Auxiliary Transmissions

[aking]

I have a 99 5 speed and considering either a U S Gear Dual Range or a Gear Vendors Under/Overdrive.



I would appreciate anyone's ideas on these products. Do they really work as advertised? Are they dependable? Which type is best. I tow a fifth wheel weighing 11,500, but also tow heavy farm tractors using a gooseneck. When we haul the tractors the total weight is 27,000.



I have been a TDR member since 1997, but this is my first post.

 

[lmills]

Dang, what kept you from posting all this time? If you thought the TDR magazine was full of info, wait till you see what you have tapped into by being on the website!

 

[Todd G]

I think they're a waste of 3k. With that much weight, you need 4. 10 gears. You'll never pay for the aux trans with mileage gains.

 

[jrobinson1]

Driving with the US Gear is nice, get into a good rpm almost any load and grade. Great for cruising empty with 3. 5's



I hear you will destroy the GearVendors using engine brakes while in OD. Its not built to brake with and the actually say and have a disconnect when the E-brake come on OD knocks off.



US Gear is a solid gear box a little rough to shift (you'll learn how to shift it smooth), works in 4wd and with E-brake.



No perceptible mileage gain just more pleasure.



james

 

[aking]

Thanks James (jrobinson) for informative reply. I am leaning towards the US Gear.

The other responses I received totally ingnored my questions. In my opinion the cost is reasonable. I am not purchasing it with increased mileagein mind. In fact, if I purchase it, it will be the Underdrive unit.

Thanks again, Terry

 

[Snow man]

Terry,if your just looking for a little more power,and Edge EZ will really help towing that kind of weight. It may make the splitter unnecessary. . Its a lot cheaper,and simpler,and you will actually pick up a solid . 5-1 mpg.

 

[aking]

I have Edge EZ, injectors, boost elbow, 4 inch exhaust, and K&N. The weak link is the 5 speed. When I'm loaded with a large tractor and pulling out of a field and the ground is soft, I need a lower first. Also I hate the spacing between 3 and 4. I realize I should have a 4. 10, but I don't.



Thanks

 

[pdolan]

aking:



The problem with both of these units is that their ratio choice was made 20 or more years ago when we had 4 spds in most light trucks, and the rev drop between shifts was around 60%. For that reason, USG is 0. 8 overdrive (and 1. 2 under). GV is even worse at 0. 78. The result is that neither one will "split" a gear in a modern transmission, you just end up with one nice step, and then a second one at 10% or less, which is totally useless.



I have looked very carefully at both gearboxes. The USG unit was originally the Doug Nash box made by USG. When that company pulled out of the market, USG updated the design and just carried on. The GV unit is the old Laycock de Normanville planetary set from Austin/MG/Volvo days, and IMHO is not any where near up to the job of heavy towing. It is also stuck with the 0. 78 ratio because they do not make the gears and have no ability nor interest in "doing the right thing".



I have been chasing this for about a year now, and the USG guys have agreed to come to the table and make a gearset that can split the top half of the NV4500 and 5600 right in the middle with 0. 8555. Don't call them looking for one yet, since it has taken a long time to do the engineering and as of next month the first test gearbox should be on the dyno, and later that month I will put it behind my ZF6 PSD at about 35,000 for some real-world, hopefully non-destructive testing. If it lives up to expectations, they tell me it will become a regular catalogue item.



Pat

 

[ata]

The Gear Vendor that I had you couldn`t use below 20 mph and you couldn`t use it in 4 wheel drive. It has an internal oil pump and it didn`t make enough oil pressure to shift until 20mph. It bolted on the back of the transfer case so you could not use it in 4 wheel drive. So unless they have changed the way they use to work it wouldn`t do you any good at low speed or 4 wheel drive.