| Author |
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Scooter808484
| | Posted on Monday, May 16, 2011 - 11:51 am: | 
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The only way that belt would maintain the same tension throughout the rear shock travel would be if the swingarm pivots on the same axis as the gearbox sprocket and on the ULY it doesn't. I think the placement of the idler pulley is probably optimized to minimize tension swings but it doesn't eliminate them.
If the change in distance caused by the different pivot locations was matched precisely by the increased belt wrap around the idler pulley, then the tension would remain constant. I don't know if that is the case, but it is conceivable. At the very least, it is located to minimize tension swings, like you said. |
Blake
| | Posted on Monday, May 16, 2011 - 11:58 am: |
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>>> The only way that belt would maintain the same tension throughout the rear shock travel would be if the swingarm pivots on the same axis as the gearbox sprocket...
You are mistaken. What you state is true for a system lacking an idler pulley. The Buell XB's and 1125's have idler pulleys.
>>> If you think I'm wrong then I'd sure like to see documentation that says it maintains constant tension.
See the Nov/Dec 2004 Fuell Magazine. |
Blake
| | Posted on Monday, May 16, 2011 - 12:03 pm: |
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Also see the final drive specifications for any XB or 1125, an excerpt from the 1125R specifications (emphasis added by me):
Final Drive: Constant path, 14 mm pitch aramid-reinforced Goodyear® Hibrex® belt with Flexten® Plus technology, 2.593:1 (70/27) ratio
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Redhat
| | Posted on Monday, May 16, 2011 - 01:17 pm: |
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Have a look at this Drive belt patent
It speaks of a constant length within 0.008"
I have drawn it out roughly, and came to the same number.
It is not something they just did, they thought about it (like pretty much everything on the bike) |
Electraglider_1997
| | Posted on Monday, May 16, 2011 - 01:18 pm: |
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Blake,
I didn't own a Buell until I bought my 2006 in Oct of 2005. Can you scan the Fuell page that proves your point and post it here, otherwise I'll be a doubting Thomas. Thanks.
Constant path doesn't mean constant tension to me. My 2006 ULY service manual actually reads under the DRIVE BELT section on page 1-27:
"The drive belt tension on a new belt will loosen after approximately 1000 miles (1600 km). The drive belt tension is automatically adjusted by the idler pulley. Axle adjustment is not adjustable."
Anyway, I'm not sure I understand what is exactly meant by "automatically adjusted by
the idler pulley" seeing that it isn't on a torsion spring and can't even be adjusted manually for all that matter. The only adjustment that seems to occur is that a new belt will automatically stretch because it is way too danged tight to begin with. |
Electraglider_1997
| | Posted on Monday, May 16, 2011 - 01:39 pm: |
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I just read that patent pdf. Interesting. I wonder what happens if the upper travel of the rear wheel on the swingarm causes the belt to skim the idler, are all bets off? |
Froggy
| | Posted on Monday, May 16, 2011 - 01:42 pm: |
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EG - Give this a read, it is from the Fuell issue Blake mentioned.
http://froggypwns.com/buellpdfs/pdf_1112_2004.pdf |
Electraglider_1997
| | Posted on Monday, May 16, 2011 - 02:09 pm: |
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Froggy,
I just read through that. Real nice work they did with that. I wonder how the BMW bike that I mentioned would stack up to what Buell engineers did with the idler. Are they equivalent or is one better than the other? Thanks for the info. I can see the severe limitations of the Free Spirits Tensioner in comparison.
I've not had real troubles with my belt other than having to replace it once at 25,000 miles. Looked somewhat rotted more than anything. |
Cpeg
| | Posted on Monday, May 16, 2011 - 03:23 pm: |
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Does the belt actually stretch?
Or does it seat itself into the pullies? |
Electraglider_1997
| | Posted on Monday, May 16, 2011 - 04:42 pm: |
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Whatever it does it sure gets easier putting the back wheel the second time around. |
Natexlh1000
| | Posted on Tuesday, May 17, 2011 - 03:14 pm: |
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I was thinking perhaps of assembling a couple of pulleys with a motor to exercise the belts before hand?
Let it run overnight, perhaps not so crazy to get the thing on?
Just a thought. |
Uly_man
| | Posted on Tuesday, May 17, 2011 - 03:38 pm: |
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You will also notice that a belt gets tighter as the bike heats up. This is because everything expands as it does so. As in the oil in the swing arm etc. I know, as I had it on my bike, and was shocked at how much it was as well.
Test this for yourself. |
Gs750t
| | Posted on Thursday, May 19, 2011 - 05:38 pm: |
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+1 on a tip from Hunn. Just replaced the belt on my 06. 18,000 miles. Soaked the belt in hot water for about 30 minutes. 90 minutes later the belt was replaced and I did not remove the pulley. |
Hughlysses
| | Posted on Thursday, May 19, 2011 - 05:43 pm: |
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Gs750t- there has been some speculation that failure of the belts is caused by water getting into the fiber reinforcement. I'm pretty sure that's complete speculation, but it'll be interesting to see if the hot water install has any adverse effects. |
Gs750t
| | Posted on Thursday, May 19, 2011 - 05:46 pm: |
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Now I'm going to drink heavily! |
