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Discussion Starter #41

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More on belt tension

Forgive me if this has been well addressed but I have spent a few hours searching the forum and did not find what I was looking for. Following is a photo of the tool I have been using for the past 8 years on my Desmo's with good success but I am now thinking that the frequency method is more precise and desirable. I have not done any of the work so far on my 999, but I plan to start. I gather from the forum that this tool will not work for that bike, correct?

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Chilehead
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The pressure tensioner tool won't work with the newer bikes. They want the frequency set perfectly, because of the timing differences when the belts get tighter and looser.
Actually, that is not the reason. Simply, it won't fit.

Frequency is no more accurate, it is simply easier to measure in a confined space.

Belt tension is belt tension, how it is determined is irrelevant.

Tom
 

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There are many reasons why they switched systems. From my readings, they moved to a laser based reader because of accuracy and simplicity. They could have easily made a mechanical tool that did the same thing and fit on the testastretta's, but they didn't. The mechanical way of measuring doesn't give you nearly the accuracy. I've used one several times and compared it to the frequency method and its WAY off.



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I cannot empirically vouch for the accuracy of any method but I will say that using the tension guage that I posted a picture of is a fussy process. It takes me a few tries until I feel comfortable with the result. Moving things just a wee bit when you are tightening makes the guage swing wildly and the result of 4 or 5 tries always seems just a bit different in terms of final position of componets with the guage reading appropriatly. I dunno, I've never broken a belt and the guage is super quick to set-up and use but it does not sound as precise as what has been described here.
 

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Just done a PRECISE valve adjustment on the 1098 - thanks Mike at EMS. Also wanted to adjust belt tension by the audio frequency method, but NO GO.
I downloaded two lots of software (shareware?) and bought the latest 'directional' mike from Logitech, with a USB connector, but could get no meaningful reading either from my belts or a guitar. Now I'm being told I may need a pre-amp (which I thought was the object in the early post) starting at $200, pay for a soundcard (better than in my new Dell Inspiron laptop) etc.
Surely I can buy a straight Audio Frequency Meter as a stand-alone instrument for this much?
Anyone care to take us through EXACTLY how you achieved the desired readings with the PC + mike method, as I have spent a lot of time (and now own a flash mike which is looking like it might be useless) and am about to head to Phillip Is. for trackdays with belts set by the old 'feel' method...
 

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Discussion Starter #49
I currently use a cheap USB powered mic and the free software. Takes roughly 10 minutes to do the calibration because it takes time for the mic to pick up the soft signals.

Why not just get a $20 instrument tuner from your local band store?
Because most tuners need a much louder signal to read. You need something that will pick up the quietness of a belt pluck. Someone did find a tuner that will work, but they never posted in this thread.



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Because most tuners need a much louder signal to read. You need something that will pick up the quietness of a belt pluck. Someone did find a tuner that will work, but they never posted in this thread.
I never had issues with the tuners that I used to use...same ones I used as a musician, either buy Korg, Seiko, BOSS, Yamaha, etc. They all have mic plug-in's also, so that would definitely help. I use a Korg tuner that works perfectly.
 

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I think I paid $20 for my mic from Radio Shack. Works great.
 

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I just replaced the original belts on my 99 996s at 4,200 miles. OEM Ducati belts (new with red writing) and set the tension with my I-phone and a cheap app (< $5.00). My inital placement of the belts onto the bike read approx 80Hz. By tightening them up with the pulleys and adjusting to within the 100Hz range the other measurements all fell in to spec - the 5mm hex wrench, 45 degree twist, flex to top of head, and stayed this way after turning the motor over a few times by hand.

It may be the app you use, but I never got any erroneous readings on the I-phone as others have.
 

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luvmyduke
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One other observation

I've been using this technique for 3 years: easy, cheap, and seemingly reliable.

The thing that I never see mentioned, on posts, or in manuals, is the variation in frequency you measure for a fixed setting of the eccentric, always at TDC, but just with the belt in different positions (ie. set the eccentric, go to TDC and measure frequency, rotate wheel to go again to TDC and measure again...repeat). I find, just like when you measure your drive chain tension, there can be quite a bit of variation, and this variation gradually decreases the more you turn the belts (always by hand). But even after it reaches steady state, there is typically still quite a wide variation, as much as +/- 12 Hz at different belt positions.

So what is the point? If you happen to measure and set your tension to 110 Hz at the slackest position, the tension at the tightest can be as high as 140 Hz.
 

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I just replaced the original belts on my 99 996s at 4,200 miles. OEM Ducati belts (new with red writing) and set the tension with my I-phone and a cheap app (< $5.00). My inital placement of the belts onto the bike read approx 80Hz. By tightening them up with the pulleys and adjusting to within the 100Hz range the other measurements all fell in to spec - the 5mm hex wrench, 45 degree twist, flex to top of head, and stayed this way after turning the motor over a few times by hand.

It may be the app you use, but I never got any erroneous readings on the I-phone as others have.

Which APP did you use? How close do you have to place the phone?
 

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Which APP did you use? How close do you have to place the phone?
Its called "EasyTune". I placed the phone, screen up and mikc end in, about 1-3 inches from the belts. You'll know when it is right as it will work like a charm.

Horizontal belt is easier to get access to - the vertical belt requires the phone at an angle (mic end is parallel to belt) to the rear of the frame.

I also ensured the belts measured in the ranges of the other methods as well just in case.
 

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Need a Little help

Hey Guys,

I'm currently in the middle of this process...I've got the bike totally torn apart to check the valve clearances, and I'm trying to "pluck" the timing belt to get a frequency reading. Is it just me or do these belts not really "pluck" very easily?

I pluck the belt, and get a THWACK out of it, but no real oscillating vibration with a frequency I can measure. Is this correct? Am I trying to measure the THWACK or am I trying to pick up some minuscule oscillation after the THWACKING?

Help!
 

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Buy a tuning fork. The one I had was for A 440, it was dead on on the sound program I intend to use. Just move it over to the proper frequency range. My manual is showing 110Hz for new belts. I think I saw 70 or 80 for used, how used I do not know. Also not sure if they can be re-adjusted to 110 or if a fall off of frequency is a wear level indicator or adjustment indicator.
 

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2000 748 timiming belts?

So, the recommended turning procedure is using freq? Measured by a computer?

What happened to the simple world?

Has it been lost to the crazy-ness of the computer age?

Old School here, looking for a simple manual method.

Later, George in Delaware
 
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