MPG Question

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bkg said:
It is so; you're not the only person who's run both and kept a close watch. It's not 50%, but it's there and valid.
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Jack up the front of your 4Runner.
Leave hubs unlocked and spin each tire by hand.
Lock hubs and spin each time by hand.
Please post back here the differences that you find.
If you do find any that are in any way significant, then you have something else going on, but anyway, do that and post back up here. Let us know.



:)
Fred
 
Foreigner said:
My mom tried to convince me of that when I first started driving. That was when Montana's daytime speed limit was "reasonable and prudent." :grinpimp:

I know that it is definitely a factor, though, so I ran some numbers:

My latest trip was to my wife's sister's place, 230 miles away. If I drive 65 instead of 70, it will take an extra half hour to get there, but save me about $8.00 at my current gas price ($2.72), assuming a 3 mpg gain. So:

+$8.00
-1/2 hour extra in the car with :bounce2: and :princess:
-being passee rather than passer
-----------------------------
=not worth it. :D
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LOL!!!!

THATS putting things in perspective! :lol::lol::lol:
 
FredTJ said:
Jack up the front of your 4Runner.
Leave hubs unlocked and spin each tire by hand.
Lock hubs and spin each time by hand.
Please post back here the differences that you find.
If you do find any that are in any way significant, then you have something else going on, but anyway, do that and post back up here. Let us know.



:)
Fred
Click to expand...

WHAT? :meh::meh: I have no idea what you are trying to say wrt mileage, but the difference is easy - the axle shafts will turn when the hubs are locked. The pass shaft will turn the spider gears and the oil movement will often turn the front shaft at a slow rate...

Bottom line; hubs unlocked = less turning mass.
 
bkg said:
WHAT? :meh::meh: I have no idea what you are trying to say wrt mileage, but the difference is easy - the axle shafts will turn when the hubs are locked. The pass shaft will turn the spider gears and the oil movement will often turn the front shaft at a slow rate...

Bottom line; hubs unlocked = less turning mass.
Click to expand...

Because if you actually try this you'll see that we're talking about hardly no difference that you can feel = no difference in fuel mileage.

Put hubs on a while ago and have measured mileage since I got the 4Runner over a year ago.
No difference.
Same with the Jeep, and the Jeep has more mass to turn in the front. Manual hubs = no difference in mileage.

Try it....



Fred
 
There is a difference... Maybe it's small, but there is a difference, because if there's not, then the last X000 years of phisics needs to be thrown out. Turning the cv axles takes power, however little. I can feel the difference when the hubs are locked, that's how much it effects my 4Runner.

Think about it, say you have 50 lbs of tools in your truck.... Most of us would probably not notice the MPG difference. Now say you have 500 lbs.... will there be a difference? 5000? At some point you will notice, and the change can't come all at once, it comes on gradually, that's just how it is.

Maybe a $50 hub swap isn't a good $ idea if you are only going to drive it 20-30 miles a week, but I blow through $200 in gas every month, so after a couple years, having the hubs unlocked is going to pay for some locking hubs.
 
FredTJ said:
Because if you actually try this you'll see that we're talking about hardly no difference that you can feel = no difference in fuel mileage.

Put hubs on a while ago and have measured mileage since I got the 4Runner over a year ago.
No difference.
Same with the Jeep, and the Jeep has more mass to turn in the front. Manual hubs = no difference in mileage.

Try it....



Fred
Click to expand...

Sorry, but you're still wrong. Your logic doesn't hold up to physics, nor does it pass the common-sense test. Easy to prove wrong anyway - do the same test on the rear axle... easy to turn should = no impact on mileage. :)

2ndGenToyotaFan said:
There is a difference... Maybe it's small, but there is a difference, because if there's not, then the last X000 years of phisics needs to be thrown out. Turning the cv axles takes power, however little. I can feel the difference when the hubs are locked, that's how much it effects my 4Runner.

Think about it, say you have 50 lbs of tools in your truck.... Most of us would probably not notice the MPG difference. Now say you have 500 lbs.... will there be a difference? 5000? At some point you will notice, and the change can't come all at once, it comes on gradually, that's just how it is.

Maybe a $50 hub swap isn't a good $ idea if you are only going to drive it 20-30 miles a week, but I blow through $200 in gas every month, so after a couple years, having the hubs unlocked is going to pay for some locking hubs.
Click to expand...

$500/month in fuel for me right now. I'd kill for manual hubs on the Tundra, but I'm selling instead... And you're response is spot-on.
 
I wouldn't put hubs on an 80 again, but there is a definite difference on my truck. Too much black ice around here, I've had my hubs locked almost constantly. It only changes my mileage by about 1.5, very modest but it all adds up. Even if the mileage difference didn't influence me I don't have faith in ADD's, too many past failures.
 
ms018kmf said:
I don't have faith in ADD's, too many past failures.
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x2, it WILL sling your grease out,,,,result, dry joint. It WILL cause drag,,,,result, however small , none the less a decrease in MPG. It WILL not let you use L2,,,,,pull very heavy load to relieve the DT a short/ any distance you want. It WILL in the event of catastrophic failure cause the front to still be connected and it is UNconnectable. It WILL cause fatigue on the grease boot, it is under constant movement and flex on a degradable moving part.



It requires absolutely NOTHING to install ASIN hubs and have the best of both worlds.


how's many iz dat?...:flipoff2:
 
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bkg said:
Sorry, but you're still wrong. Your logic doesn't hold up to physics, nor does it pass the common-sense test. Easy to prove wrong anyway - do the same test on the rear axle... easy to turn should = no impact on mileage. :)



$500/month in fuel for me right now. I'd kill for manual hubs on the Tundra, but I'm selling instead... And you're response is spot-on.
Click to expand...

your wrong.

:meh:
 
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