A/T - THM 200-R4 1ST and 2ND Gear Noise
87chevy20Number: 87-228
Section: 7A
Date: Oct., 1987
Subject: REDUCING 1ST AND 2ND GEAR NOISE
Model and Year: 1981-87 CHEVROLET VEHICLES
WITH THM 200-4R TRANSMISSION
TO: ALL CHEVROLET DEALERS
FIGURE 1 - THM 200-4R TRANSMISSION IDENTIFICATION INFORMATION:
Some 1981-1987 vehicles equipped with THM 200-4R transmissions (refer to Figure 1) may exhibit a gear noise (whine) either prior to the 1-2 shift or during 2nd gear. This condition may be caused by a wear pattern on the front planetary gears. The noise may be reduced by replacing worn gear set parts; front internal gear, front carrier assembly and front sun gear then checking and adjusting both the forward clutch shaft end play and output shaft end play to the specifications listed below.
END PLAY SPECIFICATIONS
Forward Clutch Shaft: 0.90 mm - 1.30 mm (0.035" - 0.051")
Output Shaft: 0.32 mm - 0.64 mm (0.013" - 0.025")
Note that the specifications given in this bulletin are at the low end of the range printed in the Service Manual and only need to be used to correct a 1st/2nd gear noise condition.
Refer to the THM 200-4R (MW9) Automatic Transmission section of the Service Manual for overhaul and end play check procedures and selective washer charts.