4:10's or 3:73's ?

BuffaloZone

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Oct 14, 2003
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For a 2002 Auto that -probably- won't be Supercharged, but maybe about a 25% chance that it will be. Anyone do the gear swap themselves, or leave it to gear experts for proper settings?
 
Due to you having an auto, go with the 4.10s :nice: Anyone which has never had gears before fear the gear, though I promise you that once they are in, you'll love it.




btw: my 1000th post :nice:
 
I agree. If you have an automatic, you want 4.10's. Should you decide to get supercharged after having the 4.10's installed, then you can either down-grade to 3.73's or you can just go with a taller tire for the rear when you run it at the track, that is of course if you do run at the track.

As for who you should get to do the gear install, I suggest someone who's done a gear change before and knows what their doing. Gear changes are not like installing spark plugs. If you don't get the pinion depth or backlash exactly correct to a 1/100th of a inch, you will have problems.

For the gear install, you'll need the gear set, 2 qts. of rear differential fluid, 1 4oz. bottle of friction modifier, and if you're car has more than 40,000 miles on it, I recommend getting a T-lock rebuild kit and a full bearing and seal kit. No sense in doing a good job twice. If you're planning on running this thing at the track frequently, or racing on slicks, you might want to go ahead and upgrade to a 31 spline rear end for added strength. Not that is "necessary" but its better to be safe than sorry. A transmission cooler is also a good idea at this point as heat is the number 1 killer of the automatic transmission.

As for the gear shifts and speedometer, you'll need either a chip, EEC flash, or dyno tune to get the speedomter correct and to correct your shifts. If you have any questions, just ask.
 
The reason that I'm hesitant to get 4.10s is that I never goto the track. I just like having a fast car on the street. I've heard stories of gears + drag radials = broken stock rear end. I don't want to risk that.
 
jas142 said:
The reason that I'm hesitant to get 4.10s is that I never goto the track. I just like having a fast car on the street. I've heard stories of gears + drag radials = broken stock rear end. I don't want to risk that.
As it is with everyone, the choice is yours. I personally recommend you get 4.10's anyways. If you don't, you'll probably regret it in the end. You may not race your car at the track, but you still want your car to be fast. I don't see it being as quick as you desire with 3.73's and not 4.10's.

Although there are horror stories of people breaking apart their rear ends with drag radials, it doesn't tend to be a problem that automatics have as much as manuals do. Not saying it can't or won't happen to you, I'm just saying, its not as much of a problem. If you read my sig, you can see I'm going to be upgrading my rear end to a 31 spline setup. Not that I absolutely need to do this, but its better to be safe than sorry. Not to mention I'm going to be racing at the track on slicks so there's another reason for the upgrade.

In the end, it's as the others before in the 1,000s of other threads over the topic of gears have said and I quote "Dont fear the gear".
 
If you read carefully on the back of the box of a 3.73 set, it says:

Those gears CANT be use on a car equipped with an auto transmission. Using those gears with an auto tranny will probably get you slap in the face by a fellow stanger. :rlaugh:

Seriously, i hesitated i while between the 2 and i m so glad i went with 4.10. The difference between 3.27 and 4.10 is more a " OK THIS IS GREAT IMPROVEMENT" then a " OMG, I CANT BELEIVE THIS". Meaning that i wouldnt notice the difference with a set of 3.73.

and also, dont mess with the install. Leave it to the experts. Ford did mine with 30000m on it and they change all bearings, seals, speeds sensors and labor on warranty. I had 1 day left on warranty :p
Only had to pay for oil, additive and a pairs of sleeve.

Good luck
 
speed545 said:
Leave it to the experts. Ford did mine with 30000m on it and they change all bearings, seals, speeds sensors and labor on warranty. I had 1 day left on warranty :p
Only had to pay for oil, additive and a pairs of sleeve.

Good luck


How was it an "under warranty" issue?
 
i never go to the track either.

i had 4.10s in my 96 gt (but it was a manual), and i thought they were too "short"; i'd be in 3rd gear by 25 mph, and 1st was practically useless. the neck snap factor was great though, especialy in 3rd and 4th. nevertheless, for a street car, i'd do 3.73s for a manual.

but since yours in an automatic, i think 4.10s would be ok. i don't know if you will need a new chip for the shift points or if it can handle that without needing a new chip. if not, you may still want to get a new chip to fix the speedo.
 
BuffaloZone said:
How was it an "under warranty" issue?

Tech from Ford showed me a worn bearing. Then ask me if i was under warranty and i said yes, one more day. I was already a bit desapointed with the fact that i needed 2 speed sensors and had to pay for them. ( stock in place and had to broke them) . So i ask, " if you ll be replacing that bearing under warranty, i m sure Ford is expecting to pay for some labor also?".
He said, i ll manage something for you. And this is what i got for a deal. Everything under warranty like if i was there for the bearing only. I previously declared that there was a strange noise coming out of the rear end. Instead of putting back the stock gears, he installed 4.10 that i gave him. So he covered under warranty everythings included in the process to get and replace that bearing.
 
STOP!!!!!!!! don't ever even think of 3:73's for an auto ever again. ok i have a 02 Gt and my friend has an 03 both autos. he had 3:73s put in and the only thing he got was a good chirp to second gear. i raced him from 20 one day and we were dead even and when we hit 70 i started to pull a little with my stock 3:27's
 
speed545 said:
Tech from Ford showed me a worn bearing. Then ask me if i was under warranty and i said yes, one more day. I was already a bit desapointed with the fact that i needed 2 speed sensors and had to pay for them. ( stock in place and had to broke them) . So i ask, " if you ll be replacing that bearing under warranty, i m sure Ford is expecting to pay for some labor also?".
He said, i ll manage something for you. And this is what i got for a deal. Everything under warranty like if i was there for the bearing only. I previously declared that there was a strange noise coming out of the rear end. Instead of putting back the stock gears, he installed 4.10 that i gave him. So he covered under warranty everythings included in the process to get and replace that bearing.
dang! talk about luck!
 
jas142 said:
The reason that I'm hesitant to get 4.10s is that I never goto the track. I just like having a fast car on the street. I've heard stories of gears + drag radials = broken stock rear end. I don't want to risk that.


MY buddy, Sinisterblack98 had a 98GT auto with 4.10's and a few other mods before he sold it and bought a 98 Snake. He ran it at the track several times with 315 nitto DR's without any problems. Not saying people don't break the 28 spline axle shafts, but they can hold up.