I just bought my first Mustang GT and

Rain1dog

New Member
May 22, 2004
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I am wondering how gear ratios work? If I switched over to the 4.10 gear ratio I have read about what increase in performance do I gain and what would I lose performance wise?

Thanks and first time post.
 
Congrats on new car. Its a 03 Mustang GT(5 speed). Its fully loaded. I just want it a little bit faster. SO far I have added the basic stuff it seems...air filter and flows.
 
First of all, welcome to the funny farm!!!

What year stang do you have? I will assume that it came with 3.27's stock. When asking questions in the future, be sure to tell us some more info about the car.

Gears? What you are doing is changing the final ratio in the differential. As the gear ratio number gets higher, your car will run at higher rpms to achieve the same speed as compared to stock. The car will also be quicker. Going from 3.27's to 4.10's will feel like adding about 40 hp and you will knock about .5 seconds off the 1/4...maybe more...depends on too many other factors like tires and other mods.

One thing to keep in mind when you start to mod your car are your future plans. For example, if you plan on adding a turbo or supercharger (sc) soon, 4.10's will be too much gear. But for an n/a car, 4.10's are a great choice.

You will NOT loose any performance, but you will loose about 2-3 hp as the 4.10's make a little more friction....but don't wory about this at all.

If you have an automatic, you will need to calibrate your speedo for sure with the new gears to avoid ruining your transmission. You can do this with a speed cal ($100) or a chip/programmer ($200 - $400). A chip/programmer will do a few more things for you than just a speed cal. With an auto, get a chip as soon as you can as it will firm up your shifts and rev the car higher, thus more power.

With a 5 speed, you don't have to calibrate the speedo, but I would still recomend doing it.

Either way, I would go with a programmer as it will grow with your car as you make mods (this is a whole other subject).

Bottom line, 4.10's are a great first mod or a last mod. You really can't go wrong. just be sure to have them installed by a pro.
 
Go HoTO! said:
First of all, welcome to the funny farm!!!

What year stang do you have? I will assume that it came with 3.27's stock. When asking questions in the future, be sure to tell us some more info about the car.

Gears? What you are doing is changing the final ratio in the differential. As the gear ratio number gets higher, your car will run at higher rpms to achieve the same speed as compared to stock. The car will also be quicker. Going from 3.27's to 4.10's will feel like adding about 40 hp and you will knock about .5 seconds off the 1/4...maybe more...depends on too many other factors like tires and other mods.

One thing to keep in mind when you start to mod your car are your future plans. For example, if you plan on adding a turbo or supercharger (sc) soon, 4.10's will be too much gear. But for an n/a car, 4.10's are a great choice.

You will NOT loose any performance, but you will loose about 2-3 hp as the 4.10's make a little more friction....but don't wory about this at all.

If you have an automatic, you will need to calibrate your speedo for sure with the new gears to avoid ruining your transmission. You can do this with a speed cal ($100) or a chip/programmer ($200 - $400). A chip/programmer will do a few more things for you than just a speed cal. With an auto, get a chip as soon as you can as it will firm up your shifts and rev the car higher, thus more power.

With a 5 speed, you don't have to calibrate the speedo, but I would still recomend doing it.

Either way, I would go with a programmer as it will grow with your car as you make mods (this is a whole other subject).

Bottom line, 4.10's are a great first mod or a last mod. You really can't go wrong. just be sure to have them installed by a pro.

he said it all. congrats on your car man!
go 4.10s you'll love it!
 
One other note, you will risk warrenty problems with the 4.10's. You need to know this if you care about loosing your warrenty. Is the car leased? Modding a leased car is a bad idea in my opinion.

Technically, they have to prove that the mod caused or lead to the failure to not pay, but it is not to hard to blame things on gears. Any transmission problem will now be on your dollar, for example. Most guys here, really don't give a crap about warrenties, but you should know this.

There are some folks who can barely make their car payments, they mod the car, and then run the risk of voiding a warrenty on a daily driver. They are screwed when something goes wrong.
 
Very nice info, thanks. I dont want to do to much to the car for fear of ruining the car. I would just like to do a few of the basic mods to make the performance better.

I have a 2003 GT 5 speed. So far I have added a K&N air filter and 40 ser flowmasters.

So going w/ the 4.10 ratio I would increase my redline limit in all gears(quicker acc I am assuming)? How much would this cost? Also I dont want to sacrifice high end acc for low end acc.

Thanks for all the info. I am very new to these types of cars so I appreciate your detailed reply on gears. :)
 
OK, your red line will not increase with a gear change. That ALWAYS stays the same. The taller gears act like a tourqe multiplier. Your rpms will increase faster, thus more acceleration. It's like putting on smaller wheels/tires. You WILL gain acceleration at lower rpms AND at higher rpms.

Total for gears and installation will run you $500 - $600 complete.
 
Ahh..ok. So I would run a faster 0-60 time too w/ a 4.10 gear ratio w/out losing highend speed. Now if I switched to 18inch tires from my 17's and changed to a 4.10 ratio would I negate the upgrade?


From your expierence if I run 0-60 at 6.1 w/ the new set of gears how much would I shave off the 0-60 run?
 
In theory you loose top-end speed with the 4.10's. In reality, you don't because you will now hit the top end in the power curve better. Make sense? You will get a lower 0-60 time, how much, not sure. There is not much data on this and it depends a lot on the driver and tires. But in general, I would say about 0.3 seconds.

If you go with 18 rims, you will want to choose a tire with a lower profile so that the overall height is the same. Thus, it won't matter.

But, now to really confuse things, 18 rims have stiffer side walls AND higher rotational mass. As a result, they do not get as good traction and the higher rotational mass will result in poorer performance. 18 rims are not a good choice. It's a looks thing. Keep in mind that the real racers here use 15" rims that are nice and light with tires that have high side walls.
 
If going to a 4.10 gear ratio allows for me to reach my red line limit faster than stock will I cruise on the highway at higher rpms to? I am trying to find the negative in this type of upgrade. Gaining something in performance almost always comes at a cost.
 
I just installed 3.73's in my 91 GT and that is the perfect gear for me. It makes fith gear usefull and it is still a daily driver. I shift a little more because now I am using all 5 gears, but the pull in each gear is awsome. You will see 5th gear around 90 and love the pull instead of the lag. The guys I had install mine said the 4.10's were best in the ccobra and 3.73's in the GT. I love my 3.73's.

YotaMaster

01 GT Convertible
17x9 front 17x10 rear 280M Rims
294/40/17 R 255/45/17 F BFG’s KDWS
Magnaflow Magnapack Cat Back
Hypertch Programmed
CAI, TB Spacer
Tri-Axe, Adj cable & Steeda Quad
3.73's
CHE lower control arms
chrome diff cover
 
YotaMaster basically hit it!

Although, 3.73 were not enough for me.

The downside is higher rpms, thus fuel economy. This is why Ford puts the crappy 3.27s on these cars. HOWEVER, 4.10/3.73 make the car easier to drive in higher gears which helps fuel usage.

You will see an improvement in fuel usage in the city, but a loss on the highway. It's about 2 mpgs either way.
 
Yep, I got the picture now about gears. I have a sense that reaching the red line limit faster than what it already is would become old fast w/ all the shifting I do(New Orleans traffic). This is my primary car.

Sounds like a mod that brings to mind....a 6 gear.

Once again thanks for the great info!
 
For some guys 4.10's are too much, for others it's not enough. If this is a primary car, then maybe you should go with 3.73. My stang is a third car...it's a toy. Next time, I will go with 4.30's. Make sense? It's very much a personal decision.
 
I have an 02 5 spd, and just recently got my 4.10s put in and let me tell you. This should be your first or second mod for sure.

Anything I lost performance wise is unnoticable.
5th gear is usable, I no hardly ever use first gear anymore, but if I want the torque, first gear is always fun.

Lastly highway rpms, jumped 250 rpms roughly, which doesn't make a whole lot of difference on our cars. The 4.6 seems to like being in the 2000-2500 range, and gas milage has not suffered one bit.
I recomend the 4.10s and a short throw shifter
 
You will gain your powerband earlier basically. Now granted the price in lower gear ratios (higher number 4.10's 4.30's etc.) is potential gas mileage at highway speeds & and a lower top speed. However your gas mileage will probably only be affected minimally if you get 4.10s or 3.73's and your theorectical top speed is not your actual top speed. Your real top speed should increase a few mph because your gear ratio puts you higher in your powerband at that high of speeds so you can actually get your car moving a few mph faster.

Gears are one of the best mods you can do for a reasonable price on a mustang.

kirkyg
 
Rain1dog said:
Yep, I got the picture now about gears. I have a sense that reaching the red line limit faster than what it already is would become old fast w/ all the shifting I do(New Orleans traffic). This is my primary car.

Sounds like a mod that brings to mind....a 6 gear.

Once again thanks for the great info!

Glad to see someone else from the NO area. This is my second stang. My first was a 96GT. I swicthed from stock gears (2.73) to 3.73s. No much difference in gas mileage accept on all highway trips (2-3 MPG). I use to get 24-25 MPG going from NO to Lake Charles.

My current stang is a 00GT vert. The last remaining mods are LTs and gears. I might go 3.90s this time, but I think I might not get good traction as might 50% worn Nittos can't handle the 3.27s went hit at 3k from rolling in 1st.

I haven't found any good mustang shops as the two that were here are gone.

Enjoy the car.
 
3.73's were pretty steep for fox's because they had more torque and a little lower redline. When I put my 4.10's in it really was like driving a whole different car. A whole lot better acceleration, 5th gear is useable in town, I get 23 - 24 mpg on a 1600 mile trip :nice: The only thing that got me about them was that you have to relearn driving it, because too much off the line and you'll start spinning. You will also need a speedcal to recalibrate your speedo or you will be putting phantom miles on it.