Continued struggle with belt tracking

[Stuart49]

I continue to struggle with my belt adjustment. Yesterday I jacked up the rear wheel and worked methodically at getting the belt to track slightly off the flange. At the same time I gradually reduced the tension from about 800N using the Gates sonic meter (equates to 200#) down to about 640N. I did a couple test rides and the whining/groaning at decel was almost gone! The belt appeared to stay against the flange, although one time when I looked at a stop it had a slight gap (1/8"?). So I checked the torque on the axle and replaced the cotter pin.

This morning I took a longer ride with about 20 miles on the interstate at 65-70. When I looked at stop the belt was off the flange, maybe 3/16". Another time it appeared to be against the flange. When I arrived home it was about 1/8" gap, and the tension, checked with the gates meter is at about 740N. The whining/groaning at decel is back!

I wish I were confident that the belt will stay where it is now, slight gap. And I suppose the tension is about right, just under 200#. Maybe this is as good as it gets??? I appreciate any comments.

I am planning to take a ride up to MA tomorrow, back on Tues - 550 miles each way. Right now I am not so sure about this belt?

Thanks, Stuart

[mike3069]

I think you may be "as good as it gets".

My own efforts at this just about duplicate yours. If the bet is not always against the flange, it is as close as I can get it to where they say it should be. Any more adjusting and it flys off to the outside of the flange. It will also do this if you back up, even when it's "as good as it gets".

As for the groaning and belt tension...

Before my first service I messed with this and got rid of the groaning by continually loosening the tension untill it stoped. Rode it this way for about 150 miles before the service. Had them check the tension with the belt hot as soon as I got to the dealer. It was at 350 NM. Had them check again after the oil change (cool belt) and it was at 250 NM.

They reset the tension to 1400NM and the groan came back. I am slowly reducing the tension again because I asked one of the factory engeneers about this and he said to me "Belt tension is not a critical issue as long as you do not get belt vibration issues." So far all I have noticed is that the "normal" vibration you get under slight acceleration at about 5000 rpm has moved down to around 4000 rpm.

Hope this helps.....

[Stuart49]

Mike:

Thanks for your helpful message. You are right - this adjustment is probably as good as it gets. I am generally satisfied with the tension in the 750 - 900 NM range, as I think it is adequate tension. If the belt wanders from against the flange to 3/16" gap - that is fine. The Spyder has nearly 6000 miles, so any 'bedding in' of the motor mounts, etc. is certainly done now.


Stuart

[Lamonster]

One of the problems I see is we are pulling against a cush drive and that in itself may be why it's not that easy to get this rght. :dontknow:

http://image1.frappr.com/pix1/i/20080721/d/1/a/d1afc850c8588f1f07c35e324f413ebd0_large.jpg
http://image1.frappr.com/pix1/i/20080721/c/8/f/c8fa83e54d1a0beff4bda3e2da387c970_large.jpg
http://image1.frappr.com/pix1/i/20080721/9/9/b/99bc5c9cb9f74491f635de7f1f2818b30_large.jpg

[SpyderMark]

One of the problems I see is we are pulling against a cush drive and that in itself may be why it's not that easy to get this rght.

http://image1.frappr.com/pix1/i/20080721/9/9/b/99bc5c9cb9f74491f635de7f1f2818b30_large.jpg

Lamont,

I don't know if you're experiencing any balance problems with your new rear wheel, but I noticed the yellow dot on your tire isn't aligned with the valve stem. I also noticed LOTS of weight nearly aligned with the red dot.

The yellow dot is the LIGHTEST part of the tire (measured by the tire manufacturer) and should be aligned with the valve stem -- which should be the HEAVIEST part of the wheel.

The red dot is HIGH spot of the tire (no tire is perfectly round) and should be aligned with the LOW spot on the wheel (usually marked with a notch or dimple).

If the tire has both red and yellow dots, and there is a marked low spot on the wheel, the installer should ignore the yellow dot/valve stem alignment and ensure the red dot is aligned with the low spot on the wheel. This is because an out of round wheel/tire combo can cause as much or more vibration as an imbalance, and weights can fix an out of balance condition, but not an out of round condition.

It seems a bit strange to me you would have so much weight near the light spot on the tire -- I would have expected to see the weight on the opposite side of the wheel. Do you know if your installer aligned the red spot with the low point on the wheel? If not, it might explain why you have so many weights on the wheel.

You might look around your area and find a tire shop that has a balancer capable of detecting and correcting road force variance. Read this (http://www.gsp9700.com/pub/features/how.cfm)for a good explanation of how a such a balancer works.

Wide, low-profiles tires, such as the one installed on the rear of our Spyders, are especially prone to perceived vibration problems associated with eccentricity and construction variations.

Regards,

Mark

[Stuart49]

I made a final adjustment this morning, went for a 30 mile mixed ride, and I AM DONE. The belt is generally against the flange but sometimes shows a small gap. The tension, when cold (70F) is about 6-700N, and it runs smooth, minimal whining on decel. So I'm leaving it right where it is. I know the spec calls for more tension, but I don't think it is necessary. You should see the very low amount of tension on my Buell's drive belt - engine has the same amount of power.

I've been working on high performance motion control systems for 30 years and I can't imagine why they (BRP) thinks this belt needs to be tensioned so high! It only puts a terrible strain on all the bearings - rear wheel AND the output shaft from the gearbox.

All those in this thread - thanks for your help.

Stuart

[Lamonster]

Lamont,

I don't know if you're experiencing any balance problems with your new rear wheel, but I noticed the yellow dot on your tire isn't aligned with the valve stem. I also noticed LOTS of weight nearly aligned with the red dot.

The yellow dot is the LIGHTEST part of the tire (measured by the tire manufacturer) and should be aligned with the valve stem -- which should be the HEAVIEST part of the wheel.

The red dot is HIGH spot of the tire (no tire is perfectly round) and should be aligned with the LOW spot on the wheel (usually marked with a notch or dimple).

If the tire has both red and yellow dots, and there is a marked low spot on the wheel, the installer should ignore the yellow dot/valve stem alignment and ensure the red dot is aligned with the low spot on the wheel. This is because an out of round wheel/tire combo can cause as much or more vibration as an imbalance, and weights can fix an out of balance condition, but not an out of round condition.

It seems a bit strange to me you would have so much weight near the light spot on the tire -- I would have expected to see the weight on the opposite side of the wheel. Do you know if your installer aligned the red spot with the low point on the wheel? If not, it might explain why you have so many weights on the wheel.

You might look around your area and find a tire shop that has a balancer capable of detecting and correcting road force variance. Read this (http://www.gsp9700.com/pub/features/how.cfm)for a good explanation of how a such a balancer works.

Wide, low-profiles tires, such as the one installed on the rear of our Spyders, are especially prone to perceived vibration problems associated with eccentricity and construction variations.

Regards,

Mark


The weights are from the stock tire. I told the guy that mounted the new tire not to worry about balancing it as I was going to try the Ride-On in my tire. I took all the weight off and that's all I'm using now and it's working great. :thumbup: