Auxilary Transmission Advice

[jrobinson1]

I have just joined TDR and you guys are a wealth of knowledge. Thank you. I am 1 year young into my truck and love it. Now I am starting to mess with it.



I am looking into getting a Dual Range Auxilary transmission from US Gear or one from gearvendors. I hear good and bad from both but not first hand.



I want to lower freeway RPM's and it would be nice to split gears for mountain driving. I vary loads, terain and weather constantly. So with 5 gear choices, (well 4, I rarely need to use 1st) I can't always stay in high efficiency areas for engine power with out slowing down, sometimes a fair bit. Holding speeds lowers my MPG. I will be putting in guages before going on with the Aux. install just to monitor changes.



Occassionally after having it I may want to split in 4x4 while snow driving so I am leaning to the Dual Range but I have heard stories of rough shifting and installation is more difficult. The Gearvendors seems simpler to install and a tougher unit but replaces the tail housing of the transfer case resulting in only 2wd operation.



I have hesitations to US gear due to finding returns at the local dealer but he said nothing was wrong with it just he didn't want it after all.



Any thoughts are welcome.



Are there other alternatives?



Thanks



P. S I have 3. 5 ratio (forgot that on the sig)

 

[Turbo Thom]

Well jrobinson1: I see you have lost your virginity. Your first post.



I run the US Gear and have for about 3 years. It is no diffrent than a 2 speed rear end. You don't have that shaking that the axle would give but the same principle. When the OD unit shifts there is a knock type of sound. That is what you want to hear. When you entergize with the shifter, it pre- loads a spring and when you clutch, it shifts. I just re-placed mine after 85,000 miles. I think I had to much oil in there. I found if there is to much the unit will run hot and bubble. Then the 75W-90 can't get to where it is needed.



Anyway I love mine and will run one till I stop driving my truck. Then there will be 4 feet of dirt over my body so who cares?



Good luck:



. . Preston. .

 

[Doubleclutch]

Welcome JRobinson! I have the Gearvendors on my '96. Would have chosen the USGear but the drawbacks for a stardard cab 4x4 were too much (fuel tank interference with the OD being the clencher). Love the GV. 3. 54 gears, 285 AT's and 93mph at 2000 rpm in Double over. Splits gears over ~20 mph (need >600#hydraulic pressure to shift). That means no gear split between 2 and 3rd, and no 4x4 with the gearvendor. Exhaust brake operation is VERBOTEN with the gearvendors as well. But I still love it! Good Luck.

 

[jrobinson1]

Thanks for the input.





I like the idea of 93mph@2000 I am currently running 285's and get around 68mph@2000 hence the desire for double over. I have been leaning towards the US Gear as was but I have a shop friend here that doesn't like its construction, prefers the planetary GearVendors. Sounds like they both are solid units.



I thinks I'll get the US gear. And be careful with the oil. Should have it in before end of Mar.



Thanks again

 

[Eric Horne]

I put my US Gear overdrive unit in by myself. I didn't have any problems at all, but my truck is an extended cab. If you plan on doing the install yourself, here is something I learned. The directions wanted me to cut out a brace that is welded to the bottom of the cab in order to gain clearance. My brace looked like two camel backs (two humps). I found that only the front hump would hit the transfer case. I split the hump with a cut off wheel and grinder then cut across each end of the split. That let me take a hammer and flatten the hump. I sealed the cuts and never have heard a bit of interference noise.



I also went through all the procedures for checking driveline angles. My conclusion: measure the lenght of the US Gear gearbox. Lengthen the front drive shaft by that measurement (get a whole new piece of tube) and shorten the front shaft of the two piece rear shaft by that measurement. Bolt the carrier bearing back up the way it was and go. This is what I did and have never experienced any driveline vibrations.



I have also been told to watch how much oil is put in this unit. My case will hold more than the recommended amount, but a call to the manufacturer enlightened me that to much oil in this unit causes heating problems.



I also find that it is great to be able to back a trailer, in four wheel low, up a gravel grade and then just shift into overdrive when I reach the flat and keep on backing. No stopping to shift the transfer case.



Best of luck. Oh, never shift the unit unless you have pressure on the driveline. Makes an awfull noise.

 

[jrobinson1]

I keep hearing about this knock, or noise that this unit makes when shifting that was the reason I was asking about it. I hear it is very loud with Auto tranys some guy in a review mentioned N before shifting helps.



Thanks for the install tips, I too will be putting it in and have a shop do the drivelines for me.



When it knocks is it just noise or is there shock to the driveline?



What mileage do you get out of these units?



Do you split alotta gears or just set and forget most of the time?

Will alotta shifting on the fly wear it out?



--james

 

[Turbo Thom]

Jrobinson1:

I had a one piece driveline installed. Did away with the pillar bearing.



The knock is the shifter working. It doesn't bother me, but maybe after 3 years I don't notice it as much.



Mileage? I have a heavy foot and 370's so I can't answer that. Although I get average 18 mpg.



The US Gear is a rugged unit but do not over fill. As was said, it will over heat.



Good luck.



. . Preston. .

 

[BCFAST]

jrobinson1, you are NOT getting 68mph at 2000rpm! Check out the recent threads about speed calculation with bigger tires... I think you'll be thanking your lucky stars that you haven't gotten a ticket yet! Welcome!

 

[Eric Horne]

James



It's like Turbo Thom said, the US Gear unit shifts just like a 2-speed axle in a bigger truck. Since the gearbox is under your seat and not way behind you, it's easier to hear it shifting .



Just a little back ground on shifting a 2 speed. When you move the shifting button, an electric motor on the axle (or gearbox) preloads a spring activated shifting mechanism. When you unload the drivetrain (let off the throttle or push in the clutch a little), the unit will shift from the spring force causing the knock. I was also told that the electric motor used in the US Gear box is the same on used on Eaton 2-speed axles.



Normal shifting will produce a slight knock from the US Gear unit with no driveline shutter. But, screw up a shift, and you will be looking in the mirror to see if you left parts on the road. It make a loud bang and shakes the truck. An example of a bad shift is activating the unit while costing down hill. Nine time out of ten, my unit would shift without me touching the clutch or throttle. You will see what I mean and learn where you can and cannot shift it.



The main reasons I bought my overdrive unit was to split 2nd gear and make the jump from 2nd to 3rd easier when I am loaded. Plus, the final gear ratio in double overdrive is heigher than a stock 5 speed's overdrive with 3:55 gears. Dropped my crusing RPM to an acceptable level. I also don't know about the milage because I never paid attention to it before I put the unit in.



When I am running unloaded, I usually leave the US Gear box in overdrive and use all 5 gears in the main box. But, when I am headed out to a pull with 19000 lbs of tractors on the trailer, I split allot of gears. I also pull the hills in 4th over in an attempt to save my fifth gear.

 

[jrobinson1]

Oops my bad guestamite. Good thing I don't run heavy on the throttle, might have been expensive My bad. So I have getting places a little fast.



Thanks all, sounds like I will do the US gear. Everything sounds great. Thanks for all your reassurance and tips.



I will gauge the truck before hand, just because it gives me good excuse to but also curios to see different in temperatures after this unit goes on.



james