Ford Performance not offering the 4.09 gears for the 2024. Why?

[roket]

I'm looking into 4.09 myself.

Will that void the drivetrain warranty if say the gearbox fails?

warranty is only void if what you modified can be confirmed to be the cause of failure (on factory warranty). extended warranties can be void if you stare at the company's phone number in a funny direction

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[RBGT]

The car feels much more lively. The gears along with other items that reduce rotational mass are just going to be force multipliers. My car has lighter wheels and tires even though they are more wide and aggressive. The 4.09 gears help tremendously off the line. My car had 3.73s and I feel this is the best performance mod I did on the car. My mods on my 2020 Mustang GT are in my sig.

Just saw your modes, nice combo.

Looking at a similar setup with the FP FR track pack as well.
How are you liking that? Not too harsh.

Spoke to Apex and looking that their light wheels - 19x10 square with 275/35/19 or 285s PS A/S 4.

 

[RBGT]

warranty is only void if what you modified can be confirmed to be the cause of failure (on factory warranty). extended warranties can be void if you stare at the company's phone number in a funny direction

Lol.

I knew about them being able to prove that the failed part was due to the mod, but I suspect Ford/dealers will be experts and doing that.
I'm worries they will find a remote connection between say the rear axle and trans, engine, or any other major drivetrain component.

 

[roket]

Lol.

I knew about them being able to prove that the failed part was due to the mod, but I suspect Ford/dealers will be experts and doing that.
I'm worries they will find a remote connection between say the rear axle and trans, engine, or any other major drivetrain component.

only way i can think of for them to void your warranty in the situation you provided is the ring gear shatters or something while driving, seizes the diff, and trashes the driveshaft and trans output

 

[RBGT]

only way i can think of for them to void your warranty in the situation you provided is the ring gear shatters or something while driving, seizes the diff, and trashes the driveshaft and trans output

I suppose there is an increased risk of failure whit mods vs stock.

I'll see what other do and how it drives with the 3.55 and slightly shorter tires.

With 275/35s, ratio is 3.62

 

[MustangMac67]

Not sure if this applies. My dad has an 09' crown vic he races. He installed some 4:10 rear gears in it, and it instantly felt better. Mind you this is with a tune, exhaust, and some other modifications. A lot more responsive off the line, more fun to hoon around, and oddly the rear tires got a little more worn.

 

[Katastrophe]

Any rear gear ratio starting with a 4 should be a factory option, as far as I'm concerned.

 

[VenomGT3]

I’ve put 4.09 gears on the last 2 mustangs I’ve owned 2011 GT, 2017 GT it’s a must for me, it’s equivalent to making your car feel like a real
Muscle car, everything is more aggressive. My last had 4.09 and a whipple talk about a monster. I’ve always had steeda autosports install them it works out to be 1k dollars out the door with parts and labor. And as long as you have a ford certified ship do the work it’s not an issue from what I’ve been told and I’ve never had any issues

 

[Dave2013M3]

Just saw your modes, nice combo.

Looking at a similar setup with the FP FR track pack as well.
How are you liking that? Not too harsh.

Spoke to Apex and looking that their light wheels - 19x10 square with 275/35/19 or 285s PS A/S 4.

The FR Track Kit is firmer, but still very street-able. You use the car as a daily and have to worry about wet weather? I would go with the 285/35/19s.

 

[ThreePedalPlow]

I don't believe so. I have 4.09 gears on my 2020 and if you have the D4 tranny it's a must

I’ve put 4.09 gears on the last 2 mustangs I’ve owned 2011 GT, 2017 GT it’s a must for me, it’s equivalent to making your car feel like a real
Muscle car, everything is more aggressive. My last had 4.09 and a whipple talk about a monster. I’ve always had steeda autosports install them it works out to be 1k dollars out the door with parts and labor. And as long as you have a ford certified ship do the work it’s not an issue from what I’ve been told and I’ve never had any issues

What do you guys think the top speed is once you switch to 4.09 gears? Do you think you could still hit the governor around 155mph or do you think you would run out of gear before then?

 

[MustangMac67]

What do you guys think the top speed is once you switch to 4.09 gears? Do you think you could still hit the governor around 155mph or do you think you would run out of gear before then?

The governor is for speed, not rpms. You would still hit 155, just at more than 5000rpm

 

[dollybud]

Some gear ratios with different wheel sizes.

Thanks for the informative chart. 373 gears are great but the difference between 355 are slight. I would prefer the 409 if going to the trouble of changing them.

 

[dollybud]

Does the 4.09 help quite a bit with the "low end feel" when you are just putting around town? My car has the getrag manual transmission and the 3.55 rear gear right now. I'm pretty happy with the way it is but I'm slightly interested in ways to improve the low end torque a little bit. Wondering if lighter wheels, carbon fiber driveshaft or anything else might help with that as well.

Change rear gears to 409 for big differences. 373 are good also but not a whole lot of difference then 355.

 

[ThreePedalPlow]

Change rear gears to 409 for big differences. 373 are good also but not a whole lot of difference then 355.

I'm hoping Ford comes out with a kit / tune that adds some low end torque like they did with the S550 that will allow me to go 4.09 afterwards if I'm still not happy with it. The kit for the S550 did mention it could tune for 4.09 gears. Just not sure if you could do it afterwards with the Ford kit back then. That thing added a little over 40 lbs of torque around 2,000 rpm apparently.

 

[RBGT]

Agreed, 3.55 to 3.73 is minimal. Thats a 5% bump.
You could get close to that with slightly shorter tires.

4.09 gives you 15% extra.
THats 40 to 45lbs at 2500rpm
60lbs at peak 400 rpm


Old S550 procal would allow 4.09 gears.
I'm guessing once the S650 procal is out, 4.09 will be offered as well.

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