Front axle 4X4 disconnect possible ?

[JHardwick]

We seem to be going at it from different angles. You are correct that even if the average guy gets say a 1 mpg gain, you will not see the same in your towing mpg. In that regard it is relative, but the total amount of fuel saved will be similar. Using the 30K mile example with the 17 mpg truck that gets 18 mpg with the hubs. That truck will save 88 gallons of fuel over the 30K miles with the free wheeling hubs. For your combination getting 12 mpg, you will burn 2,500 gallons to drive 30K. If you had the hubs you might only use 2,412 gallons of fuel to drive 30K (88 gallons less) and that would net you 12. 44 mpg.

First off, if a truck drove 30,000 miles @ 17mpg, and another truck drove 30,000 miles @ 18mpg ... ... ... ... the truck doing 18mpg would save 98 gallons of fuel over the 17mpg truck in 30,000 miles, not 88 gallons. That's about $450 savings over a 2 year period for most people ($225/year)... ... ... at todays fuel prices. When these hubs first became available, it would have been 1/2 of that, correct?



That's ~5. 5% savings correct?



Now, since there is the same number of available horsepower, that 5. 5% IS NOT linear. It cannot be. If a motor producing 305 crank horsepower is pulling 6,000# or 18,000#, the 3-5 horsepower used to heat the front differential oil is not linear ... ... ... ... it's 3-5 horsepower regardless of the load.



If it were linear at a 5. 5% savings, and I averaged 11. 50mpg, hubs would get me 12. 13mpg ... ... ... ... ..... OR, OR 136 gallons in 30,000 miles!



Now, I bought my truck with 14 miles on it, and it's got 425,000 miles on it now ... ... ... ... ... ... . it never gets out of that 11. 50/12. 00 range unless I'm heading west into the mountains with a big headwind ... ... ..... then I'll drop into the 10. XX range. It doesn't seem to matter if I'm at 15,000# or 20,000# to be honest ... ... ... ... speed and wind resistance make the big difference.



Now, if 3-5 horsepower is 5. 5% of total power consumed in a 18mpg truck, then it takes 73hp on average to power that truck, correct?



Now, a heavier truck with more wind load is going to take more than 73hp on average to power itself down the road. Lets assume that it takes 108hp using the fuel mileage percentages at 18mpg and 12. 13mpg.



Now, 3-5 horsepower to heat the gear oil is only 3. 7% of total power consumed. So, if I started out at 11. 50mpg, 3. 7% gain would get me 11. 93mpg ... ... ... ... ... ... ... . or, 94 gallons in 30,000 miles :-{}



I give up ... ... ... ... ... ... ... I'm leaving at 3am for a long weekend ... ... ... ... WITH my factory hubs:-laf

 

[Matt400]

I am glad I stumbled onto this thread, what a fun class! :-laf have a great weekend JHardwick

 

[brods]

Is that your disclaimer?

Huh? Not sure what you're after here. I have never cared enough to make back to back runs over the same routes with the same load to be able to say definitively that I picked up such and such mpg from the smarty or from the hubs or from whatever. For example my overall average before hubs was 15. 6 mpg, after is 17. 2 mpg. It is very unlikely that the entire 1. 6 mpg change is due to the hubs.

 

[brods]

First off, if a truck drove 30,000 miles @ 17mpg, and another truck drove 30,000 miles @ 18mpg ... ... ... ... the truck doing 18mpg would save 98 gallons of fuel over the 17mpg truck in 30,000 miles, not 88 gallons. That's about $450 savings over a 2 year period for most people ($225/year)... ... ... at todays fuel prices. When these hubs first became available, it would have been 1/2 of that, correct?



Thanks for pointing out my math error, I had forgotten I had changed my original example from 17 to 18 mpg to 18 to 19 mpg to avoid being accused of making the numbers look too good.

That's ~5. 5% savings correct?



Now, since there is the same number of available horsepower, that 5. 5% IS NOT linear. It cannot be. If a motor producing 305 crank horsepower is pulling 6,000# or 18,000#, the 3-5 horsepower used to heat the front differential oil is not linear ... ... ... ... it's 3-5 horsepower regardless of the load. EXACTLY! And the only thing that influences this is your engine’s efficiency! I’m not sure why you fixating on the 5. 5% and trying to use that across the board.



If it were linear at a 5. 5% savings, and I averaged 11. 50mpg, hubs would get me 12. 13mpg ... ... ... ... ..... OR, OR 136 gallons in 30,000 miles!



Now, I bought my truck with 14 miles on it, and it's got 425,000 miles on it now ... ... ... ... ... ... . it never gets out of that 11. 50/12. 00 range unless I'm heading west into the mountains with a big headwind ... ... ..... then I'll drop into the 10. XX range. It doesn't seem to matter if I'm at 15,000# or 20,000# to be honest ... ... ... ... speed and wind resistance make the big difference.



Now, if 3-5 horsepower is 5. 5% of total power consumed in a 18mpg truck, then it takes 73hp on average to power that truck, correct?



Now, a heavier truck with more wind load is going to take more than 73hp on average to power itself down the road. Lets assume that it takes 108hp using the fuel mileage percentages at 18mpg and 12. 13mpg.



Now, 3-5 horsepower to heat the gear oil is only 3. 7% of total power consumed. So, if I started out at 11. 50mpg, 3. 7% gain would get me 11. 93mpg ... ... ... ... ... ... ... . or, 94 gallons in 30,000 miles :-{} YES!Oo. This has been my whole point!!!! At the end of the day you have saved 90+ gallons of fuel! Over your 425K thats 1,331 gallons.

I give up ... ... ... ... ... ... ... I'm leaving at 3am for a long weekend ... ... ... ... WITH my factory hubs:-laf

Thank goodness we are finally on the same page. Enjoy your weekend and keep that front end cool

 

[ColoradoKing]

I drilled the front set of "caps" out for the hub...







Thanks for the the photo. Looks good to me, though it'd be nice if the hubs were low profile enough to hide under the caps.

 

[steved]

I will only add that the studs supplied with the DT kit are long, they prevent the caps from seating on the steel rims (or at least they did in my case)... the aluminum rims having a slightly thicker flange spaces the nut out farther (and essentially shortens the protruding stud).



Here's a picture of my winter wheels... probably gives a little better idea of how far they stick out...



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[RJWEST]

My wife likes the hubs sticking out,

Easier for her to climb up and check the oil...

 

[SierraRam]

Wow a rocket scientist has made the point, I am going to run out and take off these useless things, don't know what I was thinking. Oh thank you god of stock hubs for opening my eyes

 

[JHardwick]

I only take offense when some states that what I said was not true. Glad we can all laugh at it.

Wow a rocket scientist has made the point, I am going to run out and take off these useless things, don't know what I was thinking. Oh thank you god of stock hubs for opening my eyes

WOW ... ..... your pretty sarcastic for a "sensitive" kinda guy :-laf







I manipulated some arbitrary numbers to make your point brods. Well, at least a theory has been established, LMAO. But, if it only takes 2hp to heat the front differential oil instead of 4hp ... ... ... ... well then we got a problem! That cuts the savings in half. Then, there is also the issue of how many horsepower it takes just to stay moving ... ... ... ..... which in relation, could cut the savings down even farther.



I venture to say, that most guys (and gals) will never realize a return in their investment.







HOWEVER!!!!! The horses are hot, the beer is cold, the steaks are thick and the rain has skirted us so far!! One more day of riding, and I'm heading back to Ohio!

 

[Wasilla Rod]

I am the sap that started this thread --

I am the fool that started this whole string -- I just got back from a trip up to Chicken north of Tok with the monster camper and the 4 wheelers in tow. AFTER I get the Dodge steeler to replace leaking injectors ( Oil change went black water in 400 miles) and get a spare fuel pump to carry under the seat and replace the several bad U joints and get some decent shocks to stop the violent side to side rock-A-by baby -- I would REALY like to get a hub kit because I REALY miss the ability to hit low range for the rough stuff with out binding up so bad I am afraid some thing is going to break.

And YES I HAD to use FWD several times but would not have minded getting out to twist in the hubs --IF I HAD them.

Fuel at Glennallen $5. 35 and Tok $5. 34 and I got 16. 8 MPG. Would I take even another 1/2 MPG ? YOU BET Would hubs pay for them selves ?? Proly not ! Do I WANT hubs --YES.

I am starting to miss my old tried and true 96 !

 

[RJWEST]

That is EXACTLY why I did the conversation.
" 2 wheel low range "
PLUS
I hate to break down, And If I do , I want the parts available
to fix it. besides, it is very easy to check the old style front
bearings, using the quick spin method,
" Spin good, sound good, they are good "

Cost effective?, avoiding 1 tow job from the boondocks would surely pay for the hubs...

And, I SURELY DID NOT LOSE MPG!!!!!!
To determine this: I Don't think i need a :spread sheet, driving the same route 20 different times, calculating the density altitude variations, & checking the moon phase for gravitational differances...

Finially: Without the converstion, 4x4 on hard pack:
the truck would bind up, shudder, shake, hop;
Thats gotta be tuff on the drivetrain...

I'm Happy, and that's who counts.....

 

[Wasilla Rod]

Ditto old chap !

 

[deeselfitter]

I have the Dynatrac Free Spin kit, Works very well and picked up about 1MPG.

Sierra
What is that hub kit worth and do you know of any Canadian dealers that stock them?

 

[DGamelin]

Check with Dynatrac they will give you a list of dealers. I have over 208k miles on my truck and havent taking Spyntec off since I put them on. In the end I average 1.7 unloaded and .7 loaded. I use 2wd low all the time. I would not be with out them especially with a manual trans.


2000 2wd xc sb auto 355
04.5 3500 4wdcc dully 6 speed 373