suntour forks with another problem

petegoodyear

my suntour xcr-lo 100 forks have a small problem the seem to contain some fluid which comes from the seals when the fork is pumped or upside down. i use the bike around campus so it is left outside in the rain.

do i need to just open them up and clean inside, and if so how much do i need to take them apart.

or do i just ignore it and ride them until they break and put something decent in their place.

thanks for some help
pete

supersonic

Seals could be on the way out, but a small amount of oil is normal.

Diagrams are available from Suntour of the internals, but not sure of oil volumes.

ride_whenever

You could give them some tlc, i'd be a good way to learn, but basically do it once, then ride them into the ground and get some rebas!

Northwind

Take this with caution, I can't guarantee your XCR100s are the same internally as my XCR120s, but if they are...

Don't worry about oil volumes, there are none, it's not an oil-bath fork. They're incredibly easy to take apart- undo the 2 bolts in the bottom, then pull, that's it. No oil to spill. What you find inside is, well, very little. In one leg, a sealed gas damper. In the other, the spring and preload adjuster. The plastic cap in the left leg is difficult to deal with if you don't have the special tool, so, don't. You don't need to unless you've broken the preload adjuster. There's no need to disturb the damper or spring unless you're replacing them, and to replace large parts of these forks would be madness, so leave them.

So, next, clean out the fork legs. You may wish to marvel at their lightness, magnesium's cool stuff. Water and mud can easily get in here, "seals" is a bit optimistic, they're not very sealey even at best. I removed the seals and the plastic bushings and gave them a thorough clean, the amount of mud trapped in the seals was unreal. You need to be very careful not to distort the seals- they're not really designed to be removed. When you reassemble, you'll notice that the bushings only fit one way, there's a recess in the fork wall which they clip into.

Now, here I'll say that I run out of knowledge, and ran into just pure DIY guesswork, though I'm not bad at that. Suntour provide very little info as you've probably found out. The fork was originally lubed with some sort of sticky white grease, but I didn't use grease when I rebuilt as it was obvious that it had pushed out from the wear surfaces, and was all gathered up elsewhere in the fork where it was just, basically, muck. Instead, I used fork oil- generous portion wiped onto the bushings inside the fork lowers, and more smeared into the seals, then of course smeared the fork stanchions as well. Then, reassembled. I could have used an appropriate grease here but the fork oil gave a faster/more free response from the forks. A teflon lube may also work better. But the fork oil did the job very well. II figure on relubing them often but that's no hardship, it'll take 10 minutes to do. Grease should be longer lasting but it didn't seem to work too well in the first place. I was also concerned about compatability, there's a lot of plastic in these forks as well as the seals, and some lubes can interact badly with those.

Reassembly is the reverse of disassemnbly Push forks back together (don't force it, if it doesn't move easily then probably the bushings aren't in right), screw in bottom screws, that's it.

You should approach the lubrication with caution, I'm happy with it but that doesn't mean it's right, I might regret this approach in 6 months time. Seek more expert advice if you can... But don't worry too much about stripping these down, it's about as hard as replacing a saddle.

Oh, and I use Silkolene motorbike fork oil, because it comes in pretty colours. 15W is a very pleasing shade of blue.

petegoodyear

thanks for that, just to find some grease and fork oil. then i will give it a go. see if i can't get them in a slightly better condition.

then when they break ill buy a nice set of forks to go in there place.

thanks for your help, esspecially northwind, you guys seem to know everything.

Pete

supersonic

Northwind

Certain versions of the LO fork have a hydraulic cartridge though it may well be sealed. Though as you say, I wouldn't go opening up a sealed cart!

petegoodyear

i tried to remove the fork and could not engourage it to come off, but some more fluid drained out doesn't seem to be much left. i think i will just leave it before i make it unuseable, becuase something is better than nothing. but thanks for your help once again

Northwind

If you're worried about fluid in it, just unscrewing the bottom bolts will act as a drain- and very easy to refit.