I checked the belts on my 998 after replacing them a few weeks ago, then doing some street miles and a track day.
I used the guitar tuner, and they were both very "flat", meaning they were not as tight anymore. I took note of how tight they were, then went about trying to set them to 110 hz (A) again. They wouldn't go to 110 hz. The eccentric would only max them out at a flat G.
They would go to A at other parts of the engine cycle, where the valve springs were under tension, but not at TDC on the compression stroke.
So I just set them back to how they were when I took it apart (maybe slightly tighter), and then left it alone.
So my question is, what happened? What if I was doing some engine maintenance, and it wasn't time to change the belts yet, and I couldn't get them back to factory spec as per the manual? Are my belts hosed and I need new ones already?
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'01 996 (ASMA #17, rebuild complete, runs, needs more stuff as it goes with Ducatis)
'01 MV F4S
'02 998 www.asmaracing.com www.desmosouthwest.com
Yes it seems the tensioner roller may have limited travel as you can rotate it 360 degrees. But man is the belt tight when it reaches that point.
Are you turning the tension roller in the correct CCW direction? I will assume that by turning it CW to tension, the 'acoustic intonation' will be off as the belt span being measured is now longer or shorter than it should be. I will again assume that it would be difficult to get the 110hz A2 note with a belt span length that is not correct. Just my .02.
I know this can't be a mistake, because I'm pretty sure you can't get an "A" an octave up or down, it just won't happen. I was messing with that the first time I put these belts on just to see if it was possible.
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'01 996 (ASMA #17, rebuild complete, runs, needs more stuff as it goes with Ducatis)
'01 MV F4S
'02 998 www.asmaracing.com www.desmosouthwest.com
while I do believe that everyone's problems are equally important to them. My personal opinion on this belt tension thing is that we over think it to death.To tight is bad for obvious reasons.Again in my opinion the tension at operating temperature is the important part if you still have a little [not much ]slack at full temp your good to go. I have seen belts set with a mathisis in a cool shop that were literally as tight as a bow string when the bike was at running temp.
two cents.
There seem to be some factors that are obvious and some that are not. So what are they?
I think this is an issue in the back of every Ducati owner's mind, isn't it? Maybe only if they do the belt tension themselves
It would be cool to have a separate discussion with anecdotal evidence of belt failure from those who have been around a while. So far, these are the general reasons I've heard of:
o Idler bearing failure (why? washing the bike too much with an ventilated cover? riding in rain?)
o Over tensioning the belts
o Some freak manufacturing defect in the belts
o Belt age (probably the most common)
o Plastic idler rollers in the new bikes
(Anyone want to add to this list?)
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'01 996 (ASMA #17, rebuild complete, runs, needs more stuff as it goes with Ducatis)
'01 MV F4S
'02 998 www.asmaracing.com www.desmosouthwest.com
Because somebody did something wrong at some point during the installation.
- Didn't notice a bad pulley bearing
- Didn't notice the pulley was off-set too far
- Poor belt tension (really far off)
- Not inspecting the belts after installing to insure they're still within spec
Those are 4 things that happened to me. I was lucky to catch them because I do check my belts after every few track events.
a few points: we are not inventing the wheel here,cam belts have been in use forever on literally hundreds of applications.Ducati engines do not have heavy return springs on the valves .Their belts have a comparatively easy life .In my time as shop foreman at the local Duc dealership I never saw a failure. Improvements have been made in both belt quality and with the newer heads the belts do not have to negotiate such severe angles.If the belts are running true and they are not over tight at operating temperature you are good to go.This is not a weak point or anything to lose sleep over.If you want something to worry about keep an eye on your half rings and don't let your valve clearances get to tight.
that makes four cents
Point taken. I do keep an eye on my half rings for sure, as everyone should.
For this subject though, my original question still hasn't been commented on or answered.
Why can't I get my belts to re-tension to the proper tension? Mostly I was hoping to hear back from someone experienced in this area to say:
1. Don't worry about it (which is what I'm hearing but I still don't have warm fuzzys)
2. The belts have relaxed too much indicating impending failure
3. Some other reason
What if I was a dealership doing some other repair that requires the belts to be removed, and I know the belts were just changed last month, but I can't get them to the proper tension? Do I make the customer buy new belts or do I just "not worry about it" and roll the dice?
__________________
'01 996 (ASMA #17, rebuild complete, runs, needs more stuff as it goes with Ducatis)
'01 MV F4S
'02 998 www.asmaracing.com www.desmosouthwest.com
Wait a sec, you're saying using a sonic measuring device in an attempt to re-tighten the belts, you're unable to get the same spec as when you initially put them on?
From my experience, you can always re-tighten and get them back to spec. I mean the variance is +/- 15hz anyway...
guys, if you are having trouble meeting the required tension spec, don't forget that there are 3 different color (and size) idle rollers. I'm not sure off the top of my head which is largest, but there is a gold, silver and black tensioner.
Belt re-tension (tension check) question
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