Author Topic: Fork oil...  (Read 12635 times)

Offline F14CRAZY

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Fork oil...
« on: August 22, 2015, 10:03:37 AM »
So I decided to go ahead and change my fork oil a few days ago. I figured out my oil amount based off of this site:

http://www.ibmwr.org/ktech/fork-oil.shtml

My forks didn't have the S stamped on top, so I figured they weren't the sport ones (Drake or someone else may have changed them). I did some searching here and googled to try to figure out if I had the "BMW" forks, which I figured were also known as the Fichtel and Sachs forks, or the Showa forks.

Am I correct that the Sachs/BMW forks are 41 mm and the Showa forks are 41.3? I put my digital calipers on the forks and found 41 mm, not 41.3.

So, I refilled the forks with 330ml each, measured with an oil ratio measuring container a non-BMW dealer provided me (they didn't have the syringe kit). I figured I got the quantity pretty close though.

Questions:

Did I refill with the right amount? They feel a lot firmer and have a lot less dive which I consider to be a good thing. I read about how too muhc oil would make them "lock up" but like when I went over a speed bump I looked down and they're traveling a good amount still. Ride is not uncomfortable or jolting or anything. The oil looked like the stuff you'd find in an abused, neglected motor...I should have done it when I first got the bike.

Are you supposed to "work" the forks with the plugs removed to get more oil out before refilling?

I used Bel Ray 10w. Any objections to this oil? I read of Drake preferring Honda 10w but I slacked off and didn't go to a Honda dealer. As I've read it seems that fork oil weights are not standard between brands though.
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline bizzaro

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Re: Fork oil...
« Reply #1 on: August 22, 2015, 01:31:19 PM »
"They feel a lot firmer and have a lot less dive which I consider to be a good thing. I read about how too muhc oil would make them "lock up" but like when I went over a speed bump I looked down and they're traveling a good amount still. Ride is not uncomfortable or jolting or anything. "

So whats the problem??.  I had my seals done by a mechanic,(too chicken shit to do it myself, never again!), When he replaced the fork oil he used Bel Ray 15wt and it sucked! Front end was stiff and hard.  I switched it for some 10wt Maxima that I had around and it was so much better.  No fork dive, but it traveled well in the bumps.  Somewhere here there is a pretty comprehensive fork thread/info that helps determine which ones are on your bike by fork identification, not bike year etc.  I don't have the link right now. You must have read it because you almost quoted from it referring to the "S" stamp.  But if you like the way it is handleing, why worry. ( unless you think you are damaging something?) :dunno
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline johnny

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Re: Fork oil...
« Reply #2 on: August 22, 2015, 05:37:19 PM »
greetings...

ive used belray 10wt 15wt 20wt before... its good stuff...

one key thing abouts the forks... gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed...

j o
  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline TimTyler

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Re: Fork oil...
« Reply #3 on: August 22, 2015, 08:43:10 PM »
...gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed...

Really? My forks suck in and expel air through the seals every time I go over a bump.

I would suggest tightening the triple-tree clamp bolts (bottom first) with the axle in (and tightened) and with the wheel off the ground so alignment is not influenced.

Offline johnny

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Re: Fork oil...
« Reply #4 on: August 22, 2015, 10:29:16 PM »
yes really... ill post up a scan of the bulletin when i getts back to the quality estate...

j o
  • :johnny i parks my 96 eleven hundert rs motobrick in dodge county cheezconsin  :johnny

Offline TimTyler

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Re: Fork oil...
« Reply #5 on: August 22, 2015, 10:31:47 PM »
...when i getts back to the cheez...

Back to the estate?


Offline Zipster

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Re: Fork oil...
« Reply #6 on: August 23, 2015, 07:02:05 PM »
My friend doesn't measure the oil, he measures the air gap and makes sure the oil level is at the bottom of his gauge.
  • Northern Ireland
  • 1996 K1100 LT SE - sold with 104,500 miles in 2015; 2001 R1150RT - 68,000 miles; 2013 Triumph Trophy SE - 50,000 miles; 2007 Harley Ultra Classic - 50,000 miles (Canada bike for stateside use only)
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Offline F14CRAZY

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Re: Fork oil...
« Reply #7 on: August 23, 2015, 08:01:42 PM »
greetings...

ive used belray 10wt 15wt 20wt before... its good stuff...

one key thing abouts the forks... gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed...

j o

but johnny, do you mean to put the fill caps back on? How are supposed to fill it then?
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline bizzaro

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Re: Fork oil...
« Reply #8 on: August 24, 2015, 11:14:41 PM »
Really?  WTF?
1.Use Johnny's bag trick to catch the old oil. works great, no mess. Take your time and tape the bags up so nothing can get by um. Remove the fork drain plugs. Drain the old oil, pump the forks to try and get it all out.
 2.
 Jack or lift the front end so the forks are fully extended.
Replace the drain plugs, use new nylon washers if ya got um.  Be extra careful not to over-tighten the drain plugs, they are known to strip easily.
3.
 Remove the spring retainer screws/bolts on the top of the forks , not the filler plugs, the plugs  like to strip as well................both of mine where! 
4.
 Now you need to measure the right amount of fork oil and refill each fork with the proper amount. My forks use different quantities.  The trick here is to use a syringe or something that will let you control the flow and pour slowly and not spill or run down the face of the container  when you slow down or stop to let the oil draining into the forks catch up.  It takes a bit for the forks to fill.  Put rags around the top of the fork just in case you spill a bit.  I haven't tried um, but a baby bottle is supposed to work well. Or an old cleaned out gear oil bottle with the nipple top.  Honda 8-10 fork oil seems to be a fav. around here. Check your o rings on the top of the spring caps retainer.....................if all is all good.
4.
Close um up and ride. 


I am with Tim here.  I don't think the little o rings  hold air, but they do act as dampeners.  So you start out with as much air as you can get in fork by extending it, but it will eventually find its own level.  Good luck, and I am new here, don't know shit, but, this is how I will do it. Works for me! :riding:
BIZZ
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline F14CRAZY

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Re: Fork oil...
« Reply #9 on: August 25, 2015, 06:25:15 AM »
Really?  WTF?
1.
 Remove the drain plugs.  You drain the old oil, pump the forks to try and get it all out . Use Johnny's bag trick to catch the old oil. works great, no mess. Take your time and tape the bags up so nothing can get by um.
 2.
 Jack or lift the front end so the forks are fully extended.
Replace the drain plugs, use new nylon washers if ya got um.  Be extra careful not to over-tighten the drain plugs, they are known to strip easily.
3.
 Remove the spring retainer screws/bolts on the top of the forks , not the filler plugs, the plugs  like to strip as well................both of mine where! 
4.
 Now you need to measure the right amount of fork oil and refill each fork with the proper amount. My forks take different quantities.  The trick here is to use a syringe or something that will let you control the flow and pour slowly and not spill or run down the face of the container  when you slow down or stop to let the oil draining into the forks catch up.  It takes a bit for the forks to fill.  Put rags around the top of the fork just in case you spill a bit.  I haven't tried um, but a baby bottle is supposed to work well. Or an old cleaned out gear oil bottle with the nipple top.  Honda 8-10 fork oil seems to be a fav. around here. Check your o rings on the top of the spring caps retainer.....................if all is all good.
4.
Close um up and ride. 


I am with Tim here.  I don't think the little o rings  hold air, but they do act as dampeners.  So you start out with as much air as you can get in fork by extending it, but it will eventually find its own level.  Good luck, and I am new here, don't know shit, but, this is how I will do it. Works for me! :riding:
BIZZ

Quote
one key thing abouts the forks... gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed...

I get the idea of having the front tire off the ground so the forks are fully extended but don't get what putting the top caps on will do or when to do it in the process as johnny said above
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline bizzaro

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Re: Fork oil...
« Reply #10 on: August 25, 2015, 07:23:08 AM »
I am confused?  Old fluid out.  Reseal drain plugs. Extend forks fully. Remove spring caps on top of fork tubes. With the forks fully extended fill to the specified amount. Check o- rings for damage.....................All good? Screw the caps back on.  Good to go.  Just what are you asking in the process?
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline bizzaro

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Re: Fork oil...
« Reply #11 on: August 25, 2015, 07:35:10 AM »
"..gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed.."

 

With the forks extended, and add the correct amount of fork  oil to each fork.  Fill um with the forks extended.  I just use a piece of wood on top of a cheap hydraulic jack under the oil pan to raise the front tire off the ground.(forks are fully extended now.) It doesn't take much to raise the front wheel off the ground to fully extend the forks.  Fill um then and put the fork tops back on while the forks are in that position.(extended) I really don't understand your confusion?

  Off to work.......................see ya in the twisties.
Bizz
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

Offline K75RT Keith

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Re: Fork oil...
« Reply #12 on: August 25, 2015, 09:11:43 AM »
You get the front wheel off the ground to ensure full fork extension.  Leaving the front wheel on the ground , you might think they're fully extended but they may not be.

Working on a K-brick is like tax forms.  Don't over think it, don't read more into it than is printed.   
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Offline F14CRAZY

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Re: Fork oil...
« Reply #13 on: August 25, 2015, 09:44:02 AM »
"..gotts to put the top caps on with the front tior off the ground and the forks fully extended... this provides the proper amount of air for the suspension fluid and the valving to work as designed.."

 

Put the drain caps on with the forks extended and add the correct amount of fork  to each fork.  Fill um with the forks extended.  I just use a piece of wood on top of a cheap hydraulic jack under the oil pan to raise the front tire off the ground.(forks are fully extended now.) It doesn't take much to raise the front wheel off the ground to fully extend the forks.  Fill um then and put the fork tops back on while the forks are in that position.(extended) I really don't understand your confusion?

  Off to work.......................see ya in the twisties.
Bizz

Well to me the "top caps" are on the top end of the forks where you fill them.
  • Grand Rapids, MI
  • '87 K75C
'87 K75C w/ Pichler V1 fairing. LED's, CATZ driving lights, Audiovox cruise, LT top case, tons of other mods by Drake...


Offline bizzaro

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Re: Fork oil...
« Reply #14 on: August 25, 2015, 10:57:51 AM »
Yea, with the top fork caps open/off, n the bottom drain plugs in and tight, raise the front tire off the ground. Now your forks are fully extended and the top caps are off, right? Fill each fork with the appropriate among of fluid. With the forks extended, put the caps back on to torque specs, remove the implement you used to raise the front wheel. DONE! are u just mess n with me r what?
  • Vermont
  • Current:1994 BMW K1100LT Previous: 1982 Yamaha virago 920,1973 Honda CB550,1976 Yamaha 650 Special
See Ya in the Twisties,
 Bizz

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