Gear Venders OD behind OD trans?anyone?

[C.K. Piquup]

I`ve been contemplating using the aux.od unit behind the NV4500 in the`95 K2500.Has anyone seen or done this,auto or manual?Why,you ask.Gear-splitting!!,selectability,underdrive,and keeping the turbo spooled.Don`t know that I`ll use od/od much,but I`m planning on dropping my gear ratio.The 300hp Peninsular likes the upper 1/2 of rpm range and it likes to push(like a boat),it`s happy under load.Wudyathink?

[Dvldog 8793]

Howdy
I have a GV in my '99 w/ 4.11. My reason for the GV was to retain my 4.11 for pulling and still be able to be cruising on the hiway at 75mph without screaming the motor.
I actually tow with the GV on and the trans in 3rd. this gives me about the same ratio as my trans in OD but the GV is a much heavier duty unit than the OD in my trans. As far as gear splitting I would think it would work great as thats what they are made for. I never really could figure out that "underdrive" thing :confused: You never really underdrive the final ratio, only the #2 and up gears. In my mind that would make it a gear splitter not an underdrive. Ohwell tongue.gif
The GV is GREAT if you can justify the price. My truck gets used for a wide variety of jobs, from family vactions to hauling LARGE loads of steel. I don't know if it will ever pay for itself but saved me from buying another truck. At least until now, I just got an 84 6.2 van for the family truckster job!
I've had my GV for about 3 years and 80k miles. NO problems! The install is fairly complex but doable for the average shadetree. Maint can be expensive, as the oil should be changed every 12-15k miles and is about $18 a quart. :eek:
when the GV engages you really know it, it BANGS! With a little practice that can be minimized, but it scared the sh#t out me the first time!
I think the reduction for the GV is 42% but I'm not sure. You should also check into US overdrives.
Hope this helps!
L8r
Conley

[moondoggie]

Good Day!

I purchased my GV (Gear Vendors) Aux. OD from a fellow DP member at a really good price. I did all the work myself except shortening the rear driveshaft, & no one would make the mistake of calling me a mechanic.

My pickup has a split rear driveshaft. I had a driveline shop shorten the back 1/2 (I think) of this driveshaft. I moved the carrier bearing & mount rearward the proper amount, then shimmed it for the proper driveshaft angles, as best I could. When I had it wrong, it was caused a very noticeable sensation in the truck, sort of like a really badly separated tire, except right at launch. It also went away as speed increased.

I installed my GV to improve mpg (my pickup has 4.10 gears). I probably increase mpg by 2 or so. You might want to look at my post in What's your fuel mileage with a load? (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=1&t=004439#000014) (Click in colored text.)

In my use, the best benefit is that the engine noise GOES AWAY after I engage it at highway speeds. I had no problem pulling our US Cargo SM625TA2 trailer (looks like the US Cargo SM727TA2 (http://www.uscargo.com/uscargo/products/enclosed/snowmate.asp))(click on the colored text, except mine's 6'wide & 25' long) with the GV engaged & the tranny in OD, but it

[LanduytG]

I have the GV as well in my 95 with 4:10 gears and love it. I aso tow in double over even though they say not to. It works very well and will decrease trans temp, colant temp as well as EGT. I went from 10-11 mpg towing to 14 mpg by running double over. If you look at the chart double over is about the same as a truck with 3:45 gears. Also when it needs to down shift you go to 3rd over which is a little better than regular OD. Of course to pull in double over effectively you need to be running 70-75 mph. And as said above the engine noise just goes away. Would not be without it.

Greg

[moondoggie]

Good Day!

For my pickup with the GV I have (others may be different, I don't know), my overall ratio with the tranny in OD & the GV engaged is ~ 3.20 (4.10 x 0.78). With my tires (LT235/85R16, 4% taller than stock) my overall effective ratio is ~ 3.08.

Blessings!

Brian Johnson, #5044

[Craig M]

Our 82 has the TH400, 3 speed automatic transmission. With the gear vendors we have 6 speeds. Can Overdrive each of the 3 speeds. Going up hills with a heavy trailer this helps to keep the rpms in the range as long as possible. With the 4 speed auto you will have 8 speeds. You will have more overlaps than the 3 speed does, but still nice.

[catmandoo]

i'd like to put one in my 1/2 ton with the nv4500,and i could probably get under 3.00 ratio.i'd like to hit 30 mpg,iv'e been up over 27 but see no other way to get there.i get paid milage so over time it will be paying for itself,but if i increased milage 3 mpgs and i run 60,000 a year it would take me about 4 1/2 to 5 years to pay for it.so unless i can find one super cheap doesn't look like it's gonna happen.

[C.K. Piquup]

That`s what I thought,everybody loves the GV/OD.The best things in life don`t always come easy(or,in some cases,cheap).Cost effective?I think you have to look beyond fuel economy,and even drivetrain longitivity,to pleaseability(did I make a word?).If it makes you like what you drive more,and driving it more,it`s worth it.Many of us spend alot of time in the saddle.Why lope along on a nag,when you can gallup a steed?It`s not for everyone,but that`s my way of thinking.I already have enough into this truck to have bought a new Duramax.But, that`s over a 6 year/80,000mi.period,alot of it I`d have to do on top of the Dmax price,and it`s custom.Pleaseability!!?!!Let`s see,GV,I/C,lower gears/lockers,guess I`m not done buying my truck,yet.

[Dvldog 8793]

Well said! ;)
I always tell people that even though my truck is "paid for" I still make payments! :D
....except now they're UNEXPECTED!
...PLEASABILTy.... better call websters tongue.gif
L8r
Conley

[C.K. Piquup]

Oh yeah.Rear disc brakes,exhaust brake,air horns(hidden),air intake in right fender,...Thanks guys.

[RLAM]

Moondoggie:
Think about this. Is 2nd and over the same as 3d and under?
You betcha it is. I have a GV in my motorhome with a 4l80eod and ,to my knowledge and experiance, there is no double over drive.The GV dis engages when I am in od.

[Dvldog 8793]

Rlam-
Sounds like you might have something different than mine. My rig runs in double over(75mph at 1850rpm with 4.11 gears) and there is no real under-drive as near as I can tell, only overdriving all the other gears. The only way that it would be an underdrive would be if you could split 1st. with out another drive unit someplace this would be tough to do.
This is just how my GV works maybe they make something differnt for the RVs.
L8r

[moondoggie]

Good Day!

RLAM: Gear Vendors is easy to find on the web - they'd be the right folks to ask. I have no idea what they do in motorhomes; I do know what mine is & does. ;)

"Double overdrive" is an expression used by lots of us folks with trucks with overdrive transmissions & a GV behind it. We call it double overdrive when the tranny's in OD AND the GV is engaged.

Blessings!

Brian Johnson, #5044

[moondoggie]

Good Day!

I did some simple math. Here's the ratios if you're splitting gears. This assumes a 95 truck with the same 4L80-E tranny as mine, & a Gear Vendors Aux. OD with the same ratio as mine (0.78 OD - they may make other ratios, I don't know).

Gear--ratio--GV engaged

--1----2.48-----1.934
--2----1.48-----1.154
--3----1.00-----0.780
--4----0.75-----0.585

(Sorry about the crummy-looking chart. Tabs don't seem to be enabled for our UBB code, which would make a nicer looking chart.)

From this, it looks like splitting 1st gear in extreme pulling conditions would be quite helpful, as long as the GV minimum speed (18 mph for mine) is attained before manually engaging the GV. I think if I needed to split 1st gear, I'd figure out how to connect a pressure gauge to the GV so I could determine what the real minimum engagement speed is, which would probably be lower than the 18 mph their literature indicates.

It also looks like splitting 2nd gives not nearly as much advantage - the overall ratio isn't much better than just using 3rd gear.

Hope this helps.

Blessings!

Brian Johnson, #5044