<VV> Re backing plates

[Crawford Rose]

The difference between 60-62 and 63-64 backing plates accounts for the spacers.  The 60-62 backing plates are 3/8ths of an inch thick at the bearing interface. The 1/4 inch spacer which you are asking about compensates for the thinner 1/8 inch steel 63-64 backing plates which were introduced with the cast wheel bearings.  The spacers are essential on both sides.  Obviously, the backing plates without the spacer will cause binding when you bolt the wheel bearing down.  I learned about this when having some NOS backing plates machined for use with 63-64 cast bearings (did it twice because I forgot to measure with the bearing shield installed).

Crawford Rose