7MT Tech

[Squatch]

This is a good start, but does not account for two important things when determining how much peak torque the driveline will see.

1) Impact factor. This is an additional multiplication factor that accounts for the inertial wind up and release that occurs when you perform a drag-style launch. It is hard to predict accurately, but for a manual transmission with a plate clutch, this can be 2.5-3:1. For an automatic, the torque convertor dampens the impact some, so here the factor might only be 1.5 or 2:1. This is, as I said, an extra factor that you multiply with all the gear ratios that you also multiplied the engine torque by. So, from that point of view, your peak torque numbers are actually low.

Also, tied to this, it is most likely that the torque multiplications would disregard low range in the t-case, and would probably use 2nd gear - since 1st is a granny gear and does not act as the 1st gear in normal operation. With the low range and crawl gear, the assumption is likely to be that the duty cycle of these gears is only at low speeds and in crawling scenarios. No one in their right mind will wind up the engine and dump the clutch while in crawl/low range - that's a fast way to break the transmission output shaft, or other things.

2) Tire traction. Everything I just said is true and needs to be considered, but the actual limiting factor of max torque is tire traction. You can only generate the torque that you have enough traction to support; this comes from Newton's 3rd law. So, the tires are usually the fuse in the system - you will max out the tires (and spin them) typically way before you see 27K lb-ft on the axles. For a point of reference, even the GT500 - supercharger and everything - only puts down about 15K lb-ft at the axle before the (stock) tires break loose and spin.

A 4WD/AWD car can put down more, but it isn't double, due to dynamic weight shift. And, of course, the engineering team has to look at it in a 2WD mode as most severe, since that's the case when the tires will see their highest friction coefficient (grip levels) on dry asphalt.

The bottom line here is this - if the Sasquatch tires are Bronco's worst case scenario in terms of inertia and grip, as far as the driveline is concerned, then that limit is the same regardless of which engine is in place. If the 2.3L Sasquatch can max out and spin the tires, then the V6 won't add more peak torque to the driveline.

Nice post.

People air down tires on vehicles like this to get better grip and that's why offering "beadlock capable" wheels is important.

I'm fine with the 2.3, really, but that is where the 2.7 could make a difference. It's also not all about peak torque, but the values at low RPMs.

*I was seriously complementing a post. It actually happened. #historymade

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[wvmtneer]

I wonder if Ford is beefing up the 2.3 or MT for 2022 mansquatch? My current choice(changes weekly) is a 4 dr BD mansquatch and keeping it forever.

 

[MaverickMan]

Both transmission are plenty strong both have their own merits, personal control vs super computer lightning.

The NUMBER ONE issue with an auto and offroaders is external cooler lines. Its one more highly vulnerable not to be nicked or tweaked thing. That will end your transmission in about 20 minutes. They hang lower than my comfort zone and will be exposed to debris, mud, crud, and salt. Make em out of unobtainium and in 20 years they will leak. Guaranteed! Every auto I have ever regularly offroaded. I have to look under it everytime I get out to make sure that my day isnt over.

With a manual you could drop a turd in the case and piss on the clutch and at the most you may have to replace some wear parts after another 100 miles of driving out of no mans land.

 

[Hoofnmouth]

Both transmission are plenty strong both have their own merits, personal control vs super computer lightning.

The NUMBER ONE issue with an auto and offroaders is external cooler lines. Its one more highly vulnerable not to be nicked or tweaked thing. That will end your transmission in about 20 minutes. They hang lower than my comfort zone and will be exposed to debris, mud, crud, and salt. Make em out of unobtainium and in 20 years they will leak. Guaranteed! Every auto I have ever regularly offroaded. I have to look under it everytime I get out to make sure that my day isnt over.

With a manual you could drop a turd in the case and piss on the clutch and at the most you may have to replace some wear parts after another 100 miles of driving out of no mans land.

Oh shoot that last part so true ,i own 1 auto out of 5 vehicles i own and i have a habit of always looking under when getting in and looking where i was when i back out looking for the dreaded puddle.

 

[Laminar]

A 4WD/AWD car can put down more, but it isn't double, due to dynamic weight shift. And, of course, the engineering team has to look at it in a 2WD mode as most severe, since that's the case when the tires will see their highest friction coefficient (grip levels) on dry asphalt.

But the Bronco has 4A, which means it could very easily be expected to put down full power through all four wheels on clean, dry asphalt, requiring the transmission to transmit way more torque than in 2wd mode when the truck would be spinning a single tire through its open diff.

 

[Rollerstud98]

But the Bronco has 4A, which means it could very easily be expected to put down full power through all four wheels on clean, dry asphalt, requiring the transmission to transmit way more torque than in 2wd mode when the truck would be spinning a single tire through its open diff.

When on clean dry pavement would we be expecting 4A to kick in?

 

[HoosierDaddy]

Thank you , sir, for hitting the nail right on the got damm head.

When they sort the orders in May, they're going to be all, "Damn, would you look at that! NO BODY ordered Mid with the manual EXCEPT Badlands buyers!!! I'll be damned!"
LOL

 

[Rocketeer Rick]

But the Bronco has 4A, which means it could very easily be expected to put down full power through all four wheels on clean, dry asphalt, requiring the transmission to transmit way more torque than in 2wd mode when the truck would be spinning a single tire through its open diff.

When on clean dry pavement would we be expecting 4A to kick in?

Maybe. That really depends on the assumptions made about the 4A calibration. It is possible that the t-case will be programmed to command some torque to the front axle during a WOT acceleration, even if the conditions are dry.

But its also just as likely that they'll simply let the traction control step in and truncate torque from the engine. Heck, that could even be something that varies depending on which mode is selected (traction control for normal, command front torque in sport for performance reasons).

Either way, that doesn't change the fundamental point I was making - the tires on the vehicle are going to have the same traction limits, regardless of which engine is ahead of them. If the t-case sent torque to the front in dry on-road operation, the torque that the front will handle is probably also limited by a single spinning tire, though it will max out a lot less than the rear.

During acceleration, weight is being shift away from the front and onto the rear. So the front tires won't have the same grip. So, in very rough terms, also driving the front might increase the total system torque by up to 50 or 60% - and that assumes that (if the 4A mode is using a clutch to drive the front when not in locked mode) the 4A clutch even has that much capacity. A high torque on the front during on-road operation can possibly induce a torque steer, so they'll want to keep that minimized. Without knowing more about the actual hardware in question, the 4A mode may only be able to add 1000 or 1500 lb-ft of torque to the system. That's enough to be significantly useful in all-weather operation and such, without putting a lot of duty cycle on the front driveline. But I doubt that 4A will send as much torque forward as it could in actual 4HI mode, when it will likely go into an actual lock.

It is also worth noting that transmission torque ratings are, as I understand it, usually based on continuous-operation duty cycle. They can typically handle short-duration spikes, such as WOT acceleration in 1st or 2nd gear, above that rating. The transmission is rated on input torque from the engine; it would only send the max torque through in low gear. You'd have to assume that it would be capable of that torque multiplied by its own gear ratios. Even if the t-case is sending torque to both axles, either axle's torque capacity is going to be limited by the tire traction on that axle. So, the part that really has to be rated to withstand the potential of maxing out both axles at the same time is the part that's in the middle - the transfer case itself.

 

[Rivers90]

I wonder if Ford is beefing up the 2.3 or MT for 2022 mansquatch? My current choice(changes weekly) is a 4 dr BD mansquatch and keeping it forever.

My guess for mansquatch is lower diff gears . The lower axle gears would reduce the force on the transmission.

 

[Rivers90]

I would like to see more numbers on the 7mt

But often the most important part of a manual is good shift feel. Some have it some don't.

No one but ford people have driven the bronco yet so who knows.

 

[Laminar]

Maybe. That really depends on the assumptions made about the 4A calibration. It is possible that the t-case will be programmed to command some torque to the front axle during a WOT acceleration, even if the conditions are dry.

If it's anything like the F150, it will default to sending power to the front wheels most of the time. It releases a bit when the front wheels are turned to allow turning without binding, but otherwise there's power going up there by default.

Either way, that doesn't change the fundamental point I was making - the tires on the vehicle are going to have the same traction limits, regardless of which engine is ahead of them. If the t-case sent torque to the front in dry on-road operation, the torque that the front will handle is probably also limited by a single spinning tire, though it will max out a lot less than the rear.

Going full throttle in 1st gear in my F150 in 2H will inevitably lead to wheelspin in the first two gears, even on clean dry pavement. The tires are the fuse. In 4A, the wheels don't spin at all - every ounce of engine torque is transmitted to the ground. The tires are no longer the fuse.

Watch TheFastLaneTruck's videos of F150s at the drag strip. I've seen where they accidentally leave the truck in 2H and they just spin forever and can't get any traction. But in 4, there's zero spin - again, every single bit of torque makes it through to the ground.

But I doubt that 4A will send as much torque forward as it could in actual 4HI mode, when it will likely go into an actual lock.

It will. I've watched the duty cycle commanded in 4A and 4H, and it basically defaults to locked, only releasing on decel and when turning.

 

[Laminar]

When on clean dry pavement would we be expecting 4A to kick in?

At all times.

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