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Gearvender overdrive?

I have a Gear Vendor in my F350 cummins tow rig. It has a regeared 5 speed ford manual trans. I split 3rd gear and then I have 5th and 5th double overdrive so technically I now have a 7 speed trans. Works great. Little finicky first drive when it's real cold cuz it uses it's own oil pressure to shift. Otherwise works great. I have to shift it just right to not make bad noises but on an auto trans I've heard you can just leave them on or whatever cuz it is ok to let it shift under power. My brother-in-law changed sent this in and had them rebuild it a few yrs ago for like $1300. They said it had issues due to backing up under heavy load like when we park our camp trailers or just general backing them up in the mtns and that damages them slowly. They advised to put the truck in 4wd when backing up a heavy load so that it would split the power to the front axle also and not all the load going through the Gear Vendor. He told me it is basically a TH400 tailshaft for parts like the seal and such.
 
Truckman4life said:
I have a Gear Vendor in my F350 cummins tow rig. It has a regeared 5 speed ford manual trans. I split 3rd gear and then I have 5th and 5th double overdrive so technically I now have a 7 speed trans. Works great. Little finicky first drive when it's real cold cuz it uses it's own oil pressure to shift. Otherwise works great. I have to shift it just right to not make bad noises but on an auto trans I've heard you can just leave them on or whatever cuz it is ok to let it shift under power. My brother-in-law changed sent this in and had them rebuild it a few yrs ago for like $1300. They said it had issues due to backing up under heavy load like when we park our camp trailers or just general backing them up in the mtns and that damages them slowly. They advised to put the truck in 4wd when backing up a heavy load so that it would split the power to the front axle also and not all the load going through the Gear Vendor. He told me it is basically a TH400 tailshaft for parts like the seal and such.
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The automatic transmission setup gets an automatic shifter so you don't need to do anything, it goes in between every gear seamless.
 
imiceman44 said:
The automatic transmission setup gets an automatic shifter so you don't need to do anything, it goes in between every gear seamless.
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Yeah mine if I leave it on it automatically turns on above 15 mph and would stay on through all the gears. I have a switch on my shifter like a splitter and I can split 3rd if I need to or just take it to like 2200 rpm and hit 4th which drops me like 1000 rpm. Then I just use it after 5th if I'm going fast enough to need it.
 
From the Gear Vendors site I gather all units are 0.78 ratio. Is there an appreciable difference between 0.75 and 0.78 when towing? Seems like about 100RPM more. The 1.15 does sound nice where 3rd is too much gear for steep grades. Also double overdrive sounds awesome for cruising while not towing. With 4.10 gears and tiny tires, my 2400RPM at 70MPH would drop to 1872RPM.

4L80E 4-SPEED AUTOMATIC OVERDRIVE
1st 2.48
Over 1.93
2nd 1.48
Over 1.15
3rd 1.00
Over 0.784
4th GM O/D 0.75
Double OD*0.593
*Note: Double Overdrive not to be used when towing or loaded.
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I attached a spreadsheet (pic) based on 4.10's and 32" tires with a 465 as that as what I had experience with.

I forgot the GV ratio previously, it's .78 (guess in the past I had WANTED it to be .5, at least for cruise).

IME, trying to get over a mountain pass at a reasonable MPH/RPM towing some weight, the GV just didn't drop the RPM's enough in 2nd to allow a significant increase in MPH based on RPM. Maybe thats an aversion to listening to a BBC at 3000+RPM for prolonged periods. Cruising unloaded, it would have been nice to see a more significant drop. Double overdrive would do that.

It's odd, by the numbers it doesn't really pen out that the GV has shortcomings in this application...at 55MPH for example, splits for 2nd, 2nd OD, and 3rd is ~1000RPM each, which is essentially half what the drop is from 2nd to 3rd normally (~2000RPM)...one would think this to be ideal, and it probably is in terms of preventing excessive lugging of the engine on an upshift.

Also odd, all that said, it still felt like it was lacking the right gearing between 50 and 65MPH when loaded and climbing a hill. I suspect a torque converter would alleviate much of that impression, and much may have had to do with where the engine preferred to be running under those specific conditions.

gearing.jpg
 
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Blue85 said:
From the Gear Vendors site I gather all units are 0.78 ratio. Is there an appreciable difference between 0.75 and 0.78 when towing? Seems like about 100RPM more. The 1.15 does sound nice where 3rd is too much gear for steep grades. Also double overdrive sounds awesome for cruising while not towing. With 4.10 gears and tiny tires, my 2400RPM at 70MPH would drop to 1872RPM.
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Yeah with my trans in 5th and the gear vendor on with 4:10 gears and 285s I run just about exactly that. My speedo is calibrated for 315s though but they are too tall for hooking to my 5th wheel.
 
sweetk30 said:
gear vendors is real tight on there stuff . i have heard story's of people not able to keep the adapter off a used unit and just buy a new one . they want the old ones back .

otherwise there not super popular for talking about on any forums i have been on over the years . but never heard any bad about them .

few i have seen on ebay tend to go for almost new price .

what trans controller kit have you looked at for the 4l80-e ? lots of guys here have used www.usshift.com . i have one just not up and running yet . 4 shift programs you can pick from on the fly and you can set every thing . and lots of upgrades options in the programing like lockup in other gears . compression braking . custom gear ratio's for 4x4 t-cases like doublers .
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I looked at a bunch of different ones. Jacob's transmissions has a bunch of stuff. the main issue isn't cost, it's ease of installation. Between have trans rebuilt, new convertor, controller, Flexplate and spacers. it was less than the gearvender. but ease of installation is far better with the Gearvender. Seeing as I'm 2-3 months from moving south, and have sold much of my shop equipment... kinda looking for the easy way out. I'll be using the truck to move most of my belongings! so need to get it done. I found a place in Florida that has the unit I need for 100 less than buying direct.
 
Never saw what vehicle you are wanting to put it in, but it is a pretty long unit and rear driveshaft is going to get shorter/steeper.
 
elyon said:
Ben running one for years on TH400. 35" tires 4:10 gears. Had to swap for a rebuilt unit once. My fault I think. 70 mph turning about 2200 rpm.
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be nice in my 6.2...tired of my ears bleeding! lol
 
At least yours runs !..

My 6.2 wouldn't start today...:angry1:..think it has water in the fuel,which is now ice thanks to it being below 20 degrees by day and near 5 above at night the past 3 days here..P-O-S is pissing me off royally..
No need for overdrive, when you cant even get it to run..:surepal:
 
Hey this gearvendors place is right by my house. Always wondered what kind of a transmission business has a huge warehouse but never any cars or trucks around, makes sense now knowing that it's more of a nationwide business
 
They use the gear thrust from the helical cut planets to help drive the cone clutch into engagement when they're under power which is part of the reason they can take so much. On the flip side, any time you're reversing that power the gear thrust takes away holding power. So don't use it for compression braking, it smokes the cone clutch.

Splitting gears is good, I'd take a SM465 with a splitter over a NV4500 most of the time and for towing especially.
 
I’ve akways thought about getting one. But the angle the rear driveshaft would be at is not be able to keep ujoints happy. Maybe a 4500 some day but I don’t drive enough to make any change worthwhile. Still nice to think about having a od instead of 3000 at 65 mph.
 
chulisohombre said:
I’ve akways thought about getting one. But the angle the rear driveshaft would be at is not be able to keep ujoints happy. Maybe a 4500 some day but I don’t drive enough to make any change worthwhile. Still nice to think about having a od instead of 3000 at 65 mph.
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The truck I'm putting it in is 2 wheel drive. But yeah! my old blazer screamed on the highway! but the rear driveshaft was already at a brutal angle!
 
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