Maderita - 9-15-2018 at 04:48 PM
Amazing and true story:
Finally getting around to posting this incident form several years ago. Wife tried to leave for work in the morning in her Jeep Grand Cherokee (4.0L,
Dana 35C rear axle, open diff, Michelin M&S rated tires).
She came back in the house, somewhat frantic, saying that the (automatic) transmission was not working and that she smelled something like burning
rubber. I went outside expecting the worst. Climbed into the driver's seat. The Jeep was pointed up the rather steep hill in front of my house.
Started it up, put it in gear, gave it some throttle. No forward movement, nothing, nada. Heard a whirring noise at the rear right side. Got out for a
look...
Green slime around the right rear tire mixed with a bit of burnt rubber.
Turns out the neighbor's tree had dropped an avocado. The avocado rolled down the hill, stopping against the rear tire, next to the curb. The initial
forward movement of the tire squished the avocado. The instant guacamole coated the tire with slippery slime. I busted out in laughter, picturing the
headline, "Jeep defeated by a single avocado!!!"
Now for those of you who may not know about open differentials, limited-slip (aka: Positraction), and locking differentials, my story may encourage
you to do some research. When you read how ineffective open differentials are under certain conditions, you may be inspired to upgrade your axles.
Maderita - 9-15-2018 at 04:53 PM
Btw, the Grand Cherokee is the daily driver. The other Jeep (Wrangler) has locking diffs front and rear. Detroit Locker up front and Eaton E-Locker in
the rear (a Ford 8.8 axle).
Ken Cooke - 9-15-2018 at 06:01 PM
Open differentials work well in snowy climates. I had a Ford Ranger 4x4 that was a blast to drive when I briefly lived in Michigan.
motoged - 9-15-2018 at 08:03 PM
That's funny....
advrider - 9-16-2018 at 08:12 AM
That would make a good ARB locker add.....
David K - 9-16-2018 at 08:27 AM
I remember in the 60s my dad explaining four-wheel drive was really only two wheels driving (one in the front and one in the rear). Getting stuck in
the sand, it was obvious when you saw only one tire on an axle spinning. Posi-traction was mentioned to get both tires on the axle to 'work'.
Now, we hear about 'traction control' (uses the ABS brakes to balance tire rotation between the two per axle); 'limited slip differentials' (like
Posi-traction) that use clutch packs inside the differential to limit free spin of a non-traction tire; and 'locking differentials' which direct gear
locks both tires per axle together.
There is even higher levels of traction control, like Toyota's A-TRAC, which work more like locking differentials but without the negatives, such as
steering difficulty when locked.
Ken Cooke - 9-16-2018 at 10:52 AM
Guacamole never stopped me, but oatmeal can really test ones limits!
David K - 9-16-2018 at 12:37 PM
When the tires on one side spin... and the other side does nothing! 
