Less drag with hubs? How about someone with the kit, locking in hubs and at a given speed see how far in neutral your truck will coast to a stop. Then try it again in same spot with hubs locked. If the drag affects MPG then you should coast alot farther with hubs unlocked.

 

Good thought highway!!! I think the auto engineers have done tons of research on this subject and found that there is not significant wear to coating components or exsess drag to come out the pocket for locking hubs and REAL wheel bearings. At least we don't have the older CAD (central axle disconnect) system on our trucks...

 

Another thought - that transfer case chain is spinning all the time in 2H with no hubs as well. Definitely more wear on the transfer case. The only reason mileage drop is only 1 or 2 mpg is that the synthetic oil is so much more efficient in the diff now-a-days and the ATF is pretty thin stuff in the transer case.

I love the 91.5 with the hubs that can unlock - especially when my axle U-joint rusted up and caused stiff stearing but was still driveable in FREE position. I hate the 97 CAD system since the CAD disconnect is AFTER the U-joints and the same rusty joints would have marooned me. You would think with all the fuss now over fuel efficiency it would be time to bring back hubs (Auto or Manual)? Sometimes I think we take a step backwards for the sake of a very few dollars.

 

I have an older chevy 1-ton 4x4 w/ locking hubs. Some Chevy trucks was available with on-the fly set up too. The difference was the transfer-case. New process made a 203 and a 205. The 203 was for on the fly and 205 was for lock out hubs. The 203 full time transfer case had a warning saying that many have removed the front drive-shaft or installed locking front hubs as a means of improving gas mileage. This practice will submit the transfer-case to stresses beyond its design limits and will void all warranties. I believe they done away with the 203 in the '80's and replaced it with the 208 part time transfer-case w/ lock out hubs. 203's went in 1/2 and 3/4 ton trucks ,I have the 205 in this 1 ton. New process became New venture and I forget if they were bought out or not. The point being, who makes our transfer-cases and what is the technology mindset when they built them? New and improved or did they revert back to what used to be?

 

Exactly. A truck just doesn't seem to be a truck anymore like
they were 30 years ago. It is all about what is "convenient".

Roy

 

Our trucks are not just oversized SUV's that get out of style every few years. These are part of the family that age and grow old with us. They are supposed to be reliable over anything. They are complicated enough, more than they should be. Tonight I put my Mag-hytec DD trans pan on and next week comes the rear diff cover. I want the truck to go till I retire-10 more years. If putting manual hubs on will make the front driveline trouble-free it will be worth it. I just want to know that it will and what am I gaining before I lay down the bucks.

 

[QUOTE=Forstner;1333485]Wow! I didn't know that! But then, I don't remember any such warning coming with my rig - a 1976 GMC with the auto and 203 transfer case. I bought it new in 1976 and I am still driving it 31 years later. But I put a conversion kit in the transfer case late in 1976 and locking hubs on the front end so the transfer case acts as a full-time unit when the hubs are locked in, and as a part-time unit when the hubs are locked out. Yes, with this kit the chain still spins all the time. Whatever stresses the transfer case went through in the last 31 years and nearly 200,000 miles, they must not have been too bad because I've never had a minute's problem with it. But I guess the warranty's gone by now so I hope nothing breaks....

 

A friend of mine took in his 04 for a bad ft wheel bearing, shop had to replace both ft bearings, both axle u-joints, 1 u-joint on the driveshaft, pinion bearing and seal with 97,000 mi, all easy highway miles. He wishes they had the dynatrac kit when he bought the truck cause the repair bill he had come close to buying the kit.

 

Yep,, that's what I'm talking about. Bite the bullett for 2K now and we're good for as long as we own the truck. BTW, what about his ball joints?

 

From the April 2007 issue of Off-Road Magazine, in which they are making some modifications to a '06 Cummins Ram 2500 4X4: "Our Dynatrac Free-Spin hub kit does exactly what we knew it would do. Aside from providing user-serviceable parts and beefy, 35-spline outer axles, the manual hubs allow us to unlock over 150 pounds of turning mass when on the highway. What this has done is removed our slight front driveline vibration at 60-70 mph that came from the factory and increased our fuel economy. While we haven't noticed a gain in stop-and-go city driving, we have enjoyed an approximate 2-mpg gain on the highway. The super-strong Dynatrac Free-Spin hub kit is also one of the greatest improvements we've made to our Ram."

What's not to like?? Sounds like a win-win situation to me!

 

OK, it's on the wish list.

 

Good idea, so I did it. My hill was about .7 mi, pretty steep with a decent runout. I started at the top at 30 mph for all runs, a total of 4, 2 with unlocked, 2 with locked hubs.
Locked, my maximum speed was 53. I coasted until I went back to 30 and marked the spot. Unlocked, my maximum was 57 and when coasted the the 30 mark, I was doing 33.
On another note, I was really suprised how much heavier my steering felt.
Hope this low-tech test helps.

 

Thanks Baja for going the "extra mile" for the test. I really wasn't expecting there to be that much difference. Alot of 4X4 magazines do tests and make claims but they are there to sell product so one must take that into consideration. Your drag test is as good as I have seen to prove the hubs. Just wish it wasn't $2000.

 

That's a pretty significant difference (~10%), wonder why one wouln't get 10% better fuel mileage?

 

I had a 95 F-350 P-Stroke for 12 years with locking hubs and NEVER had to do ANYTHING to them 113k miles and I think still going! Love to get my hands on a Dana 60 out of one of thoes trucks! Ball joints for it was $40 each. Balljoints for my AAM about $75 to $101 each!