Transmission Technical Tips
  1. Test drive trans. before removal to determine repairs needed and parts to replace.  Note:  Most transmissions in the old Ford V-8's 39-48 are well worn and the only was to cure all the problems is to replace every part new as all are available and putting a new gear against an old one doesn't really cure the problem as the old teeth can ruin the new ones very fast.
  2. Questions to ask yourself:
    • Does the trans slip out of any gear on compression?
    • Does the trans slip out of any gear with throttle pressure?
    • Does the trans howl when car is moving forward with clutch pedal depressed in low gear?
    • Is the trans hard to shift out of low gear with clutch depressed?
    • Does shift lever move back and forth when on acceleration or deceleration? 
  3. Remove trans from car and disassemble checking parts as removed.
  4. Hot tank trans case and all parts.
  5. Check trans case and gear teeth for cracks and wear.
  6. Check cluster gear thrust washer surface in the rear of the trans case for wear and grooves.  (tolerance can't be held if worn)
  7. If low gear teeth are worn and rolled over it will make lots of noise and hard to shift out of low gear.
  8. Worn low gear teeth can make low gear jump out of gear under throttle pressure.
  9. If trans jumps out of second gear on compression...
    • Bushing worn in second gear.
    • Worn syncromesh.
    • Too much end play in second gear on main shaft.
    • All of the above will make second gear jump out.
  10. If gears grind when shifting into second or high gear, syncro hubs and brass rings are worn out of tolerance.
  11. Cluster gear end play should be .008 to .022.
  12. Second gear end play should be .004 to .012.
  13. When ordering new cluster gear you should buy one that has hardened steel washer that goes between thrust washer and the case to protect the case from wear.
  14. When ordering a new main shaft use the shaft without the pin for second gear as this pin breaks at times.
  15. A front bearing retainer should be used that will accept a neoprene seak instead of cork when possible to keep gear lube out of clutch.
  16. Tap and clean all threads so covers will torque evenly.
  17. Use flat file to dress all flat gasket surfaces for better seal.
  18. Always replace trans. front and real ball bearing to insure quiet trans.
  19. If trans. is noisy when in neutral and noise goes away when clutch is depressed, front bearing is bad.  If noisy when clutch is depressed the throw out bearing is bad.
  20. A worn pilot bushing can ruin front bearing and trans gears from misalignment.
  21. Check trans case for cracks.  This can cause low gear to disengage when throttle is backed off and in low gear.  This can also cause other problems.
  22. Use permatex Hi Tack to seal all gaskets.  Coat all surfaces and threads on bolts for front bearing retainer to keep gear lube from leaking out.
  23. Use Loctite to seal counter shaft ends and idler gear shaft end.  This stops external gear lube leaks.
  24. Use Teflon tape to seal drain and filler plugs.
  25. Use new grade #8 bolt for "U" joint to main shaft to insure no breakage when torqued to specs.
  26. Replace shift shaft seals 1940 and later Ford trans.
  27. Pre-lube "U" joint with AmsOil #90 to insure no wear on start up.
  28. Replace clutch cross shaft, bushings, and throw out bearing fork if needed.
  29. Plug holes where shift shafts are lubed inside cover housing to keep gear teeth chips out.  Tap threads in holes and cut plugs using fine thread bolt.  Use LocTite and center punch to lock plugs in place.  Pre-lube shift shafts when installing.  Use half moon file to deburr shift shaft bores.
  30. Use only bronze Oil Lite bushings in flywheel.  (ball bearings can fail as there is no way to lube them and is real hot from engine and clutch heat)
  31. Check shift fork for wear and replace if needed.
  32. Replace and worn shaft linkage and bushings to insure positive lever action.
  33. Use all AmsOil Synthetic gear lubes and grease for better operation and lessen wear.
From Technical Tips by Dick Flynn - Copyright 1980, 1989, 1992 Richard C. Flynn.
Used with Permission.  To order Technical Tips, click here.

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