Here is why part time 4WD should never be used on dry pavement

MoSun · 09-01-2006, 08:07 PM

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

**FJoel** · 09-02-2006, 02:35 AM

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.

FJGypsy · 09-02-2006, 06:06 AM

Excellent post with links MoSun!!! Knowledge is power!!!

**1911** · 09-02-2006, 07:28 AM

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.

**t2cruiser** · 09-02-2006, 07:49 AM

Quote:

FJoel previously 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 SMART@ss to benifit from it. (Not to say i'm NOT a Noob or Smart@ss...)

Added to my bookmarks.

Thanks Mo!

Ridge111 · 09-02-2006, 08:37 AM

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)..."

highbeams · 09-03-2006, 01:14 AM

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

qua77ro · 09-05-2006, 10:18 PM

TJ: highbeams, where was that picture taken?

bigbill25 · 09-05-2006, 10:43 PM

Quote:

Ridge111 previously 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

MauiJim · 09-05-2006, 11:12 PM

Quote:

Ridge111 previously 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