According to the wiki
http://wiki.gstwins.com/index.php?n=Upgrades.Sprocket
they have just a minor design difference, dimensions are the same. As it's not stated that they are interchangeable, I just decided to check. Besides compatibility, is there any difference in design that would make the newer model work better in some way or last longer?
Newer has a flange that keeps it from tearing up the spline.
You should be able to shim the old-style sprocket with a large fender washer; IIRC, GSJack has done this, and he has well over 100,000 miles split between two GS500s... hopefully, he'll see this thread and post more details.
That shoulder on the new-style sprockets acts only as a spacer, not really a load-bearing component, so shimming it is perfectly acceptable if you don't want to buy a new sprocket.
If you want to do this, take the sprocket to a hardware store and match up some large washers to it; make sure the ID of the hole in the washer is at least as large as the splined hole in the sprocket, so you won't have clearance issues. You could even use JB-Weld and some clamps to bond the washer to the sprocket, but that is probably overkill...
I've suggested a cheap fix; of course, you could always sell the old-style sprocket and buy the one you need, but this method will allow you to do some backyard-engineering, if you're into that sort of thing...
Copied from my recent post:
I used 3 Sprocket Specialist replacement sprockets on my 97 GS that did not have the hub over a period of approx 40k miles. I questioned SS about it and they said the front sprocket would be located by the chain and rear sprocket and would run OK without spacers or hub. This turned out to be true and every time I opened the sprocket cover the front sprocket was located right next to the retaining clip in perfect alignment.
I put same type SS sprocket on my 02 GS with the first chain replacement and ran it all winter with the rear wheel a bit out of alignment and when I checked the front sprocket in the spring it wobbled a bit on the shaft. Turned out the sprocket spline bore was worn excessively but the shaft was OK and I went back to sprockets with the hubs after that. So the hubless sprockets will work but the ones with the hub are better, must be the reason why Suzuki made the design change to add the hub back around 1993.
http://img.photobucket.com/albums/v443/jcp8832/GSbrakeschains.jpg
Thanks for the input, Jack; sorry I got the details wrong... do you think that shimming the sprocket with a large washer would work? Bonding the washer to the back of the sprocket wouldn't hurt, would it? For some reason, I seem to recall SOMEONE doing this; obviously, I thought you'd done it. My memory has failed me again...
Quote from: GSnoober on August 24, 2011, 06:07:29 AM
That shoulder on the new-style sprockets acts only as a spacer, not really a load-bearing component, so shimming it is perfectly acceptable if you don't want to buy a new sprocket.
That's not really true, the early models with unshouldered sprockets had a tendency to shred the splines if used `enthusiastically` for long periods. Suzuki introduced this mod in an attempt to reduce wear between the shaft and sprocket. The shoulder increases the amount of area on the female splines within the sprocket that the male splines on the OP shaft act on. Because the torque transmitted between the shaft and sprocket is transmitted over a greater area the forces involved will be less concentrated and therefore wear rate will be reduced. The shaft itself has never changed over the years but at the time the sprocket mod was introduced the spacer on the shaft that the sprocket sits up against was shortened to accommodate the sprocket shoulder.
Personally I wouldn't want a separate spacer behind the sprocket unless its fixed to the sprocket or the shaft itself. It would be likely to spin freely and ultimately cause unwanted wear or damage to the shaft/sprocket/shoulder.
Thanks for the input everyone. I don't have a spare old sprocket or anything, it's just that the old sprocket costs a little less, but clearly the new one is worth a few extra bucks.