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Garage Basics: Fork Oil Change

Garage Basics: Fork Oil Change

If you have to shrug, when the term fork oil pops up, and turn back to the work on your bench, you are probably the guy who has a springer, girder or leaf spring fork in his chop, and generally keeps to Harleys before the 1949 vintage.

1949 is the year when HD introduced the red-hot Panhead "Hydra Glide" motorcycle, which came with a "hydra-ulic" front end. Steel tubes sliding on steel tubes, and deep down inside long springs swimming in oil raised the riding comfort to unheard of levels, reducing back-breaking potholes, back then a daily menace to riders, to minor bumps in the road.

With all this sliding action going on, it’s no wonder the oil gets tired and saturated with microscopic metal particles due to abrasion, which makes regular change a necessity. The viscosity of fork oil can be used to adjust the damping characterisics (and levels of comfort) of hydraulic forks. SAE 30 W was standard on HDs up to 1978 (and up to ’84 on FL models). 30 weight is rather stiffish by today’s standards. It was replaced by 20 W later. If you appreciate a soft ride, go down to 15 W, or concoct your own "viscocktail" by mixing different viscosities. Make sure that you remember the mix ratio for next time.

Model specific quantities, the maintenance intervals and where to find the drain plugs are best looked up in the maintenance handbook that came with your bike, or in the relevant edition of Clymer’s handbooks. A quick read-through may help to order gaskets, if needed, and possibly replacement plugs, if the old ones look like they’ve had it. It’s not uncommon for drain plugs to be uncooperative, or strip, and generally can be a pain in the youknowwhere.

Always consider calling our phone operators, who can take the strain out of the preparations at +499312506116 or send them an e-mail at service@wwag.com   

Let’s get started:

1) Set up your bike on a stand,

eg the Becker minilift, 97-441 and make sure that there’s no weight on your front wheel.

2) Fork oil tends to dribble down

the fork legs, and it’s a good idea to place an oil absorbent mat (81-000) under the front end to avoid a mess in your kitchen. If you want less cleaning up when finished, use the PanAm oil slide to direct the oil to the recipient of your choice.

3) Open the large fork tube plugs

on top of your fork with the correct size wrench, nut or the variable size Knipex plier wrench (very useful). This lets the oil drain much more freely. Open the two (left and right) drain plug screws and let drain the oil. A little patience helps to get out as much of the oil as possible. 

4) If necessary clean or replace

the drain screws with new ones, using new gaskets if appropriate. Tighten to torque specs found in the handbook.

5) Now’s the moment for the new oil.

A funnel and a measuring beaker are your minimum equipment, but the PS oil level adjuster 91-891 is just the perfect tool to have round now. Find the correct quantity in your handbook, and fill each leg nice and slow to avoid spills and air bubbles.

6) Tighten those fork tube plugs again

(check your handbook for correct torque).

7) Time for a thorough check

that the oil only got where it was supposed to go, but not on your tires or brake discs.

All clean?

Bingo. You’re ready for the next pot hole filled summer.

From our experience we’d like to point out the possibility to

give us a call, should you encounter snags in the proceedings.

Our dudes have many thousands of two wheeled miles and countless hours spent wrenching under their belts and are ready to help.

Internet forums full of self declared experts may get you answers as well, but don’t bet the farm on them. When you’re wrenching on equipment your life may depend on, like forks, chassis components, brakes etcetera, get advice you can trust.