A small amount of dirt or rust left on the hub flange face might cause
the back plates to sit a hair further outward, possibly at a slight
angle. During a full rear brake rebuild on my '81, I recall removing
old backing plate metal that had rust "welded" onto the flange face.
As a guess, if the lower shoe anchor wasn't seated all the way, that
could cause an alignment issue of drum to backing plate. But even
though the anchor pin is a tight fit to hub, you'd think the two bolts
would cinch that part down.

This image of new backing plate etc on my '81:
https://tinyurl.com/p2vbvfzz shows how the drum lip rubbed at the
plastic inspection hole bung and removed a fair amount of material.
But, that fitment issue may've been due to the plug length being
incorrect and/or drum design. I don't recall if the bung was OE but
drums were most likely Zimmerman.

Though that level of brake work was a first time effort on my part so
it's possible a slight flaw in my work caused the rubbing issue I saw.
That said, the brakes have worked fine for thousands of miles and the
amount of material erased at the plastic plug would indicate a part
design issue.

It sounds like your drum lips are quite close to each backing plate.
Given the large forces involved when making a sharp turn, any slight
"normal" play at bearings would allow the drums to rub.

Neil.

On 4/27/21, David Boan <dboan@outlook.com> wrote:

> Hello Vanagon Types
>
> I wrote a few days ago that my new drums were rubbing on my new backing
> plates.  They did this constantly, driving straight or turning.  I reported
> that I ground a 1/16" off the drum rim and problem solved. Well, not quite,
> they are quiet when driving straight but rub when making a sharp (90 degree
> or more) turn.  The rubbing is only on the bottom half of the backing plate,
> maybe just the bottom 1/3.
>
> The brakes are working fine.  The linings are also new and I also installed
> new wheel bearings at the same time (had a machine shop do this).
>
> I am thinking that the backing plate must be out of round for it to rub just
> the bottom of the plate. I hesitate to take any more material off the drum
> to try and fix it.  I am considering just driving it for a while till I get
> the energy to replace the backing plates.
>
> I wonder why this happens just when turning.  Does anyone have experience
> with this issue?
>
> Dave B
> Boise
> 85 Westy
>

-- 
Neil n

VE7TBN

1988 Westy 50º ABA swap: https://tinyurl.com/yap5hpwt

1981 Westy 15º ABA swap: https://tinyurl.com/y9n4xob8

VAG Gas Engine Swap Group <http://tinyurl.com/khalbay>