Belt Issue

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Schwee
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Belt Issue

#1

Post by Schwee » Sun Mar 08, 2015 3:04 pm

Scratchin my head over this one.
I've been running a belt primary on my 57 rigid for over thirty years. I like it because it doesn't stretch like a chain does; adjust it once and forget about it until it breaks (keep a spare handy).
I did a rebuild last year and used the same old (like new) belt. 11mm, 1 1/2", 99 tooth.
I always check it to make sure it's pretty tight, not a lot of flap. Been OK.
A couple of days ago I noticed that it seemed a little sloppy, went to adjust it, and found the tranny back to the max and still not as tight as I like it.
Puzzled (because they don't stretch), I gabbed my brand new spare, installed it, and found that I couldn't get it tight either. If anything, it seems a little looser than the old one.
Bearings on the motor and tranny are certainly not bad enough to cause this slack.
Any ideas?



john HD
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Re: Belt Issue

#2

Post by john HD » Sun Mar 08, 2015 5:35 pm

sprockets worn down?

john

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Re: Belt Issue

#3

Post by Bigincher » Sun Mar 08, 2015 5:41 pm

After you removed and replaced the motor, was the belt loose then, or did this just happen all of a sudden?
Did you have the tranny out when you did the motor?

Schwee
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Re: Belt Issue

#4

Post by Schwee » Sun Mar 08, 2015 6:13 pm

John,
Sprockets look like new; they've only had belts rub on them.

Big Inch, I had the whole frame stripped down, but the belt seemed normal after the rebuild. However, I did have some frame work done, and perhaps I had to move the tranny almost all the way back to get the proper tightness. But still, it seemed perfect for a year. Also, I've inspected carefully and I don't see any frame integrity issues. With the belt off, both engine and tranny show no slop at all.

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Re: Belt Issue

#5

Post by Bigincher » Sun Mar 08, 2015 6:55 pm

You just answered the questions I would've had.
So apparently this issue developed later after the rebuild, since the belt was initially 'normal'. Very weird. I don't have an answer, but it seems obvious that something moved.
Belt sprockets do wear out, but not in diameter. They wear on the 'pull' side of the groove, and you can't really see the wear, but you can feel it with your finger.
But that's not relevant to your issue. Sorry I can't help.

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Re: Belt Issue

#6

Post by 58flh » Mon Mar 09, 2015 1:09 pm

A POSSIBLE thing that could affect it is--You had the Motor out of the frame.Then some frame work done.Its possible that after the motor was reinstalled-It could have taken more shimming in the front mounts.This would make the front sprocket move to the rear SLIGHTLY.That along with tranny being reinstalled Could have changed the distance between the sprockets!.As you know How ever little it may be ,It will AFFECT the belts tension.--Go over everything & make-sure the 2-sprockets are Perfect to eachother.If all is good /It may be the frame work you had done.If need be OLNY if all else is OK-You can Move the tranny back some by elongating the holes a little.----Just something to think about----Respectfully----RICHIE

Schwee
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Re: Belt Issue

#7

Post by Schwee » Mon Mar 09, 2015 1:42 pm

I see that J&P has a 96 tooth belt available (mine's 99 tooth).
Will that solve my problem? Or be too short?

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Re: Belt Issue

#8

Post by caschnd1 » Mon Mar 09, 2015 3:01 pm

3 teeth w/ 11mm pitch will be 33mm shorter. That's about 1.3" so your trans will need to move forward about 1/2 that distance or 0.65"

-Craig

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Re: Belt Issue

#9

Post by Bigincher » Mon Mar 09, 2015 4:14 pm

Schwee wrote: However, I did have some frame work done, and perhaps I had to move the tranny almost all the way back to get the proper tightness. But still, it seemed perfect for a year.
That statement is why I ruled out any frame work having an effect on this. However--- you seem unsure about it.
So just for the sake of discussion, let's assume you had to shim the front of the motor.
How much would it be-- .010" ? .020"? Would that move the belt sprocket towards the rear? Yes, but it sounds like things moved A BUNCH if the belt is that sloppy.

Tell us more about what was done to the frame? Just curious, and if "everything was fine for a year", what else happened..?

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Re: Belt Issue

#10

Post by Bosheff » Mon Mar 09, 2015 4:55 pm

Is it possible the tranny mounting plate might be loose or maybe slid forward? Sumthin caused this condition....bosheff

Schwee
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Re: Belt Issue

#11

Post by Schwee » Tue Mar 10, 2015 1:49 pm

Richie / Big Inch, The front mount is shimmed about .020", but that would rock the front pulley forward, not back, if anything.

Craig, Thanks for the calculation, sounds like a solution.

Bosheff, I agree something caused it and I hate mysteries. Judging from the fact that I elected to swap out belts last week, since I couldn't adjust the tranny back any further, clearly I had to pull it all the way back last year when I did the rebuild. Maybe a little wear on the 'pull' side of the groove, as Big Inch explains, made the difference.

So, I ordered a new belt from J&P today. 96 tooth. Free shipping with code 3BFS during Bike Week. Need to get back on the road.

I'll post the results. (Also, new and used (backup) 99 tooth belts for sale.)

Schwee
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Re: Belt Issue

#12

Post by Schwee » Tue Mar 17, 2015 7:17 pm

Update: Received 96 tooth belt from J&P (Gates - made in USA) for under $100.
Installed, adjusted everything and back on the road.

Thanks for the tips, guys.

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