Lock-Out Hub Conversion

[rhoogkamp]

Just got back from a 9342 mile southern trip pulling 16,000 lb 5-er; new truck rides beautiful and has all kinds of power, but fuel mileage sucks. I wondered if anyone has done the lock-out hub conversion and if so has it helped the mileage enough to cost justify it? Spent $$3985. 25 in fuel for a 9342 mile trip-that seems like a lot to me!



This trip loaded I averaged 8. 6 mpg and the best that I could get when I was traveling unloaded was 12. 9 mpg. I love the comfort and power, but this is expensive to run on long trips. We are getting ready for a cross country from Syracuse NY to Vancouver BC. I would like to get some thoughts if doing this conversion would pay off in extra mileage. I have had the truck into several dealers and they say everything is normal.



I pulled this same 5-er back from Indiana when I purchased it and my 2003 with six speed manual and 3:73 gears got 13. 5 mpg. I did not think the 4:10 gears would make this much difference.



I know there has been a lot of posts regarding fuel mileage and I apologize for boring everyone with this agai, but any input would be appreciated.



I will say that the without any power modifications the truck ran and pulled great, much more confortable and the additional air bags and TS3 air hitch made it ride like a car.

 

[Bob4x4]

I have never seen a 6. 7 get 12. 9 empty on the open road,how fast were you driving?

 

[EDankievitch]

I have a 2012 2500 Reg cab with the G56 6 speed that I have installed the Spyntec shorty free wheeling hub kits on. Read my post 4th Gen impressions. I have just shy of 18,000 miles on it now. If I keep my speed down around 64 mph I can squeeze 18. 5 mpg out of it. let it sneak up to 70-75 and best I can do is 16 mpg. these numbers are empty not towing. I have up sized the tires to 285-70-17's and had the speedometer re-cal. ed to match the 5% larger tires. I'm also running an old Rocktek crank position sensor that the co said gives about 1. 5 degrees of timing advance. I also have my bed covered. I have 3. 73's in the rearends. My engine rpm is 1750 at 60 mph.
I should add that if your making oil, even the slightest bit have your injectors checked. I had two that were leaking. The truck ran well and never threw a code however it would make about a qt. or two in 2500 miles. It caused the truck to go into re-gen very often and my mpg's suffered.
Hope this answers your questions.
If anyone is in need of the factory wheel bearing asy's I have a set with the stub shafts, they have less than 2,000 miles on them. I'll be at the Cummins factory tour this June I can bring them with me.

 

[rhoogkamp]

Bob -several trips were nice open road 55 to 60 MPH. I agree this does not seem right but it has been checked by dealers in Syracuse, NY and Panama city, FL when I had oil changes, they do not have any suggestions. I could understand if I was going 75-80 mph, but I do not understand this - open to any suggestions. I sure would like to get something resolved before I start on next trip in August (approx. 16,000 miles). That is why I was considering free wheel hubs.

I did pull all wheels and check & grease pads & calipers, but there is no drag there. On a very slight grade truck rolls free.

 

[rhoogkamp]

Ed, I have approximately 12,000 miles on mine and I did first oil change at 2900 miles and two others at approximately 4500 miles, I check oil frequently and have not noticed the level being excessively high over the full mark. I will watch this closely - Thanks.

How much of a difference did you see after hubs were installed?

 

[rscurtis]

They're worth almost 10% on my signature truck for highway driving, as I found out when I inadvertently left them locked last summer. I don't know how much they'll benefit your truck, as my worst local mileage in a snowstorm is better than your hwy. MPG. They are a worthwhile investment if you plan to keep the truck regardless of their FE benefit.

 

[Cummins12V98]

28K combined load 9. 5mpg. GrapeVine Pass 55 at the slowest.

 

[EDankievitch]

I saw a 1. 25 to 1. 75 mpg increase after installing the free wheeling hubs. Another plus is less wear and tear on the transfercase and front axel/ driveshaft.

 

[AABEN]

If I was not keeping the truck over 4 years I would NOT put the money out. The cost of parts and labor will cost you more than fuel will.

 

[EDankievitch]

How fast you break even depends on how many miles you drive. And if fuel goes up..... Free wheeling hubs might not be the answer but they do help.

 

[AH64ID]

I hear that 10% empty and about 5-10% loaded is pretty average for fuel economy increases. I have them on my 05 and mileage is up a little, but still too early to get a solid figure.