Suburban 1/2 Ton 2WD V8-454 7.4L (1987)
Brake Proportioning/Combination Valve: All Technical Service Bulletins
Brakes - Enhancing Rear Braking Performance
Number:
89-323-5
Section:
5
Date:
November 1990
Corporate Bulletin No.: 565001R
Subject:
HEIGHT SENSING BRAKE PROPORTIONING VALVE AND ADJUSTMENT
Model and Year:
1984-85 C2, K2 AND 1986-89 R2, V2 TRUCKS
TO:
ALL CHEVROLET DEALERS
THIS BULLETIN CANCELS AND SUPERSEDES DEALER SERVICE BULLETIN NO. 85-210, DATED JULY 1986. THE R2 AND V2 TRUCKS
FOR 1986-89 HAVE BEEN ADDED, AS WELL AS SERVICE INFORMATION UPDATED. ALL COPIES OF 85-210 SHOULD BE DISCARDED.
The brake balance on 1984-1985 C2 AND K2 Suburbans can be adjusted in order to enhance rear braking performance under lightly loaded vehicle
conditions. 1986-89 R2 and V2 Suburbans were built with this new brake adjustment.
In order to change brake balance, it will be necessary to adjust the height sensing brake proportioning valve. In addition, burnishing the brakes following
the procedure below may be beneficial on some vehicles. The following service procedure should also be used on all 1984-89 suburbans if the height
sensing linkage has been disconnected from the valve during routine service.
Important:
For vehicles exhibiting a hard brake pedal feel with a cold engine or upon quick brake reapply, reference Dealer Service Bulletin
No. 88-311-5, dated July 1988.
SERVICE PROCEDURE
Note:
Always make sure that the brakes are operational after performing brake work and before returning the vehicle to service.
^
Raise vehicle, axle must be allowed to hang free (no load condition).
^
Remove nut and disengage lever assembly from valve shaft (Figure 1).
