Help needed changing coils in JIC Coilovers

[Toyo Truck]

Hi guys,

I have an MX83 Cressida with JZX81 JIC coilovers fitted all round.
The car handles AWESOME, but it WAAAAAAAYYYY to stiff.
The springs are currently at 12kgs/mm in front and 8kgs/mm rear,
this is too hard for a street car around Sydney's shitty roads.

I have played around with the adjustment no-end, and it only has a slight
improvement. I think I have to bite the bullet and fit new softer coils into the setup
to get back some cruisability.

Firstly, does anyone know the PHYSICAL DIMENSIONS of a JIC coilover spring?
To get replacements made, I need relaxed height, and inner diameter, also coil
thickness might be good too.

Second, what SPRING RATE would you reccomend for a streeter?
I was thinking 6kg/mm front and 4kg/mm rear. Would this work OK in a 1500kg MX83?
Then I can keep these current springs for the track, cause THATS where they belong!

Any advice greatly appreciated.
Cheers,
Bart

[Norbie]

Converting this into units I understand, the fronts are about 670 lb/in which I would consider much too firm for the street; this is similar to what the V8 Supercars run. Not quite as crazy as my JZX81 coilovers though, they were about 900 lb/in!

Definitely get yourself some new springs, but you don't need to get them "made up" - the beauty of coilovers is the springs are generic. There are 2 or 3 common diameters (mine were 60mm I think), so just go to your preferred spring supplier with the required diameter and uncompressed height and they should be able to provide you with off-the-shelf springs with a variety of spring rates. Obviously you'll need to measure your existing springs but you should be able to do this without removing the struts.

I used 300 lb/in springs on my car which I find is a good compromise between ride and handling, but with a heavier car like your MX83 you might want to try 350. As for the rears, slightly softer is usually the way to go - I'd specify 350 front and 300 rear. The ideal number depends on your goals of course, but talking to other MX83 owners will be more useful in this regard.

[Stefan]

IIRC popular spring IDs are 60mm, 63mm & 65mm.

[Toyo Truck]

Hey guys,

for the sake of my back, I have removed the coilovers from my car
The rears needed rebuilding anyway.
I have had a slightly annoying pain in my back for ages and since I took out
the JICs my back seems to be feeling a little better.

I will get the rebuilt, and maybe fit them back in, or sell them.
Still havn't decided yet.

But thanks for the info anyway Norbie

PS sorry I havn't written back in a while...login problems

Cheers,
Bart