I'm the proud owner of a new 2006 F350 Crew Cab King Ranch FX4 Dually (torqshift auto 5 spd) with the Tow Boss option (4:30 gears). When hitting freeway speeds of 70-75 mph my tach shows 2300-2500 rpm's. I wish to drop the highway rpms a bit to get better gas milage and save on engine/trans wear. I'm thinking of installing a Gearvendors Overdrive unit. Does anyone have one installed on their Tow Boss Dually? Any info/help is appreciated...

Thanks,
Bob

 

gunner_bob,
Welcome to FTE.
Check out our Guidelines:
https://www.ford-trucks.com/guidelines.html
And the Read First: notices at the top of each forum, it will help you understand and navigate FTE easier.


As for your question, I am not sure what the fuel economy difference would be, but I would like to find out that is for sure.


BigF350

 

I ran a GV on my '94 F350 TD with a 4.56 rear end. It was a good setup, but doesn't compare to my new 2005 Tow Boss.

The stock GV setup has an overdrive lockout to prevent using double overdrive. I disabled that feature on the '94 because of the 4.56 rear end. Not sure if that lockout applies to the new TorqueShift tranny.

The GV overdrive would probably be like running the 3.73 rear end, at least at the top end. At the low end, it won't shift to OD until you reach about 45 mph.

 

RVRoadie,

Thanks for the reply. I talked with the gear vendor sales rep and he said the overdrive unit would drop my gear ratio from 4:30 down to around 3:30. He said my rpm's should also drop from 2,500 at 75 mph down to @ 1800-2000. Should be right in the "sweet" range to get optimal gas mileage and still have power without downshifting. It really sounds like a good setup for highway travelling. The overdrive unit you had on your 1994 F350 w/4 speed is different than the one going on the new 5 spd torqshift. It should be a good setup. I've made the decision to go with gearvendors so I dropped it off yesterday to get installed later this week. Will keep everyone posted to the road test results....Later

 

I'm picking up my '05 6.0L Exc. next week and plan on installing my GV on it. The Exc. has the 3.73, as my '00 V10 does, and I run the V10 in double OD at highway speeds with better resulting mileage. I believe that the double OD lockout is for the motorhomes (?)As I recall it runs roughly 1700+ at 75 mph.

 

Is there any way a GV can be used with a selectable locker (e.g. ARB) PLUS a factory LS diff?

Thanks

 

booker250,

You can call Gear Vendors Inc. in El Cajon CA. at (619) 562-0060 and ask for Randy. He is their resident expert who can answer your question.

Good luck,
Bob

 

Well, the results of the gearvendors under/overdrive unit install are in. First, let me tell you that the unit installed on my 2006 Ford F350 CC King Ranch Dually FX4 did not go very well, AND I found out the unit DID NOT split gears for towing, in fact, I could not engage the unit while towing because all power was lost. I was later told that any "gear splitting" is basically done by my 5 sp torqshift tranny and the gearvendors unit could only be used strictly for OVERDRIVE. Once installed I took the truck for a test drive. Shifting in/out of overdrive was not very smooth (noticeable loud "clunk"). When I reached 55 mph (without overdrive enabled) I had a very distinct vibration. Once the overdrive unit is enabled, the vibration is still there, but somewhat reduced. After several return trips to gearvendors for attempted repairs and troubleshooting, the vibration is still there (now at 60-65 mph). To make a long story short my fun meter is pegged in the red and the technician basically told me that he has encountered this unsolvable vibration problem with about a hand full of ford trucks with my 5 sp tranny and transfer case setup. Additionally, he stated most of those customers couldn't live with the vibration so they had gearvendors remove the overdrive unit and received a refund. Since my stock truck setup has 4:30 gears with the tow boss setup, my gasmileage suffered at highway speeds. On average, my truck got between 13-14 mpg at 70 mph @ 2200 rpm. Once the gearvendors unit was installed, I did get around 15-16 on the flat, and RPM's dropped about 500, but climbing hills really made the turbo boost kick in and gas mileage suffered dramatically. I must admitt going downhill the gasmileage is "sweet", but you have to go climb back up sometime.
Since I could not use the overdrive unit while towing, plus the added annoying vibration, I decided to have the gearvendors unit removed. For all those thinking about a gearvendors under/overdrive unit install, ask alot of questions first, and watch out for those nasty vibrations. Hope this response helps.......Gunner Bob

 

Bob,

I have the same rig as you!

While I'm happy with the truck as-is, I do have some experience with these OD units from my previous rig. I had the US Gear model, which is *much* tougher than the GV unit, but not automatic (push button high/low with a satisfying "clunk/bang" when engaged). It also does not have the problem with decel.

I won't get into the specifics, but have a look at USGear....I think they have a superior unit. I was very happy with mine installed on an old F350 with 4.10 gears and a 3 speed C6 (3200rpm at 65mph on a 460! had to do something!)

Anyways, good luck...I'll be watching this thread for updates.

 

I am guessing the driveshaft is out of balance...

Thanks for reporting back!!!

 

BigF350,

All driveshafts were balanced and re-balanced (that was my first guess also). I believe the vibration is in the overdrive unit itself. The tech tried everything possible, even placing a $75.00 liquid mercury balancing band in various spots of the driveshaft in an attempt to slay the vibration dragon. Needless to say, the tech is at his end and so am I.

Gunner Bob....

 

Have you taken a look at your pinion/u joint angles and carrier bearing?

 

PSD 60L Fx4,

Correct....the tech made sure all driveshaft angles were correct, and the carrier bearing mounting plate was moved to a correct spot according to gearvendors engineering dept. No one knows what could be wrong. The tech states that all vibration problems are related to the type of transfer case that I have with my 5 sp torqshift.....

gunner_bob

 

I got good results with the GV in my 94 F350 TD. It did an excellent job of gear splitting with the E40D tranny, as long as your timing was good. Since getting the 2005 F350 with TowBoss, I wouldn't even dream of messing with a GV. The 2005 is such a sweet setup for towing, there is no improvement to be gained with a GV. You were right to get rid of it.

 

I have also heard that US Gears is a by far better auxiliary transmission. They are built stronger than the GV although a little harder to operate. I would say the best think to help with mileage is to slow down. Run 65 instead of 75 and ur mileage should increase and your RPMs would go down. Just my .02