Why aren't 4.09 gears more popular?

[Ablaze]

I'm about to tighten up the drivetrain on my 2018 GT currently running 3.55s by installing BMR's poly motor mounts. Thought, why not, let's throw the 4.09s in at the same time. I had 4.10s on my 05 GT and they absolutely transformed the car in a great way.

Now I realize this is a completely different vehicle so I tried to do a little research but I didn't find much feedback. Nothing negative but nothing really positive. Is it a lot of trouble going into the rears on these cars? Maybe everyone's getting the PP and it's not worth going from 3.73 to 4.09s?

Edit: Soon as I posted this I found a thread on the drivetrain forum answering my question. This can be deleted, thanks!

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[Mikepol2]

There's a good bit of threads discussing 4.09's in the Drivetrain thread but...the main reasons people don't install them seem to be cost or the fact that they are going boosted. I have them and because the 2018 1st and 2nd gear ratios are pretty low, the 4.09's are as high as I'd want to go. I start out in 2nd gear a lot now unless I am on a hill or have to punch it. The guy that did mine is a Ford mechanic and says the shop time is really high, something like 12 hours, it takes longer than cars with solid rear axles. That said, I removed the differential myself and just gave him the pumpkin, gears, and install kit so he only charged me $200 to set the gears in the pumpkin. (That's buddy pricing, not Ford shop pricing!) BTW my car is a PP1 and going from 3.73's to 4.09's puts down an equivalent amount of extra force to the road as if you gained 40 ft-lbs of torque.

 

[Ablaze]

Mike, I literally just finished reading your posts in another thread. Great info. I didn't realize the expense or time investment was so high. I already have a GT500 so I won't be supercharging my GT. I just want that low end grunt but without the FI. This sounds like the way to go if you liked them from 3.73s to and I'm going from 3.55s..

 

[Mikepol2]

When I first drove the 4.09’s the difference was real... not just that “Yeah I think it feels faster” you get after installing a cold air intake. If you are going from 3.55 to 4.09 you’ll notice it for sure if you have the manual transmission.

 

[WildHorse]

With six speed manuals / autos or 10 speed autos anything over a 3.55 would be redundant I would think.

 

[cib24]

I have them as well, and will install them in about 3 weeks when the weather is consistently better here. I also bought a Ford Racing Torsen LSD as we basically get the PP1 spec with a Trac-Loc 3.55 rear end. Looking forward to the higher final drive and ability to row the gears more often! One of the frustrations right now is that on back roads (and all of our roads are very curved), is that you can only really use 2nd gear because most of the back roads you can't really push too far beyond 70 mph without being a dickhead. So, in much of 3rd gear at 70 mph or below you are below 4500 RPM where the car really starts to come alive.

Honestly, I would have been happy with 4.56 gears but Ford Racing didn't offer it and I was hesitant to use anything not Ford manufactured since if we have a problem over here, it takes ages to get parts from the USA.

 

[WD Pro]

Get that oily stuff off the carpet ...

WD

 

[Ablaze]

I have them as well, and will install them in about 3 weeks when the weather is consistently better here. I also bought a Ford Racing Torsen LSD as we basically get the PP1 spec with a Trac-Loc 3.55 rear end. Looking forward to the higher final drive and ability to row the gears more often! One of the frustrations right now is that on back roads (and all of our roads are very curved), is that you can only really use 2nd gear because most of the back roads you can't really push too far beyond 70 mph without being a dickhead. So, in much of 3rd gear at 70 mph or below you are below 4500 RPM where the car really starts to come alive.

Honestly, I would have been happy with 4.56 gears but Ford Racing didn't offer it and I was hesitant to use anything not Ford manufactured since if we have a problem over here, it takes ages to get parts from the USA.

That's exactly what I'm after, I just want to actually be able to enjoy shifting some more. Can't do much right now as 1st and 2nd gears are pretty tall although the power is definitely there.

 

[WD Pro]

I am also really interested to see how it goes

WD

 

[cib24]

That's exactly what I'm after, I just want to actually be able to enjoy shifting some more. Can't do much right now as 1st and 2nd gears are pretty tall although the power is definitely there.

The power is there but to be honest the gearbox makes the Mustang feel a little slow. I mean, we only have 444hp compared to 460hp in the States anyway (RHD, but my RX-7 is definitely quicker in a straight line and everywhere else honestly). The 4.09s will do a lot for more engagement and make it "feel" quicker. I'm not sure there will be a huge 0-60 mph benefit but in gear acceleration will be improved and I'm looking forward to comparing 30-70 mph and 60-125 mph times.

By the way, the headers we get on our cars in the UK are really terrible aren't they?

 

[EFI]

I'm assuming you are comparing their popularity to the SN95, New Edge or early S197 worlds. Back then, with mainly gutless engines (besides the Terminator) and 4-5 speed gearboxes one of the best mods to do was obviously steeper gears. In today's Coyote world with much improved power, torque and close ratio transmissions, they are not as popular as you have obviously seen. The Coyote engine is so good that you can extract alot of more performance out of it by other much simpler mods, so the relatively expensive to do gears are falling further down the popularity scale.

 

[cib24]

I'm assuming you are comparing their popularity to the SN95, New Edge or early S197 worlds. Back then, with mainly gutless engines (besides the Terminator) and 4-5 speed gearboxes one of the best mods to do was obviously steeper gears. In today's Coyote world with much improved power, torque and close ratio transmissions, they are not as popular as you have obviously seen. The Coyote engine is so good that you can extract alot of more performance out of it by other much simpler mods, so the relatively expensive to do gears are falling further down the popularity scale.

Yes, I think this is understood but the viewpoint in your post is narrow. The point of gears in a 2018+ Coyote with the revised MT-82 ratios is to add more engagement at speeds under 100 mph, so on-road and smaller road course driving is more engaging. Allowing you to use the gearbox more, benefit from the rev-match feature if you wish, and also ensure the car is always in that 4500-7400 RPM power band rather than often falling to 2800-4500 RPM in 3rd and 4th when hustling the car at saner speeds.

I agree that for drag racing the benefit is probably relatively minor given the broad torque curve of the Coyote engine, but that's ok.

 

[Mikepol2]

I would be surprised if anybody installs the 4.09's in a 2018+ manual car and then wishes they had installed 4.30's or 4.56's instead...I'm already starting in 2nd gear most of the time. The 4.09's are great for hilly / twisty roads. The only guys I've heard complain about them are guys who are strictly running 1/4 miles, because the 4.09's make them shift one more time over the 3.73's.

 

[shogun32]

3.73 is already too short with the -D4 manual in normal, mildly spirited driving. The older "close" ratio and single overdrive would have been better IMO but the enviro-weenies would likely have complained.

 

[cib24]

3.73 is already too short with the -D4 manual in normal, mildly spirited driving. The older "close" ratio and single overdrive would have been better IMO but the enviro-weenies would likely have complained.

You realise that the MT82-D4 with 4.09 final drive is very similarly geared to the 2015-17 MT82 cars with a 3.73, right?

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