LRN2DRV

Has anyone out there changed their gears from 3:55 to 4:10? How do you like it? I am also considering delete plates and wonder if the start off torque improves? I've improved some with an intake and tune but I want more response. What is recommended?

2k7gtcs

I've had the 4.10 gears for about 7 months and it was probably my first mod and the only one I didn't do myself.

The car is a 5 speed manual and started out with 3.31's. I can't speak for automatics, only manuals, so here's my opinions.

Originally the car seemed sluggish and didn't have the get up I expected in the low range. With the changed gears the car pulled much harder. Everything else was bone stock at this point. I did not have a tune yet and on the way home I had my wife drive next to me because the mechanic said the speedometer would be off till adjusted. Well my speedo said like 53 mph when she was doing 70. The car felt alive, I was way impressed and of all the mods I've made its definitely one of the best. I must stress that gas mileage will decrease, but I've driven like 2800 miles in the 9 months I've had the car, mostly city and always spirited averaging about 15 mpg. The gas mileage is still better than my F150 4x4 13mpg and my wife's Expedition EL 11mpg .

Long story short...after the CAI and 93 Performance tune from Brenspeed the car became a dream. I think the horsepower that was hiding was released, it was always there in the 3000-6000 range, but now low end is just so much more satisfying. It's also easier to light 'em up especially the old 235 tires, the new 285's are a bit stickier.

My $0.02 absolutely worth it , but you must have it done right, I used FRPP gears and the various install parts that are needed, but I asked around and even talked to 2 salesmen and the general manager at my local dealership, and all recommmended one mechanic to do the work. I took it to his shop and 4 hours later I picked her up. It's funny, I was really worried about such a sensitive install, but besides the obvious gear difference the rear end feels better now than stock, no whine or clunk.

titanjc

That was a great read, thanks for taking the time to type all that up. My 07 has the 3.31's from the factory, and I've been thinking about 4.10's as a potential mod over the next 5 months or so. The only thing that I'm still hesitant about is the decrease in MPG, but if the car is that much more fun to drive, I think it's a small tradeoff.

2k7gtcs

I did think of one other thing...

When you accelerate in first gear you'll be shifting to second quickly. I'm not sure of the mph, but sometimes I'm shifting in the middle of a corner after having just taken off from a light or stop sign. Also with the Lt headers I've been really concerned about noise. I was in the left turn lane at light waiting to turn onto an access road and I was gonna use first and give it a few thousand RPM's before shifting to second, then I look in the rear view mirror and see a po-po 2 cars behind me, I quickly put it in second and then accelerated away from the light easily. So if its late at night or I'm in a quiet area now I'll usually just start out in second gear.

On the plus side is that shift from first to second even with no mods was an awesome feeling, the car with the way the gears are set up just wants to freakin' launch. Most passengers are impressed with the shift to second when it throws you back against the seat.

WaltM

2KGTCS;

Thanks for the great info.

Walt

2k7gtcs

I really don't see any downsides other than gas mileage, which I'm getting 15 with all city driving, and I mean I'm driving it for fun, and highway I'm sure I could get 18 or probably 19, I'm also running Brenspeed's 93 Performance tune, so other tunes could probably give you more mpg.

The hassle I had was getting them put in. Even though I or my company has bought probably about 12 cars at the one dealership in town over the past few years, after even talking to the general manager, they simply would not do the install at the dealership. But I did get a recommendation and the master mechanic who worked their basically did it on the side in his own shop for $300 and it took about 4 hours. But I feel really lucky in this small town of 60k thats 2 hours from anywhere to ever find anyone to do such good work. He did a great job, and I was gonna have him install the headers, but after looking at installs on this site I tackled it myself. But gears are DEFINITELY NOT DO IT YOURSELF!

Five Oh Brian

I had 4.10's installed in my 2007 GT automatic. I get 15 mpg city and 23 mpg highway, just like the EPA ratings for new Mustang GT automatics. Having a modern overdrive transmission keeps highway mileage in check, even with big gears.

I personally believe there is no downside of any kind to 4.10's in our cars, and the improved acceleration is very welcome in all situations (daily driving or the racetrack). I believe they should be an available factory option and I suggest them to anyone! Some Ford dealerships will do the install (my dealership has done gear swaps on 3 of my cars, including my 07).

WaltM

I'm running a 93 perf. tune from Brenspeed as well and am getting 16.8 mpg around town. At this point, losing another mile or two isn't that big of a deal to me. I'm more concerned with maintaining drivability. It's not a daily driver, but I need it to be dependable and drivable.

It's tough to find a good shop that wants to be bothered with installing mods. My dealer won't do anything outside of warranty or maintenance issues. I'll need to look for a competent installer because I'm not qualified.

topoffGT

Unfortunately I have more experience than I wanted when it comes to gear installation. For those of you considering a change to 4.10s, make sure you get the FRPP gears that end in "A" not "M". The "M" gears are in a FRPP box, but they are actually made by Motive. Most people agree that the Motive gears are more prone to whine. I got my "A" gears from Jegs.

It is VERY important to get a competent mechanic that has the right tools and experience with gear installs! I learned this the hard way........I have been through 2 different installers for the 4.10s and just this week had a third shop swap them out for 3.73s.

IMO, if you have a N/A car, the 4.10s are great (especially for a manual car). I personally did not see a drop in fuel mileage (okay-maybe 1 mpg on the highway). Now that my car is supercharged, I decided to change to the 3.73s to help increase traction in 1st & 2nd gear on street tires.

WaltM

This is good to know. I plan on supercharging soon, and for financial reasons I'll probably go centrifical . My old SVO has 3.73s and I'm happy with it's "livelyness".

adrenalin

I am stumped. Why would changing the gears to 4:10's change the reading on your speedo? Isn't the speedo controlled by sensors on the transmission and/or driveshaft?

TacoBill

I know after my gear install, had to go into the Optional Parameters settings in the XCal2 to change the gear ratio to 4.10, so there's some relation between the axle ratio and PCM and speedo.

Noticable difference when I stepped up to the 4.10's (from 3.55's), delete plates, and UDP's.

Kicked it up another notch after the 1-pc driveshaft was added.

RKNMACH

If you aren't going to supercharge then 4:10's will be a great addition - plus the UDP's and one piece driveshaft as Bill posted.

adrenalin

Hmmm, guess I need to rethink my plans. I was going to go with 4:10's and UDP's but I have the old XCal (without display), so I guess I would need to get a new tune as well. ugh! Modding is not only addictive, it is expensive

Five Oh Brian

Doesn't cost a penny to change the gear ratio parameter in your tune with a handheld tuner. I changed mine in a couple minutes with my DiabloSport Predator tuner.

adrenalin

ya, but mine is the old XCAl, there is no display so without getting a new tune for it from someone I can't change the gear ratio. I might just get a new one anyway not that I see they are up to Xcal 3.

300HPGT

I went from 3.55's to 4.30's! wow talk about a difference. I was starting in 2nd on the street all the time. Lets put it this way.....I have a trans that has worn out synchros from power shifting and at the track with the good trans and 3.55 i ran 8.504 in the 8th and a 2.0 60' time with the bad trans and the 3.55 gears i ran 9.3 in the 8th with a 2.03 60' time. When I went to the track with the bad trans and 4.30's i ran 8.76 w/ 2.0 60' time. So if I had a good trans I would be running 8.0's in the 8th or better. I did the gear install myself after the stock diff shattered in half from a hard core 2nd gear 6500 rpm drop. I did the same with the new 4.30s and took off 4 teeth from the ring gear. (I found out that I didn't shim the pinion properly and had too much back lash) I now have 3.90 gears (4.30's were too much on the street) and have yet to take it to the track . I did the gear install again this time with a Back Lash of 0.003" and the proper pinion depth. I only did it this tight because I drive the car so hard. I also installed a Detroit truetrac as well. The car is amazing now and I can do all of the crazy shifting and 2nd gear burnouts I want. Posi traction every time thanks to the truetrac. I am a DIY kind of person and now have 2 gear installs (1 successful) under my belt.