1000 mile roundtrip...thoughts...
 

Hey guys,

So I took my truck on her first road trip. I drove from Princeton NJ to New Martinsville WV (which is about 30 miles downriver from Wheeling).

On the way there I took the pretty flat way: US 1. to PA Turnpike to Interstate 70 to WV 2.

The truck ran great. I have an issue though, which was pretty annoying. When I go from using the pedal for power to kind of gliding, when it goes through that transition the truck shakes like hell above 60 mph. Popping it into neutral is the worst. I had to use a little finesse on the way there to minimize that... I understand it's the driveshaft, but short of replacing the whole assembly, I'm really not sure what to do about it. The U Joints are brand new.

Anyway, made it there...430 miles. Took me about 7.5 hrs.

On the way home I decided to go a different way and took WV 7 to Morgantown and then jumped on 68E and then 81N to the PA Turnpike and then to US1 and I was home. 440 miles. This time it took me just under 7 hrs. Maybe 6 hrs and 48 mins, with 1 fuel stop and a quick stop for a sandwich at Arby's in Carlisle.

This was definitely a more fun road. The high point on 68E is somewhere in Maryland at 2800 ft. It took a while to get up there and then, according to the signs it was 12 miles of 6% grade on the way down. The truck sure handles those hills like nothing. She would hit about 22 PSI and 1000 degrees at 80 MPH on the steepest inclines. Good times...wasn't too many folk I didn't pass on the way up those hills.

The aforementioned vibrations were MUCH harder to avoid on the hills, as there was a lot of coasting coming down from the 'mountains' (I'm from Alaska, and if there are trees on the top, I don't really consider them mountains).

Anyway, I have yet to calculate my mileage, as my speedo is off and I have to do a little math, but I'm pretty sure it was under 20 mpg...which is a little disappointing. But I couldn't stand to do 65 on such a long drive, and my truck and tires are pretty big, so we'll see...

16.225 MPG average. Lol. Not nearly what I'd hope for. :(

Oh well..she's a monster.

Two things on the drive shaft, U-joints and clocking.
Even though your U-joint are new doesn't mean that a pin roller or two didn't fall in the bottom of the cup during install. Ask me how I know[duhhh]
The other is how the drive shaft is clocked one end to the other. If it has separated at the splines, The ends could be out of phase and/or out of balance. Again, ask me how I know[dummy]

PS, I expected you'd get better mileage than that too with the G360.

22psi,1,000 deg,80mph,fuel milage is not a concern!!!!!! x2 on checking the u-joints,phasing the driveshaft,check the carrier rubber and bearing.

That was the kind of fuel mileage I got towing my trailer to Tok and back.I was also holding 20psi and 1000° for long periods. He should be getting better.

My guess is the 33x12.5s don't help on the mileage, nor did the 80 mph cruising speed. It actually got roughly the same mileage I get when I drive around town.

If only I had more patience and could have cruised at 65, I wonder what the ol' girl would get.

These trucks are not aerodynamic at all so the faster you go the harder the engine has to work and fuel mileage will suffer.

i get like 17mpg on long trips with idling included. i have heavier tires too so i bet that doesnt help.

Is the yoke tight on the output shaft? Mine was loose, think it takes a 1 1/8 inch socket. I also have to spread the yoke on the slipjoint, it binds if I press the caps in tight enough to seat the snap rings properly, and it just takes a short jaunt to 70 to throw things out of whack if I loosen it up enough take the bind out of it.

Unless they changed things after 91 clocking is hard to get wrong. The slip joint male end has one wide spline and the female end has two missing splines 180 degrees apart so it will only go together clocked the right way.

When you put the joins together, fill the caps about half way with grease. It's a little messier but it keeps the needle bearings in place til you get them on the cross.

Not sure if it was a symptom or the problem, but the yoke was indeed loose. I don't remember it being loose before, so it might have shaken itself loose...but tightening it up sure seemed to help!

Funny...everytime I think I fix something, and it solves all my problems on the initial test drive, after a few days I realized it didn't.

Crossing my fingers this time, though! ;)

Mine would get 19mpg at 70mph and 23mpg at 60mph, so speed is a biggie with our bricks. Now with the gear vendors I get 22mpg at 70-75mph. ;)

I did about a 1,000 mile road trip about a year ago to pick up a car down in Boulder. Left at 9 a.m., got back at 4 a.m. Truck ran like a champ.

Last October I went to Indiana and got 18 with 35s and cruising 70 the whole way 70mph puts it right at 1800 with the 35s. Going on the same trip in a few weeks and am hoping to get 20 after some changes.

I averaged 65 and got about 21 on stock tires/wheels with 3.54s for two tanks in a row during my CA to WA trip.

This was measured using a GPS

I'm all stock except for a 14cm/58MM wastegated turbo and a banks intercooler.