O.K. here goes. I got an aluminum swing arm from an s4 (2001-2002) and I want to put it on my 620 (2002) to replace the steel one and to have the nicer shock. The s4 swing arm apperes to be the same one as the ducati performance part #69922091a all the hardware looked right so I started disassembling... When I started to reassemble the bike I found some things that didn't quite fit [smiley=huh.gif]. The stock 620 swing arm axle that mounts to the engine case is to long on the outside of the arm; I don't have the one off the s4, but I shimmed the axle from the 620 so it should be fine. I had to grind some flashing off the eccentrics that hold the axle to get it to fit in the new arm due to the increased wall thickness on the aluminum swing arm, no big deal. I got a set of those axle adjustment plates (the things with the hash marks for wheel alignment) from an 851 and opened them up to the proper I.D. for the 620's larger axle. I got the wheel on and noticed a few more things. The brake caliper mounting braket on the 620 has a larger slot in it than the one on the s4 so I should be able to un-screw the one in the aluminum arm and fabricate a larger one but the real head scratcher is the chain guides. They seam to be about half an inch off to the outside of the bike. (the chain's left side plates ride on the ridge of the guide.) I don't know what to do. It appers that the s4's chain is off to the side a bit more than the 620 maybe for increased tire clearance. I could either sand off the ridge on the guides or move the spacing on the sprockets (I don't know how I could do that) or maybe ducati has a different set of guides. Does anyone have any experiance in this or have a senna (I believe it's the same swing arm) I have looked at the obvious stuff like having the wheel and axle miss aligned and had it looked at by my buddies as well in case I missed something and we're stumped. Also if anyone has the plates that go on the back of the swing arm and the eccentrics (the adjuster bolt may be in a different place than the one's from a 620 because I got a set from an 851 and they are.) that hold the axle and wanna sell them let me know. I fabed a set of the plates on the back of the swing arm out of steel. They're functional but not as pretty. If you read it this far thanks I just wanna ride my bike.
Help on an s4 swing arm on a 620 (long)
1 - 7 of 7 Posts
Joined
·
332 Posts
hmmm...... S4 = 4 valve motor. I would think the motor would be physically wider and maybe have different geometry as far as chain spacing. Thats my guess.
Joined
·
340 Posts
If the chain guide is your only problem and it is only a little out of wack, I suggest a really big hammer and a little attitude adjustment. I have had to do this to my dirtbike before, of course hitting my monster would be harder to do, but you have already ground on.
If you put on the wider S4 wheel and cush drive then only the sprocket will be off and that can be changed as well. So the question becomes what do you want to do in the end. If you want the narrow wheel for handling reasons or the wider wheel for looks? You can move the drive sprocket out to the end of the drive shaft by fabricating a flat retainer plate and using a screw into the end of the output shaft. That solution has been working fine on my 908SSP for four years.
I was hoping that I could just change the chain guides and be done with it. I called my local dealer and they did some looking into the part #'s and it appers that it is the s4 swing arm is the same part # as the swing arm on the 620 Senna. Also the chain guides are the same part number so either the 620 senna has a wider wheel or they spaced the sprockets over. (the parts guy also said that in the past some parts may have the same number between different bikes but still don't fit from one to the other.) If anyone has a Senna and could take a look I'd appreciate it. Thanks for all the help guys.
Joined
·
3,178 Posts
actually, all the non ST/S4 wheels' hubs are the same, regardless of rim width. BUT that doesn't stop ducati from moving the engine right or left relative to the outer dimensions of the swingarm. (example m900ie with its own special front sprocket).
i suspect that the ST/S4 wheels hubs are the same, too, but we'll need to look at `em first.
yeah, i'm worried about chain line, too...
1 - 7 of 7 Posts
