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Sprocket and chain swap 748

Discussion in 'Mechanical & Technical' started by Fighterama, Jul 2, 2005.

  1. This is a one-man sprocket swap on a Ducati 748 superbike. Somewhat graphic intensive, and there are more images available to those who have an interest or need to see a part/process more closely.

    First, make sure you have a clean workspace, room to work, proper tools for each task, and the ability to support your bike. Have necessary washers/new hardware/clips/replacement parts that will allow you to finish the task without having to stop mid-stream as I did to get something.

    Here is the first shot, bike supported, as it was ridden last, chain with SEVERE looseness issue. NEVER let your chain get this bad!


    Remove chain guard, front sprocket cover, ziptie brake lines out of your way, make the workspace as easy to use as possible (saves time later)


    Loosen your chain adjustment device (on SSSA bikes, there will be an eccentric hub assy that rotates to tighten the chain, std swingarms will have the 2 nut adjusters). Now use your choice of a chain press/breaker, dremel, or die grinder to remove the chain. I will show 2 images, one is removing the mushroom on the pin, the other is how my hilbilly farm-boy ass did it, by cutting the actual link sides.



    Now walk the chain off the front sprocket, place the bike in gear, remove whatever retainer is keeping your sprocket nut from loosening, then remove the front sprocket nut. Std bikes will have a washer with tabs on it, and a large nut that typically requires a ton of torque to remove. Air wrenches work wonders in this job. Ducati uses 2 smaller nuts in a floating arrangement on a splined shaft, much easier to do.

    At this point in my particular exercise, I heard that oh-so-beloved sound, and I began to gently hump the air like a dog surrounded by females. Then this came into view:


    This is what my favorite man in brown had to bring:


    Okay... back to the story:

    This is a convenient time to go ahead and just finish the front sprocket assy. Slip the front sprocket back onto the splined shaft with the bike in gear, tighten the retaining nuts, place whatever protection your bike uses back in place, and the front is complete.


    As this is a 748, I will try to use general concepts but this bike is different than most as far as the brake disassembly, wheel removal, etc.

    Remove the rear wheel and axle (and brake caliper on std bikes), making sure the bike is adequately supported. This may require use of the rear brake to create resistance to get the axle nuts off, or you may have opposing nuts to do the same. Remove the rear wheel from the bike.


    Depending on your bike, you will either remove the sprocket and carrier assy from the wheel or the hub assy. In this case its the hub, so remove both axle nuts, and gently tap the carrier off the axle.


    This may require some modified supporting techniques like this...


    Remove the sprocket from the carrier, making sure to clearly mark or place each washer, nut, circlip in its respective order for proper reassembly. Some bikes carry the cush drive (rubber bushings that soften the blow to the rear wheel, thereby preventing some wheelspin) in the wheel, some in the carrier, so remove and replace according to your model. Once separated, clean everything while you have the chance, and begin the reassembly process.

    Attach the new rear sprocket to the carrier, making sure to replace each part in the correct order of disassembly. In the case of most bikes, this merely means attaching the sprocket back to the rear wheel. For Ducatisti, this is a far more laborious process involving the cush drive nuts, carrier, axle, etc. Replace the carrier on ducs to the rear axle and eccentric.


    As we have already replaced the front sprocket during the tear down process, we are ready for reassembly of the rear. On std bikes, this is the time to reinstall the wheel assy and replace the axle. Keep everything loose as there is a great deal of adjustment still to be done. Replace brake calipers if so removed.

    Have chain broken to appropriate size (95 links in my case) and begin threading chain over top of front and rear sprockets, being sure to keep the chain clean and keep as much lube on the chain as possible.


    Depending on each chain's particular joining link, reassemble the chain on the rear sprocket as it will keep the chain from moving while trying to thread the new masterlink. In my application, I was provided 2 masters, one rivet type, one RJ clip masterlink. As I have never used a clip type, I will be testing it out for a while, then depending on whether it scares me, I will be placing the rivet link (If I borrow someone's riveter).


    Now that the links are firmly in place, begin adjusting your chain to the proper tension. NOTE: For those with std swingarms, make certain to keep the rear axle as parallel as possible to the direction of travel <ie., STRAIGHT> by measuring with a ruler instead of relying on your adjusters. The better the alignment, the better your handling and decreased chain/sprocket wear. On Ducatis, the eccentric handles the alignment, so all SSSA bikes just have to concern themselves with correct tension.

    DID reccomends 20-25mm of slack at the midpoint of the bottom of the swingarm, so be sure to get very close to this measurement. Too tight will cause premature wear and possible failure, while too loose will cause wear and poor performance.

    Reassemble all guards, be sure to repressurize your brake system if so removed as it will takes several pumps to get it tight again. Take one last look at your tension, be sure ALL nuts/bolts are tightened to spec, and clean thoroughly as you have space to do so.


    Ok, go ride the piss out of it!

    Be sure to lube the chain at regular intervals (300 miles) to protect it, and for the first few hundred be conscious of tension as some chains may stretch more than others.

    In this I used an AFAM rear steel sprocket mounted on an AFAM milled magnesium quick change carrier. Front sprocket is ducati factory steel replacement. Chain is DID 520 x-ring.

    Any questions, comments, information, things I missed, photos you need, or any other assistance please dont hesitate to post, comment, etc.

    aka fighterama
  2. Make sure you have the closed end in the direction of rotation on the clip. It looks like you have it right, but I thought I would make a note to those who are going to attempt a chain change themselves. On another note, I sent my dam riveter up there for ya an ya still put the clip on. sheesh... you'll learn when the chain hits ya in the back and damages that perdy duc. Just being onry, I truly hope that doesn't happen like it did to me. Can ya tell I hate clips ? :shock:

  3. Good write up bud. So now how much bigger or smaller are your sprockets? How much for that chain? What size is the chain 520, 525, 530 ????
  4. Nice write up Eric! Having witnessed clip failure I'd go with the rivet!

  5. Ironically, it appears that your rear sprocket was "the b*tch" to remove and the front was relatively simple. My suzuki required an impact wrench to loosen the front sprocket assembly, but the rear was SUPER quick to remove (a simple 5 or 6 nuts). I spent like 2 minutes swapping out the rear and a good 45 minutes to swap out the front. Looks good, I'm anxious to see if you notice a difference in performance.
  6. I hear what your saying Johnny-B, I think the factory gets a little excited with lock tite. I guess its better they use too much then not enough. When I did my rear sprocket, one of the nuts didn't come loose. Insted the stud came loose from the wheel. Anyway just thought I would share.
  7. Nice-thanks for taking the time to do this- I think this is a area lots of riders neglect
  8. As to the clip... Im tryin it out for a few days, see how it goes, see if it loosens, etc, then Im going to switch back over to the rivet as I have both. Will definitely take you up on that riveter. I didnt put the direction of the clip info in as its on the packaging. The Duc rear is a BITCH to change, thus the rear quick change mod. Also there is no giant nut to remove on ducs, its the two small ones on the retainer, very easy to change.

    I went X ring chain, 520, from DID, cost $105 from ducsea after I talked him down a little in price. Not huge HP figs so I stuck with the smaller, lighter chain. Sprockets are stock front, +2 in the back. DEFINITELY different. Comes out of the turns harder, closed some gearing gaps in 2-3-4, and pulls up on the throttle in first now, which it didnt do before.

    Also on the working end, I get to cheat as I have a full array of air tools to use, makes jobs like this cake.

    Any other input?
  9. Did you torque the sprockets to specs-sure you did just thought I would mention it-

    lock tite-curious
    re-adjustment after x miles

    I would get the rivet link on-especially since you rail that thing- Never heard any good come from a clip link-

    After its up for a while I will delete the other posts and just lock it for info value-

    Thanks again

    Feel free to post up again if you have projects that could help others with their own issues- Its good to see someone working on there own stuff- Anyone that rides something that could kill them should know enough about their bike and upkeep to know how to do tasks that only require basic hand tools-
  10. Afam doesnt provide appropriate torque specs for their parts, so you use the gold standard of 40lb/ft of torque on non-specialty metals. Did not use loctite as these parts are made to readily be swapped, thus they have anti-backthreading measures, and since its all new, I will be keeping an eye on it for a time. Retightening will be an every ride affair until I see no loosening in all affected parts. Was thinking about the riveter, might try to dig one up this week and be done with it, so many people are saying that clip links have failed them Im a bit leary, esp on HARD rides.

  11. Shwaa

    Shwaa Retired

    Great write up Eric. Nicew pics and easy to I need to get a Duc so I can practice.