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Cb550f shock length

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McCabe-Thiele (Ted):
As has been said by Phil I too have no understaing of the complexity of bike suspension design, that does not impede me from having an opinion based on "Teds Iffy Logic".

So here it is, were talking here about a difference of 10 mm in total length that does not sound like a big deal taking into account the varying weight of any individual rider when sat on his machine has a different nul point be they 9 stone or 17 stone spring rate will be most relevant here .

I suspect the big issue is where is this 10 mm difference in length, is it in the damper section (piston travel) body allowing the damper piston to travel further down, or is it in the length of the part between the bottom spring seat and the lower mounting or a bit of both. Chain slack might be only a small  factor. Lastly is there a difference in fully compressed length?

As has  been said going for standard is best, however when they are expensive or hard to obtain then I would not be overly cocerned. I suspect aftermarket damper manufacturers will use a stock damper section length (piston travel) then make the bottom section longer to suit a variety of applications.

As we are mostly riding these old bikes sensibly not on a race track I think it's unlikely to cause us handling problems bearing in mind other factors such as tyre choice, tyre pressures, unsprung weight from different wheel rim choices.

If the dampers are not leaking, passable cosmetically I would not worry about the 10 mm.

DomP:
I'd like to keep the rear fairly close to standard but was going on the fact it has 335mm fitted where as most replacements state 320mm.

Thanks for the replies guys, good to have some opinions to mull over.

Sesman:
I was really referring to dropped yokes…🤔

McCabe-Thiele (Ted):

--- Quote from: DomP on June 21, 2025, 05:23:56 PM ---Can anyone tell me for certain the standard shock length on a cb550f,  mine seem to be standard and 335 centre to centre with the wheels on the ground.

--- End quote ---

I assume you meant rear shock absorbers are you reffering to the front forks?

Gromitdog:
Hi Dom P

From what I been told for a CB550 k3 the rear shocks should be 321mm eye to eye. The link is for K3 below but they do the part shrouded version ones too.

https://www.wemoto.com/bike/honda/cb/550/1978/17132/rear-oe-replica-shocks?srsltid=AfmBOormkEjfHZaOp4q8YC7Hsnmka3yGq7N9xvNHDM_fPSaXcXtWE4VH

But not sure which you should have for a F1/F2 possibly  the upper shrouded ones ?
I found this in my pages of useful info I think Ken might have sent it over to me a few years back

https://www.bskspeedworks.co.uk/downloads/SHOCK%20FITTING%20APPLICATIONS.pdf

Hope this helps you with your question and project build I have just replaced Muttley's 🐕 rear shocks as in the process of doing a frame rebuild and I had the partly shrouded ones on which is not the correct ones for a K3 version I believe & I think there 325mm centre to centre ones (Possibly for a Honda CB750) .

Best Regards
Nigel

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