Ducati.org forum banner

1 - 20 of 53 Posts

·
Registered
Joined
·
529 Posts
Discussion Starter #1 (Edited)
After 22k miles on my 2009 848 the time has come to renew the chain... it still 'seems' okay, but I've been bragging too much about its longetivty lately at the track, and as a result have heard many horror stories about chains breaking at high speeds (I do have a Cox Racing chain guard, but I still do not want to experience this).

So, after a lot of research, I decided to go with a new AFAM quick change carrier. I am sticking with (a new) 15t sprocket in the front, and purchased 39t and 41t sprockets for the rear. My plan is to remain stock at 15/39 for now, and probably throw on the 41t when I go to PittRace, which is a short, but quick track that has no long straights.

Regarding my stock set-up, here's what the manual says:

15t front/39t rear
525 GXW chain
No. of links: 97 + 1 joining link

In preparation for this install, I have researched this topic here a great deal, maybe too much, because now I am a little confused. Shazam and Pat, I hope you guys have a minute to chime in here.

QUESTIONS:

1. Should I change the new chain length from 98 links to 100 links to accomodate for the 41t rear sprocket when I switch to it later?

2. During my research, I saw various comments regarding the neccessity to adjust the ride height if two links are added to the chain. My ride height rod is fixed and not adjustable... what's the best way to approach this?

Thanks in advance for your help!


Charles
 

Attachments

·
Registered
Joined
·
100 Posts
If you want to go to a 41t rear you need to add a pair of links to the chain. note- I have not tried it myself but I am 99% sure from my measurements

You will want to get an adjustable rod to keep your keep your ride height the same. You will need a ride height measurement tool as well.

I am going to go either 15/38 and keep the same chain length (98) or 15/41 and add a pair of links (100) I can't decide. I have a new chain and quickchange that's been sitting here for months just can't decide on sprocket combo. I want the extra wheelbase so I can run a Pirelli 180/60 in the future.
 

·
Registered
Joined
·
1,256 Posts
Should I change the new chain length from 98 links to 100 links to accommodate for the 41t rear sprocket when I switch to it later?
It depends on the initial position of the eccentric chain adjuster. Once you select the sprocket sizes you have no control over the chain length. You have to use a chain length that places the eccentric within it's front-to-back range of movement. This sets the wheelbase and ride height.

During my research, I saw various comments regarding the neccessity to adjust the ride height if two links are added to the chain. My ride height rod is fixed and not adjustable... what's the best way to approach this?
Make a a small permanent mark on the bodywork directly above the rear axle. Sit on the bike in full gear and a half tank of gas. Have an assistant measure the distance from the axle to the mark above.

Make your sprocket and chain change. Retake the same measurement and compare to the reference distance. If necessary, raise your rear ride height by increasing the preload on the rear spring — lower it by reducing preload.
 

·
Registered
Joined
·
529 Posts
Discussion Starter #4
Thanks for the replies!

After additional research I stumbled upon the www.gearingcommander.com website, and along with your added comments above, Shazaam, it looks like I will not be adding any links. Currently with my stock setup, my eccentric rests at about 4-5 o'clock. If I'm reading the chart from gearingcommander correctly, I will need to move the rear wheel forward 8.57 mm (.34") to accommodate the 41t sprocket; There's plenty of room within the eccentric for that. It will be interesting to see what this does to my ride height.

I was concerned about not having an adjustable ride height rod, but from your description, it sounds similar to the second part of documenting and setting the sag (I just documented the numbers). I have some lowering adjustment left in my preload adjuster on the rear spring (3 threads showing at the top), so if I need to lower it, I hope that's enough!

Thanks again... it's chain bustin' time!

Charles
 

·
Registered
Joined
·
1,389 Posts
I picked up a used oem 1198 adjustable rod for pretty cheap and it took about an hour to swap them out. I didn't like messing around with my suspension settings so this was just an easier solution.
 

·
Registered
Joined
·
529 Posts
Discussion Starter #8
I picked up a used oem 1198 adjustable rod for pretty cheap and it took about an hour to swap them out. I didn't like messing around with my suspension settings so this was just an easier solution.
That's good to know. I've been looking at these over the last couple of days and see that Sato Racing and Sling Shot Racing among others have their own branded versions as well.

I'm gonna try without it first to see where everything ends up. If it turns out to be too much of a hassle or the optimal height is not obtainable, I think I just found my next fairly inexpensive upgrade.

Muchas gracias!
 

·
Registered
Joined
·
6,790 Posts
Hi Charles - Only just home - I wasn't able to access the thread before now.

This is a complex process you are heading into, and will be made vastly easier/better if you just 'bite the bullet' and pick up an adjustable tie-rod.

You will be dealing with a series of interacting variables, changing gearing on an eccentric axle with no adjustment to compensate for an altered rear ride height.

Alterations to the eccentric position can make significant changes to ride height - more than you might expect. Making the sorts of changes you contemplate can require most of the threads on the adjustable rear link tie-rod to reset the height.

The trick is to change ONE thing at a time. Ideally you can change to a gearing you want to try without changing other fundamentals of the bike's geometry, like wheelbase and ride height.

But as a general trend these bikes benefit from a lengthening of the rear wheel position, as this places a little more weight onto the front - something they lack from stock due to the length of the 'L-twin' engine.

If you want to run 15/41 gearing, you have the opportunity to slightly lengthen the rear wheel position (with a pair of extra chain links) and still be able to achieve chain tension.

You will however need to re-tap the brake stop peg about 15 - 16mm rearwards, so the caliper bracket works in the new position. (It is a 12 x 1.25mm thread, like some bike spark plugs).

If this sounds all a bit hard, I can assure you it took me about 15 minutes to do this once the bike was stripped. And the result is a more positive feel through the front end, which I can promise you is an improvement.

Perhaps just try the experiment - you can always go back if you don't like it - easier to shorten your chain than lengthen it! You can run two joining links (as I did when I first tried it) but one is better.

Let me put it this way - I liked the change of wheelbase so much I spent serious cash on a 15mm longer swing-arm so I could run the gearing I want, and the longer rear wheel position.

Do whatever you decide to do, but do it in the light of this information. Make clear measurements before you start, so you know what your baseline is. And you should be able to justify the cost of the adjustable tie-rod - they should really have come out with it.

It's just one of those things (like the steering damper) that they left off to keep the price down on the 848.
 

·
Registered
Joined
·
529 Posts
Discussion Starter #10
Thank you, Pat, that's a lot of great information.

You've got me thinking more about wheelbase now. However, I finished the new chain and sprocket installation this evening, and decided to stay with the stock chain length (98 links); tomorrow I'm going to check the difference in the ride height between the 39t vs. the 41t. I believe my wheel base is going to be about 8.57mm shorter, or about .34". I have about three turns of preload left in my rear shock, so if that doesn't get me to an acceptable height, I'll go ahead an pull the trigger on the adjustable ride height rod.

Thanks again!
 

·
Registered
Joined
·
6,790 Posts
You're welcome Charles. If your rear wheel is only 8 - 9mm forward of where it was, there may not be a lot of difference in rear ride height, if your eccentric is still on the bottom of its arc. It will probably have moved from about 5.30 to about 6.30 (viewed like a clock face from the LHS).
The greater change comes if you go to the longer chain, where the eccentric moves from about 5.30 to about 3.00. And of course the wheel has also moved back in this setting, so the distance from a fixed point on the bike is slightly increased due to this.
On the adjustable tie-rod - if you buy a stock second-hand one, free up and lubricate the threads before fitting, as they have little lube from original, and of course are exposed to a lot of dirt and moisture in front of the wheel. Mine seized up quite early on, in spite of fitting a hugger almost straight away.
And be aware that (like the gearchange linkage) the tie-rod has a left-hand thread on one end, marked with a machined groove around the LH nut. This of course is to allow adjustment without removal.
 

·
Registered
Joined
·
129 Posts
My rod seized up the 1st time I moved it. Will have to rip it off. As I didn't know about the longer chain, to try for improvement with std 1198s I fitted new std length RK chain and tried a bit of extra ride height. Got 1 thread showing on rod. With lower rear tyre presure the bike is feeling better, quicker steering and stable holding line feel. For my return to track will add some preload and a couple of clicks to compression damping on both ends. Am I heading in the right direction as not going to change tripples any time soon.
 

·
Registered
Joined
·
6,790 Posts
You have put slightly more weight over your front end by raising the rear. And yes - this normally feels more positive on corner entry.

Increasing the effective swing-arm length puts more weight over the front, as does fitting 'flatter' triple trees. Having done both I can attest to the improvement in front end feel.

These mods change the front/rear bias from about 49/51% front/rear stock to about 52/48% front/rear. This is much closer to what is considered an ideal starting point for superbikes, and is why almost every factory Ducati Superbike (from Carl Fogarty onwards) had a longer swing-arm and flatter yokes.

Begs the question as to why they didn't come out like this, but the Panigale has now incorporated something closer to these values.
 

·
Registered
Joined
·
6,790 Posts
As to adding both preload and compression damping for the track - I'm afraid it's not quite as simple as this.

How rough/smooth the track you are going to is important, particularly on corner entry and exit. And of course we don't know where your present settings are..

Add in your riding style and personal preference and there is no straightforward answer to this. Trial and error when at the track is the best idea, although we don't always have time at track days to come in and out trying things.

I usually just drop my tyre pressures (F - 33 and R - 31) and ride, and just check the hot pressures when I come in. I leave my (relatively soft) suspension settings as is.

That is with a 25mm Superbike cartridge kit in the forks with stock 1 kg springs, and a TTX with a .8 spring in the rear. (I weigh about 80 kgs, and my bike is seriously lightened).

But essentially one man's settings never suit another man. That is why the factories do so much testing for their racing programmes, with individual rider's preferred settings often being completely different on the same machine..
 

·
Registered
Joined
·
529 Posts
Discussion Starter #15 (Edited)
UPDATE with disappointing news... This evening I decided to fit the 41t sprocket to see what my initial ride height number would be, and after getting the sprocket in place I noticed the wheel would not turn--it was lodged in to the swingarm! I have a new set of Pirelli Superbike Pros 180/55 17, so the tire size should not be an issue. Unless I'm missing something, I do not believe this upgrade will work on this bike without adding at least a couple of links; then the question becomes, will two additional links allow for proper chain tension when the 39t is placed back on?

Are there any 848 owners here who have successfully completed this upgrade without extending the chain? If so, please enlighten me on how you pulled it off...

As an fyi, the total front to back rear axle travel distance if I'm measuring correctly is just north of 27mm (Shazaam, does this measurement method look right?)
 

Attachments

·
Registered
Joined
·
1,256 Posts
As an fyi, the total front to back rear axle travel distance if I'm measuring correctly is just north of 27mm (Shazaam, does this measurement method look right?)
Yes that's the correct way to measure. Thank you for doing that for me.

So, you have an adequate range of adjustment of the eccentric to accommodate the 41-tooth sprocket, but the tire to swingarm clearance won't allow you to move the axle forward enough to allow use of the same chain. Your only solution now is to add two links to gain 16 mm more chain length. A quick change sprocket carrier doesn't really result in quick change gearing — does it?
 

·
Registered
Joined
·
129 Posts
Yeah, firming up the settings is just a logical compromise as I no longer have a set up track bike. I ran it by Zeno, the guru who re-built my forks for me. Should be a good start as I did a few sessions at EC and run it with the std Ducati settings. Was fine for my pace but not ideal out on the back roads. Can't have best of both worlds, too different.
 

·
Registered
Joined
·
110 Posts
I am running 15/41 on the stock chain length.

No problems with the tyre rubbing currently but it had a few miles on it when i fitted the sprocket so a new tyre may run a bit closer.
 

·
Registered
Joined
·
529 Posts
Discussion Starter #19 (Edited)
My New Course of Action...

Okay, here's where I'm at with all of this:

I have 1 brand new Gold DID 525 ZVM-X chain that has been cut to stock size (97 links + 1 master = 98 links) and fits fine with the 848's stock gearing of 15t front/39t rear.

I have 1 new 41t sprocket for my new AFAM quick change carrier that cannot be used with the current set-up due to rear tire/swing arm clearance.

I do not want to use two master links in my chain, so I'm ordering a new 102-link chain. 100 links should be the right amount to run with my 41t, but I ordered a couple of extra just in case! (I stumbled upon www.sprocketcenter.com when looking for a good price on another D.I.D. 525 ZVM-X chain; I was amazed at their prices AND the fact that you can pick a chain as short as 98 links and save big bucks when compared to a 120 chain).

So, once the new chain arrives, the 98-linker will come off and I will size up the new chain to see if it is even possible to set the 39t in the farthest rear position (leaving a few mm for chain adjustment) and thereby--or hopefully--creating enough distance for this chain to be used with both sprockets. I'd really like to benefit from the 'quick change' aspect of the new AFAM carrier, but Chad at Sprocketcenter doesn't believe I'll be able to accomplish this. If he's right, I'll be all set with a 98-link chain for my 15/39 gearing and a 100 (or 102)-link chain to use for my 41t set up!

The good news: After a few times of changing these out I'm sure I'll get rather 'quick' at it!
 

·
Registered
Joined
·
6,790 Posts
Oh dear - you have been 'doing it tough' Charles. We were trying to save you such headaches..

So it looks like you will have to run the longer chain to use your 41T and 15T front. Which I'm sure you will like anyway.

Unfortunately you will not be able to achieve chain tension with the longer chain and a 39T rear. To swap back to the 39T you will have to run the shorter chain. Or buy a longer swing-arm, which I'm sure was not part of your plans!

I found I could only just get chain tension with the two-links-longer chain and a 40T rear and a 15T front. That was with a brand new chain.

Another factor in this is if you run increased ride height, you slightly reduce the distance between the sprockets. Conversely, if you reduce rear ride height, it slightly increases this distance.

Of course you need to allow for the chain tension to take up as the suspension is depressed. Get a big mate to sit on it for the final tension check.
 
1 - 20 of 53 Posts
Top