gear vendor, doug nash overdrive units.

[UMR_Engnr]

It is my understanding that there is a sprag clutch that takes much of the load when moving forward; however, in reverse the cone clutch takes all the load and can burn up. Offroading with this design seemed like a bad idea. What if the only way out is in reverse? Especially if you're bogged.

 

[hce]

It is my understanding that there is a sprag clutch that takes much of the load when moving forward; however, in reverse the cone clutch takes all the load and can burn up. Offroading with this design seemed like a bad idea. What if the only way out is in reverse? Especially if you're bogged.

The sprague purpose is to to hold direct while the cone clutch is shifting and not in contact on either side. In direct spring put pressure on the clutch. In overdrive hydraulic pressure applies pressure to the otherside. If the direct side of the cone clutch fails, then the sprague clutch would transfer power in direct, and would freewheel in reverse.

 

[Macrobb]

Try down shifting with the throttle applied and no clutch.

I've done it... Not entirely fun. It's really not fun when the switch wire comes loose and it randomly bounces into and out of overdrive a few times going down the highway at 60. Pretty ******* things, that's for sure.

 

[hce]

I've done it... Not entirely fun. It's really not fun when the switch wire comes loose and it randomly bounces into and out of overdrive a few times going down the highway at 60. Pretty ******* things, that's for sure.

I do this and it just slides nice and smoothly into direct. Upshifting though needs the throttle lifted or it bangs.

 

[icanfixall]

I can tell you the GV will handle what we can load it up with. For them to operate they need about 20 mph for the hydraulic pump to make enough pressure to activate the clutch. So it can reduce the 1st gear but.. It sure works well in 1st over. I can manually shift my BTS E4OD trans thru all the gears. So I really have 8 forward gears. With my 3:55 gears on double overdrive my final gear ratio is 1:96... I can only pull that gear on freeways flat ground. When I traveled from the west coast to the 2009 rally in Bowling Green Ky doing 75 to 85 mph across the US my mileage was 18.9. My crewcab was mt so no load. GV trans are very well supported. They are now made in El Cahjon Ca. They used to be made in England but GV purchased the company rights and now is handling it all. Nothing is really bullet proof. Not even the US Gear. One of the selling points of the GV over the US Gear was if the GV breaks you still have your trans. Just no splitting where if the US Gear breaks you stop right there. But Towcat has shown the impossibility can happen.

 

[jaluhn83]

About the only way you're stuck right there with the US Gear box is if you destroy the unit, and that's equally a problem with the GV - ref Calvin's post. You can have a electrical issue and not be able to shift, and maybe if you're really unlucky somehow get it stuck in neutral though that would be difficult. Even if this does happen, it would take about 2 minutes to pull the motor and manually run the leadscrew one way or the other to get into gear.

Well supported sure, but from what I understand you're paying for it.