Driveline - Clunk or Snap

Models


1980-1986 Ramcharger 4-Wheel Drive W-150 Truck


Subject


Driveline "Clunk" or "Snap"


Index

PROP SHAFT & U JOINTS

Date


December 23,1985

No.


16-01-85
SYMPTOM/CONDITION

Customer concern for a "snap" or "clunk".

^ After medium-heavy brake application to a stop is completed.
^ When accelerating from a stop.
^ At the 1-2 upshift.

DIAGNOSIS

Description of Condition

Drive line "snap" is a single snap or clunk noise sometimes heard when braking to a forward stop or accelerating from a stop. It is ordinarily heard just as a stop is completed, when the vehicle transitions from the nose-down braking attitude to the level-stationary attitude. It may also be heard just as motion begins on acceleration or at the 1-2 upshift.

Forward direction braking causes the rear axle pinion noise to pitch downward from brake torque reaction. The vehicle also assumes an overall nose-down attitude. The combination of these motions results in maximum rearward excursion of the prop shaft in the slip yoke. At the end of the stopping maneuver, the prop shaft would ordinarily slide smoothly back into the slip yoke. The characteristic "snap" occurs when the prop shaft momentarily binds in the rearward position, then abruptly "snaps" forward to the neutral position.

PARTS REQUIRED

1 Boot Package PN 4137901
REPAIR PROCEDURE

This repair consists of installing a boot package on the slip yoke.

1. Raise vehicle.

2. Remove rear driveshaft and slip yoke assembly.

3. Remove slip yoke from driveshaft. Inspect the splines on the driveshaft and in the slip yoke for wear. Replace if excessive wear is observed.

4. Remove and discard the slip yoke snap-on rubber seal.

5. Thoroughly clean all old grease out of the slip yoke and driveshaft splines with a suitable solvent.

6. After cleaning the slip yoke in solvent, clean the cup plug vent hole area with Mopar Brake and Carburetor Cleaner, PN 4318037. Seal the vent hole with an epoxy (2 part) cement (Duro Depend II, PN MITB-1, or equivalent). Allow cure time as stated in the instructions.

7. Remove the slip yoke grease fitting and install the 1/4"-28 pipe plug supplied in the kit.

8. Apply and spread not more than half the supplied lubricant to the slip yoke splines and driveshaft (Excessive grease may fill the boot and the slip yoke and result in propshaft imbalance or knocking of the slip yoke plug.)

9. Install the boot on the driveshaft and the clamp, using Miller Tool #C-4653 as follows:

a. Wrap binding strap around boot twice, plus 63 mm (2-1/2 inches).

b. Pass the strap through the buckle and fold it back about 29 mm (1-1/8 inches) on the inside of the buckle.

c. Put the strip around the boot with the eye of the buckle toward you. Wrap the strip around the boot once and pass it through the buckle, then wrap it around a second time also passing it through the buckle.

d. Fold the strip back slightly to prevent it from slipping backwards.

e. Open the tool all the way and place strip in narrow slot approximately 13 mm (1/2 inch) from buckle.

f. Hold the binding strip with the left hand and push the tool forward and slightly upward. Then fit the hook of the tool into the eye of the buckle.
g. Tighten the strip by closing the tool handles. Then rotate the tool (handles) downward while slowly releasing the pressure on the tool handles. Allow the tool (handles) to open progressively. Then open the tool entirely and remove them sideways.

h. If the strap is not tight enough, re-engage the tool a second or even a third time, always about 13 mm (112 inch) from the buckle. When tightening always be careful to see that the strap slides in a straight line and without resistance in the buckle, that is without making a fold. An effective grip will be obtained only by following the above instructions.

10. Install the slip yoke on the driveshaft. (Make sure universal joints are placed properly.)

11. Install boot and second clamp on the slip yoke with the splined stub extended approximately 1.5" from the fully collapsed position, and the boot vented at this position before installing the clamp, using the same procedure as in Step 9.

12. Install driveshaft in truck.

Road test vehicle to assure that "clunk" or "snap" is corrected.

Advise the customer that it is no longer necessary to lubricate the slip yoke.


POLICY: Reimbursable within the provisions of the warranty.


TIME ALLOWANCE:
Labor Operation No. 16-30-10-91 0.8 Hrs.


FAILURE CODE: 07 - Binds, Sticks or Seized