anybody running a GV behind their 4R100?

[towcat]

A buddy of mime is bugging me for ideas on improving his mileage on his '99 F450 CC dually. I've installed a GV on his previous trucks but have not done so on this truck. Anybody have any background or feedback?
thanks.

 

[JLDickmon]

biggest thing on a dually is the drag of the two additional tires

check and make sure the rear brakes are releasing

tire pressures

intercooler boots aren't leaking boost

umm... winter fuel is she-yit for BTU's..

longer warm up cycles

EPBV sensor & tube is clear & valve is free...

 

[silverF250]

I have looked at GV's site and they are quite expensive. You can buy a lot of fuel for the price. They also say if you plan on towing heavy or drive more than 65,000 miles they don't recommend getting one. I would be all for it if it was more reasonably priced.

 

[BIG JOE]

I installed one on my 91 5 speed. Pricey but, I was completely satisfied with it. Had it on for 75K.. not 1 problem. 4 MPG gain empty, 2 MPGs towing. Towed in 4th over.

Don't know about behind an Auto trans tho.

 

[JRJ04]

stupid question...what is a GV?

 

[BIG JOE]

stupid question...what is a GV?

There are NO stupid question on SDD JR

A GV is a: Gear Vendor (brand name), Over/Under drive aux tranny. A splitter.

US Gear, also makes one.

 

[Tail_Gunner]

I was talking to a couple of RV transport drivers who came to our store. They were telling me that overdrive units can make a hellava difference in fuel mileage. One of the guys had a Cummins 12v with a GV and claimed a pretty tall mpg figure that I had to take a "Yea, right" attitude about. I think he was saying something like 18-20 towing mpg with a monster-sized 5th wheel RV.

One thing I remember them telling me, was that one of the units, GV or US Gear, would not hold up to the use of an exhaust brake. I don't recall which it was though.

 

[towcat]

Thanks for the replies so far
This guy does pack on the miles on his truck. It's also as aerodynamic as a brick with antlers(he's got a enclosed service body with a lumber rack on top.) there's no exhaust brake on the truck and it's GV that's allergic to exhaust brakes too. He's not driving like a nut anymore and his mileage is still sub 10mpg.
bear-
I've checked all the above items already and there no issues in the mentioned areas. He comes in for bi-weekly pm's due to his miles accrued.

 

[chief2]

For what it is worth, what gear ratio is in the truck? My 99 F-550 had 4:88's and the mileage was killing me. Couldn't even have a conversation in the cab due to the motor screaming. I checked into GV and the cost was just to high. For $1500.00 I put 4:10's in the rear and picked up 2mpg. Motor is much quieter also. I tow a 18,000 lb. 5'r with no problems. 10 mpg towing, 13-15 regular driving.

 

[mspainting]

Hey chief2 how did you find out your gearing I have a 2000 F-550 & the code for the rear gearing is K & i have checked all the ccode converters & can't figure it out. At 2500 rpms I am runnig abot 62mph
thanks