NC30 fork damper rod troubles, help required.

slug675 · Post by **slug675** » Sat Dec 07, 2019 5:56 pm

I bought some late type forks for my Seed NC30, took them all apart and cleaned, fitted a Rick Oliver fork spring kit and put them back together. All seemed well except i couldn't get the damping the same on each leg. I've partially taken them back apart and found the threaded top of the damping rods are different lengths. One is about 17mm above the lock nut and the other about 10mm.
Can anyone confirm, as i suspect, the longer one is the correct one and if so anyone got a spare Or know where to get one? I will have to strip down the rest of the forks and see if there are any other differences. Cant help but think I've been sold a dodgy fork leg.

richyrd5 · Post by **richyrd5** » Sat Dec 07, 2019 7:23 pm

I could possibly have a spare damper rod,I will get pics to you when I dig it out tomorrow...your smaller could be a cbr 400 one..

magg · Post by **magg** » Sat Dec 07, 2019 10:18 pm

Damper rod forks are the early type and cartridge type are the later. You appear to be describing cartridge type fork internals with an external damping adjuster at the top of each leg, not damper rod. If so, perhaps you have not set the fork cap distances which will mismatch the damping.

slug675 · Post by **slug675** » Sun Dec 08, 2019 10:51 am

Hi you are correct magg they are the later type cartridge not the older ones, my bad. However i have reset the fork cap distances severel times with no joy which led to me measuring the thread length and finding the discrepancy.
Hopefully richyrd5 will have what i need.
Many thanks.

magg · Post by **magg** » Sun Dec 08, 2019 11:16 am

Differing thread length is interesting. If you cannot source matching parts, you should be able to achieve equal damping with differing thread lengths, unless there are other structural differences in the cartridge rods.

Post by **sa.racing** » Tue Dec 10, 2019 10:23 am

magg wrote: ↑
Sun Dec 08, 2019 11:16 am
Differing thread length is interesting. If you cannot source matching parts, you should be able to achieve equal damping with differing thread lengths, unless there are other structural differences in the cartridge rods.

As Magg said the differing thread lengths is interesting but should not effect the damping if you are resetting the clickers, when you say reset the fork cap distances can you elaborate? Are you resetting the clickers or just adjusting the cap height?

If your resetting the clickers correctly (which you probably are if your following Rick O's instructions) then I suspect you may have miss matched internals EG: different pistons and shim stack configurations in each fork leg which would explain the difference in damping.

slug675 · Post by **slug675** » Tue Dec 10, 2019 8:01 pm

I have taken the caps apart completely and put them back together, set them to 15 clicks. When i put them back on the rod and put the forks back together i get 15 clicks on one and about double that on the other which can be screwed inside the cap before stopping. This i believe is down to the different thread lengths. The top of the rods look factory finish and not messed about with at all. I haven't had time to strip the forks down and check the internals yet.

slug675 · Post by **slug675** » Tue Dec 10, 2019 8:12 pm

Hopefully this will link to a picture of the rod and thread heights.

https://ibb.co/zJP3cJv

https://ibb.co/NW2bMjP

magg · Post by **magg** » Tue Dec 10, 2019 9:32 pm

From the pictures there appears to be a number of differences between the fork legs. For one, the C ring groove placement is different. Probably of no consequence provided your setup makes allowance. Are the overall leg lengths the same, they do not appear to be a matching pair.

Regarding the top cap setting, because the threaded lengths are different, you need to wind the damping adjuster in 15 clicks on both caps, then screw the caps onto the rods until they stop and then wind up the locknuts and lock them onto the caps.This will unfortunately apply a difference pre-load to each spring that will need to be equalized by adding a spacer on the longer threaded rod. Also, given the obvious physical differences, the damping valving maybe different, but again can be remedied.

An interesting engineering exercize. Should you decide to use these fork legs and need further assistance, you can pm me.

slug675 · Post by **slug675** » Sun Dec 15, 2019 5:05 pm

Well thanks for the help all and the offer richyrd5. Magg the circlip heights are the same just a trick of the lens, they look better on the second picture. I have now solved the problem. Whoever had them before me must have completely dismantled them and put them back wrong, they came to me half assembled. The lock nut on the rod is only threaded halfway through and must be fitted with the threaded side up allowing the non threaded end to go lower down the rod, the lower part of the nut is rounded. So panic over

Pics below of before and after and the lock nut.

https://ibb.co/1m5Jq0r

https://ibb.co/pPf1MY4

https://ibb.co/GCDdyQy

NC30 fork damper rod troubles, help required.

NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.

Re: NC30 fork damper rod troubles, help required.