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1984 - 1985 Corvette: Service Bulletin: Improperly Installed Reverse Idler Shaft Roll Pin

Model and Year: 1984-1985 CORVETTE
Source: Chevrolet Service Bulletin
Bulletin Number: 85-31 - (01/09/1985)

Damage to the manual transmission may occur if the roll pin securing the reverse gear idler shaft to adapter plate (Figure 1) is not fully seated to prevent the shaft from spinning and/or backing out. To insure assembly operation results in the shaft securely locked in place, the roll pin has been lengthened from 0.50" to 0.75". When servicing transmissions with the shorter roll pin (0.50"), discard the roll pin and replace with longer roll pin (0.75") maximum.

The recommended procedure for removal and installation of the roll pin is as follows:



1. Insert small punch tool into plate boss hole and carefully drive roll pin into reverse idler shaft (Figure 3).


Driving roll pin too hard may cause to jam and result in shaft binding to adapter plate.

2. Pull reverse idler shaft from adapter plate and remove roll pin from shaft.



1. Insert reverse idler shaft into adapter plate and align hole in shaft with hole in plate boss.

2. Insert 0.75" roll pin into plate boss hole and, with small punch tool, carefully drive roll pin flush with plate boss (Figure 2).

3. Verify that shaft cannot be pulled from adapter plate.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.

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