Tips – Transmission Trouble and Remedies


Slips Out of High Gear
Transmission misaligned with Bell Housing Align transmission case to Bell Housing and Bell Housing to Engine
End play in Main Drive Gear Tighten front retainer or bearing requires bushing
Damaged Pilot Bearing or Front Bearing Replace
Bent Shifting Fork Replace
Interlock Plunger Not in Place Install
Slips Out of Second
Bent Shifting Fork Replace
Worn Gear Replace
Weak Poppet Spring Replace
Interlock Plunger Not in Place Install
Noise in Low Gear
Rear Ball Bearing Broken Replace
Gear Teeth Pitted or Worn Replace Gears
Shifting Fork Bent Replace
Lack of Lubrication Drain and Refill
Slips Out  of Gear
Weak or broken poppet spring Replace
Interlock plunger not in place Install plunger
Transmission gears or bearings worn Replace
Shift fork bent, causing partial gear engagement Replace
Transmission loose on bell housing Tighten
Damaged bell housing Replace
Noise in Low Gear
Rear Ball Bearing Broken Replace
Gear Teeth Pitted or Worn Replace Gears
Shifting Fork Bent Replace
Lack of Lubrication Drain and Refill
Hard Shifting
Interlock plunger missing Remove transmission and transfer case, install interlock
Clutch fails to release Adjust clutch pedal free travel or replace
Gear shift end worn or damaged; binding in housing Replace
Shift plate worn or bent Replace
Shift rods binding in case Replace, check case for damage
Transmission loose on bell housing Tighten
Clutch shaft pilot binding in bushing case or shift housing damaged Replace pilot bushing, measure pilot end for tolerance, examine housing
Grease Leaks into Bell Housing
Cup missing from shifter rail Replace
Gasket Broken Front Bearing Retainer Replace
Transmission Case Overfilled with Lubricant Drain off to proper level
Excessive Noise
Incorrect driving practice Correct practice
Insufficient lubricant Add lubricant
Incorrect lubricant Correct practice
Gears or bearings broken or worn: shift fork bent; gears worn on spline Examine and replace faulty parts
Overheated transmission Check lubricant grade and supply
Loss of Lubricant
Worn or damaged seals or gaskets Replace
Overfilled with lubricant Drain to proper level
Pumping lubricant from transfer case Install recessed spacer and internal seal
Loose bolts and screws Tighten
The synchronizer contains brass parts that wear more readily than steel. These parts have the responsibility to help keep your transmission from grinding gears and eliminating the need to “double clutch.” Of course, in a 60 year old transmission it could be that you have a combination of issues, all related to wear and abuse. This wear and abuse can be rapidly caused by using the “wrong” type of gear lube. Another issue is noise. Some jeep enthusiasts are convinced that a jeep transmission has to be noisy. They believe that they all are noise makers. That is just not true! Using new gears and shafts, your “like-new” transmission will be quiet. Of course, the T84J is not going to be as quiet as a transmission in a modern car but it will be a huge improvement. When I had my full enclosure set up on my jeep I would need to wear ear plugs with the cacophony of noise coming from the transmission. After rebuilding my transmission with new gears and shafts—no longer do I need the earplugs. My philosophy is “if in doubt, replace the part”. It is a false economy to rebuild your transmission and not to replace questionable parts. Of course that doesn’t mean you have to replace every part but you want to carefully measure or examine the parts for wear and tear. With a modicum of care and maintenance, the rebuilt transmission will last a long time. Source: TM 10-1349, Change 1, May 1, 1943 and Trouble Shooting And Rebuilding The T-84J