Regearing a '05 K3500 D/A

[Uncle Wally]

So has anyone done it? And not to 4.10's either. I'm looking at doing 3.54's.

I talked to my GM connection and he's says they don't have that option. So on to the aftermarket world. Anyone know of someone that makes gearsets?

I know I going to get some why's. Here why:

I had a 97 Dodge 1 ton dually 4x4 w/ manual. It handled the same trailer very heavily loaded without any issues what so ever. And it got very good mileage at 75 on the freeway pulling the same trailer. If a 210hp truck can handle the 3.54 gearset very well, I'm sure that my D/A can. It has more power, and better around town manners. The only thing I don't like is the mileage. I believe with 235/85R16's and 3.54 gears, I can be in the 20's easily light, and in the mid to high teens loaded.

Any input?

Waldo

[More Power]

Your Duramax has a lot more power, but the Allison is not a manual. It'll downshift a lot more with higher (lower numerically) differential gearing.

Haven't heard a lot of feedback yet from those with the '06 trucks, and who tow heavy and try to run in 6th (essentially 3.42 gearing). The Allison tap-shift mode may allow it operate more like a manual, but lugging at low rpms and with high torque loads could affect torque converter clutch durability longterm. We just don't know yet.

Check out Randy's Ring & Pinion (http://www.ringpinion.com) for R&P gear sets of all stripes.

Jim

[JohnC]

The Allison tap-shift mode may allow it operate more like a manual, but lugging at low rpms and with high torque loads could affect torque converter clutch durability longterm.

The "manual" mode on the new Allisons does not allow you to force upshifts or prevent downshifts. It will force a downshift as long as you aren't violating the "stupid" logic. You can get it to downshift into about 4000 RPM or so. If you put it in (say) 4 while stopped, it just locks out 5 and 6 and shifts pretty much normally otherwise. (You never know exactly what it's up to as it "learns" your drving habits... ;) )

I can't really say I'd want gearing longer than 6th unless maybe I was driving 85 all day long. It's hard enough to keep it near 55 on the back roads around here. Creeps up to 65 or 70 all by itself...

[mark45678]

Your Duramax has a lot more power, but the Allison is not a manual. It'll downshift a lot more with higher (lower numerically) differential gearing.

Haven't heard a lot of feedback yet from those with the '06 trucks, and who tow heavy and try to run in 6th (essentially 3.42 gearing). The Allison tap-shift mode may allow it operate more like a manual, but lugging at low rpms and with high torque loads could affect torque converter clutch durability longterm. We just don't know yet.

Check out Randy's Ring & Pinion (http://www.ringpinion.com) for R&P gear sets of all stripes.

Jim



Hey guys, the new LBZ trucks with a 6 speed trans DO NOT have any advantage towing even if your running light with low wind drag ! I have owned all three duramax motors and the lbz stock does have more go in the lower gears but in 5th and 6th the LBZ doesnt have any more power then a 2004.5 and new lly. Last weekend I ran threw the notch in NH towing about 3000 lbs in my V nose trailer , combine weight was most likely just about 10K. I couldnt pull the hills in 6th and I got better fuel economy running in 5th unless I was really running hard. The truck in 6th gear with stock tires doesnt have enough power at 70 mph mostly due to the turbo will not make good boost unless the motor is over 1850 +rpm. I am very happy with the stock LBZ comparied to a juiced lly and lb7 truck , stock power of the lbz is really good with out a box ! I was averaging 13.0 mpg with my crew cab 4x4 towing at 70 mph in the mountains , cant complain about that. Just forget 6th gear for towing , and for all you guys that think you need high way gears with a 5 speed dmax DONT. GM in my opinion has done a good job of matching the TQ curve of the motor to road speeds . Like I said 1850 rpm is the min speed you what the motor to turn if your towing , EMPTY 6th gear rocks (pulls my 2500hd crew no problem in the hills). For a guy with a 3500 and the stock short tires I would try a larger tire first , maybe a 235-85 or a 245-75..... With this tire and towing you need to run about 75 to make the motor pull on a hill , if your speed drops to 65 at the top of the hill your almost below the TQ peek point and your speed drops fast untill it down shifts.

[JohnC]

The truck in 6th gear with stock tires doesnt have enough power at 70 mph mostly due to the turbo will not make good boost unless the motor is over 1850 +rpm.

You're not goin' fast enough! ;)

[mark45678]

You're not goin' fast enough! ;)


true.... but towing isnt a race...unless someone you know is on the same hill !

[More Power]

Mark, Your towing experience is pretty much what I thought would be the result of having a double-OD. I also suspected the 6th gear would be most useful when running solo, and should help to produce slightly better fuel economy and less engine noise.

What are your EGT's while cruising solo on flat ground - at say 65 and 75 in 6th?

Jim

[mark45678]

Mark, Your towing experience is pretty much what I thought would be the result of having a double-OD. I also suspected the 6th gear would be most useful when running solo, and should help to produce slightly better fuel economy and less engine noise.

What are your EGT's while cruising solo on flat ground - at say 65 and 75 in 6th?

Jim


Jim I havent installed any gauges yet... I was hopeing Edge was going to come out with something soon. I talked to them 2 weeks ago the stated mid June for Beta testing , I had been on there tester list on the LLY project and signed up to do testing on the LBZ when they finaly make something. The double OD is much quieter then my 01 and the LLY trucks I had owned . I currently find its about 3/4 of a mile per gallon better then the LLY but this truck has a cap and the LLY truck had a Roll-N-lock cover.... More wind drag and weight with better fuel economy is a good thing consider fuel is now $2.75! Its just over 2 months old and it currently has 8200 mile on it with about 600 mile of towing to date.... I would have more towing miles but snowmobiling around here was non-existant this year and camping season hasnt started yet !