MT-82 D4 gearing question

[Dave2013M3]

Part of the difference in perception is that the newer cars that have the D4 also have a redline 400rpm higher.

Where a 2017 GT-PP could go 64mph in 2nd gear, a 2018 GT-PP can go 78 in 2nd gear.
...So, with the combination of taller 2nd gear and higher redline, you're waiting longer for the shift to 3rd.

Also, out of the 3 transmission choices the D4 has the biggest gap between 3rd and 4th gears. One more reason to avoid shifting to 4th at a track or drag strip: You would lose a lot of rpm.

A car with the D4 can also trigger the 155mph governor in the top 3 gears. I don't know if that's really a downside, but it's silly

While I understand that a rear-end swap is way less expensive than a Tremec swap...
A 4.09 rear end would have your engine turning faster at 75mph, where a Tremec swap would barely make a difference in 6th gear, while making the car faster in all the other gears.
(To me, the fact that my GT-PP1 turns only 2100rpm at 75mph is a major selling point, and I don't care to change it.)

Another thing to consider is that different Mustang trims come with different size tires, and that can change the effective gear ratio. The next time you need tires, you could try a size that gears your car shorter.
GT-PP2 came with the 3.73 rear end, but the tire size made it like putting a 3.90 in the car.

I would have gone with a 4.30:1 gear but the ProCal Ford Performance Pack only supported upto 4.09. I am very happy with the 4.09 gears, but 3rd and 4th is still a little light. With the 4.09 you get more leverage in 1st and 2nd than you do with the Tremec 3160 but 3rd and 4th is somewhat of a letdown.

dave

Sponsored

 

[boB]

Where a 2017 GT-PP could go 64mph in 2nd gear, a 2018 GT-PP can go 78 in 2nd gear.
...So, with the combination of taller 2nd gear and higher redline, you're waiting longer for the shift to 3rd.

Also, out of the 3 transmission choices the D4 has the biggest gap between 3rd and 4th gears. One more reason to avoid shifting to 4th at a track or drag strip: You would lose a lot of rpm.

A car with the D4 can also trigger the 155mph governor in the top 3 gears. I don't know if that's really a downside, but it's silly

If we are auto-xing and the course has a 70-75 mph section we could avoid shifting into 3rd with the D4, saving some time. At Daytona I was able to stay in 4th to go as fast as I cared to, the 2017 would require 5th and 4 more shifts per lap.
I am good with the D4 ratios although I understand where some might prefer 2017 or Tremec.

 

[ShadesOfBloo]

If we are auto-xing and the course has a 70-75 mph section we could avoid shifting into 3rd with the D4, saving some time. At Daytona I was able to stay in 4th to go as fast as I cared to, the 2017 would require 5th and 4 more shifts per lap.
I am good with the D4 ratios although I understand where some might prefer 2017 or Tremec.

Totally true.

Where I am, autocross courses weren't that fast. I walked the course and overhear people with 6-speed Miatas strategizing about where to shift up to 3rd, and back down to 4th, and in my head I'm like
"I'm-a go 65mph in 2nd, suckas! " And I rarely tripped the rev limiter in 2nd.

If I start racing my Mustang, my first gear ratio change will be with tires. Even then, I'm expecting 74mph in 2nd.

 

[WildHorse]

The torque of forced induction overwhelms the downsides of the d4. And it's negatives become positive

Not everyone goes FI. Ford doesn't offer a FI GT, therefore the 18+ MT82 just plain sucks. Haha. It's basically a highway transmission. Zero need for 2 overdrives & a 3.31 gear.

Even 3.73 don't improve it at all.

Red is the 18+

 

[WD Pro]

Not everyone goes FI. Ford doesn't offer a FI GT, therefore the 18+ MT82 just plain sucks. Haha. It's basically a highway transmission. Zero need for 2 overdrives & a 3.31 gear.

Even 3.73 don't improve it at all.

Red is the 18+

Are you able to do me one of those based on the D4 with a PP1 rear tyre with the only difference being a 3.55 v 4.09 ?

It would be very much appreciated ...

Cheers,

WD

 

[WildHorse]

Are you able to do me one of those based on the D4 with a PP1 rear tyre with the only difference being a 3.55 v 4.09 ?

 

[WD Pro]

Thank you !

WD

 

[Duece McCracken]

Part of the difference in perception is that the newer cars that have the D4 also have a redline 400rpm higher.

Where a 2017 GT-PP could go 64mph in 2nd gear, a 2018 GT-PP can go 78 in 2nd gear.
...So, with the combination of taller 2nd gear and higher redline, you're waiting longer for the shift to 3rd.

Also, out of the 3 transmission choices the D4 has the biggest gap between 3rd and 4th gears. One more reason to avoid shifting to 4th at a track or drag strip: You would lose a lot of rpm.

A car with the D4 can also trigger the 155mph governor in the top 3 gears. I don't know if that's really a downside, but it's silly

While I understand that a rear-end swap is way less expensive than a Tremec swap...
A 4.09 rear end would have your engine turning faster at 75mph, where a Tremec swap would barely make a difference in 6th gear, while making the car faster in all the other gears.
(To me, the fact that my GT-PP1 turns only 2100rpm at 75mph is a major selling point, and I don't care to change it.)

Another thing to consider is that different Mustang trims come with different size tires, and that can change the effective gear ratio. The next time you need tires, you could try a size that gears your car shorter.
GT-PP2 came with the 3.73 rear end, but the tire size made it like putting a 3.90 in the car.

Yes, that is a point people forget about!


I went with 265/35/r19 Front, 285/35/R19 rears on my Bullitt rims for the smaller diameter, for this effect. It wasn't very noticeable all in all. Im excited to regear, go lighter rims/tires and take advantage of the N/A power I make currently with my mods.

 

[MrMike]

Not everyone goes FI. Ford doesn't offer a FI GT, therefore the 18+ MT82 just plain sucks. Haha. It's basically a highway transmission. Zero need for 2 overdrives & a 3.31 gear.

Even 3.73 don't improve it at all.

Red is the 18+

Is this local software or a web site you feed data into? It's pretty cool!

 

[stang1087]

@MrMike @WD Pro @WildHorse

I built this a while back when I was bored at work lol. I didn't know people were actually using it. Let me know if you'd like to see any changes or additions. I've thought about adding actual tire sizes instead of just diameter but wasn't sure which ones to add.


S550 Shift Points | Tableau Public

 

[MrMike]

@MrMike @WD Pro @WildHorse

I built this a while back when I was bored at work lol. I didn't know people were actually using it. Let me know if you'd like to see any changes or additions. I've thought about adding actual tire sizes instead of just diameter but wasn't sure which ones to add.


S550 Shift Points | Tableau Public

Thanks!

Tire diameter is ok IMO. There's a large range of enthusiast tires sizes to cover. You'd basically have to break them up into 18/19/20 and then go from there with widths between 265 and 325, and 30-40 profile.

 

[WildHorse]

I didn't know people were actually using it.

I use it all the time ! Its a must have utility.

 

[ShadesOfBloo]

I know this thread fizzled out more than a year ago, but I have a question that I think is related:
What are the consequences, if any, of downshifting from 6th to 4th? (Or 5th to 3rd?)

As I said before, I like that my engine turns ~2100rpm at 75mph in 6th gear.
When I shift into 6th gear at the speed the manual recommends, I'm fine with low rpm as long as I don't have to accelerate.

...But at those rpm my stock Coyote has basically no throttle response.
If I'm in 6th gear and someone is giving me sass (e.g. there's a V6 Challenger that needs to pipe down) I need to shift down to give them the business.
From 6th, at most highway speeds, I need to shift down at least 2 gears.

We have automatic rev matching (and I've left it on) and the D4 has decent synchros, right? There's nothing mechanical stopping me from skipping 5th and going straight to 4th?

Can I break something that way? Am I going to put terrible wear on something?
I haven't had any problems with my transmission, and I'd like to keep it that way for a few more years.

 

[NGOT8R]

You won’t hurt anything at all downshifting from 6th to 4th and getting after it. The D4 is more than capable of hitting triple digits in 3rd and 4th. Heck, you can cruise highway speeds all day long in 4th if you wanted to. The only negative from that would be poor gas mileage, but it won’t hurt a thing.

I very rarely even use 6th gear with my D4.

 

[kz]

It's completely normal to downshift more than 1 gear unless you end up overrevving an engine. You will be more than fine doing it. I have non-rev matched D4 and have done it many times.

Sponsored