When to renew timing belts?

[J.P.]

LT Snyder and users book says to replace them at 2 yrs. I'm there, but only 4500 miles on my 1000DS motor.
They Look OK.
Is it prudent to change them? PITA to drop it at the dealer, I don't have a frequency measuring tool or specs for a DIY.
How long do you guys let it go?
Thanks.JP

[stopintime]

Maximum 2 years as a "cheap" insurance against possible disaster, but I'm the kind who does everything my dealer tells me to

[Spidey]

If the bike sits a lot, 2 years.  If you run the bike more often, the belts *can* go for more.  Some folks haven't changed their belts for like 10 years.  Then again, those people also probably haven't changed their oil.  I wouldn't have a problem running them for 2.5 years and then having them changed at a regular service interval.  You're coming close to your 6k, so if you get there soon, just have them do them then.

Here's the scary part -->  if your belt goes, you're engine is gonna go boom.

Chris Kelly of CA-Cycleworks ("chris" on the DMF) posted somewhere a cheap way to make a frequency measuring tool with a laptop.  It's a great DIY post.  I can't look for it right now, but I'll see if I can find it tonight. I also know folks that use the 5mm method for the DS motors, even though you're not supposed to.

[Smokescreen]

There was a thread on methods of tightening too, but I've not looked for it in awhile.  Supposedly you can use a 2mm allen wrench method, but I use the 45* method.  Also, you wanna make sure you don't change the cam rotation. 

When you checked your belts did you check to make sure the tensioner pulleys were still spinning freely?  One of mine went before 12 thousand miles. 

So here's the thing, like Spidey said, if your belt goes, your motor goes boom...  I change every 2 years or 12 thousand miles, whichever comes first.  In the case of Blue, they came at the same time.

[Shazaam!]

It's my understanding that a recent Ducati Tech Bulletin has changed the service requirement to mileage only. Check with your dealer.

That's good because the logic of changing the timing belts every two years escapes me.

The only explanation that I can come up with is that without SOME time limit, the timing belts would drop off the owners maintenance radar scope. The usual reasons for maintenance on a time schedule, don't seem to apply here.

For example, for oil changes when the manufacturer specifies a time criteria, they're telling you that if you ride every day, but for only short trips to work, your riding habits subject the oil to a more severe service so you should use time, not mileage, as a guide. If you ride 100 miles a week, but do it in ten trips, you should use time, not mileage as your criteria.

Motorcycle riding is often different. If you ride only for pleasure once a week for 100 miles, then you should use mileage, not time as your change criteria.

Timing belts are made of kevlar-reinforced rubber, much like some tires that have no such time limit on their replacement. It's easy to understand a mileage limit on timing belts since (except under unusual usage) it correlates directly to cyclic fatigue and wear.

So what's so special about timing belts that they need replacement on a time schedule?

If you buy a new bike and then put it your private collection and don't ride it for two years do you have to replace the belts? Of course not. Conversely, if you have a track bike that lives at the red-line don't wait to change your belts until 12,000 miles is up.

You need to use your common sense here.

[stopintime]

Same thing as with tires - they get old and the rubber looses it's qualities. Not very likely that they fall apart at the two year limit, but with wet salty roads, hot summers, dust, freezing - who knows, they might need to be changed at two years. Who would want to test them to see how long they will last? Not me

[Spidey]

Ok, I found the post from chris.  I've cut and pasted it below.  I hope it helps.  Note that I have no idea is the vibration below is the same as what you want for your DS motor. 



Here's the stock blurb I paste in reply to e-mails I get on this subject:

Thanks for writing!

SPX is no longer reselling the belt tensioning tools to me at a dealer price, so I have stopped selling the tools. Instead, you can use the "sonic" method referenced in the factory manual for ST4s (and other models). You want a vibration of 112~115 Hz. Please read the e-mail from the ST owners list referenced below for more details. For the actual frequency measurement, you can download the FREE software from this link:
http://www.techmind.org/audio/#mustun
(download his frequency counter) And then any cheap microphone plugged into your computer in combination with this free software replaces the >$400 handheld gauge or the multiple thousand dollar Ducati "mathesis" tester.



If you prefer to use the old method belt tensioning method called out by factory manuals older than 2002, you will need to contact SPX Germany directly about buying the tool, whose part # is 21-113.
Ute Naumann ute.naumann@servicesolutions.spx.com 49 6182 959 143
or
Anja Von Berg anja.vonberg@servicesolutions.spx.com 49 6182 959 148


NOTICE: this company's customer support is immeasurably awful and the main reason we "fired" them.

And then once you have the tool, you will need to fabricate shims to adapt their 15mm rollers to Ducati's 17mm spec. This is easily done by any machine shop with a lathe. They can get some metal tubing and make sleeves to slide over the rollers whth inside diameter 15.0+ mm and the OD 17 mm. You can use any material for the metal: aluminum, steel, brass, doesn't matter.

Thanks,
Chris


--
Chris Kelley
President
California Cycleworks, Inc
www.ca-cycleworks.com
619/501-2466




Thread on belt tensioning...
[DucatiST] More on Harmonic Belt Tensioning
4 messages
--------------------------------------------------------------------------------
Brent <brrrnt@yahoo.com> Thu, Feb 23, 2006 at 3:12 PM
Reply-To: st2_owners@yahoogroups.com
To: st2_owners@yahoogroups.com
Well I must say I've owned my ST4s for only a short 5 months, knowing
soon enough that the belts would need replaced, valves shimmed, and
basically a 12K service done on it. A large task at hand for never
doing any work what so ever on a Ducati, many other Jap bikes, but
not a Duck. After studying this website for, well, the past 5 months
I built this confidence on doing all of the above maintenance. Last
night I finally (waited for Shims from the dealer, I mean Italy
because they were backordered, should have called EMS) finished
reassembling the valvetrain, and installing new belts, dialing them
in to ~112Hz using the Gold Wave software that Mike had mentioned,
with a very simple microphone, next a calculation and you figure out
the frequency, all is good, and the bike is running again :-) wish I
would have seen the link for this new software that Calculates the
frequency of the sound your recording, will have to remember this for
the future 12K I put on the Duck.

So the next question that I see, which I don't believe has been
answered yet is this, Where/How is the proper place/way to measure
the frequency?? and is it TDC on both cylinders or just the
Horizontal.

I've seen the photo that Desmobee put in the photo section stating
that the horizontal cylinder should be at TDC, and just by looking at
the photo it seems obvious that the disctance between the adjustable
pulley and "crank gear" on the horizontal cylinder is slightly
different than the distance between the "crank gear" and the fixed
pulley on the Vertical cylinder, these being the two points to
measure the Frequency at. I guess what i'm getting at is the fact
that if the distance is not the same then can the frequency be the
same, especially if the tension of the belt is the same, as we
already know from Mike's graph on differnt crank position, the belt
tension does change throughout the cycle of the engine.

I really should have done this when I had the bike apart but is it
safe to say that the length of the belt is longer at the measuring
point on the Vertical cylinder than it is on the horizontal cylinder,
if this is the case then is it also safe to say that if both belts
are measured when the horizontal cyl is at TDC, we know from Mike's
graph that the belt on the Vertical cylinder is actually under more
tension because the intake cam is fully opened, which means even
though the belt is physically under more tension since it is measured
over a longer distance that the frequency will be lower and will
match the frequency of the horizontal cylinder when it is unloaded???

I feel this is the case because if it were not why couldn't the
Ducati Manual simply state to adjust the horizontal at TDC and adjust
the Vertical at TDC or give two different Values of the Frequency one
when the horizontal is at TDC and the Vertical is on the intake
stroke.

Either way where I set my belts I feel confident that they are
approximately the same tension that the old ones were, actually they
may be a hair tighter.

This may all be wrong, But I think we need more input on the issue.

Brent








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--------------------------------------------------------------------------------
Mike <wonderfuls80@yahoo.com> Thu, Feb 23, 2006 at 4:57 PM
Reply-To: st2_owners@yahoogroups.com
To: st2_owners@yahoogroups.com
--- In st2_owners@yahoogroups.com, "Brent" <brrrnt@...> wrote:

Brent, you ask a lot of good questions, I'm afraid many of them can't
be answered definitively without a more free flow of information from
Bologna. Because I had been setting my belts for the first 24,000
miles entirely by the guestimate method, I look at the harmonic method
as reassurance that I'm in the ballpark but would not rely upon it
entirely without more definitive information from Italy on the method.

I have done some temperature experiments and determined that the
ambient temperature has a significant effect on the measurment
results. I have not seen a temperature specified by Ducati for this
procedure but I assume 70 F. My temperature experiments show the belts
will measure around 7-8% tighter at 70 degrees than they do at 54 F
so I am always cautious not to tighten them too much if it is below 70
F. This corresponds to my "feel" method so I am comfortable with it.
Anyone undertaking belt adjustments with the limited amount of
information available should understand that screwing up to the point
of causing a bearing to fail or belt to break will most likely require
extensive time and money to get back to where you were.

> So the next question that I see, which I don't believe has been
> answered yet is this, Where/How is the proper place/way to measure
> the frequency?? and is it TDC on both cylinders or just the
> Horizontal.

Fariborz has scanned the relevant pages from a newer ST4s manual and I
can tell you the instructions are less than confidence inspiring. The
one thing that appears clear is the measuring point. On the Horiz.
belt it's between the drive pulley and the adjustable pulley. On the
Vert. belt it's between the drive pulley and the idler pulley.

> the photo it seems obvious that the disctance between the adjustable
> pulley and "crank gear" on the horizontal cylinder is slightly
> different than the distance between the "crank gear" and the fixed
> pulley on the Vertical cylinder, these being the two points to
> measure the Frequency at.

The distance will vary slightly depending upon the position of the
tensioner pulley but my measurements show that when I have the proper
tension the distances are very close to being equal. So I don't let
that concern me.


> I really should have done this when I had the bike apart but is it
> safe to say that the length of the belt is longer at the measuring
> point on the Vertical cylinder than it is on the horizontal
> cylinder,
> if this is the case then is it also safe to say that if both belts
> are measured when the horizontal cyl is at TDC, we know from Mike's
> graph that the belt on the Vertical cylinder is actually under more
> tension because the intake cam is fully opened, ....

Wait a minute. First of all, the graph on my website is of the
*vertical* cylinder (I should post that so it's clear) and all TDC
measurements are relevant to that. Secondly, when the intake cam is
fully opened there may be more or *less* tension on the potion of belt
being measured depending upon which side of the cam lobe the rocker
has fallen to. In otherwords, it is nearly impossible to stop the
engine with the intake cam fully opened, the closer spring pressure
(coupled with the natural play in the belts) makes sure it is on one
side of the cam lobe or the other. And as far as I know there is no
good way to tell which side it is on. That's why I always adjust my
belts with the valves on that cylinder closed (it takes the cams out
of the picture).


> I feel this is the case because if it were not why couldn't the
> Ducati Manual simply state to adjust the horizontal at TDC and
> adjust the Vertical at TDC or give two different Values of the
> Frequency one when the horizontal is at TDC and the Vertical is on
> the intake stroke.

If you find a definitive answer to that one, let us know!

> Either way where I set my belts I feel confident that they are
> approximately the same tension that the old ones were, actually they
> may be a hair tighter.

The most dangerous condition is too tight because you will break a
belt or fry a pulley bearing. I believe the spec is tighter than it
needs to be for reliability purposes, I think it is spec'ed there to
reduce valve timing flutter (or irregularities) that would be caused
by a looser belt. Ducati is all about performance.

What temperature was the engine when you set the tension? If you think
it might be too tight it's a good idea to fully warm the engine
without the belt covers in place and then check the tension
subjectively with your finger. I feel I can get a pretty good idea of
how much pressure there is on the pulley's by feeling the tension
subjectively. If it seems unaturally tight it might be time to step
back and wonder where you may have gone wrong. Just be aware that
mistakes here can ruin a good ride and be very costly.

I think Fariborz may have some feedback on this as well. 'Borz, are
you into your belts yet?

Mike Mullen
http://home.comcast.net/~mmullen38/home.html

[Quoted text hidden]


--------------------------------------------------------------------------------
Spencer <sperho@gmail.com> Thu, Feb 23, 2006 at 5:48 PM
Reply-To: st2_owners@yahoogroups.com
To: st2_owners@yahoogroups.com
Mike wrote:

My temperature experiments show the belts will measure around 7-8% tighter at 70
degrees than they do at 54 F so I am always cautious not to tighten them too
much if it is below 70 F.

-------------------------------


By 7-8% tighter, do you mean that the frequency is 7-8% higher? or is the
actual *tension* 7-8% higher? The relationship is nonlinear.

Spencer

[Quoted text hidden]


--------------------------------------------------------------------------------
Mike <wonderfuls80@yahoo.com> Thu, Feb 23, 2006 at 7:28 PM
Reply-To: st2_owners@yahoogroups.com
To: st2_owners@yahoogroups.com
--- In st2_owners@yahoogroups.com, "Spencer" wrote:

> By 7-8% tighter, do you mean that the frequency is 7-8% higher?

Exactly. Frequency is the only objective method I have to measure belt
tension.

Mike Mullen
http://home.comcast.net/~mmullen38/home.html

__________________
Chris Kelley
for tech info :: www.ducatitech.com
to buy Ducati parts :: Ca Cycleworks :: ca-cycleworks.com

[Ducnial]

I'm with shazaam,  true rubber does age a bit but heat is by far its worst enemy.   Heat acts to two ways to deteriorate  the belt.   1) Heat continues the vulcanization process after the fact and causes the rubber to harden and become brittle.  2) Heat decomposes the polymer (chain scission) causing it to loose tensile strength.  Kevlar cords are basically impervious to wear but heat can cause the loss of adhesion of cord to the rubber. This increases frictional heat within the belt.

What all this means is if you thrash the hell out of your bike on a regular basis,  go for long periods where the engine temperature is at it max. Or live in a pretty hot part of the country (read southwest) then you probably ought to change them every couple years no matter what.

Its pretty simple to access their condition. Pull the covers and look for rubber shedding on the inside of the cover,  if you see more than a very thin layer add 1 to the equation. Inspect the belt teeth looking for wear or rounded teeth edges, if they look worn add 2 to the equation.  Flex the belts on the inside looking between the base of the teeth for cracks, if you see some add 3 to the equation. Inspect the edges of the belt looking for fraying, if you notice any add 2 to the equation.  Add everything up and if its 3 or greater then you probably ought to change them no matter what. 

While you are in there access the belt tension by plucking them like the banjo, if they don't seem to "ring"  then they may be loose and should be checked. Ducati has a instrument to measure the frequency, anybody know what the freq is?  < thanks Spidey, 113hz >. Finally try to wiggle the pulleys and the tensioner,  if they wobble then the bearings need replacement.

Obviously if you loose a belt or skip more than a tooth or two then the valves will crash into the piston during the compression or exhaust stroke.   Short stroke and large bore engines like Ducati's are particularly susceptible because the combustion chamber is so shallow, 90% or more of the combustion chamber volume is taken up by the diameter of the piston as opposed to the clearance height.  Ducatis even have special head gaskets with various thickness and "squish" designed to minimize the clearance between the head and piston, sometimes less the  0.7 mm clearance.

BTW/ would someone please add Ducati to the spell check dictionary, this is ridiculous. 

[Bill in OKC]

I just replaced my belts.  I have less than 5K miles but I've had the bike for 2 years.  I didn't think the belts looked bad but Ducati says replace them every two years no matter what they look like.  If the factory says this, they must have some type of data to back it up - maybe warranty claims - who knows...

[bigiain]

If you buy a new bike and then put it your private collection and don't ride it for two years do you have to replace the belts? Of course not.

A lot of people I trust say "yes". (Having said that, I know of a few stories of people with expensive rebuilds resulting from belts run past 20,000km/12k miles, but I don't remember hearing any stories of people doing damage from low mileage but older-than-two-years belts...)

Not that it matters to me much, I replace my belts every 10 or 11 months due to mileage...

One thing to remember about the belts on a Ducati (particularly the two valvers) is that they turn around significantly smaller pulleys than in a lot of other applications - I know cars with gates belts often have 60 or 100,000km belt change intervals, but the diameters of the pulleys they run on is two or three times as large and the dinky little ones on my Monster. That, coupled with the maybe 20% higher rev limit, has _got_ to stress the rubber belts more...

big

[bazz20]

A lot of people I trust say "yes". (Having said that, I know of a few stories of people with expensive rebuilds resulting from belts run past 20,000km/12k miles, but I don't remember hearing any stories of people doing damage from low mileage but older-than-two-years belts...)

Not that it matters to me much, I replace my belts every 10 or 11 months due to mileage...

One thing to remember about the belts on a Ducati (particularly the two valvers) is that they turn around significantly smaller pulleys than in a lot of other applications - I know cars with gates belts often have 60 or 100,000km belt change intervals, but the diameters of the pulleys they run on is two or three times as large and the dinky little ones on my Monster. That, coupled with the maybe 20% higher rev limit, has _got_ to stress the rubber belts more...

big

i agree big even tho those belts dont have too push vavle springs down they are under more stress from heat than anthing else especaly air cooled bikes , was talking to the head tech at melbourne ducati and yes people have had belts let go so it dose happen , bazz

[ellingly]

I'm a 2 year kinda guy. It's not that expensive, and it's cheaper than new valves and pistons.

I've had a timing belt go in my car, I can think of more fun things to do than wait for a tow home... and then there's the whole fixing thing.

I live in a hot and cold part of Australia, I commute on the bike, and 2 years is about 16,000 km so I'm only 4000 km short. Plus, hey, the oil should be done then - why not just make it one trip to the mechanic rather than keeping on visiting him. None of the mechanics here are attractive, so I don't see why I should have to see them more than I need to .

[Howie]

The idea of a service interval is to replace items before they need to be replaced, and with vital item like a timing belt, particularly on an interference engine wit very expensive parts,the interval should be extremely conservative.  Time does come into play, since both the rubber and the belts do both age.  Bikes in long term storage may cause the belt to take a set around the pulleys, similar to a tire flat spotting in storage.  There is also the possibility of the belts going through more heat stress in a low mileage vehicle since this may mean local low speed riding accompanied with high heat for longer periods of time and more run time for less mileage.

Will most belts on low mileage bikes last for more than two years?  Probably.  The real question is why take the chance?

[Capo]

Backup for Ducnial's post, is the fact that some of the Ducati sportbikes have a cooling duct in the belt covers. Life under the covers is hard both for bearings and belts.

[ScottRNelson]

I've discussed belt change intervals with Jim Davis, the Ducati mechanic at Nichols Sportbike Service.  He has probably had his hands on more Ducati engines than just about anybody else in the country, including a few that had broken their belts.  He told me that if a bike sits for six months or more at a time, the belts are more likely to break after two years.  For sure, if a bike has sat for two years without ever running the engine, you're taking a big chance of the belts breaking.  But if the bike is ridden regularly, there is no problem at all going three years on the belts.  It usually takes me about three years to put 12,000 miles on my ST2, so I go by mileage.  On my 888, I get them changed after three years.