GM Celebrity/Century/Ciera/6000 1982-1996 Repair Guide

General Information


Transaxle is the term used to identify a unit which combines the transmission and drive axle into one component. All 1982-86 models were equipped with MT-125 manual four speed transaxles. In 1987-88 Muncie five speed transaxles were used. The 4-speed transaxles use cable actuated clutches while the five speed clutches are hydraulically controlled utilizing a clutch master and slave cylinder.

All forward gears in this design are in constant mesh. Final drive from the transaxle is taken from the output gear, which is an integral part of the output shaft; the output gear transfers power to the differential ring gear and differential assembly. The differential is of conventional design.

The 4-speed transaxle assembly is a constant mesh design, combined with a differential unit and assembled in a single case, the forward gears are in constant mesh. For ease of shifting and gear selecting, synchronizers with blocker rings are controlled by shifting forks. A sliding idler gear arrangement is used for reverse gear.

The components consists of: an aluminum transaxle case, an aluminum clutch cover, input gear (shaft), output gear (shaft) and the differential assembly. Preloaded tapered roller bearings support the input gear, output gear and differential. Selective shims, used to establish the correct preload, are located beneath the right hand bearing cups.

The halfshafts which are attached to the front wheels, are turned by the differential and ring gear which are controlled by the final output gear.

The differential, consisting of a set of 4 gears, is a conventional arrangement that divides the torque between the halfshafts, allowing them to rotate at different speeds. Of the 4 gear set, 2 are known as differential side gears and the others are differential pinion gears.

The differential pinion gears, mounted on a differential pinion shaft, are free to rotate on the shaft. The pinion shaft, placed in the differential case bore, is at a right angle to the drive axle shaft. The Hydra-Matic Muncie 282 (HM-282) transaxle is a 5-speed unit. The gearing provides for 5 synchronized forward speeds, a reverse speed, a final drive with differential output and speedometer drive.

The input and output gear clusters are nested very close together, requiring extremely tight tolerances of shafts, gears and synchronizers.

The input shaft is supported by a roller bearing in the clutch and differential housing and a ball bearing in the transaxle case.

The output shaft is supported by a roller bearing in the clutch and differential housing and a combination ball-and-roller bearing in the transaxle case.

The differential case is supported by opposed tapered roller bearings which are under preload.

The speed gears are supported by roller bearings. A bushing supports the reverse idler gear.