1964 - 1966 Corvette: Service Bulletin: Gear Shift Control Assembly Buzz

Subject:   Gear Shift Control Assembly Buzz
Model and Year:   1964 - 1966 Corvettes with Manual Transmission
Source:  Chevrolet Technical Service Bulletin
Bulletin No:   TSB #66-65
Section:   VIIb
Date:    June 13, 1966

TO:  ALL CHEVROLET SERVICE PERSONNEL

Complaints of gear shift control lever buzz on 1964 through 1966 Corvettes with manual transmissions (3-speed or 4-speed) can be attributed to the mounting of the control lever assembly on the transmission.

All Corvettes produced after the date 3-21-66 are equipped with the crossmember mounted gear shift control assembly.

Complaints of shift control lever buzz on earlier units should be corrected by repositioning shift control assembly from the transmission housing to the frame crossmember.  This is accomplished by removing the transmission extension mounting bracket and mounting the new bracket on the frame crossmember.  Details of the repositioning procedure are covered on the following page(s).

GEAR SHIFT CONTROL ASSEMBLY BUZZ - 1964 - 1966 CORVETTES WITH MANUAL TRANSMISSION

The following instructions detail how to reposition the gear shift control assembly from the transmission extension housing to the frame crossmember on 1964 through 1966 Corvettes with manual transmissions.

1. Remove shift levers at transmission.
2. Position jack stand under transmission and remove transmission mounting assembly and bracket.  (See fig. 2, items 1 and 2.)
3. Remove exhaust system bracket moving two exhaust clamps rearward toward crossmember.
4. Remove two bolts which attach lever assembly to present mounting plate.
5. Move lever assembly with rods attached down and forward to gain access to three Allen-head screws securing mounting plate to extension.
6. Remove Allen head screws from mounting plate (7/32" Allen wrench required).  Discard mounting plate when removed.
7. Scribe a line 11/16" down from top surface of crossmember on rear side (See fig. 1.)
8. Move new bracket, Part No. 3888263, into position from rear of crossmember.
9. Loosely install bolt through front leg of new bracket through mounting tab on front of crossmember (center in slot).  (See fig. 2, item 6.)
10. Using bracket as template, locate position of holes to be drilled at center of bracket slots. (fig. 1)
11. Remove bracket and drill two 9/32" holes in rear of crossmember.  (See fig. 1.)
12. Loosely install new bracket using two 5/16" self-tapping screws and washers at rear attachment. (See fig. 2, items 4 and 5.)
13. Install shift lever assembly to new bracket.  (Install lower bolt first to align bracket for starting upper bolt.) Tighten securely.
14. Reinstall shift levers to transmission securely.
15. Reinstall transmission mounting assembly and bracket and exhaust support.  Tighten all bolts securely with exception of bolt holding new bracket.
16. Adjust new bracket laterally to provide desired 1/8"* clearance between transmission extension and bracket, then tighten bracket screws securely.  (See fig. 1.)
    
    * Clearance in excess of 1/8" may cause binding in reverse operation.
    
17. Check lever crossover operation.  If shift mechanism does not operate smoothly, rod adjustment may be necessary.