De-rated 6 speed manual 07.5

[cwomack]

Why would Dodge de-rate the 6. 7 with the manual 6 speed (610 ft/lbs) when the automatic is rated at 40 ft/lbs more? And is it ture that the Aisin 6 speed automatic is only going to be available inthe cab & chasis models?



C. Womack

 

[Semicrazy]

I can not answer the de-rated question. I can only suspect that you can better torque manage with the auto, the same thing that GM has done for years with their trucks, the manual version is derated. And I think now GM does not even offer the manual anymore for for the new body style. I just went to their website and a manual trans is not even listed as an option anymore, just the new 6spd auto for the 6. 0L gas and Allison 1000 6spd for the 6. 6L D-max.



But I can tell you that, yes, the CC only gets the 6sp Aisin auto.

The pick-up trucks get the new 68RFE which is a 6sp auto as well.

 

[cwomack]

Thanks, Semicrazy. Good handle. Was wondering if the de-rating for the manual is because it isn't strong enough for the 650 ft/lbs of torque for the 6. 7. Is the Aisin 'stronger?' Or the other automatic trans for the 2500? Drove a new 6. 7 auto quad 2500 the other day in Santa Rosa. California. They've got it priced at $45k--which seems steep. They have 07 5. 9's priced around $36k. But I'm getting off topic. (By the way, I assume the reason we now see a 6 speed auto is for better overall fuel economy? And why has Dodge gone to the larger 6. 7 when the 5. 9 was doing fine? Won't the fuel mpg numbers be lower for the 6. 7 relative tot he 5. 9? and no smog check for the 5. 9 but yes for th 6. 7's. Will the 6 speed automatic get as good mpg's as the 6 speed manual? Did Cummins have to go larger to accommodate new emmissions equipment?)

C. Womack

 

[cerberusiam]

Derated due to the DMF, and, lack of TQ management.



Evidently the 5. 9 was unable to meet emissions so enter the 6. 7 from this point forward.



The 6 speed autos are a 3 planetary system with double OD. The splits on the gears are much better and since they are fully electronic all the TQ management and shift control can be managed by the ECU.



Will they get better mileage? That remains to be seen.

 

[FATCAT]

The only reason I can see other than the "Torque management" baloney is that the 6-speed manual is really a glorified car transmission. DC should use a real manual truck transmission in a truck ... just makes sense. There should be NO REASON that they can't put a manual transmission rated for at leaset 860 lbft.

 

[SBeretz]

I think the G56 Manual is a Medium Duty truck transmission that is used in Mercedes Trucks overseas. I think the derating may be for DC thinking people will abuse the clutch and expect it to hold up to the 650ftlbs, if that makes sense. They have to cover the clutch for 12K miles so it is in their best interest to make sure that nobody can tear it up until it gets outta warranty. I would think with the normal frictional losses associated with an automatic a manual would still put about the same power down on the dyno. . Some say the Allison sucks up as much as 40HP. . Just guessing though. . I drive a Stick. Scotty

 

[Doubleclutch]

I'm pretty sure cerberusiam has the answer- Why the DMF (dual mass flywheel) in the first place???? Not to handle MORE torque, is it? That's called "Torque Management" for us nuts & bolts guys. I have a VERY strong suspicion that the reason DC went to the 6 spd. auto was purely for MPG. The GOV. has tied their hands with emissions (you don't think those post ignition shots of $$$ fuel are for mpg do you?) and they needed to do what they could to get the truck lighter, for MPG... like using shiney aluminum case manual transmissions instead of reconstituted battleship anchor cases that can handle 880 ft-lbs. New autos don't give up much in hp or tq... it's that computer thingie, the great equalizer! Once the T/C is locked, the Dyno can't tell a difference.

Greg