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  #11  
Old 05-08-2014, 10:04 AM
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Ozz Ozz is offline
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Quote:
Originally Posted by zabmasonry View Post
while I hear the points about more gears in a 1-ton. I don't really see the need other then just seeing it on paper. The difference between a heavy haul peterbilt and a f550 is that the pete has a power to ratio of 170lb/hp vs the 550 which at gcvw is at 115. The difference is even greater if you're talking about a truck with a pickup bed. In addition the diesels in pickups have a significantly larger power band. My sense is that 6 gears are more then enough for a 1 ton, especially in an automatic transmission.

I'd also point out that a lot of heavy trucks are going to 6spd transmissions. For example the cat on road trucks have a 6sp auto.
My C12 has a wider power band than say... A series 60 detroit. It's a dozer engine. It has to. That's why Cat can het away with fewer gears. It works off highway. Not on
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  #12  
Old 05-08-2014, 09:53 PM
zabmasonry zabmasonry is offline
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I guarantee you that the hp and torque curves in a C12 on highway is completely different then a C12 in a dozer. Electronics make that change even more noticeable, but even a completely mechanical system would have a different curves.

As for the two speed rear end. I can't even begin to explain how bad of an idea that would be. an auxiliary transmission might be more applicable, but a two speed rear-end is just a recipe for disaster.
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  #13  
Old 05-08-2014, 09:58 PM
Pressedun Pressedun is online now
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Originally Posted by salopez View Post
chevy had talked about bringing out a 12 speed Allison for 2014. there was also talk of an 8 speed with 2 speed rear. these would have been awesome.
Chevy also has rumors of getting back into the medium truck market, I wouldn't hold your breath on that one.
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Old 05-09-2014, 10:16 PM
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Ozz Ozz is offline
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Quote:
Originally Posted by zabmasonry View Post
I guarantee you that the hp and torque curves in a C12 on highway is completely different then a C12 in a dozer. Electronics make that change even more noticeable, but even a completely mechanical system would have a different curves.

As for the two speed rear end. I can't even begin to explain how bad of an idea that would be. an auxiliary transmission might be more applicable, but a two speed rear-end is just a recipe for disaster.
Maybe on the C12. I can say the ACERT power band is wider than most on road trucks. Maybe that's just my particular rig, but that's been my experience. And you cannot deny that CAT's eartmoving background hasn't influenced that. But, I'm not a CAT engineer so I can't definitely say that.

I worked in a truck company before I went into this full time, and our new at the time Seagrave had a 5 speed auto connected to a Series 60 with a massive turbo. And that truck flew.

Yes, a two speed rear in a one ton is no bueno. Honestly, a 7 speed with the first six spread a little farther apart and one kicking in to where I spin low RPMs at 65 I would be very happy with.
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Old 05-16-2014, 09:50 AM
TuffTurfLawnCare TuffTurfLawnCare is offline
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Can you imagine the warranty claims on a two speed rear end from people not knowing how/when to shift it. You would be hearing the grinding of the diff in every neighborhood. LOL. I had a friend with me in a single axle dump with a split rear, he said " I could do that it looks easy". I told him, no I just make it look easy. He didn't believe me, so I tried to teach him. After an hour of him trying, he just couldn't get it. Some people can't. I couldn't imagine him trying to figure out an 8LL with the high/low selcector on the front, and thumb switch for deep reduction let alone an 18spd and splitting every gear.

Driving 8LLs 18spds and 10spd (I despise the Mack 10spd, worst shifting tranny ever) is a skill. Doing it effectively and without damage, even more so. So many companies are going to autos as its easier and cheaper to hire a wheel holder than a driver. With the power to weight ratios of 1ton trucks, I don't think there is a need for 8spd trannys. They have the power and the rpm to get their weight rolling without rowing through the gears. Even international 4700's with a dt466 and a 6spd will do well enough for most around town or short highway trips, even though they are tapped out around 2300rpm at 65mph.

As for adding gears, the ability is already there, mechanically. With electronic controls, they activate different clutches in automatics to get different gear ratios at the output shaft. I.E. first gear with the OD clutch would give you a spot between 1 and 2. 2 with OD would give you a spot between 2 and 3. With an automatic, you could split gears with the converter lock up too. Run through 1st, lock up the converter and drop the rpm 2-500. Then shift to 2nd and unlock the converter at the same time. Run through 2nd and lock the converter, etc etc. On my Jeep, I had my converter on a toggle switch so I could lock it in 1st gear during long down hill decents while off road, thus taking advantage of the available engine breaking. When driving Round the streets, I would play with it and turn my 4spd into an 8spd by locking the converter in each gear and unlocking it at the shift I to the next highest.


I must add, I did love the T800 I drove with the 550 horse N14/8LL combo. That Cummins with dual 10" unmuffled stacks would shake windows...something about the "pop" of the N14....
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