Yelo

hmm...that was a combo that hadn't crossed my mind...I was just thinking of the UD, the OD and lower gears was something I hadn't thought about...and I would STILL have the 3rd gear split

let me look into this more...I'll let you know what I decide

BTW...I now have a 180* thermostat....I just haven't installed it yet

hodgeee

Yelo, that is funny that I read this thread. The Gear drive that can be used on our trucks is rated at 1200hp. My friend got one on his truck since he moves a trailer with between 3000 to 15000 lbs of hay on it. He has a 2500 GMC with the duramax, and 4.10 gears, and had a huge problem when towing a full 15000 lb load. The Gear drive cost him $2300 installed for the 4l80e. He was told by gear vendors to run at least a 4.56 rear for the open freeway, and then he could tow with loads of under 8000 lbs, or when empty would get a great gear reduction for improved gas mileage. His activation switch is right by his left foot on the floor. It uses one of those old high beam style switches that you step on to click it on and off. The gear drive is rated to change the ratios within 1/8th of a second. My friend states that it takes about a week to really get used to shifting with it for performance sake, to be fast, but it has made a huge difference in performance acceleration. But the big thing of course is when he is towing. He said that it has doubled the effeciency of towing in his truck by about 50%. He also stated that he got an average 4mpg improvement when towing, and got an 8mpg improvement when cruising to California empty. He says that he now gets 24mpg on the freeway compared to 16 for normal driving, and 16 when towing with a full load instead of 12mpg.

Those numbers sound high to me, but he has never lied to me before, and I have seen that 3 axle trailer he uses with the third wheel to pull that mountain of hey!

If you really need this get it, you won't regret it, but if you are towing ok, and just contemplating, it is a lot of money. Just depends on how much you tow. I have heard the guys with the allison transmission have no complaints when towing anything.

Yelo

hodgee....thanx for the info !!, I will look into the OD and lower gears as opposed to the UD and stock gears....

the Allison tranny has crossed my mind....it WILL bolt to a LS1 pattern, has the lower first gear and taller OD as well as a fifth gear (kind of a split third).....It looks to be close to a direct bolt-in but the price is kinda steep (no more so than the GV, 2 sets of gears and installation though)

hmmm....what about an Ally/GV combo .....never mind, that would be like $8K

hodgeee

I just went for a ride in his truck yesterday. I went to the same tranny shop as him, and he gave me a ride home yesterday when I was getting my gear swap and we had a big conversation over his modification.

He also looked into the Allison transmission. He was told by the Master Tech at Chevrolet, that the bellhousing is different, and the computer programming is different also, but Chevy has had many customer requests into being able to change into that tranny. Due to this according to the tech, Chevy is putting together a package to do the swap with any 2500 or 3500 truck after 1999 model year. It is supposed to include the tranny, a new shifter column for the cab, a different gauge cluster for the listing of the 5 gears, the new bellhousing and flywheel, and a computer reprogramming, all installed for right about $5000. You have to also get your driveshaft custom fabricated.

Now they did not have that at the time, that is why he went with the GearDrive!

Hit Man X

The Allison is a beast! It ha nice low ~3.10:1 1st gear and a nice close ratios from 2-4. I believe that trans is controlled by a seperate ECU for it only mounted near the big fan. On the '03 I drove it only have P-R-N-D-3-2-1...when you turned OD off, a light in the cluster came on. I can't remeber on the 8.1/Allison I drove a while back was the same way or not.

Yelo

thanks !!, I was under the impression that the Allison had the LS1 pattern.....oh well

hodgeee....did I get it right from your first reply about the GV that the towing capacity on the highway went down with the GV overdrive ??....to 8000lbs ??, or is that only when the OD is on ??

hodgeee

No, when in top gear with the GearDrive engaged, it was recommended to him by the company to not engage the GearDrive if towing over 8000 lbs!

parish8

iTrader: (6)

not sure if this is a concern of yours but the units i have looked at before can only be used in 2wd.

Hit Man X

Yup our newer automatic transfercases don't have a tailshaft so there is no where for that unit to go.

parish8

iTrader: (6)

huh, your right, i was saying it only works in 2wd but it looks like as of now it will only work for 2wd guys.