Hitchcocks Forum

I noticed a CLUNK when I pulled my bike (2010 G5, 10,000 miles) onto the centre stand. Comes from top of LH fork. The sound can be repeated by rocking the bike on the stand, and occurs as the forks reach the fully uncompressed state. It doesn't happen off the stand, and the bike seems to be handling fine as usual.
Recently I drained out the grey sludge and replaced with SAE10 fork oil. There was a slight problem removing the LH cap nut to drain the oil - it was turning in both directions, along, presumably, with whatever it's attached to inside the fork. A whack with an impact wrench eventually shifted it, but I'm wondering if all the prior turning back and forth of it has dislodged something inside.
The diagram in the workshop manual isn't very helpful in seeing what's attached to what.
Any thoughts?
Thanks,
Will

Good morning Will. All the workings are inside the bottom alloy slider. Only the main spring goes up as far as the top of the stanchion. The bottom nut you removed is on the bottom of the "Hollow slider stud", but I would call that the "inner damper tube". There is a nut (Shown as no2 on diagram) on top of this damper tube that holds the top damper valve in place. I guess it might be possible that if you spun the damper tube fast enough whilst attempting to undo the bottom drain nut it could have loosened this upper nut on the damper tube, then the extra slack could then be heard as a clunk. If it worries you, it might be best to undertake a complete fork strip down to check and take the opportunity to renew bushes and seals and clean out all the old gunge with paraffin. BTW, sometimes applying the brake and rocking the bike can cause a clunk but this is sometimes the small movement between the brake plate and the brake locating slot in the fork bottom.

Just noticed you say it is a 2010 G5 model, I cannot confidently say the internals of the fork on this late model are the same as the earlier Classic forks, but if you have a diagram for them (I don't) you can see and compare the likeness for yourself and therefore the possibilty of what I suggested could still exist.

Thanks Les. That is pretty much what I was visualising - the damper tube undoing itself at the top while I was turning it by trying to get the cap nut off at the bottom. There was a good deal of turning back & forth before I hit upon the impact method, so it does seem likely that's what's happened.
My next move was going to be removing the cap nut again and seeing if I can then turn the damper tube with molegrips (well padded around the threads!) in the hope that it will bite and screw itself back in at the top. It's a long shot I know, and probably unlikely, but sometimes the gods are in just that kind of mood......
Otherwise, yes, it looks like a strip down job, grrr.....

Will is there enough thread exposed to lock two nuts together? You could wizz it round clockwise with an air gun socket driver then or use an electric drill to drive the socket. The chance of it tightening up would be slim though and we are not absolutely sure if the top nut did come loose in the first place!

There's enough thread for two thin ones, but I don't have anything that'll fit. The molegrip idea was a non runner. I drained the oil again, removed the front wheel, caliper etc as per the workshop manual, which then tells me to "gently tap the fork bottom downwards and remove the bottom tube". As it turns out, this is balderdash. Nothing short of a hacksaw will remove the bottom tube - not gentle tapping nor heavy tapping verging on whacking!
I've had enough and will now reassemble it and see what the local bike mechanic says.
Luckily I have another bike to ride while the tracherous Enfield is off the road yet again......

Update -

I took the bike to our local bike mechanic - a long time rider of Enfield trail bikes. He said the forks were "topping" and it's nothing to worry about, since it doesn't happen on the road, only on the stand. I told him I'd changed the oil about 100 miles ago, and he thought perhaps I should try something heavier in there, although he agreed the damping is fine as it is.
The SAE 10 I put in the forks is certainly a lot thinner than the (not very much) grey sludge which I drained out. Perhaps it took the 100 miles to work through the system. Anyway, I'll try something a bit thicker. Not sure whether to go for 15w or 20w.
Thanks for your input Les. I'm greatly relieved that it's nothing to worry about and I can carry on thumping....

Hello BIKERBILL -------I'm with LES H on this one as I also have not been privy to the G5 forks drawings as yet. However from my recent winter forks overhaul ( 2005 Classic 500 & Bullet65 a few years back) I can tell you that the fine thread protruding out of the lower leg has a habit of also "threading" itself into the close-fitting aluminium. Try this---(worked for me)---put the cap nut back on and screw back on until just nipped. Unscrew about 2 turns. Holding the lower leg in one hand simultaneously apply a constant DOWNWARD force whilst also applying some smart, UPWARD blows to the cap head with a heavy COPPER hammer. I had to get someone with enough "gravity attraction" to sit on the rear seat to counter-balance----'er indoors did the trick !! Remember to remove that flat, sealing washer as well before attempting this. Continue in this manner until the damper rod is just inside the hole. Now use that "gentle downward tapping of the leg"----and all should be well as there is only a small distance to go. Later, when the lower leg is removed, I filed the hole until the damper rod passed through freely. Replace the flat washer with new ( Fibre and Wellseal did the trick. I don't have the luxury of a local bike mechanic myself------ I AM that person so the buck has to stop with me. Again---this was with a Classic 500 and may not be exactly the same as your G5. Don't give up---GET EVEN and have another go. GOOD LUCK !!!!

Thanks for the tip Alan - I've stored it for when the time comes...
Meantime I'll thicken up the oil a bit and leave well alone, at least while the good weather's here. The bike is handling fine as ever, so maybe it is just another harmless Enfield "quirk" to add to all the others.....

-------PS, forgot to add that my forks also go "Bump in the night" as well. It rides ok, corners well, so I just leave it alone. Get out there and have a BALL !!