What transmission for Bocephus (formerly Great White): POLL!

[MaxPF]

OK, so for those who don't know, Bocephus as I am now calling it is the K5 Blazer in my sig, and is currently running a Cummins backed by a 4 speed non-OD manual. I had planned on swapping in a 6 speed Allison slushbox, but now I am thinking about running a 6 speed OD Eaton-Fuller. So, what do you all think? Here's the candidates:

In this corner, weighing 330lbs, sporting 6 speeds with a double overdrive, and used in many a Duramax-powered Chevy truck, the Allison 1000:

And in this corner, weighing in at a beefy 360lbs, sporting 6 speeds with a 7:1 creeper 1st gear, used in lots of medium duty trucls, the Eaton-Fuller FSO-6406A:

Keep in mind the above trans ain't some slick shifting sports car transmission - it's a truck tranny and it shifts like one. If I run the Ally I will have paddle shifters for manual shifting if I so desire. Either box will get backed by the all-gear 203-205 doubler. Also keep in mind that I already have BOTH transmissions, as well as the electronics to run the Ally, so it's not like I would have to buy one or the other.

So, what say you?

 

[Bigunit]

Personally, I'd take the 7:1 creeper gear over the double overdrive.

 

[06 H3]

For the DD aspect I think the allison would be better but for wheeling I would take the 7:1 creeper. I wouldn't be concerned about the 30lb difference and I think if u can get used to the creeper trans on road id go with that

Sent from my DROIDX using Tapatalk

 

[alrock]

Why can't I vote for a transmission AND get bacon? Mmmm, bacon. Slushbox, much easier.

 

[LagunaH1]

I'd vote for the Allison. To each their own of course, but I love wheeling an automatic.

 

[MaxPF]

The one cool thing about the Ally is the manual shift mode, so off-road I can essentially shift it like a manual if I so choose. Also, the Ally is closer to being installable, and will take less money to put in.

The main advantage of the stick is less parasitic drag. In DMax trucks the ZF manual trucks typically get about 1-2MPG more than the Allisons. Thats not really that big of a deal either since the truck is so cheap to own and operate anyway (I just got 5 year tags, which costed $70).

I dunno.... when my ankle isn't bothering me I really enjoy driving the stick. OTOH, when it starts acting up i really HATE working the clutch. I may have to get it operated on some year, which means if I run a stick i wouldn't be able to drive it for possibly months

 

[Hunner]

I have a 3/4 ton Dodge Cummins turbo diesel and had Suncoast Converters in Panama City, Fla. install a triple lock torque converter and do some of their other mods to my "slush box" and now if you have your foot in it, your cup will fly out of the cup holder on the dash when it shifts when the turbo is boosted up from 18 stock to 38 modded.
The fluid drive is real positive and when it locks up, you know it.
I have seen people smoke a clutch try to use a manual on a ramp pulling one of these beasts out.
The auto just keeps cranking out smooth torque as long as you have traction.
But then you know that.
Years ago when that Duramax got mated with the Allison I was down there and they were working on a converter for that.
I tow up to about 28,000 lbs, no slipping I can tell, so the tranny temp stays down and I added a double deep pan.

I seem to separate the carcass plys on my tires so I started running Commercial grade tires.

It's cnc made from these billets.

No wimpy stock studs on here that get bent a few thousandths and cause shudder. I also had straight cut overdrive gears put in and do tow in that mode.

I know guys running 1000+hp with these and they have many more mods depending on what level you want to go to but, no slush box on these.
I had mine tuned for torque and towing and kept it at about 600hp and 600ftlbs by Garmon Diesel in Atlanta.
I thought you did all that tranny magic?
Give them a call if you want to add their product to your Allison.
http://www.suncoastconverters.com/

 

[MaxPF]

OK, so after the poll combined with some hemming and hawing, I will stick with the original plan - run the Allison.

One big reason is RPMs on the road. The Cummins is most efficient at it's torque peak, which is between 1500 and 1600 RPM (somewhat dependent on timing). Above that, efficiency (and mileage) drop off, especially after about 2000RPM. Last year, coming home from Big Lake, Alex and Jerry were pushing us to do 75. The poor Cummins was turning around 2300RPM and drank fuel. Even at 65MPH I turn 2k and economy isn't as good as it could be. Unfortunately, the Fuller has a .78 OD cog, and with 4.10's I would still be turning essentially the same RPMs at any given speed as I do now. The only advantage would be the ability to downshift at 65MPH without redlining the engine - with my current trans I have to slow to 45MPH to downshift, which sucks on a grade when the EGT's are climbing

The Allison has gearing that is just too good to pass up. 6th gear is a .61 overdrive, while 5th is a .71 OD and 4th is 1:1. In 6th gear at 65MPH I will be turning 1560RPM - right in the MPG sweet spot. At 75 I will still only turn 1800RPM. Even better, I can downshift TWICE at 65MPH without overspeeding the engine: dropping to 5th will turn 1815RPM, while dropping to 4th will turn 2550RPM. The 2500RPM range is where the Cummins makes peak HP and lower EGT's, so I can flat-foot it up the mountain passes loaded with a trailer and camping gear without melting down the engine

So, yeah, I will miss rowing through the gears, but OTOH I gain a lot as well. Hopefully I am Choosing Wisely.