Suspension - Tapping Noise From Rear Shock Absorbers: Overview

9229mitsubishi01

NO. TSB-91-34-002

DATE September, 1991

MODEL 1991 3000GT


SUBJECT:
TAPPING NOISE HEARD FROM REAR SHOCK ABSORBERS


PURPOSE

This Technical Service Bulletin describes how to eliminate a tapping noise which may be heard from one or more of the rear shock absorbers.

AFFECTED VEHICLES

All 1991 3000GT FWD and AWD vehicles equipped with ECS.

DESCRIPTION





While driving, a tapping noise may be heard from one or more of the rear shock absorbers. If present, the noise probably comes from underneath the shock absorber trim cover. (Figure 1).





Two conditions may cause the tapping noise:

First, the lower internal locknut of the shock absorber may have become loosened if the upper shock mounting nut was removed using an impact wrench. To prevent this from occuring, never loosen the upper nut with an impact wrench. Follow the nut loosening procedure shown in Section 34 of the Service Manual. (Figure 2.)


Second, the shock absorber's upper spacer may be seated off-center from the piston rod. (Also refer to Figure 2.)

The spacer installation can be checked by performing a simple measurement of the upper piston rod end. This measurement is described in Step 3 of the CORRECTIVE PROCEDURE Section of this TSB.

A production modification has been in effect since 01/21/91 for FWD vehicles and 03/01/91 for AWD vehicles. The modification includes elimination of the upper spacer and a reduction in the length of the shock absorber piston rod end and collar. For vehicles made prior to the production modification dates, the tapping noise can be corrected, see corrective procedure.

NECESSARY MATERIALS Before beginning the corrective procedure, the following materials should be easily accessible:

- 1991 3000GT Service Manual, Volume 1.
- Gasket Adhesive
- Clean Shop Towel
- New Rear Shock Absorber Upper Locknuts (P.N. MB573244)