Fork Travel

[chalky]

I've just stripped and my forks twice. One of the seals leaked so I changed both again. After the first rebuild I had problems with the forks bottoming out, but I sorted that with preload.

Decided to check the travel before installing the fork cap, and I only have 100mm of travel. The shop manual states it should be 130. Everything appears stock, and I can't judge anything from before the rebuild as I restored the bike as soon as I got it.

Does anyone have their forks in a state of disassembly where they can check the distance between fully compressed, and fully extended? Or does anyone know what the correct measure is please? It might save me a another strip.

[seth]

did you fill the cartridge by pumping the damper rod before topping up the fork oil

[chalky]

I did. I've just taken them apart again to have a look. On the K5 and onwards there's a yellow bush that inserts into the bottom of the stanchion - it has a lip to stop it going all the way through. It's a different part no to the K2 and I can't find any pictures of the K2 bush.

Although I expect the K2 to be different due to the part no, I'm surprised that it doesn't insert into the bottom of the tube - it's 2mm too fat and doesn't have the lip. It's also 3mm long which is equal to the amount of travel lost I have 1mm vs. 13mm in the shop manual. So has someone put the wrong part in, or is this the correct set-up? It's odd that the bush fits perfectly into the bottom of the fork leg - kinda like it's supposed to.

If the spring fully compresses before the tube bottoms out [which seems logical], then I guess it's normal. If the tube bottomed out first it could well jam in there and damage the lower slider bush.

If anyone has a set of K2, K3, K4 forks stripped, good if you could tell me if the bush is yellow or white, does it fit inside the stanchion, and does it have a lip at the bottom.

Thanks

[seth]

you didn't say what year it was k2-k4 are same internals k5 on are the same but early and later internals are NOT interchangeable
different spring lengths oil levels and cartridges between them even the fork stantions are different.

[seth]

p.s. welcome along to the forum I'd get myself along and introduce myself to everyone and then have a good look through the various threads as a lot of info on forks difference's and servicing them .

[Hooli]

From memory on stripping my forks the bush is white on a K2.

[chalky]

My zero isnt working on the keyboard....edit:

Although I expect the K2 to be different due to the part no, I'm surprised that it doesn't insert into the bottom of the tube - it's 2mm too fat and doesn't have the lip. It's also 30mm long which is equal to the amount of travel lost. I have 100mm vs. 130mm refered to in the shop manual. So has someone put the wrong part in, or is this the correct set-up? It's odd that the bush fits perfectly into the bottom of the fork leg - kinda like it's supposed to.

IIs a K2. I just need a pic of the K2, 3, 4 pladtic bush, or comfirmation that it doesnt insert into the stanchion as is the case on the K5+

[seth]

they are totally different parts its strange but true .
i once got a spring kit (k2 to got my k6) from a friend and thats how i know nothing is inter changeable
.

[Hooli]

They do insert into the bottom of the fork, mine often stick there when I take the fork internals out.

Dunno if this pic is any use as those plastic bits stayed in the fork legs, but it does show all the other internals for K2 forks.

[chalky]

Thanks Hooli.....that at least confirms the rest of the internals on mine are original. Can't see the bush clearly enough to determine if mine is the same.

A couple of observations though...
a) Mine fit snugly into the bottom of the lower fork tubes, and stay there when the damper & stanchion is removed,
B) The damper rods fit inside perfectly
C) Mine don't insert insode the stanchions, so the bottom 30mm of travel is lost - that said I dont think the stanchions can compress down that far with the springs and stanchion cap fitted. If it did I'd expect to see impact damage on the plastic bush.

I assume then that its the correct part....but a close up pic of the bush would give me peace of mind

[chalky]

Ok guys finally figured it out. Hoolis pics confirmed what Seth noted in an earlier post - the tubes on the early models have oil return holes close to the bottom of the stanchion, the later models are higher. Makes no difference but easier to identify which ones you have. My K2 forks are completely standard except for the stanchions which are from a K5. The K5 also has a different bush arrangement [yellow with a flange ]and it fits onto then damper which is a tapered step [the K2 is fairly straight]. The K2 bush can be seen in the shop manual photo and is white with a 1mm taper and no flange.

So I assume that the K5 bush wont go onto a K2 rod [due to the tapered step inside], and....the K2 bush won't go into a K5 stanchion because it's too fat. I figure mine were changed at sometime and the wrong stanchions were ordered [most places selling them don't differentiate between years], so whoever did it was stuck with the same problem.

As the bush is 30mm long and doesn't go inside the stanchion, it does theoretically limit fork travel to 100mm [vs 130mm]. But the primary purpose of the bush is to locate the damper rod, and judging by it's condition it never comes into contact with the stanchion - so no harm really, other than it being a bit more tricky to reassemble.

Thanks to Hollie and Seth for their input and for inspiring me to think about the issue a bit harder. Bottom line is they are likely going back together as is, and will make do the tie-wrap test to ensure they're definitely not bottoming.....that is, unless I open up the stanchion hole by 2mm

[Hooli]

Glad you've worked it out, sounds a bit of a bugger that one.

[seth]

glad you worked out the problem.
just a thought rather than opening up the stanchions could you get 2mm off the spacer to make it fit.
id think thats much easier and if it don't work much cheaper to replace the spacers than a new set of stanchions.

good luck

[chalky]

That would have been the best choice seth, but the wall thickness of the bush starts at 2mm going out to 2.5mm at the fat end. I'd be left with less than 1mm after I allowed for clearance.

I doubt it'll do any harm to the stanchion....just got to grind off 1.2mm all the way around. Depends how hard it is....and I'm thinking its probably very hard. Might compromise and take 0.6mm of the bush, and 0.6mm from the stanchion

[seth]

you might be surprised as the stanchions are chromed last during production of them and only in the wearing areas so good luck and take it slow and easy .