3TJ Forks - taking apart?

[Mike Shelby]

Hi - Has anyone any knowledge/tips concerning taking apart FZR400RR 3TJ/4DX forks to put new seals in?

I've tried searching google and youtube but most guides seem to be done using cbr600 forks.

Just wondering whether the internals all come out pretty much complete and held/stay together or if everything comes apart and if I'll have washers, spacers, springs etc all over the place? Don't want to get them all apart and not know how they go back together

Not a job I've done before but want to do it myself so I know for future - but any tips or knowledge about what to expect would be greatly appreciated.

Is it possible to just drain the oil and pull/lever the old seals out from the top and slide in the new seals without completely taking them apart and can the forks be flushed out with anything to get rid of any dirt etc?

Also tempted to put heavier oil in - They should be 10w standard but thinking for 13 and a half stone 15w would be better? From what I gather each leg should have 509mm in - is that correct?

Many Thanks

[Evilchicken0]

I'm at about the same place as you, I need to replace a blown seal.

I think (because I haven't done this yet) that you need to pull the seal out with the stanchion, you can't do it from the top, or at least not easily. This is good because you can wash all old oil off the parts. I'm look to mix 10 and 15 wt oil when I build them up.
As far as I know they're "simple" forks not cartridge type

[Mike Shelby]

Ah ok Boris thanks - I don't have a manual for this bike to refer but I'd assume if I can get one for the FZR600 they'd be pretty similar - just worries me about getting them all back together in the right order. I have a vision of me sitting amongst a puddle of oil with bushes, spacers and springs that have dropped out everywhere and not know how to fix it! Lol

Also with having an R6 shocker of the rear (which is quite a lot firmer than the standard shock) that using 15w would help balance out the front end to match the rear. Most Japanese people tend to be smaller and lighter than us in the UK hence thinking 15w might be the way to go

[Mike Shelby]

One tip I have picked up is to remember to 'loosen' off the nuts on the top of the stanchions before undoing the fork clamps and removing the forks - otherwise the whole tube will just spin around in the lower leg with no way of easily gripping it without damage

[dobbslc]

As above but loosen the top yoke bolts first as they will grip the top of the tube and nut. Put some pressure on the top nut as the spring will try to escape. Obviously support the bike using straps on the yokes or frame before undoing anything. Pull them out and drain out the stinking old oil. Old clothes needed here!
You will need to undo the Allen cap head bolt on the bottom of the forks next 8mm I think. Use a good quality allen driver bit on a ratchet because if you round it off you're stuck.
You will probably need to hold the damper rod still inside the fork bottom as it will want to spin around with the bolt, Sometimes you can shamfer a broom handle down and jam it in otherwise you will need a long bar with the right sized nut on it.
Once that's out take out the dust seals and don't forget the circlip on top of the oil seal.
Then bolt the fork bottom into a vice and pull hard on the stansion a few times to bash out the fork seal and top bush. it can feel brutal doing this!
Now clean and reasemble. Be careful with the new seals use some oil on them.
Fill with oil and bolt back together using a new copper washer, I always use some thread lock on the bolt.
That should do it!

[Wraith]

You beat me to it.............

I just spent ages writting Step by Step Instructions

[dobbslc]

That took 20 minutes on my phone!
Add anything you think I've missed out though.

[Mike Shelby]

You beat me to it.............

I just spent ages writting Step by Step Instructions

'Step By Step Instructions' - is VERY good for a monkey like me!!

So does everything inside the forks all fall apart - or will all the internals stay fastened together?

Thanks for all the advice chaps - this is new territory for me

[Evilchicken0]

You should be able to take the spacer and spring out once you've taken the top nut off.

[Evilchicken0]

Try page 133 in the 3TJ parts manual for the exploded diagram