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Old 07-29-2009, 03:18 AM
  #10465  
Redwood
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Join Date: Dec 2008
Location: Scotland
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Originally Posted by espresso1967
Needing some help with cams and belt tension. My kit came pre-built so I am sort of going backwards and making appropriate changes.

According to the setup it is setup up with cam A tension front 3 rear 30.

Now I am still new to the tc5 but from what I see they look like cam B with holes in them. Someone correct me if I am wrong here so even though the setup calls for cam A looks like cam B was installed.

I am running a 17.5 brushless and hoping someone can point me in the right direction of how tight/loose the belts should be.

Also having a bit of a hard time reading the tension numbers. I'm looking at the manual and starts 17 from left to right 32 what increments are being used to read the numbers?
Everyone seems to have a different way of thinking about how best to set your belt tension. Some think to make the belt as loose as possible without it slipping, to get a very free running drivetrain. I personally don't like this as the belt flaps up and down a lot at high speeds. Any energy going into moving the belt up and down is energy wasted.

So I try to find the sweet spot between loose belts to free the drivetrain but not loose enough so the belt can start to flap at high speeds.

I read in another thread that Josh Cyrul, the (lead?) designer of the T.O.P. Photon had done some testing into this exact issue and come up with the result that 4mm travel up or down is the right amount for maximum efficiency.
Who am I to argue with that, so I just set my belt so that when I push down on the belt, it can only move 4mm. Seems quite tight but not too tight. Probably also this is for mod racing, which probably requires a tighter belt than say VTA since higher speeds will make even a relatively tight belt start to vibrate.

So to summarise my waffling: For any motor, set your belt tight enough so that at top speed your belt doesn't vibrate, but no tighter. At mod speeds, this is apparently 4mm of belt travel (up/down travel)

Regards

Neal
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