Fork oil...eewww

[shiggsy 529]

Decided to take advantage of the clement weather and set about doing a much needed change of my steering head bearings. As I was dropping the forks I thought I'd change the fork oil as well.  Didn't much like what came out, smelt pretty rank too.

 

approx 33k miles old.

 

Edited February 18, 2017 by shiggsy

[Guest bonekicker]

Shiggsy Not very nice at all--is it full of magnesium oil or something like that?? or just plain dirty?? Did you take some pic's --showing how you did the service work?? 

[Guest machinman]

Did you use tapered or OE type bearings,? I recently just re-greased mine.

[shiggsy 529]

No just some reference pics, there are already a couple of good tutorials on head bearing changes floating around.  I'm going to put tapered head bearings in, they were already changed under warranty at the 8k service. All the bikes I have had seem to go through head bearings fairly rapidly, I think the roads around here don't do them much good.

Edited February 18, 2017 by shiggsy

[Mike5100 2,061]

Apparently my 2016 fork oil was like that when it was swapped at 8k miles.  I would have expected it to last longer - I wouldn't have known except I wanted to try a lighter oil.

Mike

[embee 7,288]

I reckon as a rule of thumb that fork oil deteriorates significantly beyond 10k miles. If you get any moisture at all in there it can smell like a camel's jockstrap, I always suspected it's bacterial but may be wrong, not pleasant stuff anyway, I wouldn't recommend a dab behind the ears on a Friday night if you have any hope of pulling.

 

...oh no, I'm beginning to sound like Andy .........................

[Guest Mac750]

Yes moisture and condensation contaminating the fork oil degrading the oil.   Bacteria can form as the heat generated in the tubes whilst in use and the dark, damp conditions are ideal.

Ever set off a water fire extinguisher that's been in a nice warm office for three years Phew!. 

Fresh fork oil transforms the front end which becomes instantly noticeable because we had adapted to the poor fork operation as it slowly deteriorates over time and use. 

8 hours ago, embee said:

I reckon as a rule of thumb that fork oil deteriorates significantly beyond 10k miles. If you get any moisture at all in there it can smell like a camel's jockstrap, I always suspected it's bacterial but may be wrong, not pleasant stuff anyway, I wouldn't recommend a dab behind the ears on a Friday night if you have any hope of pulling.

 

...oh no, I'm beginning to sound like Andy .........................

 

[Dunnster 1,650]

Might be time I did the same looking at that liquid!

what head bearings and fork oil did you use to replace the old?

[shiggsy 529]

The tapered bearings and races I got online from Marksman Industrial, they list a set of the NC700X, the lowers were Koyo, the uppers were unbranded, used Rock Oil EP lithium based grease with them.  I was actually planning to do my chain and sprockets this weekend but the chain's not turning up until Monday, so rather than waste the weekend weather I thought I'd dive in and do the head bearings, and If I was going to do that I may as well do the fork oil and also the tappets. So as a spur of the moment thing, the bike shop I was in had a choice of Silkolene 10 or Rock Oil 7.5, went for the Rock Oil.

[Guest Mac750]

I was talking with an oil sales rep some time ago regarding motorcycle lubricant's as my BMW forks at that the used a thin aircraft oil used in damping landing gear apparently.  

I was surprised to be told fork oil sometimes is or is not what we think it is.  In other words the fork oil of one supplier will act differently to the fork oil of another although for example they may both say 10w .

 

This is down to blending, processing and also markets the oil is aimed at.

The race market is significantly different to the street use market as the product takes a hammering during racing and is designed to be changed more often and can even vary from country to country. 

On normal road use some cheaper brands are better than top name and in other cases it is best to go for the premium brand and not to touch the cheaper products.

I pointed out this does not help us the day to day motorcyclist Joe public. But he answered that in normal street use the average rider wouldn't tell the difference between two bottles of oil classed as 10w, one being a  premium and one normal priced. 

So I re did the fork oil on my MZ with cheapo fork oil and it felt fine and I used the much more expensive air craft stuff in the BMW and ...

They both felt exactly the same. 

Makes you wonder .

[Guest sykospain]

Here we suffer greatly from the sudden, severe suspension shocks caused by driving over Raised Pedestrian Crossings - "sobreelevados".  Many of which are illegally high and steep and which in many German urban areas have mainly been bulldozed flat, on the basis that they cause more vehicle-exhaust pollution by drivers standing on the brakes as they approach, then slamming the gas pedal down after crossing one, than if they were simply to cruise normally straight through the empty crossing - admittedly at maybe a higher speed than they should.

Nevertheless, our local car maintenance workshops love the old sobreelevados,  'cos it means they have to keep in their spares stores a permanent stock of suspension bushes, knuckles, trackrod-ends, driveshaft rubber boots, etc., for when motorists come in saying their car is behaving as if it were being driven by Oliver Reed after he'd downed ten glasses of Scotch.

So think what the blasted eyesores are doing to our bikes' forks...

 

[Mike5100 2,061]

1 hour ago, Mac750 said:

I was talking with an oil sales rep some time ago regarding motorcycle lubricant's as my BMW forks at that the used a thin aircraft oil used in damping landing gear apparently.  

I was surprised to be told fork oil sometimes is or is not what we think it is.  In other words the fork oil of one supplier will act differently to the fork oil of another although for example they may both say 10w .

 

This is down to blending, processing and also markets the oil is aimed at.

The race market is significantly different to the street use market as the product takes a hammering during racing and is designed to be changed more often and can even vary from country to country. 

On normal road use some cheaper brands are better than top name and in other cases it is best to go for the premium brand and not to touch the cheaper products.

I pointed out this does not help us the day to day motorcyclist Joe public. But he answered that in normal street use the average rider wouldn't tell the difference between two bottles of oil classed as 10w, one being a  premium and one normal priced. 

So I re did the fork oil on my MZ with cheapo fork oil and it felt fine and I used the much more expensive air craft stuff in the BMW and ...

They both felt exactly the same. 

Makes you wonder .

Embee has previously given some good info on this subject. There are tables produced by a few labs that helps us decide what brands and weights are equivalent. Our bikes come with a Showa fork oil of nominally 10wt and if you fancy putting in a lighter weight oil then you need to consult the tables because another manufacturers 7.5wt oil may actually be more viscous than the standard Showa stuff

I have now got Fuchs 7.5. in - Murray can tell us whether it's more or less viscous. In any case I'm pleased with it

mike

[steve916s 11]

On 2/18/2017 at 18:14, shiggsy said:

Didn't much like what came out, smelt pretty rank too.

On my ER5 the oil is always coloured with grey PTFE particles worn from the bushes. Wonder if NC bushes are Teflon coated?

[embee 7,288]

This is what you want to look at

http://www.peterverdone.com/archive/lowspeed.htm

 

There's a white table about halfway down which lists the measured viscosities for a large number of commercial fork oils. Probably the most relevant numbers are the viscosity at 40C (in centistokes, the viscosity unit, cSt), and the Viscosity Index (VI) which indicates the variation in viscosity with temperature, higher numbers are generally better (less variation).

 

I'm pretty sure the NC forks will have the Showa SS-8 oil from the factory, a nominally 10wt oil around 36cSt and VI of 200. My oil of choice is the Fuchs/Silkolene 7.5W PRO RSF which as you see is about 35cSt/VI=300. This has since been re-branded as Fuchs/Silkolene Maintain RSF, same stuff.

 

Other oils are available.

[shiggsy 529]

I remembered embee's post about how he found\thought the Silkolene 10w was to harsh and he went for the lesser version. I know I have a different brand so its probably apples and oranges. Rock Oil SVI is not on the list but I looked it up and its not the far behind the Silkolene 7.5w.

[Dunnster 1,650]

23 hours ago, shiggsy said:

The tapered bearings and races I got online from Marksman Industrial, they list a set of the NC700X, the lowers were Koyo, the uppers were unbranded, used Rock Oil EP lithium based grease with them.  I was actually planning to do my chain and sprockets this weekend but the chain's not turning up until Monday, so rather than waste the weekend weather I thought I'd dive in and do the head bearings, and If I was going to do that I may as well do the fork oil and also the tappets. So as a spur of the moment thing, the bike shop I was in had a choice of Silkolene 10 or Rock Oil 7.5, went for the Rock Oil.

Thanks shaggy, much appreciated and other forum members for the info