are actually a taller overall gear ratio when tire size is taken into account.

Interesting.

 

[Joe5.0]

I had 3:73's installed in December and absolutely love them.

Everyone needs to do them, they are a must have.

Joe

 

[Lethalchem]

I had 3:73's installed in December and absolutely love them.

Everyone needs to do them, they are a must have.

Joe

Don't supposed you got any before and after track times with gear change only?

 

[Joe5.0]

Don't supposed you got any before and after track times with gear change only?

Unfortunately I do not. The car will hit the track this summer:burnout:

Joe

 

[Lethalchem]

Finally got a call back from my dealer regarding my question about installing gears. They will not do it. I'm going to hit up the other ones in the area to see if they will.

 

[COOL COBRA]

Parts were ~$220 from Tousley Ford, for the gears and a small parts kit (was able to reuse the pinion bearing), plus shipping ($50 to AK, but still a better deal than I could find anywhere else).

Labor was free. My buddy has been doing drivelines for decades, and did it for me. Made me feel like a putz. I did my own swap on my 95, and took about 10 hours just to get the pattern "good enough", and they still make some noise. He took longer to get the old carrier and pinion out than he did to set up the new gears, and they're dead on. I swear he didn't even crawl under the car, but kinda stood back and underhanded the carrier in like a softball pitch--and the pattern was perfect. It's fun watching an expert at work. No noise, smooth as can be. :beer:

You cant beat the price! I figured it would be higher than that.
Ive been contemplating a gear swap for awhile. Cant make up my mind.
Sounds like you're liking it 44.

 

[Husky44]

Lethal: no tune required. Ford dealer can reset the gear ratio for you. I'm not an expert in this, but have talked to several folks, including the service guy at the dealership, and it's a preset selection to change gear ratio from 3.31-3.73 (or several other common ratios). Hope to get mine in Friday.

If that's the only reservation you have, then go for it. You're exactly right about the feel that's missing.

Lethal, and others: Bad news. Although it is a pre-set selection in the dealer's computer, it doesn't work, and Ford says they don't support the computer reset. See my other post here where I'll be keeping folks informed on my progress getting this resolved.

 

[Lethalchem]

Lethal, and others: Bad news. Although it is a pre-set selection in the dealer's computer, it doesn't work, and Ford says they don't support the computer reset. See my other post here where I'll be keeping folks informed on my progress getting this resolved.

Yup, that's consistent with what I've heard on here. That's what I figured.