Thinking about gears

90_Red_LX · Sep 18, 2005

Hi guys, I've been debating either 3.55 or 3.73 gears lately. I was wondering what you guys would pick. As far as daily driving, it's mostly city with just a few miles of highway driving everyday. As long as my gas mileage doesn't take a large hit, I don't mind. However to get to a track or the closest well known cruise strip, it's about an hour to each one of highway speed driving. Would it really kill me, even though I don't go down to each one a whole lot?

What all would you reccommend for the gear install? Would you get some type of rebuild kit with new bearings or w/e for the rearend, if so what kind would you get? What about the trac-lok? I don't think myn is shot, but I'd like to have it done while I'm in there, how much to have clutches for it? What kind of rear end fluid would you guys run?

Finally, since it's my daily driver, is it feasible to drop the car off around 7-8 in the morning, have the gears installed, a new trac-lok rebuilt, and whatever else and expect it to be done by the end of the day? Around 5 or a little after? I would assume so, but I know little about the work required to perform the task.

The car has around 96k on it. I just bought some headers and underdrive pulleys, and thought it would be a good way to round out this series of mods with gears. Thanks!

marine_2003 · Sep 18, 2005

I have 4.10 gears and they suck down gas, the 373's are real popular among a lot of people, as for haveing them installed in a day, that would depend on how busy the shop is.

slow93 · Sep 18, 2005

3.73S would prolly suit you best.i have 4.10s and drive everyday but the furthest i drive is about 35 miles one way so it doesnt see that many highway miles.

IntenseBlue · Sep 19, 2005

Stick to 3.73s. I'm not a 4.10 hater, but they're not highway friendly. Not sure about having the diff. rebuilt, but a simple gear install should take about 8hrs. The lubricant that was put in my rear was FRPP. I haven't had any problems with my gear install and neither have any friends with theirs. Good luck and you'll love it.

BTW, i picked up 1mpg city with my 3.73s.

cevtv · Sep 19, 2005

IntenseBlue said:
but a simple gear install should take about 8hrs.

More like 2 hours..........

.

cleanLX · Sep 19, 2005

I've had 3.73's and 4.10's with stock motor setup.
Around town and at the strip I enjoy the 4.10's much more than the 3.73's.
85mph with 4.10's puts you at about 3000rpm, and, even tho it's only 300rpm more than with 3.73's is a noticable difference in fuel consumption. Never measured it, but, by fuel usage on the way to the track, I'd guestimate a loss of 3-4mpg at 80-85mph over use with 3.73's.
Personally, I would not go 3.73's again, I'd go straight to the 4.10's.

Good luck.

IntenseBlue · Sep 19, 2005

cevtv said:
More like 2 hours..........

.

My bad, didn't mean to put 8, I meant to put 3. Close enough.

darthcual · Sep 19, 2005

Obviously the bigger the number the faster you'll go!

Foxfan88 · Sep 19, 2005

3.90s

nosmatt · Sep 19, 2005

4.88's

anything else, and your just not serious.

of course, im puttin in 3.73's

slow5poh · Sep 19, 2005

i put 3:55's in my gt. they might be a good way to go for the best combnation of fuel economy and performance. (if u have a five speed) seems like w/ 3.73 or 4.10 u would have a very short first gear, and would have to shift alot. but they probably get it off the line a lil better

90_Red_LX · Sep 19, 2005

It'll be 3.55 or 3.73 gears. Thinking 3.55. I like the way with a 2.73 it pulls you through the gear, but I just don't have enough power to have it pull like I want. And I doubt it will change for a good while so I think I'll gear it.

Anyone have any info on rebuilding the trac-lok with extra clutches?

If your already in the rear differential, would you just have the gears and trac-lok done, or order a kit and have it installed with new bearings and whatnot?

Thanks!

Black 93 Fox · Sep 19, 2005

I have 3:73's and love them a few of my friends have 4:10's and 1st gear is like nothing its really short, I say go with 3:73's

slow5poh · Sep 19, 2005

i didn't chage the tracloc in mine yet. but i do recomend doing a install kit with all new shims and bearings, seals, etc. would suck to do the gears and then have a bearing problem or something. they sell the kits at summit and jegs for like 100 bucks. also, please take it to a reputable shop, or a rear end shop. i took mine to a general repair shop, and the ****ed it up the first time. it was ok the second time, but a few months l8er the pinion seal is leaking and one exle seal..........

Jaswir · Sep 19, 2005

i just ordered my 3.73 going to rebuild it all track lok and replace barings

Ford Racing 3.73 = $90 Bucks USED
NEW track- lock kit = $45.00
New Baring KIT = $100 bucks
Install = $210

$445 For everything not bad

niklid05 · Sep 19, 2005

Not to highjack your thread but has anyone tried the 3.90's? I dont think ford makes them, but I was thinking about going the 3.90 route. It seems it would be a happy median between 3.73's and 4.10's. I will only drive the car 3-4 times a week, while I drive my Festiva the rest. I would love to get 4.10's but I'm not sure that would be the best thing to do. Hell I'd even get 4.30's, I just dont know how they would do on the highway.

Realmongo · Sep 19, 2005

Here is what Ford Racing put on their site in the FAQ section:

Q.: I have heard that an axle gearset change is a very effective way to increase performance in my Mustang. What gear ratio do you advise that I use?

A.: 1986-95 Mustangs with a 5.0 and a 5-speed work well with 3.55 gears.
1986-95 Mustangs with a 5.0 and an automatic work well with 3.73 gears.
1996-2003 Mustangs with a 4.6 SOHC and a 5-speed work well with 3.73 gears.
1996-2003 Mustangs with a 4.6 SOHC and automatic work well with 4.10 gears.
1996-2001 Mustang Cobras with the 4.6 DOHC/5-speed work well with 3.73s.

Note: The above suggestions are general recommendations. Gear-ratio selections may change depending on modifications to your engine. For specific applications, call the FRPP Tech "Hot Line" (586-468-1356) for professional advice.

GRGT1994 · Sep 20, 2005

niklid05 said:
Not to highjack your thread but has anyone tried the 3.90's? I dont think ford makes them, but I was thinking about going the 3.90 route. It seems it would be a happy median between 3.73's and 4.10's. I will only drive the car 3-4 times a week, while I drive my Festiva the rest. I would love to get 4.10's but I'm not sure that would be the best thing to do. Hell I'd even get 4.30's, I just dont know how they would do on the highway.

To me it seems that the difference between 3.73 to 3.90, as well as the difference between 3.90 and 4.10, is so small, it's really insignificant. You are splitting hairs (unless you are building a bracket racing machine and need to dial in your gearing).

You are only talking about 5% difference at each step from 3.55 to 3.73 to 3.90 to 4.10. Not a terribly big deal. The difference between 2.72 and 3.55 is like 30%. You're gonna notice that. Whereas the difference between 3.55 and 4.10 is only 15% - noticeable, but not huge.

In short, its the step up to 3.55 that really matters. Where you settle from there is just window dressing. So pick whatever gear you think makes sense, based on whatever whim you choose.

Me? I went nuts with 4.10's in a 5 speed (though mine is a 'vert and a heavier car that the fox bodies). Add to that I did an HCI. Now 1st gear is crazy, and 2nd is a total blast!!!

srothfuss · Sep 20, 2005

Everyone say's don't fear the gear... But I am happy with my set-up as far as performance / MPG goes. Having the gear makes driving so much more fun and getting on the highway a blast!

tjm73 · Sep 20, 2005

You'll want the 3.73's. I've had both the 3.55's and the 3.73's in the same car. With the 3.73's I still get 23mpg on the highway. Around town the car is very easy to drive. The car won't work very hard to move with 3.73's which will reduce the need for the engine to really "work" which means less fuel is needed. You will likely see an increase in mpg with the gears in around town driving.

Thinking about gears

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