The primary on my 2008 Dyna has been a little on the noisy side for some time now. Oh, it’s not so bad, just a little annoying intermittent noise, sort of resonating in the primary case, and only at low-speed deceleration. Hard to describe, as those noises tend to be.
The other day I was doing some interval service on the thing anyway so I decided to open it up.
Everything looked fine, I think. The chain looks great, no burrs or signs of any abrasion. This primary has the automatic tensioner, and its shoe looks great, too. No grooves or other signs of wear. If I press down on the bottom of the chain, simulating the forces of deceleration, I get about a half-inch of deflection, maybe a little less. There’s no specification for that in the service manual but it seems reasonable to me.
These images of the innards are clickable for more detail.
The only thing that might seem a little questionable to me is the toothed ramp at the bottom. There’s a toothed block that rides up the ramp with the help of a spring on the right side of the block, visible to the right of the wedge-shaped block in the image above.
In the image below it appears that the teeth might be a little buggered up. I could see that happening, maybe, under seriously hard deceleration. After all, the levers that translate the downward force to a force against the teeth would serve to amplify that force, and how much surface area could those teeth offer against those forces?? Well, it could happen…
Trouble is, I’ve never seen a new automatic tensioner so I’ve got no frame of reference for what normal looks like. Tomorrow I’m going to be at a dealer for other reasons so I may have the opportunity to chat up a tech and/or see what a new part looks like.
Until then, if any readers have comments I’d love to hear ’em.