Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.2.fluke 9/24/84; site fluke.UUCP
Path: utzoo!watmath!clyde!cbosgd!cbdkc1!desoto!packard!hoxna!houxm!vax135!cornell!uw-beaver!ssc-vax!fluke!jeepcj2a
From: jeepcj2a@fluke.UUCP (Dale Chaudiere)
Newsgroups: net.auto
Subject: Re: Wrong!!
Message-ID: <894@vax1.fluke.UUCP>
Date: Mon, 18-Feb-85 10:28:33 EST
Article-I.D.: vax1.894
Posted: Mon Feb 18 10:28:33 1985
Date-Received: Fri, 22-Feb-85 08:13:46 EST
References: <617@topaz.ARPA>
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 47

> Uh - This should be pointed out for the benefit of all us fo-by owners.
> 
>    From: jeepcj2a@fluke.UUCP (Dale Chaudiere)
> 
>    Case 2:  If you every buy a 4-wheel drive vehicle, you must rotate the 
> 	tires.  Any difference in tire diameter from front to back will 
> 	cause the  transfer case to bind, except on the most slippery 
> 	surfaces.
> 
> What kind of truck are *you* driving?  Any full-time 4wd vehicle has a
> set of spider gears in the transfer case, which let the front and rear
> shafts rotate at different rates.  In fact the front and rear punkins are
> often different ratios, which makes this necessary.  Naturally, if you
> lock the shafts together and drive on dry pavement, you'll get torque
> windup across the drivetrain which will undoubtely break something.
> Tire diameter therefore has nothing to do with what the 4wd drivetrain
> is doing.
> 
I am driving one of the majority of conventional part-time 4-wheel drive vehicles that are on the road.  (Jeeps, Land Cruisers, Toyotas and the majority of
American makes).  These conventionals rotate the front and rear drive shafts at
exactly the same speed.  The first versions of fulltime 4 wheel drive made by
Ford, Chevy, and Dodge had only a spider gear type setup in the transfer case.
(no limited slip)  This allowed the power to be transfered to the driveshaft
with the least resistance.  Thus without limited slip in either differential, 
you just had a choice of one out of 4 wheels slipping instead of one out of two
like a normal car.  The little lever in the glove box locked the spiders in the
transfer case making it behave like a conventional 4 wheel drive transfer case.
The big three quit making this type of fulltime 4 wheel drive when they finally
admitted the reduced gas milage, when used on hard surface roads.  Jeep
Quadratrack has a limited slip setup in the transfer case.

I have never heard of the front and rear differentials having different ratios,
except on trick sand drag rigs with small front tires and large paddles on the
rear.  The spider gear type setups in transfer cases were never designed to
compensate different ratios front to rear.

> I have a '74 K10 Blazer into which I bolted a ''half-time'' kit that makes
> it full-time rear drive and switchable front wheel drive.  [Especially
> after *losing* the front CV joint one trip back from Boston.]  With this
> arrangement you not only save some gas, but if you lose a U-joint miles from
> anywhere, you can take the rear shaft completely *out* and get home on the
> hitherto-unused front one.
> 

Yes and the kits I have seen for this conversion come with a new shaft for the
transfer case that converts it back to a convensional setup,  (no limited slip
in the transfer case).