Re: [T3] Top Torsion Bar Question

[Greg Merritt <gregm@vwtype3.org>]

<x-flowed>At 4:27 PM -0800 1/22/06, Doug Brashear wrote:
>  Is this i common problem? Is it something I can simply adjust out?

Yes, and yes.

It is a little tricky to get the hang of what's going on with the 
mounting of the upper torsion bar and how it's adjusted, and in many 
of these old cars it has worn differently from how the manuals 
expected them to wear.

The bar runs through the top tube, of course.  However, the two ends 
are very different.  One end has a flat on the side, right at the end 
of the bar.  There is a sort of conical dimple machined into this 
flat.  This end of the torsion bar is designed to be fixed in place 
by a conical-tipped socket head (iirc) screw that's mounted in the 
top of the trailing arm, vertically, in a threaded hole in the 
trailing arm.  It's supposed to seat down tightly in the matched 
dimple machined in the torsion bar, and hold that end fixed.  There 
is a big lock nut around the socket head screw to keep it locked 
down.  If you like, the torsion bar and the trailing arm on this 
fixed side become as one single unit, like a giant letter "L", sort 
of.

The other end of the torsion bar is different.  Its end has been 
drilled and threaded along the torsion bar's axis.  The trailing arm 
for this side slides onto the bar, and a bolt mounts horizontally 
through an unthreaded hole in this trailing arm, and then screws into 
the torsion bar itself.  This *single* screw is used to draw the 
trailing arm and the torsion bar together, and pull *both* trailing 
arms up tight to the front beam assembly.

Now!  Manuals expect slight wear to develop due to the pivoting of 
the trailing arms, and the way to get rid of such wear is to tighten 
up (but don't overtighten!) this horizontal bolt.  Trouble is, is 
that for many Type IIIs, unexpected wear has occurred at the *other* 
end of the torsion bar.  Remember that little dimple in the flat of 
that end of the torsion bar, where the set screw jams into the 
conical dimple?  Well, that dimple gets beaten up, and can wear into 
a little trough.  There is now slop where the set screw meets the 
torsion bar, and it no longer secures the assembly sufficiently.

You could try an adjustment at the intended-to-be-adjusted end, and 
this might help for a bit, but, as the car drives, it will beat up on 
this set screw and its troughed dimple, which aren't really mated 
properly, and it will quickly become loose again.

So, the trick is to take care of the set screw end.  If the damage to 
the torsion bar is not too bad, you may very well be able to get away 
with loosening the other side to get some slack, tightening the set 
screw so that it finds home jammed into the lowest part of the 
troughed dimple, and then adjusting the meant-to-be-adjusted side 
according to spec.  This procedure worked well for my on my '71.

Hope this helps, and is at least a little bit clear!

-Greg

p.s.: as you can tell, I forget if the dimple is on the left or right 
side.  I think it's the left, and the adjuster is on the right... but 
I forget. :)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

</x-flowed>