Reading that the DCT TCM is finally fully cracked

[engineermike]

I don't see this in practice. There is a time when acceleration is reduced during the shift.

In characters 0 and 1, Ford elected to intentionally reduce engine torque during the shifts. Typically, it retards timing to accomplish this. However, as in the case with character 2 (drag mode), it makes full torque through the shift. There is no loss in acceleration.

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[K4fxd]

However, as in the case with character 2 (drag mode), it makes full torque through the shift. There is no loss in acceleration.

If this is the case the DCT will be slower.

Would be nice to be able to test this.

 

[Angrey]

I think we should divide this convo into two categories. The 10R80 is useless above a certain power level for gears 7-10.

The highest HP cars running it are essentially gearing the differential to create a 6 speed and the other 4 gears are simply cruising gears treated like overdrive.

Something about the particular combination and sized of engaged guts/internals makes 7th and up weak. Not really an issue for moderate or meager builds.

Truthfully it seems like we've not seen the torque limitations of the DCT yet because of the nanny features in the TCM, but even with those builds that seem to trick the TCM as a workaround, we've seen pretty big HP cars run the DCT with zero internal upgrades and it's largely stood up to the task (at least we don't see many failures posted).

The 10R80 is obviously much more finnicky when it comes to temperature range. Shift quality and reliability is affected if you try to run it out of a fairly narrow temp band. Now, that's resolvable with a cooler and proper logic, but I'm not sure that's gonna be the case for die hard track builds that are abusing the heat limits around a track at 5k+ rpm for 30 minute sessions.

It remains yet to be seen which one would be more problematic with integrating into previous model/gen dash and controls. Not sure you could do a swap/upgrade to a 10R without the digital dash. Likely/probably a similar case with the DCT as well (or live with wrench lights and stuff like cruise control that doesn't work).

 

[WildHorse]

If this is the case the DCT will be slower.

Fortunately it's not the case .
Everybody knows STOCK drag mode with the 10R80 is garbage.

 

[engineermike]

Everybody knows STOCK drag mode with the 10R80 is garbage.

What, specifically, is wrong with it?

 

[WildHorse]

What, specifically, is wrong with it?

the slipping, the flaring, the overly harsh shifts, the almost random TQ lockup.

 

[engineermike]

the slipping, the flaring, the overly harsh shifts, the almost random TQ lockup.

Drag mode is supposed to be harsh.

As for the rest of it, where are you getting this information? Many commercial tuners and most fast cars use character 2 in all modes and it works fine the way ford programmed it up past 150 in the quarter. It isn’t great at light throttle but that’s not what it was designed for.

If it’s slipping or flaring then the transmission is shot.

 

[Andy13186]

10R80 avg shift time is .3 seconds 5 shifts is 1.5 seconds, total time lost to shifting

Tr9070 is .08 seconds, 5 shifts is .4 seconds total

lmao if you think thats true, what is your source? 10r80 accelerates harder during shifts than when in gear

 

[K4fxd]

lmao if you think thats true, what is your source?

Looking at logs. Looking at when the shift starts until the shift ends.

 

[mejohn50]

Here’s a snip from a log using shift character 2 (drag mode) in the 1/4 mile on a 10R80. This is from a Whipple cal, but it uses almost entirely OEM shift character data. I lowered the torque modulation on the 1>2 and 2>3 shifts, which is why torque drops on those shifts, but the rest are commanding full torque on the shifts.

Green is RPM and white is engine brake torque.

 

[Angrey]

Here’s a snip from a log using shift character 2 (drag mode) in the 1/4 mile on a 10R80. This is from a Whipple cal, but it uses almost entirely OEM shift character data. I lowered the torque modulation on the 1>2 and 2>3 shifts, which is why torque drops on those shifts, but the rest are commanding full torque on the shifts.

Green is RPM and white is engine brake torque.

It does seem to support the idea that it's "accelerating" harder (creating more torque) for the shifts from 3-4, 4-5, and 5-6.

Per your comments, you've softened the 1-2 and 2-3 and that's smart, on a big power car the total torque multiplication is probably in the 10,000 ft-lb range on a PD blown car in first gear. Assuming perfect traction those would be the harshest torque shocks to the drive line. However, in reality, in big power cars there's rarely perfect traction so I suppose the 3-4 would be the candidate for harshest loading, as the multiplication is about half and there's sufficient traction to see every bit of the torque applied onto the driveline components.

 

[K4fxd]

It does seem to support the idea that it's "accelerating" harder (creating more torque) for the shifts from 3-4, 4-5, and 5-6.

The question is, is the on coming clutch slipping?

The engine is supplying the same or more torque, but is it getting to the wheels?

 

[engineermike]

So I took @mejohn50 's raw data for the 4-5 shift from his posted log and put it on a graph with a stock 2020 GT500 3-4 shift so they can be compared (these shifts were just a few mph apart). It's quite eye opening. Keep in mind this is a stock "drag mode" 10r80 shift vs a stock GT500 DCT shift.

If you go by the timestamps in the native app (vcmscanner), the 10r80 shift completed in 165 ms, while the DCT shift took 278 ms. It actually looks like the rate of rpm drop is about the same, but the DCT just had more of an rpm drop to deal with, so it took longer at the same rate.

The torque management is a key difference. Since the DCT must release torque for some time period, albeit small, you can not apply full engine torque during a shift. You see the DCT spark timing drop to -18 deg at this time while the 10R80 held timing constant due lack of torque modulation in drag mode. In fact, the total duration of reduced torque in the DCT, including what appears to be 3 stages of it, was surprisingly over half a second(!), though the deepest cut was under 100 ms.

 

[Angrey]

The question is, is the on coming clutch slipping?

The engine is supplying the same or more torque, but is it getting to the wheels?

Very true.

 

[K4fxd]

Not sure what mode the trans was in on the logs I have but obviously not Drag.

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