[DeTomaso] Shorter front shocks?

[MikeLDrew at aol.com]

In a message dated 4/5/16 13 40 50, detomaso at poca.com writes:


> Has anyone done an analysis of the viability of running a bit shorter 
> front shocks?  With the typical length front shocks, and springs on the heavy 
> side, it appears that the nose is a bit higher than I want at the lowest 
> spring position.  I could probably use lighter springs adjusted for the 
> desired height, but I'm not sure that is a good solution.
> 

>>>That is assuredly a bad solution.   Ride height should be controlled by 
spring height, period.   Ride characteristics should be controlled by spring 
rate, period.

Since you have adjustable spring perches, however, if you have your perches 
set as low as they go and the ride height is too high still, the 
inescapable conclusion is that the springs (NOT the shocks) are too tall.   FWIW, 
every adjustable Pantera shock/spring package I've ever seen will allow you to 
lower the car TOO much, which makes me wonder what kind of deal you have 
going on?   Have you started with a tried-and-true combination and then changed 
to longer and/or stiffer springs?

Realize that effective spring force and spring length are interrelated and 
need to be controlled against one another.   If you have a spring of a given 
advertised rate, and you cut it in half, you double the rate.   So what you 
need to do is decide what spring rate AND what length you want/need, and 
then buy exactly that....

It took me a long time to figure out exactly why that was true; intuitively 
it made no sense to me at first.   Here's the explanation:


Say you have a spring that is 12 inches long, with 12 coils on it, and you 
put a 500 pound weight on top of it and it compresses one inch.   That means 
each coil compressed 1/12th of an inch, for a total compression of one 
inch.   The spring rate is 500 lbs/inch.

Now, cut it in half.   Put a 500 pound weight on it, each coil will still 
compress 1/12th of an inch, but since there are only six coils it will only 
compress 6/12ths, or half an inch.   500 pounds compressed it only half an 
inch, so it would take 1000 pounds to compress it a full inch, thus the spring 
rate is 1000 lbs/inch.

Presuming your existing spring rate is appropriate, you may need to buy 
shorter springs with the same rate.   Even if they are two inches shorter, you 
would then have adequate adjustment in your perches to set the ride height 
where you wanted.   

But I'm still skeptical overall of your situation.   Tell us exactly what 
you're using?

FWIW I had Carrera coilovers on my car initially; those springs were 
considerably longer than those on the Konis that replaced them....

Mike
-------------- next part --------------
   In a message dated 4/5/16 13 40 50, detomaso at poca.com writes:

     Has anyone done an analysis of the viability of running a bit
     shorter front shocks?  With the typical length front shocks, and
     springs on the heavy side, it appears that the nose is a bit higher
     than I want at the lowest spring position.  I could probably use
     lighter springs adjusted for the desired height, but I'm not sure
     that is a good solution.

   >>>That is assuredly a bad solution.  Ride height should be controlled
   by spring height, period.  Ride characteristics should be controlled by
   spring rate, period.
   Since you have adjustable spring perches, however, if you have your
   perches set as low as they go and the ride height is too high still,
   the inescapable conclusion is that the springs (NOT the shocks) are too
   tall.  FWIW, every adjustable Pantera shock/spring package I've ever
   seen will allow you to lower the car TOO much, which makes me wonder
   what kind of deal you have going on?  Have you started with a
   tried-and-true combination and then changed to longer and/or stiffer
   springs?
   Realize that effective spring force and spring length are interrelated
   and need to be controlled against one another.  If you have a spring of
   a given advertised rate, and you cut it in half, you double the rate.
   So what you need to do is decide what spring rate AND what length you
   want/need, and then buy exactly that....
   It took me a long time to figure out exactly why that was true;
   intuitively it made no sense to me at first.  Here's the explanation:
   Say you have a spring that is 12 inches long, with 12 coils on it, and
   you put a 500 pound weight on top of it and it compresses one inch.
   That means each coil compressed 1/12th of an inch, for a total
   compression of one inch.  The spring rate is 500 lbs/inch.
   Now, cut it in half.  Put a 500 pound weight on it, each coil will
   still compress 1/12th of an inch, but since there are only six coils it
   will only compress 6/12ths, or half an inch.  500 pounds compressed it
   only half an inch, so it would take 1000 pounds to compress it a full
   inch, thus the spring rate is 1000 lbs/inch.
   Presuming your existing spring rate is appropriate, you may need to buy
   shorter springs with the same rate.  Even if they are two inches
   shorter, you would then have adequate adjustment in your perches to set
   the ride height where you wanted.
   But I'm still skeptical overall of your situation.  Tell us exactly
   what you're using?
   FWIW I had Carrera coilovers on my car initially; those springs were
   considerably longer than those on the Konis that replaced them....
   Mike