Did Ford Ruin their Manual Trans? - Engineering Explained

[Silver Bullitt]

So about a 10% efficiency loss based on Ford's 460 HP advertising.


Norm

Yup, at least for M6.

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[boB]

I was assuming the use of a 1.00:1 transmission gear and hypoid gear efficiency in the middle of the range (neither horribly inefficient nor exceptionally efficient).

Indirect gears would show lower efficiencies due to the power having to be transmitted across more pairs of gears.

I'm fully aware of other parasitic losses. The math is easier when you work on a torque basis with rotational inertias and rotational accelerations that are consistent with forward acceleration of the car. It's a huge spreadsheet, though, about 13,000 KB by the time I added the ability to compare two separate cases. The basic acceleration simulation is something I've been tinkering with off and on since about 1968.


Norm

You *are* an engineer (retired)! Me too (electrical). I was working on such a spreadsheet around 1990 when I ordered a transmission where I could select gear ratios but the spreadsheet got too large (back when we had math coprocessors) so I just selected gears that a similar power/weight car had. ;)

 

[Semp1]

I agree 4.09's are absolutely worth while in general. My only complaint (and what keeps me from doing it) is that 2019+ cars need a tune to run a regear over 3.77.

Actually Forscan hasn’t been updated by Ford to allow the rev match to work with a gear retune at 4.09. So if you want them rev match needs to be turned off.

 

[Hack]

Have to say I can't see any benefit to being able to get easy wheelspin in 2nd gear as well as in 1st. Once you've made overall gearing in 2nd short enough to be useful as a 1st gear, what's the point of having a transmission gear even shorter (and less useful) than that?
Norm

I have 3.73s in my 2017 with stock Pirelli PP1 tires and I don't have an issue with wheel spin even in first gear. Yes it can happen, but it's really easy to modulate the throttle. And definitely not a problem with wheel spin in second gear. Spinning in second is a bit of a problem in my Fiesta ST, but not in the Mustang.

I think 4.09s might be too much for my 2017 with the older MT-82, but in a newer Mustang where Ford wrecked the manual transmission gearing, 4.09s would be a good choice.

For the road course the new MT-82 gears are probably just great, but they will make the car too tame on the street unless you want a subdued cruiser. I loved the GT350 gearing on the road course, but I always found the gears to be annoyingly tall on the street. By the time you get to the engine's power band you are breaking the law.

With the Voodoo it's ok because it makes enough power at lower RPM to still be fun. Plus the sound track.. But with a Coyote I get put to sleep on the street if it doesn't have more gear than the 2018+ cars do.

 

[Semp1]

Have to say I can't see any benefit to being able to get easy wheelspin in 2nd gear as well as in 1st. Once you've made overall gearing in 2nd short enough to be useful as a 1st gear, what's the point of having a transmission gear even shorter (and less useful) than that?


Norm

The gearing with 4.09’s are perfect. It by no means feels like your mustang with 4.10’s for example. It’s just not the same the gears just aren’t short Even with 4.09’s.

 

[Semp1]

I have 3.73s in my 2017 with stock Pirelli PP1 tires and I don't have an issue with wheel spin even in first gear. Yes it can happen, but it's really easy to modulate the throttle. And definitely not a problem with wheel spin in second gear. Spinning in second is a bit of a problem in my Fiesta ST, but not in the Mustang.

I think 4.09s might be too much for my 2017 with the older MT-82, but in a newer Mustang where Ford wrecked the manual transmission gearing, 4.09s would be a good choice.

For the road course the new MT-82 gears are probably just great, but they will make the car too tame on the street unless you want a subdued cruiser. I loved the GT350 gearing on the road course, but I always found the gears to be annoyingly tall on the street. By the time you get to the engine's power band you are breaking the law.

With the Voodoo it's ok because it makes enough power at lower RPM to still be fun. Plus the sound track.. But with a Coyote I get put to sleep on the street if it doesn't have more gear than the 2018+ cars do.

4.09’s are not out for a 2017. The gears for that year would be 4.10’s. And yes they feel shorter than an 18 with 4.09’s.

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