Grinding Sound When You Let Off the Accelerator 2008 Yamaha

ChefRski

New Member
Bought a used 2008 48V Yamaha Golf Cart for the campsites and all works well but there is an unusual grinding sound you hear when you let off the accelerator. I don't know if its breaks, or bearings or what and was hoping that someone out there could diagnose it from the sound. Any help is certainly appreciated. Hopefully you can hear the sound well enough when I let off the accelerator.

All help is appreciated.



 

Rstaley

Active Member
Those can be hard to pin down, but probably the majority of times it is caused by a bad commutator bearing in the motor. Particularly if the noise is more of a “rattle” than a real grinding. When they go bad, the noise gets amplified by the vibration it causes by everything around it. The bearing is fairly easy to remove (with a bearing puller). A new one can be pressed on using hydraulic press. Some people beat the new one on with a pipe, but I certainly don’t recommend that. While the motor is apart, it’s a good time to look over the brushes (possibly replace them) and look at the commutator (might need turned and polished). Other than that, it’s just a piece of cake (just kidding). If you are thinking wheel bearings, there would usually be some tendency for the noise to change with hard turns. The rear end could be the problem (input shaft bearings, etc.) but MUCH less likely than the motor from my experience. Good luck, Ron
 

ChefRski

New Member
Thanks Ron. Trying to diagnose this so I can do the repairs with a friend if possible first. The reason I bought electric was to avoid engine issues.
 

Rstaley

Active Member
If it has a radio, you could always just turn it up louder when you let off of the gas, that's what I do (just kidding). If you conclude that the motor is the culprit, depending on your level of mechanical experience and tool availability, it might be easier (although more expensive) to take the motor to a shop. I know that isn't what you wanted to hear. In trying to pin it down, you can jack up the back end, get out your "el cheapo harbor freight stethoscope" and spin the motor and try to locate the source of the noise, but it is still difficult to be sure because you have to get it to make the noise while your working on it. If you do that, remember that the COMMUTATOR bearing is on the end of the motor AWAY from where it attaches to the rear end. The rear end provides the THRUST bearing (input shaft bearings), so I'd start there and "listen" around. It's certainly easier to do with 2 people; one to "drive" while the other one listens. Good Luck!!
 
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