Reatta V6-231 3.8L VIN C SFI (1990)
Alignment: Customer Interest
Frame/Suspension/Tires - Shake or Jitter
Bulletin: 91-10-40
Date: Dec. '91
Ref. No.: 91-286-10
Corp. Ref. No.: 111516R
SUBJECT:
CONVERTIBLE SHAKE AND/OR JITTER
MODELS AFFECTED: 1990-91 REATTA CONVERTIBLE
THIS BULLETIN IS BEING REVISED TO CHANGE SERVICE PROCEDURE. PLEASE DISCARD BUICK BULLETIN NO. 91-10-26.
Some shake/jitter is a normal condition under certain road and/or climate conditions. Efforts to completely eliminate shake/jitter are often futile.
However; some shake/jitter may be improved.
There are two basic types of shake associated with the Reatta convertible. First, a shake on rough roads, or when driving over railroad tracks, which
dampens out after initial impact and should be considered a normal characteristic. No attempt should be made to try to repair this condition. The second
shake or jitter, a constant shake between 50-65 mph, (similar to tire imbalance), on smooth roads at ambient temperatures above 70 degrees F, can be
addressed on 1990-91 convertibles. Use the procedure outlined below to improve 50-65 mph constant shake.
SERVICE PROCEDURE
1. Road test vehicle (with owner, if possible), to determine if the shake/jitter is as described in the second part of paragraph two (2) of this bulletin.
2. Check and rebalance all four wheel and tire assemblies as described in
Section 3E of the 1991 Service Information Manual.
3. Road test the car on a smooth road at 50-65 mph. If the shake is still objectionable, continue to Step 4 (1990 vehicles) or Step 5 (1991 vehicles).
NOTE:
If tire non-uniformity is suspected even after balancing, temporarily install OEM assemblies from another Reatta vehicle and reevaluate
to confirm shake condition.
Figure 1
4. Adjust the rear standing height (1990 vehicles only) by adding a 10 mm shim, P/N 1648853, under the rear spring trim height adjustable shim. The
10 mm shim should be installed under the 5 mm shim. If this is done, the tab does not have to be removed and the shim will nest properly. If the 10
