<VV> regarding nylon strut rod bushings and shock absorber lower brackets

[Louis C. Armer,Jr.]

To recap for those who may not have read the original post:

>Hey all, I am in the process of pulling Darth Vair's drivetrain in 
>order to find the reason(s) for his five
>cylinder orneriness and along with this I am going to return to 
>non-nylon bushed strut rods. Upon removal
>of the strut rods and inspecting the camber bolt area I have 
>discovered a possible problem on both trailing
>arms. This is what I found at the area where the lower shock 
>absorber bracket is welded to the trailing arm.
>The reinforced area where the camber bolt goes through both the 
>reinforcement and the shock mounting
>bracket has enough space between the layers to easily run an index 
>card or thicker piece of paper up in the area
>and past the oval bolt hole cutout. Both sides exhibit this space 
>and it appears as if initially there was NO weld there.

This appears to be normal for LM lower rear shock absorber brackets 
and the cure for additional strength at these
brackets is to mig weld for reinforcement. I have not done this yet 
but time permitting it will get done.

>
>When I examined the area on the front side of the strut rod bracket 
>I found the reinforcement on both sides to be
>just alike and with no space between the apparently factory welded 
>layers of reinforced metal. This area is reinforced
>to hold the outer strut rod bushing and have the camber bolt 
>assembly pass through the strut rod and thus allows for
>the rear alignment adjustment. I don't have any other trailing arms 
>handy to determine if the area of space was there
>originally or if I might have broken welds because of stress caused 
>by nylon bushings being used at inner and outer
>strut rod mountings. Any observations of viewable strut rods and or 
>past experience with a similar problem would be
>welcomed and please post the list as this may be a possible failing 
>of LM trailing arms caused by the strut rods in
>conjunction with nylon bushings.

I feel that this area's flexibility between the two layers of 
metal,  combined with nylon bushings, may have been enough
instability to cause my camber bolt adjustment to loosen enough to 
drop camber often enough to be considered failure.
I used factory camber bolts, grade 8 lock washers and grade 8 long 
nuts on both rear trailing arms and these were
consistently tightened with either a 15" or 18" breaker bar so I 
doubt that they were not torqued to normal or above
  foot lbs.

Darth has had a crown bracket on the tranny since restoration and has 
run Clark's nylon bushings at all strut rod ends
for over 11,000 miles. The crown bracket shows no signs of distortion 
or cracking. The trailing arm brackets show no
signs of distortion or cracking. The inner nylon bushings are 
slightly worn where the metal bolt bushing passes through
them but the wear appears to be constant on both inner bushings and 
there is no wallowing out or "ovaling" of the inner
bushings and both still exhibit a tight outer fit in the tie rod ends.

I am now going to use Corvair Underground's middle stiffness urethane 
strut rod bushings and continue to use the crown
bracket but per Warren Leveque's recommendation I am relocating the 
strut rod mounting holes to 1 1/4" higher on the
crown bracket to level the strut rods position. This combined with 
the welding and the inherent shock absorbing of the urethane
bushings will hopefully eliminate any further camber dropping incidents.

Thanks to all for their input and especially to Seth and Warren for 
their sage advice.






CORSA Member
CORSA Tri-membership Chairman
Corvair Atlanta Member
Corvair Atlanta BOD
Corvanatics Member
SECC Member

1965 Corsa Coupe
1964  Greenbrier
1966 Monza Convertible
1966 WTBRT #112 xcrosser 1/2 owner
http://carmerjr.home.mindspring.com/