Call me crazy, but this is my 2nd fork seal to go south in a few months, and I wonder if there may be some sort of correlation here.  I keep the weight on the bike balanced on both sides, so unless the k100s naturally ride in this way, something is up.  My front tire wears on the left side as if that's where it sits most the time.  The right fork seal is leaking (again, and a lot).

Here is a picture of the front tire, and you can see all the oil / dirt on the fairing in the background from the leak.


https://imgur.com/88eJTx4

over filled ?

tyre wear looks about right for left hand side of the road drivers ....camber of the road !

some of that looks like scolloping from braking late, perhaps you have a feeling of greater confidence going into left handers? Just that little bit harder than the right handers over 10 to 18k miles can be that evident.I take it righthanders involve a gutter and the left a centreline? The fork seal with a sports braced forks, does require you to seat the forks whilst compressed then lock up the axle, even minor skewing of the fork might be sufficient to cause leakage, worth tinkering with to see if it stops.

I don't think it's overfilled, and I don't think it's being caused by a slight skewing of the forks as it's been fine for a few thousand miles.  

Also, 10-18k miles on a tire?! What are you using!  This is maybe 6-7k miles and that's a touring tire.  Anyways, right, I had forgotten abut road crowning and all that.  I'm thinking my next tire will be non-directional so I can just take it off and flip it around when it starts to wear a bit.  2x tire life then!

crikey ....my sport demon on the front is well over 22000 kilometres and still not down to the wear markers

but I guess all you guys ride harder than this old goat


but I agree there is a settling procedure for lining up the forks ....wonder if one has a slight bend ?
did I see somewhere that there is a bush down on the fork sliders inside the bottom leg ..wonder if its worn a little ?

No man the seal wear might be fork alignment and worth a fiddle the tyre is more rider style or inflation level than a fork issue and we use kilometres here so stuffed that one up meself 10 to 18000klms on a shall we say entheuiasticlly riden bike, anyone want to buy a vowel seems i got more than needed maybe i should have said keenly riden

Oh maybe try a stringline the tyres treatment and see how they are related

I have seen a lot of that on chain drive bikes from bad alignment but not on BMWs. would pay to check the alignment, bit of a pain with the centre stand but it can be done and having 2more hands makes it a heap easier. Check your forks for vertical when centred as even a slight twist at the steering head will cause that.

Well as you're going to need a new seal and a new tyre I'd ensure that the alignment is correct on reassembly before doing anything else.

Who replaced the seal last time? Who refitted the wheel after the last tyre change?

Under the oil seal it's a stepped washer, if that is mounted wrong way it can cause a leak.

I dont think this is right, even without oil it must be the same hight.
Put some weight on the back of the bike en see what is happening.

Fairly normal with the wheel turned in that direction.

Possible wheel bearing, is worth a check and replacement.

I seem to remember RicK G advising against using Pyramid brand fork seals. Could your replacement have been one of theirs?

Just a thought.

Paul.

Yeah I found out the hard way and as many here have been saying for ages use the OEM seals they work best.

It might just be that the pipes are so worn and/or have some damages on surface that new seals won't work any better than old ones. I have this issue on my bike.   New fork pipes are 400euros / per unit and it is too much for me, so I just clean up pipes after rides..

(I had a pair of OEM seals installed by professional mechanic last summer.)

I have this problem with one stanchion, Showa forks, on my K75 and am going to try a two pack plastic metal to fill in the pin prick marks that have caused my seal damage, fit a new seal and hide behind gaiters, something that should be fitted by BMW during  manufacture. John

Is it posible to fit fork gators to a K100LT.  I want to keep the winter road crap off the chrome.

Mike

Give these a go Mike they do the job and don't cost near as much as the ones Motobins are selling
http://www.amazon.com/Rancho-RS1952-Shock-Boot/dp/B000CPCCFY

Have you checked Motorworks for reconditioned fork tubes?
They are offering them for £72 exchange per tube and will send them for a deposit until you return your old ones.
That's a lot less than €400 a side.
I could not get the original forks on my '84 to stop leaking. One side had a few pits but the other looked fine. Maybe just wear.
Picked up a perfect later set with the brace on eBay for about £60.
Handles better but a little on the firm side compared to the originals.

The forks currently on this bike are from a k1100 I think.  I replaced the original forks because when I took them off to replace a seal (on the same side), I found the shaft was pretty worn.  So I found this set on eBay for around $120 USD and they looked pretty good.  I installed them myself, unaware of that "install while compressed" thing which I still don't really understand.  I don't really understand how the fork could be twisted?  There's a bridge and the axle to make it stay straight in relation to the other one.  I feel that I might be misunderstanding something there.

After the installation of these forks, there were no leaks or issues for quite awhile, I'd guess around 4-5 months of daily commuting.

On a side note, I just ordered those gaiters that Rick posted.

Also, what happens if I run the fork with low or no oil.  Will it cause damage, or is it just a resistance change?

When you install the forks and the wheel it's possible to end-up with alignment problems if you just tighten everything without compressing the suspension once or twice.

Go back to basics.

The manual (BMW) guidance on tightening the axle bolts is, with the bike on the main stand and the front wheel raised, to tighten the axle end bolt and then the left side axle pinch bolts. Take the bike off the stand. Compress the forks a couple of times. Bike back on the stand and then tighten the right side axle pinch bolts.

If I have disturbed the fork brace, I do the above first before tightening it. The brace needs to be working with the correct front axle alignment, not against it (which can be the case if the brace is tightened first).

Ohhhhh oh yes, of course.  Yes, I did that when I installed the forks.  I was over thinking what was described earlier in the thread.  I had it in my head somehow that he meant the forks had to be held in the compressed position during installation.  Silly me 

The forks like any other mechanical contraption need lubrication so without it they will wear very quickly and be damaged beyond repair.