Auto Shift Transmissions

I'm still waiting to see an auto shift go through mud, pea gravel, start on a 25% incline and drag next to an I-shift or Mdrive. My argument or challenge hasn't been answered yet. I'm still waiting to hear why the Allison is not a good OTR transmission. I'm still kinda bamboozled why the argument that an Allison will shift at 1,650 RPM is bad when every auto shift will do the same depending on weight, speed and grade.

THe only thing I can say, they have gotten much smoother, maybe more reliable. But, you just can't compare the two.

 

Still waiting...

 

It uses a torque converter. This means the entire unit is heavier, requires more frequent maintenance, costlier repairs, & it has an additional 0.5-5% energy loss depending on the conditions.

 

Well, lets compare. The HD4060 is 893 pounds, the 18 speed is 713 pounds. So, 150 pounds really isn't that much. So yes, the Allison is a little heavier.

Frequent maintenance? Well, every 300k, 48 months, or 6k hours for general duty, it requires a fluid and filter change. That's it.

Costlier repairs? What actually breaks on one of these Allison trans that makes it costly? And energy loss? Well, I'm not sure about the stats on energy loss. The Allison has more power taking off and more torque than a manual can produce. There is less wear and shock on the drive line with the Allison, no clutches to adjust or replace either.

So back to you daf105paccar, you still never admitted if an auto shift can climb a 25 percent grade from a stop, drive through mud, creep through pea gravel or compete with a manual on ice.

There you have it folks, Allison transmission for the win.

 

The HD4060 is a 5 or 6 speed, correct? So why are you comparing with with a 18 speed?

Here's a better comparison:

Eaton Fuller 10 speed manual: 592 pounds
Allison TC10 10 speed automatic: 1074 pounds.

Aside from loosing nearly 500 lbs in payload (very important with today's heavy emissions packages), 500lbs is worth over 0.01 mpg.

Anything and everything. $600 Torque converter vs $400 clutch. $1000 Transmission electric control module vs...nothing $4000 core vs $1200 core

When the torque converter is slipping, it is consuming ~5% more power than a comparable manual transmission. This is why manuals have 12-15% drive train losses on the dyno while automatics have 17-20%. When the torque converter is locked that drops down to ~0.5% (still slightly higher due to the extra inertia from the automatic's heavier rotating parts).

Just think about transmission temperatures and how much more heat automatics produce -- the energy that creates that heat comes from your engine...

More power? nope -- that comes from the engine. More torque I believe, though I don't need any more for general OTR work -- I rarely use 1st gear as it is. Shock on driveline? I'll give you that with a new driver. And the clutch on my truck lasted 1,200,000 miles (and even then it only got replaced because the transmission was down to replace a crankshaft seal).


I don't doubt that there are specialized cases where an automatic is the best choice, but for a general OTR application the manual is tough to beat.


From a fleet's perspective, automatics & auto-shifts shine when paired with new & inefficient drivers who don't shift their manuals like they should. 30% of mpg comes from the driver so if a product can improve the worst drivers' mpg by 10% -- the fleet is probably better off adopting it even if it causes the best drivers to lose 5%. That's what is happening when they make these claims.

 

The Alllson goes into lockup at around 2-3 mph, so torque converter is not even being used at that point. But the TC can sure make a difference on startups, especially in extreme situations. As for the increased repairs per your assertion, it also comes with 5 yr / 750,000 mile warranty like any AMT or manual out there, and service maintenance is comparable.

 

Now I will admit to not knowing the difference between one auto or another however.....for the third time in one of these auto lover threads, I will challenge any auto lover to the following:

Search TTR for transmission problems and for every problem you find with a manual I will find two with an auto. And for what reason do we need these computers and solonoids and microchips?????

I predict my challenge will get no takers this time either. I don't care what warranty is offered, they have a history of being problem-atic.

 

The Allison is not an autoshift and doesn't have the problems an auto-shift has. They are pretty bullet proof transmissions.