Fork oil?

Anybody here experimented with alternatives to standard fork oil? I may be speaking blaspheme to some in the forum but there are a lot of different fluids that can be used for hydraulics. My old Honda Magna can use motor oil or even ATF.

Thoughts?

exo55c said:

Thoughts?

Click to expand...

Yeah. Read through NEPRT and search is your friend. Oil (including fork) has been talked about many, many, many times on this forum...including alternatives.

We haven't had a Fork Oil thread for months, inquiring minds want to know!

exo55c said:

Anybody here experimented with alternatives to standard fork oil? I may be speaking blaspheme to some in the forum but there are a lot of different fluids that can be used for hydraulics. My old Honda Magna can use motor oil or even ATF.
Thoughts?

Click to expand...

If yer 2 cheap to buy fork oil, you shouldn't have a motorcycle, that would be my thought. I thought yesterday was friday.

Many of my bikes ( past and present ) have used ATF

in the forks.

ATF and fork oil share characteristics suitable for forks

that are not common to most other types of oil.

Dextron II, or some other flavour?



Brodie

Dextron has slip additives. Whereas type F has friction enhancers, If I had to choose, it would be dextron. Originally designed so that grandma couldn't feel her cadillac shifting gears.

Da Wolf

Motul 7.5W fork oil.

Drops mic and walks off stage.

I recall reading an article somewhere that alleged that the consistency in the actual viscosity of fork oils is very poor compared to labeled viscosity across the spectrum of brands. The discrepancies described were significant. Anyone else recall seeing this?

Pterodactyl said:

I recall reading an article somewhere that alleged that the consistency in the actual viscosity of fork oils is very poor compared to labeled viscosity across the spectrum of brands. The discrepancies described were significant. Anyone else recall seeing this?

Click to expand...

There aren’t any viscosity standards for conventional fork oil expressed as 5wt, 10wt.....however Suspension Fluids whose viscosity is shown as 85/150, 125/150....are pretty consistent between brands.

Take a look the following chart from Peter Verdone:

https://www.peterverdone.com/archive/images/content/motorcycle/PVD-ISO-Viscosity-Data.gif

wetwolf said:

exo55c said:

Anybody here experimented with alternatives to standard fork oil? I may be speaking blaspheme to some in the forum but there are a lot of different fluids that can be used for hydraulics. My old Honda Magna can use motor oil or even ATF.
Thoughts?

Click to expand...

If yer 2 cheap to buy fork oil, you shouldn't have a motorcycle, that would be my thought. I thought yesterday was friday.

Click to expand...

It's only partially about the cost of "fork oil". I have to agree with SLK50. If ATF has the same characteristics and can be had at my local Autozone for less $$ then why wouldn't I use it?

I agree, ATF is hydraulic fluid, and so it may be suitable for use in a hydraulically dampened suspension. But... the viscosity of ATF is much thicker than what the FJRs forks were designed for. (Edit- there are a few examples of ATF viscosity in the chart linked to by MCRIDER above).

That means that the amount of damping you get at a particular orifice opening will be more, so you may not be able to adjust the clickers enough to get optimal damping. Also, those clickers only adjust the low speed damping. The high speed damping is set internally with fixed orifices and flexible shim stacks, so your high speed damping will definitely be too high with ATF unless you do some major fork revalving. I just use the ATF to flush the forks out, drain it out well, and then put in some good suspension fluid of close to the same viscosity as the Yamaha stuff.

I agree with Fred.

Id like to add, that while ATF may be suitable

for forks, I do not use it in my FJR.

However I do use it in my XR650L.

Most ATF has a red color.

Would be easier to see a leaky fork seal.

I've only used Bel-Ray fork oil in my life. Not that it's any better than any other brand, but just for the sake of consistency. It is true oil weights between brands vary and a 10w by one company may not be the same as a 10w from another.

However if you only use one brand, you have a clearer reference to go by , provided you have used that brand long enough to establish that reference point. I switched out the stock oil (which was supposed to be a 7.5w oil) with a 10w in one bike I owned. It was evident that both oils behaved the same, and I was looking for "slower" oil, so I went to a 15w instead getting the results I wanted.

Doing this with several bikes through the years has given me some predictability when changing the fork oil as to how it will behave. It can still be a challenge as the given weight of the stock oil can be inconsistent too. (Yamaha fork oil verses Kawasaki fork oil) But if your trying to fine tune your forks, it just makes more sence to stick with one brand.

I recently changed the OEM oil in my 14A. Went with Honda showa 5 wt. the difference in the low speed dampening was very impressive. I also ended up backing off the preload 3/5th of a turn.

Im 6-0, 205 pounds, live in the middle of what must be the worst maintained roads in the country, and would consider myself a moderately aggressive rider.

I spent some time and $$ with Dave Moss, a transplanted Brit suspension guru and racer.

He had me change from Yamaha Fork Oil to Maxima 10WT Standard Fork Oil.

After a day of many adjustments and test rides I ended up here for a baseline setup:

I'm 265# so this may not work for you.

Front Compression 12 clicks out

Rebound 5 clicks out

Preload 1 1/2 lines showing

Rear set to firm and 3 clicks out

If you increase front preload, increase front rebound dampening

bigjohnsd said:

I spent some time and $$ with Dave Moss, a transplanted Brit suspension guru and racer...
If you increase front preload, increase front rebound dampening

Click to expand...

Why would you need to increase the rebound damping because you increased ride height? Adjusting the preload does not change spring rate or load. It only changes the ride height.

Also, Maxima 10w is about the same cold viscosity as ATF, which is about twice the viscosity of the Yamaha fork oil. It would be a pretty poor choice for stock valving in an FJR fork. The unadjustable high speed damping will be twice as stiff, and that means the suspension will be unresponsive to bumps and dips in the road surface. Maxima 5w would have been a better choice, IMO.

Fred, I don't have any answers to these questions. All I know is that it works, the ride and handling is much improved over what it was.

I'm happy! There are some things I choose not to understand further.