If the rear of your car sits at the same level or slightly
higher than the front [measured from beneath the wheel arch
rim to the ground over the centre line of the respective
wheels] then the springs have probably been changed for the
longer non-SLS version.
Free standing on the bench, [which of course doesn’t help
you when they’re installed!] the non-SLS spring is about 1�"
to 1�" longer than the SLS spring due to the fact that it
has one extra ‘active coil’ - i.e. (from memory) six coils
instead of the SLS spring’s five coils [something you may be
able to judge whilst installed]. Otherwise they are of
similar wire gauge, coil diameter and material. Because of
this extra coil in the non-SLS spring, they are in fact
slightly ‘softer’ [i.e. they deflect further for a given
load] than the SLS ones they replace.
The paint markings you see on your currently installed
springs are not indicative of the type of spring fitted.
Those markings are, as far as I can establish, simply a
method of identifying matching pairs of springs in terms of
length and strength. They are used to indicate to the
mechanic how many [if any] and which thickness of spring
packers are to be fitted to top and/or bottom of the spring
pan to compensate for differences in spring length due to
manufacturing tolerances.
Since you’re replacing the shocks [which is probably the
sole reason for the ‘spongy’ ride] you will be able to
measure the free standing length of the removed springs on
the bench [and count the active coils]. If the spring
overall length is about 9�" you have the SLS spring. If the
spring measures somewhere around 10�" -to- 11" [perhaps less
allowing for a little ‘sag’] you have the standard spring.
BTW, I recommend Bilstein shocks - I like 'em.
Good luck.
Bryan N
'91 Sovereign 4.0 [89 K]
'91 MX 5 (Miata) 1.6 [94 K]
Cambs, England
The spring measurements I quoted are for the bare springs
sitting on the bench [the ‘free length’]. Although I didn’t
actually measure the new non-SLS springs before I fitted
them, I estimate [and am pretty confident] that they were
getting on for 1�" longer from seeing them standing on the
bench next to the SLS springs [which I have measured
subsequently at 9�" - I still have them in my garage].
Perhaps you would let us know the actual free length of the
springs removed from the damper assemblies on your car.
Don’t forget that you can add about �" to their overall
length by adding the maximum number of plastic packers [two
thick packers @ �" each] to raise the rear of the car even
more.
Bryan N
'91 Sovereign 4.0 [89 K]
'91 MX 5 (Miata) 1.6 [94 K]
Cambs, England----- Original Message -----
From: “Tom Keohan” tomkeohan@hotmail.com
To: <@Bryan_N>
Cc: modern@jag-lovers.org
Sent: Friday, April 05, 2002 9:49 PM
Subject: Rear Shocks- '90XJ6
Bryan:
Thanks for the tip on the rear springs. I’ve got the
shocks (dampeners) out
and will measure the springs tonight as per your spec’s on
the SLS vs. non
SLS springs. I assume the lengths you mention are for
springs removed from
the spring seats and dis-assembled from the shocks, is
that right? If so,
I’ll measure them once the springs are free from the
spring seats (done at
my local dealer of course). Or are the lenthgs you mention
for the assembled
spring/shock? I suspect that my '90 Sovereign has the
converstion springs
installed, but your spec’s for the springs will tell me
positive.
Just clearing my ‘inbox’ and found your earlier message.
Did you ever manage to measure the free length of the
springs?
Bryan N
'91 Sovereign 4.0 [90 K]
'91 MX 5 (Miata) 1.6 [94 K]
Cambs, England----- Original Message -----
From: “Tom Keohan” tomkeohan@hotmail.com
To: <@Bryan_N>
Cc: modern@jag-lovers.org
Sent: Friday, April 05, 2002 9:49 PM
Subject: Rear Shocks- '90XJ6
Bryan:
Thanks for the tip on the rear springs. I’ve got the
shocks (dampeners) out
and will measure the springs tonight as per your spec’s on
the SLS vs. non
SLS springs.
Did you ever manage to measure the free length of the
springs?
Bryan N
'91 Sovereign 4.0 [90 K]
'91 MX 5 (Miata) 1.6 [94 K]
Cambs, England----- Original Message -----
From: “Tom Keohan” tomkeohan@hotmail.com
To: <@Bryan_N>
Cc: modern@jag-lovers.org
Sent: Friday, April 05, 2002 9:49 PM
Subject: Rear Shocks- '90XJ6
Bryan:
Thanks for the tip on the rear springs. I’ve got the
shocks (dampeners) out
and will measure the springs tonight as per your spec’s on
the SLS vs. non
SLS springs.