Overall manual transmission problems in my opinion are less common than problems with automatic transmissions. In fact the problems I have seen in most manual transmissions where actually caused by inexperienced drivers. I actually "pity the cars" that are used for teaching people.
To follow in this article will be some of the more common issues I have seen when working on manual transmissions. If your complaint or problem is not addressed in the information below it may be a good idea to check for technical service bulletins on your particular model.
Here is the perfect example. Recently a friend of the family "Chrisy" That owns an Acura RSX was having serious manual transmission problems. The main complaints being gear clash noise and hard shifting.
This particular driver is very experienced and had only driven manual transmission cars for the last 15 years. When I looked for service bulletins for the RSX I found several known issues documented by factory publications. These technical service bulletins indicated that internal updated parts exist to solve these particular problems.
Not only did this save me from pulling the front drive transaxle out of the car in my driveway (not fun) but Chrisy got the repairs done for free. After they put the fancy Honda back in service the driver said the improved parts made a big difference in shift feel.
Gear clash is a common complaint and is best described as a grinding noise during shifting. This type of noise can be the result of a gear set remaining partially engaged while trying to engage another gear set. Clash can be caused by incorrect clutch adjustment or binding shift linkage. However, using the wrong fluid can aggravate the condition.
Incorrect fluid selections especially on some Honda, Acura and BMW models can also cause gear Clash problems. I have learned a lot about the importance of fluid selection and how this relates to the outside temperature on my own car. See what manual transmission repairs where needed after installing the wrong fluid in a 1988 300zx.
Finally, on the subject of choosing the right fluid for your manual transmission, use recommended fluids. They're listed in the owners manual. I've tried substituting in a pinch using off the shelf fluids with poor results. Some company's use weird stuff like synthetic gear oils of varying weight. Below are some examples from Ford, Honda, Chrysler, GM and Nissan. All of these genuine fluids have 4-5 star reviews on Amazon.
Jumping out of gear is another common complaint with transmissions that have high mileage. If the manual transmission jumps out of gear and into neutral you should first check the gear shifter and its attaching linkage for looseness or damage. Sometimes they use nylon bushings at the connections and these can deteriorate or fall out completely.
Another common cause of a vehicle to jump out of gear would be damaged or broken transmission and engine mounts. A visual inspection of these mounts may not reveal a problem. sometimes you have to pry up on them to see if they are in tact. A worn input shaft pilot pushing or bearing that is pressed into the center of the crankshaft can also cause this type of problem.
If all of those items are found to be in good condition, chances are excessive internal clearances are the cause of the transmission jumping out of gear.
Another type of standard shift transmission problem is hard shifting. If the shift lever is hard to move from one gear to another you want to start off by inspecting the clutch operation as well as the shift linkage. Wrong fluid selection can cause hard shifting manual transmission problems.
Internal components like shift rails, shifting forks and synchronizers can cause hard shifting also. Damage to these internal components will often show up as metal or brass flakes in the lubricant. This can shine like metallic paint if held up to sun light, illuminated with a flashlight or the flakes can be seen clinging to the drain plug magnets.
Although I am not a believer in miracle fluids as a general rule of thumb, when looking into the SynchroMax fluid it did receive rave reviews. I have used the synchro max fluid in maintenance situations at the special request of vehicle owners.
I have not used it to solve any problems. I would not expect miracles from anything in liquid form. For more common problems associated with manual drive trains, clutches and axles you can visit the repair module from this next link. Also more stories about my own personal manual transmission problems.
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