[07stanggt]

Here the issue has come up a lot so this is what the big boys say. Its from MM&FF


>>>Changing the gear ratio in the rearend is one of the biggest bangs for the buck and a time-honored tradition in hot rodding. "Gears are a torque multiplier, and allow the engine to use it and get through the rpm range faster for quicker acceleration," says Tony Gonyon of HP Performance. Typical gear ratios from the factory (2.73, 3.08, 3.27, and 3.31) are designed for a mix of mild performance, miles per gallon, and rpm range at cruising speeds. The new Mustangs are offered with 3.55 gears as an option, but for the most part, the rear gears from the factory aren't optimal for drag racing or the performance we expect out of our cars. Also note, when talking about gear sizing, the lower ratio gears are numerically higher--4.10:1 is a lower ratio than 3.73:1.

If you own a 5.0 Mustang, the two most popular gear choices are 3.73s and 4.10s. With 3.90 gears coming to the market in the past few years, that size has become more popular. Automatic-equipped cars will benefit greatly from 4.10 gears because of the greater rate of acceleration. Typically, anything numerically higher than 4.10 reduces driveability, as highway cruising rpm is drastically higher and performance tends to fall off with stock engines' power range.

The Two-Valve crowd should go after lower gear sizes such as 3.90s and 4.10s. Justin Burcham of JPC Racing says, "These cars don't have a lot of torque, so they respond well to gears." He also says that with 3.90s or 4.10s, the rpm drop-off on gearshifts is not as severe, and that helps performance. Those enthusiasts with Three-Valve combinations found in '05-up Mustangs should run 4.10 gears, as unanimously selected by Gonyon, Burcham, and Mike Dezotell of Dez Racing. They said that for enthusiasts who don't want something as steep, the 3.90s are sufficient, but nothing numerically smaller works well to warrant the gear swap. The more hard-core drag racers out there should consider 4.30 gears.

[WILD Jeff]

Good stuff, REPS

[07stanggt]

thanks wild man.

[CH53Driver]

I'm still going with 3.73's. Everyone who I talked with that drive GT500's say as you add HP to this car, you will quickly find that the lower gears (4.10's etc) almost become uselss on street tires. So I think 3.73's are a good middle ground because the 3.31's that come on the GT500 suck.

[07stanggt]

its your choice bro. Traction is an issue for sure. but its an issue either way. I dont get it myself, back in the day guys were pushing 500hp and running 4.10s, 4.30s 4.50s. in push rods that were low end tq monsters and the tires werent as good back then. Throw some drag radials on that car get some 4.10s and HTFO.

[Emay]

CH53, vouch for the comment whole heartedly within the supercharger world. If my car was a dedicated track car with the ultimate in suspension set up for traction it would be a completely different story. Traction is zero on the street, DR's or not at my power level. It's only fun for so long and then it's old.

[Emay]

Originally Posted by 07stanggt its your choice bro. Traction is an issue for sure. but its an issue either way. I dont get it myself, back in the day guys were pushing 500hp and running 4.10s, 4.30s 4.50s. in push rods that were low end tq monsters and the tires werent as good back then. Throw some drag radials on that car get some 4.10s and HTFO.

Back then they were not going for a stance or look. These days people are. Big heavy cars with a rake are a thing of the past, but they were perfect for setting up weight transfer for superb traction.

[07stanggt]

yea thats true emay. I understand what your saying and agree. But you also know that the myth of cars being a lot heavier back then isnt really that true. 65 stang is lighter then my stang. and dodge had some cars with 400+cubic inch engines that we sold as drag packs so to speak rolling of the lot at 2900lbs. The rambler????

[07stanggt]

but no one was getting traction back then.

[BWAL]

good article.. i saw that in MM&FF a while back too

[07stanggt]

i can see supecharged guys on the street not doing it. My car will break loose well into second gear, if i stand on it and im making a lot less tq then you guys.


Yea i thought it was a great article.


By the way curb weight of a 68 gt with a 390 is 3400 something, lighter then me. no heated power leather seats, computers, airbags, six disc cd changers.

[gragra73]

Tomorrow I am supposed to have my 4.10s installed. I am really looking fwd to it.

[07stanggt]

you be smiling ear to ear as soon as you roll of the lot. going from wht 3.31s?

[gragra73]

3.55s. I am guessing I will need to take it easy for the first 500 miles or so. Easier said then done.

[mswift5]

Just had my 4:10's installed a couple of weeks ago and wished I would have done it in 05 when I got the car. I am supercharged and it is a daily driver with 60K miles on it. Like a brand new car.

[07stanggt]

Originally Posted by gragra73 3.55s. I am guessing I will need to take it easy for the first 500 miles or so. Easier said then done.

take it easy for five hundred miles? i dont know the definition of that. I dropped the clutch pulling out of plaza ford after they installed the gears with the whole shop cheering.


Yea you heard the man he wished he would have done it in 05. Thats is the usuall consensus with guys who get 4.10s.

[Vapor8]

Is there any whine or noise when going with 373 or 410. I was told there was a whine by dealership. They also recommended 373 with my automatic, especially if going with a supercharger.

[07 STROKER]

I layed into my new 355's right away...now they whine a little but i can live with it...if it gets worse ill have ford replace under warrenty again

[gragra73]

Originally Posted by 07stanggt take it easy for five hundred miles? i dont know the definition of that. I dropped the clutch pulling out of plaza ford after they installed the gears with the whole shop cheering. Yea you heard the man he wished he would have done it in 05. Thats is the usuall consensus with guys who get 4.10s.

Don't the gears have to be broken in? Would it be safe to drag my car this Saturday? By this Saturday, I will have about 175-200 miles on the new gears.

[07stanggt]

I dont know man. dont listen to me. I was raised on a philosophy of break it in like ya drive it. I didnt take it easy at all. When i got home that night from getting my gears installed i handed a sti his ass. You search my threads you can see the post of that day and that sti. And I havent stoped smiling yet. got probably 59,000 on my stang now driveing it like i stole it. Not one problem. I have no gear whine. These freaking cars are tough if you ask me. Ask the ford guys I guess, or some techs on this site. But you arent going to tell me that drag racers dont make gear changes the night before they race.

Then again on my 750 gixxer your not suppose to go over 6000rpms for the frist 600 miles. LOL that lasted about 10 miles.

Only rule i do respect is when breakin an engine in dont keep it at the same rpm for long periods of time.