Transmission Misalignment

• Your transmission will work to full specification only if the actual transmission unit is aligned properly in your engine. Missing pins that hold it in place or bent pins can cause the transmission to tilt. This will cause bearings that make the transmission run smoothly to wear down. If dowel pins are missing, you can either make new pins or purchase them from an auto parts store. If the transmission has been misaligned for an extended period and things have worn down, make sure to replace those parts before putting it all back together. Common parts that wear down are the flywheel and the flywheel bearings.
  
  

Worn Clutch

• If the gear box clutch is worn, the shaft assembly of the transmission, what connects the transmission to the rear axle of the car, may increase the cycling of internal components, causing unneeded wear to the transmission. The clutch should be taken apart once a year (either by you or by a mechanic) to make sure it is seated properly and is not worn down. When this is done, the clutch is cleaned, and the drive disc assembly and clutch drive pulley are checked for wear. The clutch drive disc, which can be a cone as well, will need to be checked for wear and alignment. The clutch assembly must be checked, as does the bearing that keeps everything running smoothly.
  
  

Transmission Fluid

• It is recommended that you get the transmission fluid changed every 30,000 miles. Transmission fluid lubricates the transmission, ensures that it does not overheat and keeps the gear changing smoothly. To replace the fluid, a mechanic must drive the car for a few minutes to get the fluid warm. Once the engine is warm, a plug is removed from the bottom of the transmission to drain the fluid away. Once this is done, the plug is returned and the transmission is once again filled with fluid. Manual transmissions will use either gear oil or common engine oil to lubricate the transmission. If you do not know what kind your vehicle uses, check the owner's manual.