Dodge Durango Forum II

How your trac-loc works(or doesn't!)

"Trac-lok. Steel clutch plates are forced together by a pair
of Belleville springs. Belleville springs are basically
washers that are deformed into a cup shape. Smashing the cup
back to flat "compresses" the springs. They are pretty
strong, but have very limited travel. What that means is
that as the clutch plates wear a little bit, the Belleville
springs lose their preload quickly and stop applying
pressure to the clutch packs. The main force on the clutch
pack is the Belleville spring, with some additional force
coming from the pitch angle of the spider gear/side gear
teeth. The spider gear teeth are thick at the bottom and
thin at the top. As more torque load is applied to the
differential, the spider gears try to force the side gears
away, and this adds pressure to the clutch pack which helps
to transfer more torque. That's why applying the brake
lightly can help to engage a limited slip diff. These diffs
are notoriously difficult to reassemble, because the spider
gears are under tension. Disassembly is easy though, because
the clutch packs are almost always worn out."

http://www.bc4x4.com/faqs/yj.cfm?cat=7&faqid=157

Sat Jan 31