How can I tell if my shock/springs are worn out?
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From: Biker Dude on 25 Feb 2010 15:44 The bike is an 82 Kawie KZ550 - C3, and I'm contemplating some suspension work. The obvious work would include the installation of new spring/shocks and rebuilding the forks. Before I begin I am wondering if the repairs are really needed at this time. Are there specific, objective tests of these components that say "go" or "no go"? Or are decisions made by "If it feels worn out it is"? I do have a toolbox, a Clymer manual, and a positive mental attitude. So tell me, Fount of All Knowledge, what are the objective means or methods to test these components? Thanks in advance, Biker Dude.
From: The Older Gentleman on 25 Feb 2010 15:57 Biker Dude <jacobsenpaule(a)hotmail.com> wrote: > The bike is an 82 Kawie KZ550 - C3, and I'm contemplating some > suspension work. The obvious work would include the installation of > new spring/shocks and rebuilding the forks. > > Before I begin I am wondering if the repairs are really needed at this > time. Are there specific, objective tests of these components that > say "go" or "no go"? > > Or are decisions made by "If it feels worn out it is"? > > I do have a toolbox, a Clymer manual, and a positive mental attitude. > So tell me, Fount of All Knowledge, what are the objective means or > methods to test these components? > Objective testing would require all sorts of measuring apparatus and kit. You'd need to measure the springs against factory length as new, measure the spring rate against factory spec, etc etc ad infinitum. Just assume that on a bike that's nearly 30 years old, and which was built with crude suspension in the first place, that the shocks are knackered and the forks probably worn out too. Mileage helps here - under, say, 20k miles, you might be tempted to leave things alone and only replace if you can feel (for example) a bouncy rear end and soggy forks. Over 30k miles and still on the OE shocks? Throw them away and take it as read the front will need attention too. Rear shocks are dead easy to sort - unbolt old units, throw away, bolt on any decent branded pattern that fits. Forks: I'd start with some quality pattern springs, a fork oil change - the manual will give the right viscosity - and maybe new seals. All pretty simple stuff, and cheap too. Remember that, like I said, you're dealing with an old bike with a very old-style chassis. There's not much you can do to make it handle like something more modern. But a simple rear shock change and a fork rebuild will definitely help. I wouldn't bother getting more ambitious than that. -- BMW K1100LT Ducati 750SS Honda CB400F Triumph Street Triple Suzuki TS250ER GN250 Damn, back to six bikes! Try Googling before asking a damn silly question. chateau dot murray at idnet dot com
From: paul c on 25 Feb 2010 19:45 The Older Gentleman wrote: > Biker Dude <jacobsenpaule(a)hotmail.com> wrote: > >> The bike is an 82 Kawie KZ550 - C3, and I'm contemplating some >> suspension work. The obvious work would include the installation of >> new spring/shocks and rebuilding the forks. >> >> Before I begin I am wondering if the repairs are really needed at this >> time. Are there specific, objective tests of these components that >> say "go" or "no go"? >> >> Or are decisions made by "If it feels worn out it is"? >> >> I do have a toolbox, a Clymer manual, and a positive mental attitude. >> So tell me, Fount of All Knowledge, what are the objective means or >> methods to test these components? >> > Objective testing would require all sorts of measuring apparatus and > kit. > > You'd need to measure the springs against factory length as new, measure > the spring rate against factory spec, etc etc ad infinitum. > > Just assume that on a bike that's nearly 30 years old, and which was > built with crude suspension in the first place, that the shocks are > knackered and the forks probably worn out too. > > Mileage helps here - under, say, 20k miles, you might be tempted to > leave things alone and only replace if you can feel (for example) a > bouncy rear end and soggy forks. > > Over 30k miles and still on the OE shocks? Throw them away and take it > as read the front will need attention too. > > Rear shocks are dead easy to sort - unbolt old units, throw away, bolt > on any decent branded pattern that fits. > > Forks: I'd start with some quality pattern springs, a fork oil change - > the manual will give the right viscosity - and maybe new seals. All > pretty simple stuff, and cheap too. > > Remember that, like I said, you're dealing with an old bike with a very > old-style chassis. There's not much you can do to make it handle like > something more modern. But a simple rear shock change and a fork rebuild > will definitely help. I wouldn't bother getting more ambitious than > that. > > > From the shop manuals I've seen, usually the only spring check is length. That's pretty easy. Rear shocks wobble and bounce when they are shot, especially on turns, that's pretty easy to check too. Standing on the pegs and leaning on the front shocks is pretty easy as well, just compare with how a new showroom bike feels. Some old-style forks need a special bit to undo, not sure about Kawasaki, but with some filing you can make the square tip for many Suzukis from a larger hex socket bit. Putting new front seals in isn't hard but needs care and gentleness to put them in square and there's no point if there are a lot of scratches or corrosion. One or two little scratches usually don't matter. Pretty important to make sure both have the same amount of fork oil Straightening front forks isn't hard but it's best done with an H-press and a true table, maybe even a dial gauge. However a straight edge is good enough for making sure they aren't bent more than 1/8" or so over two or three feet. Any little grit can work its way into rubber and ruin fork stems. I know quite a few riders who clean chains religiously but never wipe down their fork tubes!
From: paul c on 25 Feb 2010 19:52 paul c wrote: .... Forgot to mention one trick I've seen but is not mentioned in all shop manuals - before removing front stems, try to loosen the bottom bolt on traditional forks, ie. before unclamping from the tree, might save having to put them in a vice or using a impact wrench or driver to get those old bolts undone.
From: paul c on 25 Feb 2010 20:08
paul c wrote: > paul c wrote: > ... > > Forgot to mention one trick I've seen but is not mentioned in all shop > manuals - before removing front stems, try to loosen the bottom bolt on > traditional forks, ie. before unclamping from the tree, might save > having to put them in a vice or using a impact wrench or driver to get > those old bolts undone. Everything might go well as it has a few times for me, except that a couple of times I forgot to have a pan and some rags handy when I unfastened the tube, pointing down and spilled oil on the floor. Even a few hundred ml's of fork oil makes a nasty mess. |