Changing Fork Oil.................First time for me

[bizzaro]

1994 K1100LT

So I have done searches, and I am sure it is here somewhere about the procedure for changing fork oil.  I cant find specifically two things.
Torque settings and do you extend your forks or compress them when you put the filler plug back in.  Here is where my confusion begins:

My Clymer manual says to actually "pump" the air out before replacing the plugs!?  I have read here and other places you want the air in there for additional dampinging......................And the BMW manual also says to extend the forks, fill with proper amount of fluid and replace caps!  So which is it?  I am guessing with the forks extended? But what do I know...........................nothing! :dunno

Secondly the torgue settings in both books are all over the map?  I think Clymer says cap torque is 20 N-m.  And the BMW manual says 10 N-m in a couple of places, and  5 N-m in another.  (yep same book two different torgues for the  same screw :nono) 

I do know the drain  plug is "just tight enough". Frankenduck warns of this in his BMW Primer advice. Many have stripped them, so, hopefully these are not an issue already,(like some idiot has got there and mucked them up already) and I can just snug them up.  Should I add a bit of thread lock to the drain plugs?

Thanks in advance,
Bizz

[stryder]

My forks are probably way different on my '87 K75, but based on what I read many years ago about the drain screws, I have always pulled the forks and drained them upside down and have never touched the drain screws on mine. That way I can also give them a good kerosene rinsing before refilling with fresh oil. There will always be an air gap in the forks, above the oil, determined by the oil height. I think what you are reading means to pump the sliders to firstly, to get more oil out, springs out, and afterwards, when filled with fresh oil, springs in, to get air bubbles/pockets out of the oil to get the right oil height and operation before putting the caps back on.

[johnny]

greetings...

pictorial here...

the way i change my fork oil is to take it out for a spin... hot fork oil drains lotts better than room temperature for oil...

i loosen the top fork caps before i put it on the center stand... loose enough to let the air in butts not too loose to let the innards out... then i putts it on the center stand... use a pre measured precut 2x4 from the ground to under the tree to hold the front tior off the ground...

i tape quart zip lock baggies to the fork to catch the oil... i back out the tiny screws at the bottom back... let it and its o ring flow into the baggie... will retrieve those later...

let it go for a while... when you think its done... remove the 2 x 4 and getts on the seat... squeeze the front brake and bounce the forks to squeeze some more out...

back on the center stand with 2 x 4 back in place... then reinstall the tiny screws and o rings... no twerk for me... i just tighten them so they are tight... dont give it that extra cause they will strip...

then i remove the top caps... then getts ready to filler it up with ss8-10... one side getts more than the other... i pour it into a measuring cup... suck it out with a flovour injector... push it into the top of the forks...

after both sides are filled... with forks completely extended... i put the caps back on... no twerk... just by feel that they are tight...

thats it...

suspension fluid getts bad dirty very fast... sometimes i will drain the fork oil... fill it with automatic transmission fluid... go for a ride... drain and refill with ss8-10... its amazing how much junk comes outta the forks...

j o

[bizzaro]

Thanks guys..................Stryder, fork oil was changed less than a month ago. The guy put the  wrong weight in!(15) So I just needs to trade it  out. 
Johnny........................Let see if I got this straight.  Warm up fork oil. Loosen fill plugs. Loosen drain plugs.  Drain. Pump after it settles a bit and drain somore?  Replace drain plugs with a "French torgue wrench,"Finesse"! Then, with forks extended, fill to specs,(350 and 400 cc). Replace fill plugs and tighten  with a German torque wrench, "gouten tiett"? Ride off into the sunset smiling? :riding: Is that about right? And your photos are great.  Love your garage.  Mine is just like that except it is not paved.
Thanks Again,
BIZZ

[johnny]

rodger that... its the way i do it... some take the wheel off and drain from the very bottom bolt...

i always put paper or cardboard down cause ive been known to spill...

can use aluminum foil to cover brakes... the oil will flow fast... dont want it on the brakes...

finesse it... dont force it...

j o

[TimTyler]

... some take the wheel off and drain from the very bottom bolt...

That's what I do.

Make sure you have new crush washers whether you drain from the drain bolts or the big very bottom bolts.

[bizzaro]

Mission accomplished!  Thanks for the bag trick Johnny. Worked like a charm.  Just a couple o drops of oil got loose on  the abs side. What a handling improvement, Holy shit.  I can actually feel the road now! :clap:

Tim, how would you pump your forks with the wheel off to push the last few drops of oil out? Put a block of wood under the forks? And does draining from the bottom change the fill quantity? I  will be changing the front tior soon and may go that way.

Problems:
1. Tried to pour fluid into a funnel from a beaker.........................big mistake. I had no flow control.  I lost a good bit of fluid, and got fork oil all over the  bike! :nono Had to guesstimate loss-age and add accordingly. Next time its a baby bottle with a nipple.

2. The drain screws where fine. My right fill plug was stripped......even though it did back out for the fill,  when I went to replace it, it went in and just spun loose.................shit......I could not get it to bite and back out. WTF.  I had to take off the fork cap and back out the fill plug putting pressure on the inside of the fill plug with a gear puller.  All the while turning the fill plug with an allen wrench on the other side.(where the F did I put that third hand?) It got cross threaded in the process so I just screwed the fork cap it back on for now.  I will be ordering a new fork cap with filler plug as soon as I find out what forks are on my bike? :mbird

3. In removing the fork cap I got a look at the inerds just enough to see a unique space washer that is only on K1 and K100 bike forks?  MY bike is a K1100LT!!?? :dunno  The K100 takes 400 cc's per fork and the K1 takes 440 to 450 cc's?  So I gots to figure out which forks I have and do this again once I figure out which fork cap I need to order and how much fluid it takes. 

AT ANY RATE THE HANDLEING IS MUCH BETTER!!! :riding:

[Scott_]

I hear you on the stripped fill plug... I had one strip on me a few years back. Like you, I had to remove the fork cap and replace it with new.
Since then, I just remove the entire fork cap when I change fork oil. No longer have to worry about stripped plug threads, or replacing the crush washer that went with it.

[johnny]

i remove the entire fork cap too for the same reason... my filler plugs are also striped... what i did was wrap them with electrical tap... tapering it thin at the bottom and thick at the top... then slowly screw them back in... finds enough threads to latch on down in there... makes their own o ring and tightens up real nice...

the bug was whack like that... the burd is whack like that... and the brick of the corn is unmolested... yeeeehaaaaaa...

j o

[TimTyler]

Tim, how would you pump your forks with the wheel off to push the last few drops of oil out?

By hand.

[bizzaro]

Tim I don't understand pumping the forks "by hand"?


Johnny, You have an RS right?   Anyway I was going to do a similar fix as you did except use epoxy on the filler plug screw!  But try as I will, I can't get it out.  No matter what I have tried it will not back out, even with pressure on it!  So I am considering having it welded in place. Or stuffing the hollow inside cap with RV?  I am not sure if RV would stick or how long it would last, if at all?  I have Red, Blue, and Ultra Black on hand.  Would any of these work?
 
Thanks to all...................................BIZZ

[TimTyler]

Tim I don't understand pumping the forks "by hand"?

With the bike on the center stand, the engine supported with wood blocks and the front wheel removed, grab the lower forks and move them up and down.
Obviously you won't compress the springs but you'll create pressure that will shoot the old fork oil out through the drain.

If your forks have never been cleaned inside you might benefit from it. It's not rocket science but it takes patience. Overhauling the forks was about the first maintenance I ever did on my K75 and I had no moto maintenance experience at that point.

[bizzaro]

OK, like Johnny said in my first post ever on this site;

 

greetings...

stop your freaking and commence to motobricking...

  I looked up my parts at Maxes and the micro fiche shows that  the correct forks are on my bike.  Color me dumbass.  The Clymer manual is not exactly correct!  I know big surprise right :falldown:  Clymer manuals are a bit like the internet.  Lots of good information available, but just as much is inaccurate.  You have to have the wherewithal to discern between the two!

[BlitzenGruv]

greetings...

 sometimes i will drain the fork oil... fill it with automatic transmission fluid... go for a ride... drain and refill with ss8-10... its amazing how much junk comes outta the forks...

j o

Nice trick. The disc-brake forks on '70s Triumphs actually use ATF for fork oil.