View single post by Esprit2
 Posted: 04-07-2017 05:58 pm
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 289
Good information, thanks for sharing. It's that kind of input that will help zero in on a preferred tension recommendation.

The tension varies with crank position. I've checked the tension in 10 degree increments for two full revolutions (ie, a 4-stroke cycle), and the graph of the results is a regular roller coaster ride. So it's important to check and set the tension at TDC. Explore if you wish, but set it using a tension gauge at TDC.

Around 1997 or so, Lotus issued a new procedure for the HTD round tooth belt only. It called for the use of a Clavis Frequency Meter to set the tension to 100-110 Hz at 30 BTDC. I find it much easier to set the crank to 30 BTDC than to TDC. The tension in the belt is higher at TDC, so it's more difficult to move it precisely, and it moves in jerks. If you're right next to the TDC mark trying to sneak up on it, pulling... pulling... then it jerks beyond TDC. Frustrating.

At 30 BTDC, it's easier to turn the crank, and you can roll right up to the TDC mark and stop, first time, every time. The only problem, there's no tension recommendation for the trapezoidal belt at 30 BTDC. That would be another grassroots effort.

So, out of curiosity, what tension are you zeroing in on at TDC? Then what is the corresponding tension at 30 BTDC? Curious minds want to know. Well, at least one does.

Thanks & Regards,
Tim Engel