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Autopapyrus · GAZ Valdai Next (2nd generation)
https://autopapyrus.com/guides/gaz/33104-valdai/input-shaft-disassembly-of-the-manual-transmission/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

GAZ Valdai Next (2nd generation): Input Shaft Disassembly of the Manual Transmission

The exact component-by-component procedure for the transmission fitted to the Valdai Next with the YaMZ engine is not documented in publicly available service materials. Below is the general principle for disassembling the input shaft of a truck manual transmission. During disassembly, check the actual torque values, ring sizes and part order against your own transmission.

Difficulty: Hard Time: 3-5 hours (including transmission removal, inspection and reassembly) Steps: 15 Tools: Bearing puller (two-jaw or grip type), press or drivers, 13-19 mm wrenches and sockets, snap ring pliers, copper or aluminum drift, hammer, oil drain pan, transmission jack or floor jack for the transmission, caliper, micrometer, parts washing tub

Part

  • 🔩 Input shaft bearing set (front and rear), snap rings, input shaft seal, seal in the bearing cover, housing and cover gaskets, transmission fluid of the grade specified by the manufacturer

Step by step

15 steps
  1. Prepare the vehicle: park it on a level surface, chock the wheels, and disconnect the battery negative terminal. Drain the oil from the transmission.
  2. Remove the driveshaft, the clutch release actuator (cylinder or cable), the sensors and electrical connectors on the transmission, the mount brackets, and any exhaust parts that are in the way. Support the transmission with a jack and remove the crossmember mount together with it.
  3. Separate the transmission from the clutch housing and pull it out along the input shaft axis, without letting the weight of the transmission hang on the shaft. Remove the clutch release bearing and the fork.
  4. Secure the transmission on a stand or workbench. Clean the exterior, then remove the rear housing cover or extension housing, the shift lever and the shift mechanism. Before disassembly, mark the position of the forks and rods with paint.
  5. Remove the front input shaft bearing cover together with the seal. Note the number and location of the adjusting shims or rings: they set the axial play.
  6. Disassemble the housing: remove the mounting bolts and separate the housing halves or the cover along the split line. Do not pry with a screwdriver on the mating surface; use only the jack-off bolts provided or light taps with a drift.
  7. Remove the input shaft together with its bearing from the front wall of the housing. If the bearing in the housing has an outer snap ring, remove that ring first. Apply force to the outer race of the bearing, not to the gear.
  8. Remove the bearing snap ring on the shaft, then press off the bearing with a puller, placing the jaws against the end of the inner race. Do not strike the gear or the synchronizer ring.
  9. Remove any synchronizer parts present on the splined section of this shaft: the synchronizer ring, the spring ring and the thrust washer. Lay them out in order on a clean cloth.
  10. Remove from the end of the drive gear (the nose of the shaft) the bearing that supports the front end of the countershaft or output shaft. This is a needle or roller bearing. Drive it out with a drift from the inner cavity.
  11. Wash all parts and inspect them for: pitting and scoring of the gear teeth, spline wear, marks on the bearing journals and seal surface, and the condition of the synchronizer cone. If the bronze or molybdenum coating of the synchronizer ring is worn, replace the ring.
  12. Measure the journals with a micrometer and check bearing clearances against the tolerances. Replace any bearing that has play, makes noise when spun, or shows heat discoloration. Also replace the snap rings, seals and gaskets.
  13. Reassemble in reverse order: press the bearings on using a driver against the inner race (onto the shaft) and against the outer race (into the bore). Before assembly, lubricate the parts with clean transmission fluid, and lightly lubricate the seal lip.
  14. After installing the shaft, check that it rotates freely and check the axial play. Tighten the cover fasteners in a crisscross pattern, using the torque values from the manufacturer's specifications for your transmission.
  15. Reinstall the transmission, fill with oil to the level of the fill/check hole, then check operation in all gears and look for leaks after a test drive.

Common mistakes and warnings

  • If the drive gear on your transmission is made as one piece with the shaft, it cannot be replaced separately: when the teeth are worn, the whole shaft must be replaced. This job requires a press, precision measuring tools and experience. This assembly is critical to safety on the road, so if you lack experience, it is better to leave the disassembly to a specialized transmission shop. The transmission is heavy, so work with a jack and a safeguard against it falling.