It has been a long time since I was here and there are many roasts on my now 9-mo old Bullet. One of the things that many Bullet owners have endured is the motor noise that comes from belt tension on the Drive Motor. Tom at Sweet Marias has mentioned it in his Bullet videos and IIRC, the Aillio brothers have also noted it here. It has always bothered me listening to that baseline sound because it sounds like something chafing at the rear of the Bullet. Recently it also got a lot worse and I knew I had to investigate.
So, today I removed both rear panels to access the motor and check things out. Basically, it appears the new (more bothersome) noise in the motor area is coming from the metal Belt Pully that attaches to the motor. That Belt Pully and the head of the set screw that holds it in place have been making contact with the adjacent surface on the Bullet. Here’s a pic of what I observed after removing the motor. In the photo, you can see where the pully has been scoring the surface that it was contacting.
That wasn’t difficult to address with a very slight repositioning of the pully (and set screw) on the motor shaft. But that motor noise the Bullet makes from the belt tension effect on the motor remained. So, I decided to tinker with that one. I loosened the two motor mounting screws and quickly discovered that removing some of the tension on the motor eliminates that chafing motor noise that I’ve heard since I bought the Bullet.
The problem with changing the belt tension on the Bullet is that the motor mount-design doesn’t really allow for it to stay put. That is because of the smooth rubber washers used to contact another smooth surface on the Bullet’s frame. There isn’t anything that properly holds the Motor Mount’s position. If you try to adjust it (and secure it in a new place) the whole mount just slides back to where the chafing noise returns. It would be like trying to set belt tension on an automobile alternator without having a positive hold on the mounting bracket when tightened.
I found (and followed) a post from Jacob that suggests heating the rubber washers to improve grip. It made no difference in my case, but was worth a try. I’ve shared photos of the washers below (before and after).
Improving the rubber friction so your belt will not come loose
The only other thing I found was to reduce the force from the Motor Mount Spring upon the Motor Mount. So, I applied some back-pressure to the spring so that it wasn’t pushing so hard against the Motor Mount. That helped with the noise and I’m hoping that the belt will still have enough tension to avoid jumping teeth. I think that it looks and feels OK, but a load of beans run through will be the best test.
If anyone else has found a better solution, I’m all ears…