Stick-Slip Condition (Quadra-trac "klunk")

Contributed by: Francis M. Barnett

The original question as it came in to JEEP-FULLSIZE:

Date: 01 Feb 96 16:46:42 EST
Subject: QT - klunk, klunk

This is for you Quadra-Trac guys. Whenever I slow down or go realll slooow I
hear this klunking sound ... I'd like to think it's some gears that shift very
hard ... it's not just a sound you can feel it too.

As it turned out, this and variations of it turned out to be a very common problem with FSJs (You can re-read the entire dialog by feeding the words 'qt' and 'klunk' to the archive search engine).

Francis Barnett, in a rather definitive and well written posting, graced us with the following answer, which should explain most Quadra-trac "klunking":

Straight from the Manual:

Stick-Slip Condition.....When the brake cones in the Quadra-Trac limited slip differential stick and release, it is under a torque windup condition as in a conventional transfer case. Sudden release of the cones under this condition results in a constant, pulsating, grunt-like or rasping noise. This is a low-frequency noise that is most noticeable to the driver at slow speeds, such as when slowly turning a corner, or when maneuvering to park the vehicle.

Stick-slip noise will not occur when the vehicle is driven in a straight-ahead position. If a noise similar to stick-slip, but much louder, occurs in the straight-ahead position, the chain should be inspected for excessive looseness

Proper lubricant is important in preventing stick-slip noise. Use Quadra-Trac lubricant or equivalent only. Multi-grade, detergent-type oils must not be used. A stick-slip condition caused by improper lubricants may be corrected by completely draining the Quadra-Trac and low range unit (if equipped) and refilling with the specified lubricant.

NOTE: If a vehicle is not driven for a week or more, the stick-slip condition may occur when the vehicle is first driven. This is considered normal and should be of no concern, as the noise will usually disappear with continued driving.

Uneven tire inflation pressures and mismatched tire types and sizes will also cause stick-slip noise. All tires must be inflated equally and must be of the same size and type.
(End Quote)

The manual also goes on to say that stick-slip continues it may be corrected by checking the tire pressures, and changing the QT fluid. The manual also advises to (Quote) Drive vehicle in circles, both clockwise and counterclockwise for approximately 15 minutes to allow lubricant to circulate throughout differential NOTE: When driving the vehicle in circles do not turn the wheel to the stop position. (End quote)

Hopes this helps someone.

Francis M. Barnett
Beaumont, Texas US