[DeTomaso] Adjustable upper rear A-arms

[MikeLDrew at aol.com]

In a message dated 12/2/15 8:13:20 PM, kenn_green at yahoo.com writes:


> I have a vague recollection that some of the modified upper rear control 
> arms included adjustment to reduce possible binding in the rear suspension 
> because the upper ball joint may not exactly line up with he top of the 
> carrier?  It seems like a control arm with adjustable frame ends could be 
> adjusted to align the ball joint with the carrier?
> 
>>>I know what you're thinking...but no.

Some adjustable upper A-arms have the adjustment on the inboard (chassis) 
side, but most have it on the outboard (hub carrier) side.   Normally, the 
A-arms prescribe a roughly 90-degree angle with the hub carrier at rest, which 
becomes less or more than 90 degrees as the suspension travels through its 
arc.   This changes only slightly if the car is lowered an inch or so.

If I understand you correctly, your premise is that the car could be 
lowered so much that the angle between the upper A-arm and the hub carrier would 
become so acute that the ball joint would be bound up.   That would require 
an extreme amount of suspension movement, so much that the chassis would hit 
the ground first.   Nobody would ever lower a car that much.

But even if it was possible or desirable to lower the car that much, the 
only way to avoid the binding problem (never mind the fact that the chassis is 
dragging on the ground) would be to raise the inboard end of the A-arm.   
One could achieve this by moving the mounts upwards on the chassis (in fact 
Les Gray's Gr4 race car chassis was modified, in the front I think, with 
alternative A-arm mounting locations, something done in the USA after it came 
here, I think), but you couldn't achieve this by putting a vertical adjustment 
on the A-arm itself--at least not reasonably.

Not that we're really talking reason here...:>)

Mike
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   In a message dated 12/2/15 8:13:20 PM, kenn_green at yahoo.com writes:

     I have a vague recollection that some of the modified upper rear
     control arms included adjustment to reduce possible binding in the
     rear suspension because the upper ball joint may not exactly line up
     with he top of the carrier?  It seems like a control arm with
     adjustable frame ends could be adjusted to align the ball joint with
     the carrier?

   >>>I know what you're thinking...but no.
   Some adjustable upper A-arms have the adjustment on the inboard
   (chassis) side, but most have it on the outboard (hub carrier) side.
   Normally, the A-arms prescribe a roughly 90-degree angle with the hub
   carrier at rest, which becomes less or more than 90 degrees as the
   suspension travels through its arc.  This changes only slightly if the
   car is lowered an inch or so.
   If I understand you correctly, your premise is that the car could be
   lowered so much that the angle between the upper A-arm and the hub
   carrier would become so acute that the ball joint would be bound up.
   That would require an extreme amount of suspension movement, so much
   that the chassis would hit the ground first.  Nobody would ever lower a
   car that much.
   But even if it was possible or desirable to lower the car that much,
   the only way to avoid the binding problem (never mind the fact that the
   chassis is dragging on the ground) would be to raise the inboard end of
   the A-arm.  One could achieve this by moving the mounts upwards on the
   chassis (in fact Les Gray's Gr4 race car chassis was modified, in the
   front I think, with alternative A-arm mounting locations, something
   done in the USA after it came here, I think), but you couldn't achieve
   this by putting a vertical adjustment on the A-arm itself--at least not
   reasonably.
   Not that we're really talking reason here...:>)
   Mike