A belt under the microscope

Very cool!

Thanks for doing this

 

Claudio, very neat!

Some pointers, while the rubber fabric blend will wear on the surface the cracking you're looking for is actually buried in the belt, it's the aramid or fiberglass fiber 'rope' that is wound on the form the makes up the belts tensile construction, think of it like belting in a tire. That 'rope' is what actually carries the load.

It may be difficult to expose the cording inside the belt as it's molded into it when constructed.

What materials do you normally work with in the lab?

 

Reminds me of John Steinbeck's "The Pearl." When Kino, a poor fisherman, takes an enormous pearl to market, a corrupt dealer puts it under a magnifying glass to show Kino how chalky and low in quality the pearl is, to trick Kino into a lower price. Kino didn't know all pearls look like that under magnification.

Not that you're this merchant, I'm just reminded of the story. Carry on.

 

Interesting, but before you conclude that the wear is obvious you need a control for comparison. Take some photos of a new belt.

 

Not to dismiss your effort as it would be an interesting study, buy I believe you will have a hard time making any correlation based on mileage and age. More significant factors are variations in belt tension, contamination, other related mechanical failure, and abuse. I uses the term abuse loosely in reference to a car that is used for touring with engine running mostly in the 3 to 4k rpm range compared to a car that is frequency tracked with rpm near red line frequently.

Belt failures seem to come in two types. Shearing of the cogs which is often due to some form of fluid contamination, like oil, and failure relates to some other factor, such as failure of a cam drive pulley bearing causing the belt to misalign and subsequently ride up on the pulley fence and be cut, then snap. (I am all too familiar with the latter ).

 

I have posted this before here but worth mentioning again:

I was speaking to someone at a car event last year who had a new belt fail owing to a manufacturing fault. Dayco admitted this, but refused to pay any compensation for the damage.

It turns out that the belts are made on a very wide "buck" which contains many belts and they are then sliced down into the width of each belt. Each belt has a series of numbers which indicate its location on the buck before it was sliced off (example picture).

The failed belt had "001, 002, 003" etc, meaning it was the one right at the edge, and had not been corded properly. Dayco admitted that they should be discarding the first belt on the buck, and the last. We dont know how high the numbers go up to but anyone receiving a belt with "001" should discard it.
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So, you work at a place where you can use SEM facility for your own private amusement / personal activity ?!

Wow --- you must be the owner of the place !

 

Wow! Only 11 months. Was this a failure or was there another reason for removing this particular belt?

 

The belts were off my 308GTSi. They had 10,500 or a bit more miles about 13 months. They were in good shape when I removed them. I was pulling them for other reasons. I would have left them on the car but in the interest of the original thread I felt it was a good time donate them. When I removed them they looked good to the naked eye.

 

Nice thread, thanks for sharing!

 

We need to see a new belt

 

That's good information to know. It would be nice to know what #s appear at the other end of these "bucks".

 

If possible, it would be extremely interesting to examine a belt that came from the edge of the production buck. Might the filaments on the very edge be an accident waiting to happen?