Oils ain't oils.

[tri boy]

http://www.peterverdonedesigns.com/lowspeed.htm
Good read for those who wish to compare fork oils. Chart at the bottom is telling.
A point that I noted is that most damper rod type forks like c/stroke34ish, so basically ATF Mobil could be used, but obviously not the top end oil with regards to corrosion resistance etc.
Definitely not the choice for cartridge units though.
I will leave it for the experts to comment.

[Pussy]

That's a good link... cheers tri boy

[pete376403]

Whats ATF lacking in corrosion resistance? I've rebuilt plenty of automatic transmissions and never seen a one rusty inside (unless the trans cooler in the bottom of the radiator has failed.
Shouldn't be any water in the forks anyway...

[Robert Taylor]

Whats ATF lacking in corrosion resistance? I've rebuilt plenty of automatic transmissions and never seen a one rusty inside (unless the trans cooler in the bottom of the radiator has failed.
Shouldn't be any water in the forks anyway...

Condensation is a big factor

[Robert Taylor]

http://www.peterverdonedesigns.com/lowspeed.htm
Good read for those who wish to compare fork oils. Chart at the bottom is telling.
A point that I noted is that most damper rod type forks like c/stroke34ish, so basically ATF Mobil could be used, but obviously not the top end oil with regards to corrosion resistance etc.
Definitely not the choice for cartridge units though.
I will leave it for the experts to comment.

We have a very high quality Ohlins oil we are now using in many damper rod forks, 35 cst @40 degrees C. But without launching into a tirade of detail about ambient temperature sensitivity there are so many variables with these forks that especially affects rebound return speed. There is so much uncontrolled bleed caused by poor tolerancing, also very often by poor assembly alignment of the damper rod itself. The detail ( or lack thereof ) can make a HUGE difference.

[CookMySock]

We have a very high quality Ohlins oil we are now using in many damper rod forks, 35 cst @40 degrees C.

What is its' viscosity index ? What is the base stock ?

DB

[Badjelly]

Thanks for that, mate. I'd been wondering how viscosity index was calculated. Now I know:

VI = 100+(10^(LN((EXP(1.0727+0.6175*LN(cSt@100)+0.9744* (LN(cSt@100)^2)+(-0.3764)*(LN(cSt@100)^3)+0.04824*(LN(cSt@100)^4)))/cSt@40)/LN(cSt@100))-1)/0.00715

[Robert Taylor]

What is its' viscosity index ? What is the base stock ?

DB

V1 445 Highly refined mineral base stock. Very slippery, low friction.

[CookMySock]

V1 445 Highly refined mineral base stock. Very slippery, low friction.

Very Nice. Makes everything else look like carrot juice.

DB

[Robert Taylor]

Very Nice. Makes everything else look like carrot juice.

DB

The VI figure I quoted was wrong, after I went in and scrolled through a plethora of manufacturers spec cards last night. The manufacturer of most of Ohlins oils is a state owned Norwegian company Statoil. Something has been lost in translation Norwegian / Swedish / English. The 445 figure I quoted was a reference figure to something else that is printed in Norwegian. I will request this and see what bounces back but dont hold your breath.
I note with interest that 2 companies, both Ohlins and WP are not as forthcoming with full info, maybe they are protective because of commercial sensitivity etc. But both companies are at the very top of the tree with the quality of their suspension so I have absolutely no doubt that the oils they use and specify are commensurate with the performance of the product.
I can certainly vouch from my own experience that the Ohlins oil we are now almost exclusively using is very very good.
There is also a very serious factual inaccuracy in the article that Triboy refers to. It is stated that one part number of Ohlins oil is used for Ohlins shocks, nothing could be further from the truth. There are in fact THREE different specifications for Ohlins shocks and the correct specification is detailed for each individual shock on the spec card for that shock. That is one of the many reasons why they should only be serviced by accredited service technicians who have the appropriate training and knowledge of the product. Beware of ''imitators'' who in fact have no specific training whatsoever, have never heard about centistroke ratings and will carelessly use something else that is not really appropriate. Oils aint oils.....

[CookMySock]

I'm trying hard not to be an arse here, but many companies will not release specs on their product because they would rather have everyone follow their word blindly. This leaves their advertising material full of persuasion techniques that have no real basis in science.

DB

[Robert Taylor]

I'm trying hard not to be an arse here, but many companies will not release specs on their product because they would rather have everyone follow their word blindly. This leaves their advertising material full of persuasion techniques that have no real basis in science.

DB

I can very well understand why many consumers have developed a cynical and less than convinced attitude to many product claims. You buy a product and base some of your judgement on the pr hype, only to end up being bitterly disappointed because it just hasnt lived up to expectations and / or is not actually fit for the purpose for which it was sold. As an over-generalisation I would suggest that many budget priced products are the worst offenders.
In the world of suspension there used to be a slogan for a budget product entitled ''dial a ride'' May I suggest that many consumers must have ended up thinking this is actually about dialing in the degree of backache they are going to feel! And in all languages I would hasten to add that the word Quality is now one of the most mis-used words. The sad thing is that for many the perception of quality has been incessantly dumbed down.
In going in to bat for top shelf companies such as Ohlins and WP I would suggest ( and actually know it to be true ) that their major pre-requisite in everything they do is quality. I dont think there is anything sinister in these very companies being a little protective of specifications. And as I recall in excess of 10% of the worlds economy is piracy / copyright infringement, 70% or greater of that comes from ( you guessed it ) mainland Asia. Indeed Ohlins have a member of their staff dealing with this full time.
I think one of the biggest areas where you can often be misled is magazine tests, especially in a small country. The magazine owners will be ''economical with the truth'' as it would be an ''inconvenient truth'' to say it how it really was. They are competing for advertising dollars. Masterminds of brainwashing such as Joseph Goebbels must be laughing in their graves.
I dont blame you for questioning in a world full of those who blindly follow.

[svr]

II think one of the biggest areas where you can often be misled is magazine tests, especially in a small country. The magazine owners will be ''economical with the truth'' as it would be an ''inconvenient truth'' to say it how it really was. They are competing for advertising dollars. Masterminds of brainwashing such as Joseph Goebbels must be laughing in their graves.
I dont blame you for questioning in a world full of those who blindly follow.

What passes for motorcycle `journalism' in this country is a total joke. I have not read a reasonable, clear, critical evaluation of any product (or topic, actually) in 30 yrs of reading NZ motorcycle `literature'. I assumed the reason was general motorcycling and intellectual incompetence, but it seems there is also a commercial explanation.
Thanks for the missing piece to the puzzle.

[CookMySock]

You buy a product and base some of your judgement on the pr hype [....]

Not any more.

but it seems there is also a commercial explanation.

"commercial explanation" - I like that. Another word for "spin" ?

cue - telecom advert..


DB

[riffer]

There's some interesting reading there, and it's helped me understand a bit what's happened with my forks.

You see, I've had a problem for the last 18 months with the bike having a small shudder under braking which wasn't reflected in a pulsing in the brake lever.

I've rebuilt the steering head, rebuilt the brakes and changed the oil in the forks at least three times. I've had the dialout on the rotors measured to ensure they were straight but to no avail.

Until recently. I blew another fork seal on the forks (it's a common event) and had a good talk with the bike shop who speculated that the fork oil I was using wasn't working with my riding technique and suggested I change to Spectro Golden 85/150, which is a much lighter oil than the Spectro 10wt I was using (and also is exclusively for cartridge forks).

Looking at the chart it seems the cold viscosity of the 10wt was 32.80 and warm was 5.60 with a VI of 111.

And the Golden 85/10 was 3.82 and 16.90, with a VI of 150.

Now, with the 85/150 I'm using two more clicks of preload as it's a bit softer at lighter preload being a less weight oil, but the difference is staggering. Particularly at lower speed. There's a lot more movement there. The forks would just crash over the bumps before and I'd get a bit of headshake accelerating hard out of corners in 2nd gear (RF's are not known for their light front ends too). Now it smooths out the bumps a lot better, and best of all, there's not a trace of the brake shudder any more.

This is a bit of a relevation to me, that the fork oil can affect braking. I'm guessing that the fork oil wasn't moving smoothly through the valves and shim stacks (I'm still not au fait with all the workings of the hidden components inside the cartridges as I've never dismantled the cartridges) and was causing some kind of hydraulic lock when the forks were moving quickly, like under the load that braking would cause on a front-heavy bike on rough roads. Although shudder seemed to be found at all speeds and even on smooth roads so I think the cartridges just didn't like the oil.

I'm not convinced of the benefits of spending $1000 on a $5000 bike to get optimum suspension performance at the front end, however I am curious as to the effect an oil with an even high VI would give in terms of consistency of performance at different temperatures. Upper Hutt can change a lot over the course of the year. I change fork oil in winter and summer so it could be that I could use a different oil for the summer to winter.

Am I on the right track here?