OOh zombie thread. Sorry about that.
Its a race bike. Moreso independent comp/reb adjustment than quick removal as i have no experience playing with shim stacks.
Ah yes of course, dont want to make it uncomfortable for yourself.
NC30 Cartridge Fork Issue
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dx400r
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magg
- Senior Member
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- Joined: Mon Sep 20, 2010 11:55 pm
- Bike owned: VFR400
- Location: Blue Mountain NSW Australia
Re: NC30 Cartridge Fork Issue
Shimming is half the fun LOL. And I am still not satisfied, although I can at least alter the compression damping without affecting the rebound. This is the issue I have with the OEM design.
Am I correct to assume that you have found the lack of independence an issue during track setup?
Am I correct to assume that you have found the lack of independence an issue during track setup?
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magg
- Senior Member
- Posts: 1914
- Joined: Mon Sep 20, 2010 11:55 pm
- Bike owned: VFR400
- Location: Blue Mountain NSW Australia
Re: NC30 Cartridge Fork Issue
Thought I might add another chapter to this saga, to thoroughly bore the pants of everyone.
For anyone contemplating refurbishing their forks I would recommend shimming the bushes on both the upper and lower fork tubes to eliminate any movement. Otherwise under load the bushes will bind resulting in poor compliance and impact harshness. A loose fit for the bush in the lower leg is simply the result of manufacturing tolerances and perhaps wear, while the looseness in the fit between the upper leg bush and the lower leg bore is the result of wear of the bare alumimium after 20 years use. Newer fork designs use hard anodizing to give a tougher working surface. New bushes will not eliminate this looseness because the worn aluminium parts are not being renewed.
Shimming the bush on the upper for leg will require honing the first 100 mm of the lower tube bore so that the "oversize" bush will slide into the oversize lower leg. How much honing is trial and error but too much is not a problem because the first 100 mm of the lower is not used in the fork action.
The bush located in the lower leg can simply be packed with shim material to achieve minimum clearance with the upper tube.
I have applied this process to a couple of bikes with good results. To further reduce stiction you could also try SKF oil & dust seals, they appear to offer an improvement also.
This process can be applied to NC35 forks also, just swap the words upper and lower in the text.
For anyone contemplating refurbishing their forks I would recommend shimming the bushes on both the upper and lower fork tubes to eliminate any movement. Otherwise under load the bushes will bind resulting in poor compliance and impact harshness. A loose fit for the bush in the lower leg is simply the result of manufacturing tolerances and perhaps wear, while the looseness in the fit between the upper leg bush and the lower leg bore is the result of wear of the bare alumimium after 20 years use. Newer fork designs use hard anodizing to give a tougher working surface. New bushes will not eliminate this looseness because the worn aluminium parts are not being renewed.
Shimming the bush on the upper for leg will require honing the first 100 mm of the lower tube bore so that the "oversize" bush will slide into the oversize lower leg. How much honing is trial and error but too much is not a problem because the first 100 mm of the lower is not used in the fork action.
The bush located in the lower leg can simply be packed with shim material to achieve minimum clearance with the upper tube.
I have applied this process to a couple of bikes with good results. To further reduce stiction you could also try SKF oil & dust seals, they appear to offer an improvement also.
This process can be applied to NC35 forks also, just swap the words upper and lower in the text.