Gear Vendor OD Experience
#1
01-26-2006, 09:16 AM
Gear Vendor OD Experience
Got a 91 F350, 7.3l, E40D, 4:10's, 4x4, non-turbo, P235/75/R16 tires, and I am considering adding a "Gearvendor" Overdrive unit between the transfer case and the rear axle to increase fuel economy and improve engine power delivery to the rear wheels.
Has anybody done this? What lessons did you learn? Will the truck run at highway speed (55mpg) in double overdrive? What kind of milage increase did you get by doubling up on the Overdrive?
Has anybody done this? What lessons did you learn? Will the truck run at highway speed (55mpg) in double overdrive? What kind of milage increase did you get by doubling up on the Overdrive?
#2
01-26-2006, 11:55 PM
#3
02-01-2006, 10:44 PM
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I just purchased an 89 7.3 IDI 5speed OD w/the GV unit in it. I drove it from NE to SD to get it home.
410 gears..... w/OD OFF in 5th its ~2000rpm @55
W/OD ON I can do ~70 at 2000rpm, a happy 65 keeps it at about 1850 ish and pulling down about 18-20 mpg w/camper.
Id does pull nicely w/ OD on in 5th gear at 55 but it has a sidewinder turbo.
I just bought the truck w/this overdrive in it but I dont think I would have wanted to do that hiway drive w/o the overdrive. In fact, that overdrive system was the biggest deciding factor on bidding on this truck and I can say Im not dissaointed after driving several w/o the overdrive.
The price of the overdrive is high but IMHO its money well spent if you see hiway speeds often.
410 gears..... w/OD OFF in 5th its ~2000rpm @55
W/OD ON I can do ~70 at 2000rpm, a happy 65 keeps it at about 1850 ish and pulling down about 18-20 mpg w/camper.
Id does pull nicely w/ OD on in 5th gear at 55 but it has a sidewinder turbo.
I just bought the truck w/this overdrive in it but I dont think I would have wanted to do that hiway drive w/o the overdrive. In fact, that overdrive system was the biggest deciding factor on bidding on this truck and I can say Im not dissaointed after driving several w/o the overdrive.
The price of the overdrive is high but IMHO its money well spent if you see hiway speeds often.
#4
02-02-2006, 09:35 AM
Thanks all,
That does sound real good, appreciate the feedback.
Really good Hi-way data Casey.
I am also thinking that for city driving I would keep the GVOD on OD which would basically give me the equivalent of a 3.22 rear end without actually changing rear ends. That should give me a considerable milage boost for city driving as well.
Again thank you for all the feedback.
That does sound real good, appreciate the feedback.
Really good Hi-way data Casey.
I am also thinking that for city driving I would keep the GVOD on OD which would basically give me the equivalent of a 3.22 rear end without actually changing rear ends. That should give me a considerable milage boost for city driving as well.
Again thank you for all the feedback.
#5
02-02-2006, 10:12 AM
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The orig owner of the truck was organized enough to leave the owners manuals for EVERYTHING in a box in the truck. As I have read w/the overdrive system is this..
It uses a pressurized clutch pack and needs to generate about 600 psi to work properly and safely. This doesnt happen below about 25mph.
What you will end up with will probably be 1, 2, 3, 3hi, 4low/hi 5 low/hi but it does work quite well. Mine was added to the truck about 70K miles ago and still works great.
The electronics w/the overdrive unit prevent its use at these low road speeds and in 4x4. I found I really only used it in 4th sometimes but usually when I got to 5th gear, I just used it for a sort of 6th gear and it was very happy on the hiway. I have really only put 500 mostly hiway miles on this truck since I wont it off ebay so my actual experience is limited to that.
I can already tell you that if I had a truck and an extra 3K and had to choose between OD and turbo....I would go w/the OD
Thats my .02
Tony
It uses a pressurized clutch pack and needs to generate about 600 psi to work properly and safely. This doesnt happen below about 25mph.
What you will end up with will probably be 1, 2, 3, 3hi, 4low/hi 5 low/hi but it does work quite well. Mine was added to the truck about 70K miles ago and still works great.
The electronics w/the overdrive unit prevent its use at these low road speeds and in 4x4. I found I really only used it in 4th sometimes but usually when I got to 5th gear, I just used it for a sort of 6th gear and it was very happy on the hiway. I have really only put 500 mostly hiway miles on this truck since I wont it off ebay so my actual experience is limited to that.
I can already tell you that if I had a truck and an extra 3K and had to choose between OD and turbo....I would go w/the OD
Thats my .02
Tony
#6
02-02-2006, 11:29 AM
Ok, lets type this again, darn email crashed just before I was going to sent this:
Well I learned something new,
The 25mph speed limit makes sense if the GV has an internal shaft driven oil pump. You need a certain shaft speed to get 600 psig on the clutch pack. This could be overcome with an electrically driven external hydraulic pump.
Of course then there is the issue with heat generation during low speed/high torque operation. Again this could probably be handled with an external cooler.
But, in the end it probably is the gears that can't handle the low speed/high torque. Darn those laws of physics.
Well the GV unit is still a great idea, just a little less great than what I thought yesterday.
By the way, I am currently struggling with my E4OD. It is working properly but the constant torque converter lock/unlock at city speeds is driving me crazy. The diesel E4OD seem to by design lock the T.C. at 35mph and unlock at 30mph. It just happens that normal city traffic around here is usually 30 to 35 mph.
Sebastian.
Well I learned something new,
The 25mph speed limit makes sense if the GV has an internal shaft driven oil pump. You need a certain shaft speed to get 600 psig on the clutch pack. This could be overcome with an electrically driven external hydraulic pump.
Of course then there is the issue with heat generation during low speed/high torque operation. Again this could probably be handled with an external cooler.
But, in the end it probably is the gears that can't handle the low speed/high torque. Darn those laws of physics.
Well the GV unit is still a great idea, just a little less great than what I thought yesterday.
By the way, I am currently struggling with my E4OD. It is working properly but the constant torque converter lock/unlock at city speeds is driving me crazy. The diesel E4OD seem to by design lock the T.C. at 35mph and unlock at 30mph. It just happens that normal city traffic around here is usually 30 to 35 mph.
Sebastian.
#7
02-02-2006, 12:54 PM
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#8
02-02-2006, 01:01 PM
You are right, I can turn the OD off with the button but that will cost me milage.
Some other guys on the tranny site have suggested toggles to directly lock/unlock the converter but that is risky and very cumbersome so not a good solution. I would basically be manually doing what the computer is already doing all the time.
What I was looking for is a way to re-program or adjust the computer so it locks up say at 25 mph and unlocks at 20 mph so the TC stays always locked when driving city traffic.
Some other guys on the tranny site have suggested toggles to directly lock/unlock the converter but that is risky and very cumbersome so not a good solution. I would basically be manually doing what the computer is already doing all the time.
What I was looking for is a way to re-program or adjust the computer so it locks up say at 25 mph and unlocks at 20 mph so the TC stays always locked when driving city traffic.
