Change that fork oil!
Road Warrior
Joined: Aug 2008
Posts: 1,474
Likes: 1
From: Acworth, Ga
Dont kid yourself with the above statement. The forks are constantly moving...metal against metal...with the weight of the bike and whoever else is riding it. They do take a great deal of abuse/wear.
Road Warrior
Joined: Nov 2008
Posts: 1,636
Likes: 7
From: Jackson, Michigan
I'd stand behind Uncle on this one. It should be metal against seal most of the time. You don't have the heat generated by combustion and you don't have the mechanical forces you'd see in a gear box (tooth to tooth forces). Just saying.
Thread Starter
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Road Warrior
Joined: Feb 2007
Posts: 1,785
Likes: 4
From: Oklahoma
"Undemanding" is a relative term. Compared to what is needed to lubricate a Tourpak latch or clutch lever, I guess fork oil faces severe duty. But compared to the demands of a motor or tranny, it is insignificant.
Stellar HDF Member
Joined: Jan 2008
Posts: 3,036
Likes: 65
From: Earth
Quote:
Originally Posted by SpiderPig View Post
So what is the difference between fork oil and non-detergent motor oil if you use the same weights?
Originally Posted by SpiderPig View Post
So what is the difference between fork oil and non-detergent motor oil if you use the same weights?
Why would yo want to use motor oil if fork oil is designed for the the forks?
Cruiser
Joined: Oct 2004
Posts: 245
Likes: 3
From: austin, Texas
Mine looks the same way every time that I change it at 10K. I use H-D Type E. The first time, my forks started banging like my steering head bearings were loose, but an oil change fixed that. I agree with you. Change that fork oil.
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Road Warrior
Joined: Nov 2008
Posts: 1,636
Likes: 7
From: Jackson, Michigan
I swapped mine for the firmer oil as I'm a lard *** and I wanted the improved handling/diving. And ya know - it worked! It sucks up bumps better, less unsettled reaction.
Road Warrior
Joined: Nov 2008
Posts: 1,296
Likes: 3
From: Cheltenham, UK
Let me restate your question from a different perspective. If you were a marketer, why would you want to sell someone a generic product at a basic price when you can do a little marketing razamatazz and triple or quadruple your profits? The only relevant question is whether a given product is up to the job at hand. Forks, like primary cases, are very undemanding environments for lubricants. ATF (or basic motor oil) has a long history of working well in them. The main thing is to keep the lubricant reasonably clean. I choose to save the high dollar heavy artillery XYZ additive lubricants for applications where they make a difference.
I am not fully conversant with the exact design of the forks in the HD touring range but traditionally...
Forks (and all suspension for that matter) needs to dissipate energy based on 2 variables, namely displacememt (crudely simplified as "how deep is that pothole") and velocity, (namely "how steep are the sides of that pothole"). If you have the benefit of studying fluid dymamic theory you will begin to understand the dashpot principle which essentisally boils down to a frictional resistance based on the resistance between 2 closely spaced mechanical components seperated by a viscous fluid. In the case of a fork, the inner and outer sleeve are seperated by the fork oil, and the rate at which they move relative to each other is damped by the fluid. This takes care or the "velocity" component, the old fashioned forked used to have a spring inside which took care of the "displacement" component. Look at a typical car shock absorber which has the outer coil spring and the inner damper. Take out the spring and the car would sag down, take out the damper and the car would bounce up and down like a yoyo each time it hit a bump - 2 different but complimentry functions
So, why use fork oil vs engine oil vs cooking oil for that matter. Each lubricant carries additives which facilitate performance in a specific environment. In the case of fork oil, shear strength (tearing resistance) is really important.
In summary, do not be cynical about working fluids. They are not "the same thing in a different bottle" - use the right stuff. The additives in the fluid are very different and designed specifically for each application