BMW motorcycle telescopic fork alignment procedure, Randy Glass page 6


6 – The Y-Plane
glass plate












Start by checking the fork tubes alignment in the Y-plane.  This is where you need the piece of plate glass approximately 10″x12″ or so.  I was quoted $3.25 at a glass shop for a 10×12.   When you order the glass BE SURE to request that they polish the edges.  It will make this tool a lot safer and more pleasant to handle.  With the polishing charge my total came to about $5.00.

Before you proceed you may want to de-grease your hands and lay a folded blanket under the forks if you have not already done so… Just in case!

With one hand, gently hold the plate of glass against one of the fork tubes and then allow it to swing, like a gate on hinges, your holding-hand being the hinge, towards the other fork tube until it touches the other tube.  Now check the other side for variances in alignment in this way: In the photo I am holding the glass plate on the fork leg in the general area marked by the yellow dot.  While holding the glass against the leg in that spot I checked the opposite corners marked in yellow as “A” and “B” in the picture.  The glass should meet the other tube all along its length- that is, it should be completely flat all along its length on both tubes at the same time.  It should not “rock” at all.  When you push with the free finger there should not be a clicking sound of the glass against the tube at either corner.  If you are not sure, you may want to try putting a .001 or .002 feeler gauge between the glass and the plate to check for zero clearance along it’s length on the “free” side (the side you aren’t holding).  Now reverse your setup- hold the glass against the other fork leg in the area indicated by the blue dot over the left fork leg and push the glass at “C” and “D” to test for a “click.”

      Another way to use the glass (actually a mirror is being shown here) is to hold the pane at the bottom against the fork tubes as is demonstrated in this photo, then using a finger of the other hand press the plate against the forks lightly at the top corners of the glass.  Use this method as well as the one above to give yourself some reassurance that the readings are the same with both methods.  This method is a good one to show smaller variances (as little as .001) than the method above.  Use both methods, if for no other reason than to supply as much data as possible before proceeding.  You don’t want to go off realigning fork tubes that weren’t misaligned in the first place.
glass plate

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