Harley-Davidson Maintenance: Change the forks oil

When was the last time you changed the oil of the forks? Probably the answer to this question is "never", "I don't remember," or something like that.
This is how it is usually, the truth is that the forks do not give us too many problems in custom models, since normally on these motorcycles it is not conducted sports and the braking are usually relatively moderate. It is therefore that we do not normally perceive that it is a part of the vehicle that also requires attention and maintenance, and that the oil inside also degrades with use and needs substitution, since it loses its lubricating characteristics, it is emulsified (it is mix with air and moisture) and the yield of damping is reduced.

Using the service manual
Specifically, it is indicated in the Harley-Davidson models manual that the oil has to be replaced every 32,000 km (every 4 engine oil changes).
Well, precisely this task is what we are going to carry out, following as always the step -by -step indications of the workshop book.
The first thing we have to do is put the motorcycle vertically, well using a central elevator or through a rear wheel support.
After this step we will place a drainage tray Under the fork with which we are going to work and then we will extract with a screwdriver the drainage screw,

and the oil will begin to leave the hole. The screw is one -use, it should not be reused, and you have to be careful when extracted, since it is quite soft and the head of it can be spoiled.

When we stop out, we will ride the motorcycle and while we press the front brake we will compress the damping several times, thus pumping the oil inside. Be careful, put the tray in the right place, since with this procedure the oil comes under pressure.

Tip: If the oil is mixed with air bubbles or has light brown color it is possible that fork checks need substitution.
At the moment that stops falling oil we have finished drainage, we clean the bar well and return to install a New screw With its washer, squeezing it at 2 nm.

We fill with new oil
Once we have the ready fork we have to insert the Special forks, for this there are 2 different methods:
-We can use the amount indicated by the manufacturer, for this we will need a graduate measurement jug.

-The oil level can also be measured in millimeters from the edge of the bar with a Special tool.

In both cases we must always follow the recommendations of the workshop manual regarding the quantity and type of oil, custom motorcycles usually use a density between 5W (light) and 20W (heavy).

Next we have to remove the filling cap from the upper part of the fork tube, the first thing we will do will use an elevator to slightly lift the front wheel of the ground, thus discharging the pressure of the internal spring of the suspension.

The next step consists of loosening the upper shell screw,

In this way it will be easier for us to unscrew the fork screw-tapa, using a Specific special tool.

You have to be cautious to unscrew the plug, since it is under the pressure of the dock and can fly and abolish the tank or the fender.

We only have to fill with the right amount of liquid, using a small funnel with a rubber, or the typical paper "cucurucho".

If we have followed the manual method that indicates that we use the extraction syringe now it would be the time.

Final checks
With the correct amount of oil in the fork we can already thread the upper plug of 60 Nm, after which we will thread the typical screw of greater than 45 Nm.
We have to repeat exactly the same procedure with the other bar, and we can lower the motorcycle and test it gently on the road so that the new oil recirculates.
With these simple steps you will see that you have rejuvenated the dynamic behavior of your motorcycle.

Frank Burguera

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