auto versus 6 speed

[miller_wb]

I am with KenF.

 

[Hohn]

I searched high and low for my six-speed, leftover '02 (bought in Aug '02). A 4x4 SB QC 5600 truck is VERY hard to come by in GA!



I don't tow. I like to have that capability to help others out who need something moved, but I don't own anything that I can tow, and it will be a long time before I do. But I bought the 5600 ANYWAY!



Auto transmission Advantages:

1) Convenience

2) Convenience

3) Convenience



Manual transmission Advantages:

1) Fuel Economy

2) Low cost to BOMB ($1K vs $4K+)

3) Durability over the long haul

4) More control-- I have the smartest ECM in the world making my shift decisions-- a human brain.

5) More ratios= more flexibility and control



Since I was raised to believe that "convenience" is basically a code word for "laziness", I just couldn't see any advantages to the auto trans. My truck plays daily commuter, hot rod, towing loaner for friends, and rescue rig for those not fortunate enough to own a CTD.



I'd still consider getting an auto for one reason only-- my wife struggles with the 6-speed. I'd really like to be able to share my CTD ownership pleasure more with her, instead of it just being "my truck". It's difficult for me to truly enjoy things without her-- she's the best.



That said, I'm loving my 6-speed. I once had to slug in stop and go traffic for almost 4 hours (coming back from skiing Breckenridge on I-70-- the tunnel, and it was black ice all over), and THAT was pretty miserable. But it's a small price to pay in the long term for the benefits of ownership that the 6-speed give me every day...



Justin

 

[Jeremiah]

... ... ... .



That said, I'm loving my 6-speed. I once had to slug in stop and go traffic for almost 4 hours (coming back from skiing Breckenridge on I-70-- the tunnel, and it was black ice all over), and THAT was pretty miserable. But it's a small price to pay in the long term for the benefits of ownership that the 6-speed give me every day...



Justin

What tunnel? Eisenhower is west of Breck, on the way to Vail. But you're right: I-70 can be the pits on holidays and snow weekends. Fortunately, I never drive it. I come across Hossier Pass to Breck.

 

[klenger]

What tunnel? Eisenhower is west of Breck, on the way to Vail.

I don't think so. Better get out a map.

 

[Matt400]

Auto transmission Advantages:

1) Convenience

2) Convenience

3) Convenience

Better add in safety cuz IMO an auto is safer on the boat ramp with park and park brake vs just the park brake.

Manual transmission Advantages:

1) Fuel Economy

4) More control

Not so sure on those, my final drive is taller than a stick and I get 19. 5 unloaded.

Since I was raised to believe that "convenience" is basically a code word for "laziness", I once had to slug in stop and go traffic for almost 4 hours (coming back from skiing Breckenridge on I-70-- the tunnel, and it was black ice all over), and THAT was pretty miserable.

Come on now, it really wasn't miserable... your just lazy.

 

[gsbrockman]

but I have to say that I do not agree with the allison comment ,being they have more claims(warrantee claims) per 100 units built. so is that a better unit?

Great point... we have read the same info. Also, I don't think the Max puts all its power to the ground in 1st and 5th gears (de-tuned in those gears). Sounds like a little too much engine and not enough transmission to me.

Greg

 

[hasselbach]

Great point... we have read the same info. Also, I don't think the Max puts all its power to the ground in 1st and 5th gears (de-tuned in those gears). Sounds like a little too much engine and not enough transmission to me.

Greg

That's not true, the dmax puts all power to the ground in 1st and 5th, and the service manual per the computer section says so. How did you arrive at that conclusion? The only time the computer defuels is in 4 low and when it limps due to problems noted.

 

[Bertram65]

I was also under the impression the LLY reduces power in 1st and 5th, think I read it on the diesel place, the LB7 does not that I am aware of. Are you talking about the LLY or LB7?

 

[hasselbach]

I've got both the factory service manuals for the lb7 and the lly, and both note that defueling only occurs when a problem is noted, such at temp, slippage, etc in the trans. Manuals do not indicate anywhere that any such defueling occurs in 1 or 5th gear.

 

[KBennett]

This thread has really wandered... . Duramaxes, tampons, Eisenhower tunnel. :-laf

I'll put my vote in on the 6-speed. Much simpler design so I can probably fix it myself after the warranty is up.

I had the auto and traded for the 6-speed. One word BLAH! All I lost is convenience and what good is the mighty Cummins if the transmission can't hold up to it? On the 6-speed every gear is locked and I get 6 choices rather than 4.



JMO

 

[hasselbach]

6 gears vs. 4? actually that's not true, the TC is a variable gear, and I think the dodge unit has a torque multiple of 2. 5 to 1, so the automatic has more than 4 gears due to the variable nature of the TC. In fact, if you do the math, at max stall, the automatic is actually lower in gear ratio than the stick. . 2. 5 times 2. 48 = a first gear ratio of 6. 2, which is lower than the 6 speed.

 

[KBennett]

6 gears vs. 4? actually that's not true, the TC is a variable gear, and I think the dodge unit has a torque multiple of 2. 5 to 1, so the automatic has more than 4 gears due to the variable nature of the TC. In fact, if you do the math, at max stall, the automatic is actually lower in gear ratio than the stick. . 2. 5 times 2. 48 = a first gear ratio of 6. 2, which is lower than the 6 speed.

I think we found someone who likes to argue here



My point is that I get 6 LOCKED gears. You can do the math all day long but a locked drivetrain is more efficient than a torque converter.

I have not driven a Duramax with the Allison but I know people that have them and like them. As far as durability they have a good reputation as long as you keep the motor in front of them stock. The 47RE and 48RE are the same way.

On edit: I don't know about the Duramax but I have not needed any more torque from my Cummins in 1st gear than it can provide.

 

[hasselbach]

manual gears are not more efficient.



In a static operation usage, yes, that may be true, but you don't drive at 60 mph always, on flat ground, never varying your loads, etc... how do I know this? read on, maybe you will learn something that is not on two guys garage...



a variable geared transmission, whether by a variable planetary setup or by fluid coupling where the motor is kept in its most efficient operating range is by far superior for operation at a non static mode of operation. ie, going up and down hills, different speeds, different loads...



gm and other car companies are proving this with their hybrid cars right now. . all new prototypes are using variable geared transmissions, not stick shifts. (still with me?)



When I was at UCLA, one of our engineering projects for our master thesis was to get the most mileage or work out of an internal combustion engine. In all tests, by keeping the engine closest to the point of 100% volumetric efficiency (less pumping losses incurred), power output to fuel consumed increased. How do you keep the engine at this operating window? In all cases it was through some sort of transmission that allowed the engine to operate in the limited window imposed, and in all cases it was either a fluid coupler or variable range transmission. Therefore, by keeping the engine say at a identified RPM point which the engine operated most efficiently, work performed was at the lowest energy consumed. We also found that if you could design a transmission to operate with the engine never dropping below the peak torque output, acceleration was superior to say a 5 or 6 speed, and mileage was much better. TC technology has come a long way in 10 years, and soon you will see even more efficient designs that have even higher multiples.



Last note, converter actually increase torque output, and max torque is the point when the stator has stopped spinning. That's how you can get torque multiples of 2 to 2. 5 to one. Locking up the converter does not create torque, it make the converter actually less efficient like a clutch. One to One lock up does not create torque.



ah, check and checkmate. .

 

[KBennett]

manual gears are not more efficient.



Last note, converter actually increase torque output, and max torque is the point when the stator has stopped spinning. That's how you can get torque multiples of 2 to 2. 5 to one. Locking up the converter does not create torque, it make the converter actually less efficient like a clutch. One to One lock up does not create torque.



ah, check and checkmate. .

We don't need to go over how a torque converter works, I understand the theory.

I would agree at the engine level that a torque converter allows the engine to be more efficient by operating at it's peak. But at the transmission level why do you have a great big cooler on the front of an automatic truck and not on a 6-speed? I can choose the gear my truck needs to be in to create the most efficient torque needed without all that heat going through the intercooler making the engine less efficient.

 

[EEdmondson]

I agree that running an engine at max torque or max efficiency rpm is more efficient than a manual transmission, but... . I think a TC wastes a lot of energy (heat). KBennett said it above, all that heat has to have a transmission cooler.

 

[hasselbach]

We don't need to go over how a torque converter works, I understand the theory.

I would agree at the engine level that a torque converter allows the engine to be more efficient by operating at it's peak. But at the transmission level why do you have a great big cooler on the front of an automatic truck and not on a 6-speed? I can choose the gear my truck needs to be in to create the most efficient torque needed without all that heat going through the intercooler making the engine less efficient.

Oo. Oo. Oo. denial denial denial. .



yeah, you might be able to find that one gear that works for that one instance at that given point in time, but a TC is not one gear, or two gears, or even 6. . Its VARIABLE, and properly designed, it can do more than your 6 speed. HEAT, yep, that is a by product of creating TORQUE. But I don't see heat being a big issue now, since it doesn't seem to be a big problem per the posts I've read. Face it, you are limited to 6 specific points on a graph where your 6 speed is optimal, thats it. (sorry, not my rule, its the rule of physics). A properly operating TC will plot an efficiency curve that will blow the manual shift away. Guys, this isn't the 1950's anymore. Ozzy and Harriet aren't on the tube, and manuals aren't the most efficient manner to transmit torque into movement.

 

[EEdmondson]

Hasselbach, It's 2004 and I don't see that CVT, that I've been reading about for 30 years, offered on CTD's yet. Time to go watch Ozzie, Harriet, David and Ricky.

 

[hasselbach]

oh, you don't know what a TC is?? Now that explains your past post... Instead of Ozzy, look up 'fluid thermodynamics, hydraulic coupling, principles of fluid coupling, efficiencies of fluid coupling, etc on the web. You will get some pretty good reference articles about how they work, why they work, etc.

 

[KBennett]

Oo. Oo. Oo. denial denial denial. .



yeah, you might be able to find that one gear that works for that one instance at that given point in time, but a TC is not one gear, or two gears, or even 6. .

I am tiring of this argument. You like your auto, I like my 6-speed. On paper you auto is a wonderful thing, in the real world it did not work as well as you suggest for me. I have made my point and I'm outta here.

 

[EEdmondson]

In your earlier posts you indicated that the TC is a continuously varible transmission that will change ratios to keep the engine at max torque or max efficiency. Where can I buy it? Maybe in the age of the Jetsons.