Belt-drive transmission

[WickedFog]

I'm not saying that Kevlar, nylon, or carbon fiber stretch. I am saying that a timing belt stretches. I don't care what it's reinforced with, it stretches.

I guess I can see the reinforcement also working it's way inward, so technically the rubber portion of the belt stretching outward as the two materials kinda separate over time. That just dawned on me. So maybe so if that is what is happening.

 

[JCsRCcar]

I would again argue that timing belts are reinforced with fiberglass and or kevlar typically, depending on how much money you spend on them. Having worked for a company that made carbon fiber, kevlar, and fiberglass materials, I can tell you for certain those materials do not stretch.

I would also argue that what anyone is suspecting to be stretching is simply the inside diameter and the teeth of the belt wearing, which would make one believe the belt has stretched. The teeth may appear to still be fully engaged in the gear, but what you can't see is that the teeth of the belt are designed for an interference fit. A worn belt may still engage the teeth, but the loss of material over time will make the teeth more of a slip, or looser fit. There is of course going to be wear on the pullies as well, making it seem even more like the belt has stretched.

Just my thinking. No expert, but Kevlar and fiberglass simply do not stretch. Especially in the amount necessary to allow for a whole tooth out of timing.

Very well said!

 

[Mrgoodwrench35]

I guess I can see the reinforcement also working it's way inward, so technically the rubber portion of the belt stretching outward as the two materials kinda separate over time. That just dawned on me. So maybe so if that is what is happening.

That's exactly what I would think is happening. I've never cut one up and examined it to that extent, but that would make sense.

 

[Tunedfrog]

I thought about installing the belt drive kit in my Xmaxx but that's as far as I got.
I'll just keep it like it is.

 

[Lumikko]

Agreed. The recommended interval is 80 or 100k so yeah, it was a little overdue. The belt looked suprisingly good for its age though.

Don’t forget the 5-year interval; it’s whichever comes sooner. If it had 20 years on it, the belt should have been changed twice at that point.