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Discussion Starter · #1 ·
My main belt tensioner pulses or moves in and out at a regular interval at idle. The movement appears to coincide with the white lettering passing through the tensioner pulley. I'm going to replace both belts this week.

Anybody else had this sympton? Can a belt get flat-spotted?

:-?
 

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Replacing your belt isn't a bad idea. I had one walk off in my very first track session after my T1 upgrade and had another come halfway off in a qualifying session at TWS this year (noticed it on post qual check and replaced belt - learned my lesson on the first one and carry spares now).

But, my tensioner seems to vibrate a little as well and my motor is essentially brand new. It may be normal. Not really sure. Haven't seen a lot of them...
 

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ROSSO Z said:
Can a belt get flat-spotted?
No. Not and last very long afterward.

There are two things that can make the tensioner flap, irregularities in the RPM of the engine (like the lope we all have at idle) and "resonance" resulting from those irregularities and other sources of excitation like vibration.

The belt and tensioner behave like a set of springs coupled to a mass (the tensioner of course uses a spring. The belt is a "spring", too). Excitation at a frequency that is near or at the fundamental of the system will cause reinforcing oscillation (think of a pendulum on a clock only at a much faster rate). That resonance can definitely cause a belt to jump a pulley.

The Katech solid-tensioner, recently discussed in another thread, is an example of a "fix" for this problem.
 

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I saw this car yesterday and the original complaint was a odd noise.

The noise seems to occur once every revolution of the belt or every time you see the letters on the belt you hear a light thump (for lack of a better description).

The belt is about four years old and he DE's the car frequently. The belt should be replaced regardless and I think it will solve the problem.
 
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