My opionion, if your car is a daily driver and you still want some decent gas mileage go with the 3:55's.
I have them on my 88GT and there fine. Only thing is that for me it is not a daily driver and I occasionally drag race it so the 3:73's would be more fitting, and im not at all worried about gas mileage.
Hey guys, check this out. I just checked my axle code and it's a Z, so I guess I have 3.08's, right? That being said, I'm about to do a head/cam/intake swap. I don't think 3.55's would be that big of an improvement, and almost everyone I talk to with 3.73's says they wish they had gone with 4.10's. I drive 25 miles to school and back every night on the highway, so I'm a little skeptical about 4.10's. What do you guys think about those new 3.90's? Do they even make a speedo gear for that? Thanks....
Originally posted by jeff90lx I just installed 3.73 and a spool into my 90lx, if I had to go make the chioce again I would go 3.55's. I just finished the install earlier today and sure as **** if I didn't see a brand new 2003 gt that wanted a piece of my 5.0. We rolled out from about 45mph, I was on it hard and pulled him by about 3 car links but I ran out of tach in fifth at about 115mph or maybe even 110mph. So if you like that top speed or drive on the highway much I would stick with the 3.55's,
that just dosent seem right... you should still be able to hit atleast 160 with 3.73's, what tranny do yo have in your car? a T5? either your speedo is way off... or youve got like 5.XX gears...
Originally posted by jeff90lx well 86 cobra, I have 245zr17's and I can only go about 120 at red line in 5th with the new 3.73's my car pulls very hard up to that,but it won't go any faster. My speedo could be off though?
I have a mainly stock 88' GT. I have Motorsport 3.55s. They work good. I have a friend with a 91 LX convert. He had 3.27 and said he could not feel a difference between the stock gear(3.08) and the 3.27. He jumped to 3.73 and loves them the cars auto too. I love my 3.55s. Great on the highway and I've done a 135mph in 5th at like 3,800rmp. My opinion is stick stock car 3.55. And auto stock car 3.73. If you run track alot i'd make a 3.73 jump it will go better in 1/4 mile. I have the list of mods at the bottom and my car runs high 13.s. That with a beat 2nd gear and grinding it ever time it goes into that gear at the track.
How do you think putting gears in a car will make it go faster. I mean 3.55s or 3.73s. If its a stock cars. A 2.73 stock geared Mustang will run you up to 150mph. Now you throw in 3.73 to get a kick in the pants bottom end and you think it will run 160. NO you loose top end to gain bottom end. And saying the speedos off... Why don't you just let the police officer tell you what your speed was when hes slamming your head on the hood of his crown vic and cuffing you. You can flat foot your car with a mainly stock motor remember and never hit red line in 5th. Whats wrong with that you say. Try 5th gear is OVER DRIVE. Like a .65 gear in the tranny. The car doesn't have the guts to pull you to red line in 5th OVER DRIVE. Deffinatly 4th cus 4th is 1 to 1. That mean everything is turning at the same time almost. I have 3.55s. A stock motor and the basics and I can flat foot my car in 5th get 3,800 3,900 and shes all done. Has nothing else to get her to move. Thats right around 135 give or take 5 to 10 mph. If you talking built motors thats a whole different ball game.
It all depends on the moter, you have to have torque and horsepower to push that final gear in the tranny and all that weight of the car. The tranny helps you do that until fourth gear then its all moter.
i put 3.55's in my (intake and exaust only mods) 92 notch and fried first, spun second, chirpped third, and get 280 miles to a tank. and i need a tune up
Originally posted by jeff90lx well 86 cobra, I have 245zr17's and I can only go about 120 at red line in 5th with the new 3.73's my car pulls very hard up to that,but it won't go any faster. My speedo could be off though?
5th gear RPM is: 5145 at 150 Mph
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2007 GT Prem, loaded, JBA AB
1997 GT 5 sp, Magnaflow packs and TriAxe
1978 F250 Ranger XLT 2wd 7.5
I chose 3.73s five years ago, not once have I ever wished I went with 3.55s. I have put 75,000 miles on the car in that time. I have driven from CA to TX and back, twice. The car sees a lot of highway use, probably 75-80% of my driving is on the freeway. I have gotten between 21 and 24MPG on the freeway with 3.73s, even with the engine work I have done. i get about 16 MPG in the city with 3.73s. These numbers are withing 1-2MPG of my 2.73s.
BTW, I went 148 MPH with 3.73s and 245/45R17s at 5000 rpm.
Also, I ran the car for a year with just 3.73s, K&N, and flowmasters. They worked every bit as well then as they do now.
I have 3.55 with a 3.27 first gear tranny instead of the 2.95 or so standard trans. First gear is pretty short. Makes it seem like 3.73 or maybe a little more off the start. I get about 22 on the highway. 3.73 is too much for a daily driver. I guess it depends on how far you go to work.
