Fork Oil Question [Archive] - Kiwi Biker forums

Slim

16th February 2005, 17:02

The Man has just changed the fork & brake fluids in my bike, preparetory to my March trip & he found something interesting with the fork oil.

One forks oil was perfectly fine, but the other one was smelly & cluggy. I know for a fact that both forks had new oil 2 years ago, so why would one deteriorate and the other not??? :spudwhat:

Blakamin

16th February 2005, 17:07

slightly leaky seal... attracted water??

moisture in the air.... seals aren't airtight...

Slim

16th February 2005, 17:15

That was my first thought, but The Man reckons the seals are fine. :spudwhat:

Blakamin

16th February 2005, 17:22

are they usd forks? could be the drain bolt or whatever is not airtight... could be a lower level of fork oil and condensation.... :spudwhat:

FROSTY

16th February 2005, 17:23

my only suggestions there is -1 Its the motorcycle gods playing with ya head or
2) The "fact" re both fork oils bein changes was in fact wrong.maybee they changed one lot of fork oil twice

erik

16th February 2005, 17:37

Maybe something (ie: a mouse, a spider) fell in one of the forks last time half way through the oil change? ;)

Paul in NZ

16th February 2005, 17:50

Maybe the bike sits in a place where the sun falls on one side and not the other so condensation forms on one side and not the other..

Paul N

Slim

16th February 2005, 18:04

The 97 CBR6 does not have USD forks, and in fact does not even have drain holes at the bottom of the forks at all.

Both forks definitely had their oil replaced last time - the oil was incredibly smelly that time & only replacing one would have resulted in some interesting handling problems.

The bike is garaged most of the time & only sees the sun when it's being ridden.

So we basically don't know, right? The biking gods are playing with my head I reckon. I might sugest to The Man that we check them in 6 months maybe...

Jackrat

16th February 2005, 18:50

That was my first thought, but The Man reckons the seals are fine. :spudwhat:

The seals can be ok and still let moisture in.
Which side was it,I'm betting the right.
It's the most exposed and not under much pressure when the bikes on the side stand.
Your fork oil should also really be changed every year as well,IMHO.
I use hydraulic fluid and stynthetic brake fluid.
I've found that the most exspensive stuff really does work the best.
Go figure huh.

Hitcher

16th February 2005, 18:59

I know fork oil about this topic...

Paul in NZ

16th February 2005, 19:18

I know fork oil about this topic...

You must be in suspense-ion then

MikeL

16th February 2005, 19:25

I know fork oil about this topic...

He he he...
That is truly inspired. :niceone:

Mongoose

16th February 2005, 19:33

You must be in suspense-ion then

Thats oil forked up

Slim

16th February 2005, 19:40

The seals can be ok and still let moisture in.
Which side was it,I'm betting the right.
It's the most exposed and not under much pressure when the bikes on the side stand.
Your fork oil should also really be changed every year as well,IMHO.
I use hydraulic fluid and stynthetic brake fluid.
I've found that the most expensive stuff really does work the best.
Go figure huh.
Interesting. I'll ask him which one it was & report back.

Can you explain the "hydraulic fluid & synthetic brake fluid" comment please?

:spudwave: to the comediennes, you got me :lol: with that lot. :killingme

Motu

16th February 2005, 20:42

The seals act like a valve - they may not let oil out,but will let water in,specialy if there is water around on the upstroke.To completly seal a sliding cylinder a seal needs to be truly double lipped,like two seals back to back.A fork seal has a wiper only on one side - but I have visions of true double fork seals,maybe they exist.

XTC

16th February 2005, 20:49

The seals can be ok and still let moisture in.
Which side was it,I'm betting the right.
It's the most exposed and not under much pressure when the bikes on the side stand.
Your fork oil should also really be changed every year as well,IMHO.
I use hydraulic fluid and stynthetic brake fluid.
I've found that the most exspensive stuff really does work the best.
Go figure huh.

I disagree.... I reckon the sludgy one was on the left as all the sludge and goop would drain to the left fork when bike is on the stand :2thumbsup

Jackrat

16th February 2005, 20:52

Interesting. I'll ask him which one it was & report back.

Can you explain the "hydraulic fluid & synthetic brake fluid" comment please?

:spudwave: to the comediennes, you got me :lol: with that lot. :killingme

Instead of dot rated fork oil I use hydraulic fluid or Auto trans fluid,I belive it holds up better.I can't prove this other than from exspreince, but it also works better than standard oils in primary cases with bikes that have separate primarys.The brake fluid is just mineral based or synthetic like engine oils.
I used mineral for years but when I couldn't buy it I bought synthetic instead and it made a big difference to the performance of my brakes.
One thing that may have caused your fork oil problem could be that the side affected was already contaminated in some way.
If this is the case the bacteria left would/could breed.
This could also be a load of waffle but it got me thinking and it's what I came up with.
Hey there must be an answer somewhere :spudwhat:
Cheers

Blakamin

16th February 2005, 20:52

I disagree.... I reckon the sludgy one was on the left as all the sludge and goop would drain to the left fork when bike is on the stand :2thumbsup
via the axle or the handlebars??? :killingme

XTC

16th February 2005, 20:56

via the axle or the handlebars??? :killingme
Christ everyone knows that there are special oil channels thru the triple clamps that keep the fork oil levels between the forks in sync....

Jackrat

16th February 2005, 20:56

I disagree.... I reckon the sludgy one was on the left as all the sludge and goop would drain to the left fork when bike is on the stand :2thumbsup

Yeah, good on ya' mate. :niceone:

Slim

16th February 2005, 21:24

One thing that may have caused your fork oil problem could be that the side affected was already contaminated in some way.
If this is the case the bacteria left would/could breed.
This could also be a load of waffle but it got me thinking and it's what I came up with.
Hey there must be an answer somewhere :spudwhat:
Cheers
That sounds plausible to me - the bacteria/contamination theory.

Thanks for the explanation of the fluids you use.

And thanks for your contribution Motu. I'm thinking we change the fork oil in 1 year & do both fork seals at the same time. Any thoughts what to use to clean out the forks in answer to Jackrats bacteria theory?

And you comediennes are still :killingme

Blakamin

16th February 2005, 21:30

A wash-out with prepsol, acrylic paint thinner, isopropyl alcohol or another evaporating solvent will do it (provided you take ALL rubber bits out)

Slim

16th February 2005, 21:32

Interesting. I'll ask him which one it was & report back
The answer from The Man was .... "The 2nd one ..." :whistle: :lol:

Motu

16th February 2005, 21:46

I just fill with kero or such like,pump up and down,drain...keep doing it until they come clean.I only use fork oil when I'm being a fussy bugger,99% of the time I'm with Jack and use ATF,moving up to a thicker hydraulic oil if I need to.Some of the old bikes,like my XS1 I just kicked out of home took a 30 weight fork oil.

scroter

19th February 2005, 08:13

checking in six months sounds like a good idea. its a piss easy job anyway. the hardes part is getting the forks off the bike and then putting them back when youve finished.

Oscar

19th February 2005, 09:19