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I know this has been brought up before, and some still might argue that you can drive your part time 4x4 on pavement under certain conditions.

I ran onto this link a long time ago but forgot where. Lucky for me and our forum members I found it again.

Follow this link http://www.4x4abc.com/4WD101/driveline-bind.html for a good example of what can and probably will happen to your ride if you do think it's ok.

MoSun
 

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FJoel said:
Nice link! Seems like a no brainer to anyone who actually wheels and likes to know what is going on inside/under their vehicle. MUST READ FOR NOOBS or SMART @SSES.

Nice post MoSun.
Harald Pietschmann's site ( and Highbeams) has demystified many things about 4WD for me. Very informative site, you don't have to be a NOOB or [email protected] to benifit from it. (Not to say i'm NOT a Noob or [email protected])

Added to my bookmarks.

Thanks Mo! :bigthumb:
 

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Isn't it saying that if you have a center diff and it isn't locked then it's ok?

"...and center differentials have been employed since then to correct the problem"

"The extreme tension and pressures caused by the absence of a center differential (or caused by a center diff that has been locked)..."
 

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It is a good link, but kinda written with a fatalistic slant to it.
I have driven 60 plus miles of freeway (anza borrego to riverside ca) at 75 mph in 4 wheel high, with the same model transfercase as the one pictured (NP231) in my jeep and 2 years ago and still bash up the beast on a regular basis.
hereis me 2 weeks ago in the jeep with the abused case

I discovered I was in 4 high when turning into my Driveway and felt bind for the first time. Now if I had been in 4 low, I firmly beleive something would have broken.
In heavy downpours I still pop into 4 high. Yes it is not good to drive a parttime 4x4 in 4x4 on dry pavement, and really bad to drive in 4 low, but 4 high I have done in many different makes because I brain farted and did not click out untill I felt driveline bind
 

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Ridge111 said:
Isn't it saying that if you have a center diff and it isn't locked then it's ok?

"...and center differentials have been employed since then to correct the problem"

"The extreme tension and pressures caused by the absence of a center differential (or caused by a center diff that has been locked)..."
Yes, but only the MT's have center diffs (a.k.a. Full Time 4WD)...

--Bill
 

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Ridge111 said:
Isn't it saying that if you have a center diff and it isn't locked then it's ok?

"...and center differentials have been employed since then to correct the problem"

"The extreme tension and pressures caused by the absence of a center differential (or caused by a center diff that has been locked)..."
EDIT: Gah, ^^ bigbill beat me to it!

I was wondering the same thing-- and yes, as long as there's a center diff to deal with differing driveshaft speeds in turning (and it's not locked), then you should be fine. For example, Subaru all wheel drive works this way-- it's full time with an unlocked center diff (well, if you want to get techical, all the diffs are unlocked, but the focus here is on the center diff).

I thought both MT and AT FJs would have the same drivetrain-- but the MTs have the limited slip Torsen center diff, and as such are full time 4WD. Auto trans FJs don't have a center diff (only a 4WD transfer case) and therefore can't be used on dry sufaces (where no slippage is allowed when turning).

I agree that it may be blown out of proportion a bit, but seeing that pic of the grenaded transfer case should be enough to convince AT owners into shifting back to 2WD :)
 

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MoSun said:
I know this has been brought up before, and some still might argue that you can drive your part time 4x4 on pavement under certain conditions.

I ran onto this link a long time ago but forgot where. Lucky for me and our forum members I found it again.

Follow this link http://www.4x4abc.com/4WD101/driveline-bind.html for a good example of what can and probably will happen to your ride if you do think it's ok.

MoSun
I think the original post or question brought up was whether you "could" not "should you", especially in adverse conditions. You can't compare the gearbox out of some older model vehicle to a newer updated one.

Don't get me wrong, I don't think a trip from Houston, TX to Phoenix, AZ in my part-time 4WD FJ in 4H is a good idea regardless of driving conditions. But if the roads are way crappy or I'm driving 20 plus miles on isolated gravel/sandy on or near our land near Mexico City I'm going to be in 4H.

Heck I did it in my Grand Cherokee with over 80,000 miles on it ALL the time. Especially while looking for some good surf spots in Mexico on way crappy roads.

Guess I'll wait for the I told you so's.

FJoel said:
Nice link! Seems like a no brainer to anyone who actually wheels and likes to know what is going on inside/under their vehicle. MUST READ FOR NOOBS or SMART @SSES.
Exactly, hey some of us actually wrench and have a general understanding of how things work. Doesn't mean we won't disagree.

http://www.revo1.com/subbietranny/

P.S.
Ohh yeah, a majority of the binding in wheelin occurs while turning, especially with a tighter turning radias.
 

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that's why I'm glad to have full time 4wd.

But..same thing can happen with your center diff locked in a full time 4wd right?
 

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This is a repost, but what the hey :)

Tire air pressures vary. Tire wear differs. Tires end up with slightly different diameters. Roads aren't always as straight overall as they seem.

Pretend the front tires are 31.5" in diameter.
Pretend the rear tires are 31.4" in diameter.

A tire 31.5" in diameter travels 8.246680715673 feet in one rev.
A tire 31.4" in diameter travels 8.220500776893 feet in one rev.

Drive your manual mandated monthly 10 miles in 4Hi.

The 31.5" tire turns 6402.5759963825 revolutions.
The 31.4" tire turns 6422.9663657980 revolutions.

The rear tires experience twenty revolutions more than the front tires. :eek:

No, that's not the real world, tires aren't round and I've ignored significant figures. But it's enough for me to follow the recommendations of an owners' manual and leave a part-time transfer case in 2WD on the pavement. My 2¢.

YMMV :D
 

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The picture is of a blown Chrysler transfer case. Somehow I think Toyota is going to hold up much better. I agree that driving a part time 4x4 at 70 in 4H is foolish. I also think that Toyota knows what it's doing and the manual does not sya to take it off road before engaging 4H on a monthly basis.
 

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philipl said:
The picture is of a blown Chrysler transfer case. Somehow I think Toyota is going to hold up much better. I agree that driving a part time 4x4 at 70 in 4H is foolish. I also think that Toyota knows what it's doing and the manual does not sya to take it off road before engaging 4H on a monthly basis.
that is not a Chrysler Tcase, it is the tcase they put in jeeps however, and yes they can end up like that. However to get into that shape I believe the torque reduction of 4 low would more than likely have to have been used. Another big factor is several companies make a 4 to 1 ratio for that case, the np231, which is engineered for a much higher ratio, 2.61 to 1 I believe. They make another case that is engineered for a 4 to 1, which is used in the rubicon, Since the Ruby came out in 03, a lot of guys have been throwing 4 to 1 gears in the 231 and having splitting problems.
Now. as I have mentioned, I have run highway speeds in 4 high on dry pavement in several different machines, without ill effect. I do not do it because I want to see broken parts, but because **** happens. I think being so scared of something can be more negative than not fearing it. Yes there is benefit to running a few miles once a month in 4 high, being to scared to do it could be worse.
 

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"windup" is less of an issue with transfers with coaxial driveshafts such as the FJ40, because no bending moment is applied to the case.
 

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Someone should tell Toyota, since that bastion of liabilility-avoidance the owners manual says to drive it in 4WD for at least ten miles every month.
With the understanding that you follow the other recommendations in the manual for transfer case usage...mainly, don't drive in 4wd on dry pavement.

Take it on a dirt road and drive in 4h. If you aren't doing 10 miles a month in the dirt, worrying about your transfer case and front diff getting lubed up probably aren't much of a concern. ;)
 

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Someone should tell Toyota, since that bastion of liabilility-avoidance the owners manual says to drive it in 4WD for at least ten miles every month.
I was surprised with the wording of the OM also.

Four−wheel drive system (part−time four−wheel drive models)

“H4” (high speed position, four−wheel drive): Lever at “H4” Use this for normal driving on wet, icy or snow−covered roads. This position provides greater traction than two−wheel drive.

You should drive in four−wheel drive for at least 16 km (10 miles) each month. This will assure that the front drive components are lubricated.
So if the roads are wet, go ahead and put in it 4Hi?! :eek: So says Toyota.
 
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