SOHC.co.uk Forums > CB500/550
Not understanding 500 front suspension 🤔
Oddjob:
The washer and tube look like an attempt to get more spring preload Ted. I'd remove them and measure the springs free length as they are known not to be the best springs in the world, a little too bouncy was the general opinion at the time.
I'm not 100% sure but I seem to recall the tight end of the spring goes to the bottom not the top.
You can drive the new fork seals in with a large socket Ted, saves buying a seal driver. The clips can also be replaced with stainless ones to avoid them rusting. I'd also advise filling the underside of the seal with silicon grease, it helps to stop the spring getting rusty and failing, which is surprising as it should get covered in oil but it doesn't seem to as I've found the bottom of the seals just covered in rust off the spring. Same with the upper spring if it's exposed to the elements.
Myself and Roo bought some fork caps that you can adjust the preload on along with an air valve so you can have air assisted forks, they reckon a bit of air (around 5-10psi) in the forks helps to stop the fork oil foaming.
https://www.ebay.co.uk/itm/362877892416
https://www.ebay.co.uk/itm/314092799547?hash=item492163c63b:g:-sIAAOSwg81i6JUh Those are for the CB450/500T but it's the same seller, if interested just send them a message. Roo has fitted his and found they are too high and hit the bars unless you wind down the preload till it's got 10mm of preload or 2 rings left showing. If your springs are tired that may be just what you need anyway.
McCabe-Thiele (Ted):
If the original springs gave a bouncy ride it might be worth leaving it as it is - I did not ride the 500 any great distance but the ride & front suspension seemed oaky to me for my Sunday afternoon riding style.
I'll check the spring length first if I can work out how to get the nut undone as the shaft just rotates - I can undo the lock nut partly by using a pair of nuts on the thread to hold the shaft but then it refuses to come undone any further due to the remaining spring load - I will see if I can get a tool I have to hold the bar to stop it from rotating.
Not keen on returning it to standard if they were not great in the first place - clearly someone has modified it to cure a short coming.
I'm thinking some replacement better springs will be either expensive or no longer obtainable.
McCabe-Thiele (Ted):
I've managed to undo the lock bolt with an odd tool I have without damaging anything now the Genie is out of the bottle.
The free spring is 445 mm in length - not looking forwards to putting it back in place even without the tube spacer!
The Haynes Manual talks about the servicable spring limit being being 425 mm so the spring length is good.
Any observations or comments welcome ?
I'm minded to put the springs back without the tube spacer.
The spacer is 28 mm long plus a 2 mm washer making it 30 mm in all.
The closer wound coils are at the top end - not sure if that is the right way up - the photo in my manual appears to show the closer coils at the bottom. I
f it ends up too bouncy/soft maybe tinkering with the fork oil might compensate ?
K2-K6:
--- Quote from: McCabe-Thiele (Ted) on January 02, 2023, 09:04:43 PM ---I've managed to undo the lock bolt with an odd tool I have without damaging anything now the Genie is out of the bottle.
The free spring is 445 mm in length - not looking forwards to putting it back in place even without the tube spacer!
The Haynes Manual talks about the servicable spring limit being being 425 mm so the spring length is good.
Any observations or comments welcome ?
I'm minded to put the springs back without the tube spacer.
The spacer is 28 mm long plus a 2 mm washer making it 30 mm in all.
The closer wound coils are at the top end - not sure if that is the right way up - the photo in my manual appears to show the closer coils at the bottom. I
f it ends up too bouncy/soft maybe tinkering with the fork oil might compensate ?
--- End quote ---
Easiest to seperate function to make spring decision Ted.
Spring rate (poundage) has to be set to support machine and rider and should be more or less correct as is.
Preload (squashing it static) sets the ride height of the vehicle, too little and it'll just sit too low in it's travel before you even need the suspension.
Damping (oil viscosity, flow internally etc) just controls the spring and kinetic input thats acted apon it from riding. It won't compensate for the spring as it can only speed up the mass movement or slow it to give control in pace over the forces acting then.
Broadly, without good reason it's wise to put it back as it was.
For fork caps under pressure I let them go to full length (maximum space for spring) then push the cap down with a socket and non ratchet breaker bar, turn it backward until you hear the thread lead drop into place (picks up the first point at which the threads can engage) and while still pushing on it start turning it clockwise to begin tightening. This usually picks up the threads no problem and allows fairly easy installation.
McCabe-Thiele (Ted):
I like the idea of the fork springs being as they were - the spacer tube is not even cut square as I would like it to be.
My current thinking is to find a 15 mm spacer in place of the existing 30 mm tube & washer arrangement. That would give me a bit more pre-load than standard but not so much that the coil was put so far of shape when at rest.
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