On the right side of your Harley, behind the transmission side cover (aka clutch end cover) you will find the transmission door bearings. These two bearings are critical as they support the heavy load at the end of the transmission main and and counter shafts.
It is not uncommon for these bearings to eventually fail due to high mileage, lack of maintenance, or abuse. Some symptoms of a bad door bearing are: howling sound from transmission – hard neutral – excessive vibration – hard shifting.
If one of these bearings, or the Harley throw out bearing breaks and spreads debris into the transmission case; the entire transmission gear set will need to be removed and the transmission completely rebuilt. In this instance, the entire drive of the motorcycle will need to be removed before being able to remove the transmission gear set.
However, if one or both of these bearings are failing but still intact; or you are interested in doing preventive maintenance, these bearings can be replaced without the disassembly and removal of the primary drive assembly. You can accomplish this with a specialty tool/plate type puller, that you can either purchase or make yourself. The tool is necessary to be able to pull the door bearings off of the transmission shafts.
Once the transmission trap door is removed from the case, you will be able to press out the old bearings and press in a new set. **Remember to always press on ONLY the outer race of the new bearings during assembly** Clean your gasket surfaces and evenly draw the transmission door back over the transmission shafts with the stock trap door hardware.
It is of utmost importance that the Harley throw out bearing is replaced. The failure of this bearing is more common and although small; the needles of this bearing can disperse throughout the transmission damaging other bearings and even breaking gears. We suggest changing this bearing every time you are in this area.
If your transmission has high miles, or has had “a hard life” due to aggressive riding; consider replacing your door bearings and Harley throw out bearing as preventive maintenance. It will save a lot of time and money in the long run.