High tension of tail timing belt

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When I built my CMT 500 kit I was astonished about the high tension of the timing belt.

Other than with the 450 helicopters the tension of the belt seems to be fixed; or in other words even when pushing the rear tube in as much as possible the tension is higher than what is considered correct at 450s.

I understand there are now ball bearings holding the two axes an either side (making changing the belt quite more difficult), and these should carry the extra force.

But given the considerably higher force needed to turn the rear rotor I wonder if this is neccessary and helpful.

Or is there something wrong with my mechanic or belt?

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burnt42 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (DE) USERID: 404364 Newbie Joined: 12/May/2012 Online Status: Offline Posts: 4	Quote Reply Topic: High tension of tail timing belt Posted: 12/May/2012 at 9:46pm
	When I built my CMT 500 kit I was astonished about the high tension of the timing belt. Other than with the 450 helicopters the tension of the belt seems to be fixed; or in other words even when pushing the rear tube in as much as possible the tension is higher than what is considered correct at 450s. I understand there are now ball bearings holding the two axes an either side (making changing the belt quite more difficult), and these should carry the extra force. But given the considerably higher force needed to turn the rear rotor I wonder if this is neccessary and helpful. Or is there something wrong with my mechanic or belt?

WTWUK Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (GB) USERID: 976346 Hobbyking Addict Joined: 16/Jul/2011 Online Status: Offline Posts: 2340	Quote Reply Posted: 12/May/2012 at 11:25pm
	It should not be overly tight - was it difficult to get the belt over the pulley at all?

burnt42 Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (DE) USERID: 404364 Newbie Joined: 12/May/2012 Online Status: Offline Posts: 4	Quote Reply Posted: 13/May/2012 at 7:43am
	The belt can only be installed with the belt gear disassembeled, because other than on 450s, the axle is hold by one bearing on bottom _and_ top. Then it needed some force to drag the rear tube out far enough (thus tightening the belt) that the gear could be mounted together and in the frame.

hairykarts Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum (NZ) USERID: 424820 Hobbyking Addict Joined: 24/May/2010 Location: auk nz Online Status: Offline Posts: 455	Quote Reply Posted: 14/May/2012 at 9:24am
	Threads on here already about this ,, just shorten the tube by 1-2 mm. sand on a flat suface and mark the tube first .
	I must remember .... when inverted .... down is up and up is down .