355 to 373

[WildHorse]

i think @WildHorse did the install recently himself. Not the same gears, but same idea.

Yes Sir. 3.31 to 3.73. Ford quoted me almost 2K. I said yeah, nah.

FR 3.73 $200
Strange bearings $50
Timken seals $50
FR axle nuts $11
Royal purple 75w140 $40
FR friction modifier $5
356 buckaroos total + my time. But I generally don't charge myself haha.

I already had the dial indicators, but you can get a decent set for under a hundo.

It was a pretty straight forward process. If you've change ring & pinions before, it's no different on the super 8.8.

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[WildHorse]

Ok getting a little confused would I be better off with 373s or 410s?

18+ MT82 with a 4.56 gear is equivalent to a 15-17 MT82 with a 3.73 gear.

 

[Superspirit]

And most find the 4.09 to be the sweet spot for the 18 up.

 

[WildHorse]

4.09 to be the sweet spot for the 18 up

That's like a 3.31 gear with the 15-17 trans.

 

[zworld]

Ok I have made up my mind, I will do 409 gears and also upgrade to the torson lsd. I'm going to have a local speed shop do the work. What other parts do I need to order?

 

[zworld]

That's like a 3.31 gear with the 15-17 trans.

Yes but I want to also put in the torson and it doesn't say it will go up to a 456 gear set.

 

[Issues]

Ok getting a little confused would I be better off with 373s or 410s?

I don't know why nobody has tried 390s seems like a good combination in a 18+ . In the past peeps said 390s make noise IDK. This is the gear I'm gonna try. I want my cake and eat it too.

 

[Superspirit]

Assuming 27" tall tires, 7000 rpm shift point, MT82 D3 trans:
1st: 37
2nd: 54
3rd: 81
4th: 104
5th: 138
6th: 212

Don't like it cause ur shift into 3rd before 60 mph, and into 5th in the 1/4 mile.

Assuming 27" tall tires, 7000 rpm shift point D4:
1st: 45
2nd: 70
3rd: 102
4th: 145
5th: 179
6th: 234

Much better for the D4. On par with D3 w/ 3.31 gears.

This is from another thread about this.

 

[zworld]

Ok I'm going to do the 409 gear set and the torson diff. I know I'll need the also get the gear install kit as well. I'm going to have a shop install for me are there any other things I need to buy? Oil and the friction fluid as well, what type?

 

[WildHorse]

are there any other things I need to buy

I listed it in post #16. If your staying NA I'd go 4.56. Just my humble opinion.

 

[MRGTX]

Many have done this. I linked a thread in an edit. Mine go in Tuesday

Last I checked (back toward the end of summer) the vast majority of people who had done the swap had 2018 and earlier cars. The software in the 19+ cars is different and it requires a bit more electronic intervention to work properly.

I found this out the hard way with my swap from 3.55 to 4.09 in my '20.

I ended up slapping down an extra $600+ for an NGauge and a Lund tune, the only benefit of which was to make the computer not freak out.

Now, ford offers a solution which should save you a couple hundred bucks...and it will pass emissions too.

And most find the 4.09 to be the sweet spot for the 18 up.

I have to agree with this. After driving around with this final drive ratio, the car pulls much better and the whole system seems to be happier. It's hard to put a finger on where that feeling is coming from but it seems like this was the intended ratio for the third gen Coyote and the gas misers came along and choked it down with the lower numerical ratios.

 

[MRGTX]

One more thought on the "happier system" with the 4.09s;
I also swapped to 4.10s/torsen in my Dart Sport and I have that experience to compare with the mustang.

So that ratio had been long programmed into my head as the ideal combo for a hotrod....but having put a few thousand miles on it now, this ratio is not the same kind of match for the Dart's drivetrain as it is for the Mustang. Sure, the Dart pulls better on the average but the 5.9 Magnum is all about the low end grunt and the 4.10s, when paired with the 3spd built Torqueflight auto, the engine is very often spinning past the peak of the power band. In any situation other than a drag racing start, the car is probably no quicker than it would be with 3.55s or whatever....and it may even be slower. It's a weird feeling to stab the gas, have the engine kick down and pull..then you get a big surge of acceleration when it upshifts and drops back into the power band.

This won't be a problem when I eventually rebuild the engine to breathe better and pull through the top end but for now, it's not ideal...and not at all like the Mustang.

The Coyote's broad power band and peak power at high RPM means that almost any time you can spin the engine faster, the happier you'll be. Honestly, I wonder how 4.56s would be.

 

[K4fxd]

Has anyone run 4.09 with the 6R80?

I have a 3.73 gear pumpkin but wonder if I should swap gears.

 

[WildHorse]

Has anyone run 4.09 with the 6R80

1st gear would be useless.

 

[Kong76]

Couldn't imagine going to 3.73s. My 3.55s are short enough. First gear is almost useless. Can't even get halfway through a light before needing to shift.

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