Spohn 738-QX - Manual (Page 3)

No matter which type of spindle you have, you will need to grind for clearance of the
bottom black adjuster housing on the QA1 strut. If you hold the QA1 strut on the
stock spindle you will notice that the bottom mounting bolt hole will not line up with
the bottom mounting hole in the spindle because the black adjuster housing on the
bottom of the QA1 strut is contacting the spindle. Holding the strut in place, mark
the area of the spindle where you need to grind it down for clearance as shown
below.
If you have the heavy spindles you will also notice that the top mounting hole in the
QA1 strut doesn't quite line up with the top mounting hole in the spindle, just
enough that you can't get a bolt through. If you have the heavy spindles you will also
need to slightly grind the top radius area of the factory spindle as shown below.
No matter which type of spindles you have, the small amount of clearance grinding
that is required will not effect the strength or integrity of the spindles. You are only
removing a small amount of material. The spindle modifications required for 1LE
front brakes remove much more material from the spindle and people have been
doing that for decades without any issues.
Step-By-Step Pictures
Step 1: Mark Where We Need To Grind (Heavy Spindles Shown)
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