1963 - 1965 Corvette: Service Bulletin: Drive Line Noise

Subject:   Drive Line Noise
Model and Year:   1963 - 1965 Corvette
Source:  Chevrolet Technical Service Bulletin
Bulletin No:   #1069
Section:   IV
Date:    January 7, 1965

TO:  ALL CHEVROLET SERVICE PERSONNEL

A clunking noise may occur in the drive line of some 1963-65 Corvette on initial vehicle movement in either forward or reverse gear.  This could be caused by loosening of the differential carrier support bracket front attaching bolts.  Loosening of these bolts will also result in elongation of the bracket bolt holes.

If elongation of bracket bolt holes occur, the differential carrier bracket should be replaced with bracket Part No. 3868799.  However, the original service bracket Part No. 3820186, can be used by reinforcing it as shown in Part I of this bulletin.  In conjunction with the installation of the bracket, it will be necessary to secure the forward attaching bolts as outlined in Part II of this Bulletin.

In production, the problem has been corrected by using a cotter pinned through bolt in the forward location of the support bracket.  however, 1963-64 and early 1965 differential carriers will not accept this bolt and drilling of the carrier should not be attempted.

Differential carrier bracket replacement procedure is outlined on Page 4-3 of the 1965 Corvette Shop Manual.

PART I - Re-work of Bracket Part No. 3820186

1.  If reinforced bracket, Part No. 3868799 is not available, obtain Part No 3820186 and weld one flat washer, (Part No. 3818180) on each outside surface in line with existing holes (See Figure 1.)

PART II - Safety Wire Procedure

1.  Obtain (2) 7/16-14 x 1 300M bolts and drill a 3/32 inch diameter hole through the head of each.

2.  Drill a 3/32 inch diameter hole through the lower flange of the carrier bracket directly below the forward bolt hole (both sides of bracket).

3.  Install new bracket using modified forward attaching bolts.  Torque forward attaching bolts to 65 ft. lbs.

4.  Safety wire the forward bracket bolts to the bracket with stainless steel safety wire (1/16 inch O.D.) or stainless steel welding rod (1/16 inch O.D.).

NOTE:  Be sure the straight wire form the bolt head to the flange hole is on the tightening side of the bolt. (See Figure 2).

5.  Tighten the wire sufficiently by twisting the ends together.  NOTE:  Over-tightening will cut the wire at sharp bends.