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Over/underdrive

3bals

3bals

Retired Firefighter
Messages
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Location
Minnesota
Years ago I was looking at installing a 2 speed gear splitter on my K2500. I had located one that goes between the transmission and the transfer case, that way you could use it in 2X4 and 4X4 (not like gear vendors that only work in 2X4). I never pulled the trigger, but now am thinking of installing one in my Jeep XJ and now I can't find them. Does anybody have a link?
 
Have you called Gear Vendors and asked about a customized unit for in between the transmission and transfer case. They can do that too.

From their website

"Fact is, when you are in 4X4 there is very little desire to use GearSplitting and overdrive unless you are racing (and we do make the in-between kit for that purpose), "

"US Gear Ranger" the "Nash overdrive" is no longer made that I know of.

I'd like to know how exactly the GV works and feels.

I believe they have to have a minimum speed to shift up. I don't know but will they automatically downshift if the minimum speed is not maintained ???? How long does it take to shift up or down? Can the downshift be locked out until desired?

The split shift that interests me is the NV4500 2-3 gears. How fast would you have to get in 2nd to split shift? Stock with 3.73's when towing uphill I have to rev 2nd to ~3-3200 rpm to get into 3rd without lugging 3rd.
 
US gear was the one that mounted in between, and went out of business quite awhile ago now(almost 10 years now I believe). The gear vendor is also called a laycock overdrive. Volvo factory installed them back in the 70's. They need about 10 mph ground speed to have enough rpm's for the pump in it to hydraulically engage the cone clutch. Cone clutches are nice in that they require very little pressure to engage, they actually pull the clutch together tighter under load. But they have very little reverse holding power(like in engine braking, you cannot do that with them).
 
The US Gears unit was a nice piece and stout as all hell. Damn bloody shame they discontinued making them and the replacement parts (like you'd need any anyways) about a decade ago (right when I was thinking about adding an OD for better fuel mileage and still maintaining 4WD double over) like @THEFERMANATOR said. Can NOT find used units ANYWHERE!
 
I found some new US Gear units IIRC in California ~5 years ago. The shop did not have any couplers for GM's though, only for Fords automatics :(
 
FellowTraveler said:
I think they are still available to bolt to FORD 9"differentials too....
Click to expand...

Ohh that is good to know.
I’m a chevy guy, but be honest. There is no more sucessful rear end than the ford 9”. I could even fit them in the hummer. Crazy strong and so many options, while being low priced too. Sorry Dana fans- you loose this one. It’s the ford starter design argument all over again- just accept defeat and move on.

I have dreamed about an overdrive option for the hummer. An under/overdrive on any diesel makes sense. Kinda why big rigs have it... but 4 wheel drive adds a layer of suckyness to it. I want to look into it for my hummer, but don’t at same time cuz I might just want it. And want vs afford is a battle I haven’t been winning lately. Haha. Cool to know incase my dinaros start multiplying.
 
Will L. said:
Ohh that is good to know.
I’m a chevy guy, but be honest. There is no more sucessful rear end than the ford 9”. I could even fit them in the hummer. Crazy strong and so many options, while being low priced too. Sorry Dana fans- you loose this one. It’s the ford starter design argument all over again- just accept defeat and move on.

I have dreamed about an overdrive option for the hummer. An under/overdrive on any diesel makes sense. Kinda why big rigs have it... but 4 wheel drive adds a layer of suckyness to it. I want to look into it for my hummer, but don’t at same time cuz I might just want it. And want vs afford is a battle I haven’t been winning lately. Haha. Cool to know incase my dinaros start multiplying.
Click to expand...
SEE: http://hone-o-drive.com/hone-o-drive/
 
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