Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Supersports: SS / SuperSport / Supersport 950 > Snapped Chain...

[Jools]

When you think about the aggro that chains have to take it amazes me that chains of any description don't break more often.

After all, all the power of the bike gets transmitted through the chain, along with a bit of whiplash as you get in and out of the throttle, and every bit of the chain has to take the same amount of tension.

When you think that every one of those little pins has to take the same load...

When you think of the huge number of chains produced as well, statistically, every manufacturer is bound to produce a duff one that creeps through quality control every now and again

[Shazaam!]

AFAM doesn’t manufacture chains. According to their website “AFAM chains are made to our exacting specifications by the world's leading chain makers from Italy and Japan.” It’s my understanding that AFAM 520 and 525 chains are currently sourced from DID.

9XX Ducati stock chains are DID Superbike Series 525HV X-ring. DID’s website indicates that the 525HV will be/is discontinued and replaced by the DID 525ZVM for bikes over 900cc’s. The main difference is that the 525HV has a tensile strength of 9,120 psi, the 525ZVM, 8,974 psi. I assume that Ducati will change its specification at some point to accomodate this two percent strength reduction.

Whatever replacement chain you consider, it should meet or exceed this strength rating. The Tsubaki 525 QR Series has an average tensile strength of 7,040 psi so I’m curious which Tsubaki chain is rated higher than the DID.

I personally like the looks of a gold chain, so when I need a new chain I’m going to order Hond@ part number 06405-MAS-003 for a 96-97 900RR which is actually a DID 525HV, but with gold finish side plates.

A number of owners have changed to a 520 chain size for weight savings. The arguement being that if a 520 chain is OK for a race bike it’s OK for a street bike.

Bad idea. The chain manufacturers recommend 520 chains for 750-900cc bikes and 525 chains for 1000cc bikes on the road. A 525 chain is wider, with thicker plates, so it’s about 10% stronger than a 520 chain.

For example, the DID Exclusive Racing Series 520ERV2 chain has a tensile strength of 8,250 psi. with a weight savings over an 525HV chain of around 128 grams. Since the 520 and 525 chains need different sprockets, replacing the rear sprocket at the same time with an quick change rear with an aluminum sprocket will save an additional 475 grams.

A number of race bikes will use a 520 chain with no problems, but a race bike’s chain is inspected and replaced much more often and the lighter weight of a racebike results in lower chain loads than the street bike version. No matter how much horsepower a bike has, the maximum chain tension occurs during a wheelie, so the weight of the bike-plus-rider is the controling factor.

Heavier street bikes (and riders) will experience higher chain tension than race bikes.

Another factor that will affect chain survivability is front spocket size.

Ducati bike models have a wide range of torque output and the size of the chain and Ducati’s selection of sprockets reflect this range of outputs. All Ducati current models, except the 748 and 749, come with 15-tooth front sprockets. The 748 and 749 series (with the exception of the 749R) all have torque outputs below the 78Nm of the original 916, so they are supplied with 14-tooth front sprockets. The 748’s get 520 chains. The more powerful 749R (82Nm) is 15-tooth.

The 749’s get 525 chains, probably more for parts standardization than for strength. I remember from the product introduction that that was one of the major design objectives of the new models.

Starting with the higher torque 916-series (and 749R), and continuing with the 996, 998 and 999, the factory moved to a 15-tooth front sprocket and a 525 chain. Why? Because more torque means more chain tension and a 15-tooth front sprocket lowers the tension in the chain by seven percent. A 525 chain has a tensile strength that’s ten percent higher. So you get an overall 17 percent stronger setup.

Still-higher torque SP, SPS, R and Corsa models output over 100Nm so how do they survive with 14-tooth sprockets and light-weight 520 chains? That’s easy. Once you get over a certain torque level (for a given weight bike) the bike will wheelie before the chain tension exceeds it’s strength limits. At least for awhile ... chains on these bikes don’t usually see 15,000 miles of service.

So, what does this suggest about changing our final drive components? Three things.

First, as a general rule, it’s better to increase the rear sprocket size to avoid the higher chain tension resulting from a smaller front sprocket. Changing from a 15 to a 14-tooth front sprocket will result in a seven percent higher chain tension.

Second, the heavier the bike, the higher the chain tension needed to make it wheelie and the higher the maximum chain tension it will experience. So, a 680 pound 916-plus-rider will generate a higher chain tension than (say) a lightweight Corsa-plus-jockey or even a Suzuki GS-X. When a chain under tension elongates 10 percent, it needs replacement - frequently for a Corsa bike.

Third, combining a change to a smaller front sprocket with a change from a 525 to a 520 chain on a higher-torque model Ducati will significantly weaken the final drive load capacity. Reports of chain failures are common enough, so it may not be wise to ignore this point for the sake of saving 275 grams of chain weight.



[Edited on 12-7-2004 by Shazaam!]

[scully]

Originally posted by Jools
When you think about the aggro that chains have to take it amazes me that chains of any description don't break more often.

After all, all the power of the bike gets transmitted through the chain, along with a bit of whiplash as you get in and out of the throttle, and every bit of the chain has to take the same amount of tension.

When you think that every one of those little pins has to take the same load...

When you think of the huge number of chains produced as well, statistically, every manufacturer is bound to produce a duff one that creeps through quality control every now and again

Hey you know what Jools I was only thinking the same thing myself when it happened! Must be incredible pressure at times on such small pieces of steel and it sure is amazing it doesnt happen more often. Just hope it doesnt happen again, still count myself lucky both me and the bike stayed in one piece! 10 minutes earlier I was hammering down the A151 slightly over the speed limit
Anyway AA have just collected it and its off to Italia although they say chains arent normally covered by the warranty! Its only down 6600 miles for gawds sake!
Next conversation will be interesting with them...

[Iconic944ss]

Shazzam as always is pure class and hes very right about gold chains looking cool

[Jools]

Originally posted by scully
Anyway AA have just collected it and its off to Italia although they say chains arent normally covered by the warranty! Its only down 6600 miles for gawds sake!
Next conversation will be interesting with them...

Well, big torquey V-twins are hard on chains what with all those big power pulses going on and the fierce engine braking that the chain has to put up with (in the opposite direction to the power coming in), so they tend not to last as long as IL4 chains (for a bike with similar power that is - Hyabusa's and the like excluded). Having said all that, I replaced my first chain at the 12K service. I could've squeaked another couple of thousand miles out of it I suppose, but decided to get it done while it was in for it's service and save the aggro of changing it just a few month later. my bike is on a 14 tooth front sprocket so it probably gives the chain an even harder time, but 12-14K seems like the going rate having spoken to other 2 valve owners. 6600 seems woefully short life, cos they ain't cheap especially when all the sprockets and chain wear as a unit and all have to be replaced together

[Jools]

Originally posted by Iconic944ss
Shazzam as always is pure class and hes very right about gold chains looking cool

Shame about the boots though!

[nelly]

The Afam cahin is made by DID. It still has DID on the side plates......
It's a Tsubaki that Rushjob has fitted, not an Afam.

The Tsubaki, despite the numbers, does last longer and needs adjusting less. Maybe it's down to the quality of the lubrication and assembly from the factory? I don't know. The grease on the SigmaR chain is very thick and sticky whereas the DID is quite thin in comparison.
The figures will be quoted on a new chain, and no matter how well the chain is looked after, if the basic design and assembly is inferior, then it ain't going to last??
I've fitted virtually nothing but Tsubaki for the last 18 months or so and not had one come back or complaint.
Feedback like Rushjobs is not uncommon, hence my preference for the brand.

[Rattler]

Iconic - what's with the boots????

[keefer]

/\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\
yea they look like trainers

[moto748]

I've got a Tsubaki on my bike,
and it seems to be lasting very well.
Alloy rear sprocket too.
Certainly looks like it'll outlast
the DID chains I've fitted in the past.


This
thread
is
in
a
hell
of
a
state...

[Edited on 7-12-2004 by moto748]