A/T - Torsional Rattle With TCC Engaged
Number: 83-T-5Section: VIIc
Date: Nov., 1983
Subject: TORSIONAL RATTLE - 1982-83
"K" TRUCKS WITH 6.2L DIESEL ENGINE AND THM 700-R4 TRANSMISSION
TO: ALL CHEVROLET DEALERS
Some 1982 and early production 1983 "K" trucks equipped with 6.2L diesel engines and 700-R4 transmissions may experience a noticeable torsional rattle when the converter clutch engages in second, third or fourth gear, under light to moderate throttle at speeds below 40 mph. This rattle condition which is torque converter clutch/drive train related, can be improved by increasing the TCC engagement speed to 40 mph.
FIGURE 1:
This can be accomplished by replacing the converter clutch throttle valve, sleeve and spring in the valve body with P/N 8642970 (Figure 1). This service package will consist of the following:
^ Valve - Converter Clutch Throttle
^ Sleeve - Converter Clutch Throttle
^ Spring - Converter Clutch Throttle
^ Instruction Sheet
If an objectionable rattle still exists after installing the service package, additional noise dampening can be achieved by filling the propshaft with urethane foam per the following recommended procedure:
1. Obtain a urethane foam dispensing system, Insta-Foam Product's Model #9.5 Froth Pak Kit or equivalent, which is a small volume kit complete with all the required chemicals, dispensing equipment and instructions. A maximum of one
(1) Froth Pak Kit will be required to foam-fill a propshaft from a long wheel base vehicle such as a Suburban or Pick-up.
2. Remove propshaft from vehicle.
Illustration:
3. After pivoting U-joints to allow a drill bit access to face of yoke, drill a 21/64" hole in face of each end yoke. Use caution not to damage U-joint seals (see illustration).
4. Wrap and tape U-joints with cloth.
5. Following directions and observing caution notes on kit, fill propshaft with spray foam from the top hole while maintaining propshaft in vertical position.
When foam begins to ooze out of application hole past the nozzle, enough foam has been dispensed. To prevent spewing of foam on operator, part, etc., do not remove nozzle from yoke until foaming activity subsides and set-up begins.
6. Allow foam to set, then remove U-joint cloth cover.
7. Drill out each end yoke hole and plug with silicone RTV rubber adhesive sealant (hi-heat resistance).
8. Reinstall propshaft assembly in vehicle.
Labor Operation Number: T0084
Labor Time : .9 hours
Add to foam fill propshaft .7