Im new to the performance aspect of mustangs, ive always loved them but now i got the need for speed seeing as how my roomate has an 03gt vert that runs 13.1 here in colorado springs. My question is my gt is an automatic and everyone tells me i should put 4:10 gears in it rather than 3:73 however i am worried that on the highway my rpms will be up over 3 grand. i know what 4:10 gears feel like cause my roomate has them in his but his car is also a 5 speed so its different ya know? I just got rid of a 94 mustang gt that i put a t5 in out of an 89 svo- big mistake cause on the highway i was up over 4 grand at 70mph, i just dont want a replay of that because i actually plan on keepin this car. Any helpful advice you could pass along would be greatly appreciated, Thanks
4:10 gears in an automatic?
- Thread starter Cherry99GTvert
- Start date
joshjwc9
Active Member
If your long term plans are to supercharge this car with a twin screw supercharger, get 3.73's or 3.90's. Otherwise the increase from the stock 3.27's to 4.10's is negligible. I plan on either turboing or putting a Tork Tech or KB on my car so I got 3.73's. The highway cruising RPM's will increase but the car will be in its powerband earlier on the street.
Usually most people see a small increase in city MPG's and a slight decrease in highway MPG's. That is once you stop pedaling it the first week after the gears are installed. The super really picky guys who really care about MPG's tend to always go 3.73's with 5 speeds, and most auto's get 4.10's.
Usually most people see a small increase in city MPG's and a slight decrease in highway MPG's. That is once you stop pedaling it the first week after the gears are installed. The super really picky guys who really care about MPG's tend to always go 3.73's with 5 speeds, and most auto's get 4.10's.
Flghtmstr1
Member
I have 3.73s in my automatic, and when the car was naturally aspirated, I think it was a good compromise. I was doing a ton of highway driving at that time, so I knew 4.10s would have been too much for me. For what it's worth, I didn't see my fuel economy change at all.
Of course, with the blower, even 3.73s are a bit much lol.
Of course, with the blower, even 3.73s are a bit much lol.
So its not gonna really be that much of a difference then? I would like to supercharge it eventually, Im gonna do the 4.6 swap out of a lincoln mark 8 and utilize the aluminum block and thats just the start of what i plan to do in the near future. I was just worried if i took a road trip my rpms would be too much for the engine with 4:10s but the way you guys are talking i might just try them and then later swap them with somthing lower if i supercharge it
trinity_gt
10 Year Member
If your car currently has the original 3.27 gears in it your new RPM will be ~1.25x with 4.10s. So if you're turning, say, 2000RPM in top gear at 70MPH now you'd see roughly 1.25*2000 or ~2500RPM with the new gears.
Given that verts already carry a weight penalty over their coupe cousins and you've got an auto, 4.10s seems like a no-brainer to me.
Re supercharging: if you plan a centri, 4.10s are the way to go. If you're thinking twin-screw or roots-style, you might consider 3.73s since they produce big-block torque pretty much off-idle, especially if you go with a stall converter too.
Given that verts already carry a weight penalty over their coupe cousins and you've got an auto, 4.10s seems like a no-brainer to me.
Re supercharging: if you plan a centri, 4.10s are the way to go. If you're thinking twin-screw or roots-style, you might consider 3.73s since they produce big-block torque pretty much off-idle, especially if you go with a stall converter too.
streethorse
15 Year Member
4.10s are an amazing mod for an auto. Pair them with an SCT SF3 tuner. I re-maps the shift pattern to be so much better than stock!
80mph on the highway is 3000rpm. Its absolutely fine. I'd be pissed if I'd been timid and got the 3.73.
A bunch of auto guys swear by 4.30s, and I would love to ride in one to see how it is...
80mph on the highway is 3000rpm. Its absolutely fine. I'd be pissed if I'd been timid and got the 3.73.
A bunch of auto guys swear by 4.30s, and I would love to ride in one to see how it is...
scupking
Active Member
I have to disagree with you. Before I did the torque convertor, the gears plus the old tuner chip I had (mainly for the speedo recal) were far more than negligible.
4.10s+JMod valve body+TC=FUN
joshjwc9
Active Member
I meant to say that the MPG change is negligible, but from the performance aspect your arse meter will be quite impressed! 
I meant to say that the MPG change is negligible, but from the performance aspect your arse meter will be quite impressed!
Aight
Just beware that your MPG WILL change (DECREASE) with 4.10s/TC/valve body
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