What overdrive unit for my diesel?

71-LS6 · #1 07-18-2006, 12:24 AM

Now that the reality of $3/gal, soon to be $4/gal. diesel has set in, I want to install an aftermarket overdrive unit on my diesel. I've got an 05' Dodge 4wd 6spd Cummins diesel dually. I drive everywhere, sometimes towing as much as 15,000 lbs of equipment or my race trailer w/ car.

Who makes the most bulletproof unit? There is no reason that I can't at least drop 500 rpms on level ground at hiway speeds, and when it's empty, I want even more. Has anybody had much experience with the units that bolt on to the tail housing?

lzdick · #2 07-18-2006, 03:26 AM

I know the Allison that they are putting in the Chevys' and Dodges' is great. I drove a Chevy (with the Allison) a year or two ago that was given to its owner by the NASCAR folks for the exhaust work he does for them. I hooked my trailer to it and took it for a test and it was outstanding. I now have a '04 PowerStroke but unfortunately no Allison (only on F-450 and higher). I would strongly recommend investigating into this Allison unit. PM me and let me know what you learn.

Good luck,
Rich

71-LS6 · #3 07-18-2006, 06:40 AM

Rich, thanks for the lead, I'll check em' out. I was surprised at the number of different vendors that offered them, but I wondered if most weren't made by one or two manufacturers and just stamped with different name plates. Whatever I end up with is gonna get a workout.

71-LS6 · #4 07-26-2006, 05:41 AM

After searching for the last month, I've decided to go with a unit called the "Auxillary Transmission" from a company called US Gear. The unit is rated to 35,000 lbs GVWR, and is available for GM, Ford, & my Dodge. They are available with an overdrive ratio of .80 or an underdrive of 1.25. The bad news, is that on my 4WD truck (maybe all trucks, I didn't care about the other applications) they mount between the transfer case and the transmission. Aside from the obvious modifications (driveshafts, linkage, ect. ect.), I will have to remove a little floor pan from my rear passenger area. On a Dodge, that will leave me one seat designated for children and midgets only.

The cost will be somewhere north of $4,000.00, but at 1,000-1,500 miles a week, it should pay itself off with in a year. If this works out, I'll start learning how to burn manure and Cheetos too, gotta do something fast, my fuel bill is eating into my racing budget.

Chevy454 · #5 07-26-2006, 06:23 AM

Or, you could buy an '06 GM Duramax...they're getting a 6-speed Allison automatic now with a double overdrive I believe...

L78steve · #6 07-26-2006, 07:49 AM

Check out the Gear Venders unit.It mounts after the transfer case.I've got one and it works great.You can also gear split with it.

Paul D · #7 08-01-2006, 08:03 AM

What kind of increase in fuel mileage should you expect with an overdrive unit?