jaholmes

Last winter I put on a set of JIC coil overs with heavy springs on my C4S. 10k front / 14k rear. The plan was to do a lot more track days over the summer and I only got to do 1 f-n day. I feel like I ruined the car with such heavy springs. I have also realized it's too nice to track and will be looking for something else for track duty.

I think JIC shocks are very good and wondering if it's worth it to just swap out the springs with softer springs. Something in the M030 or HR range. The other option is go to PSS-10 or Bilstein HD's. I did do the install myself so the install is not an issue.

Any options on how soft to go with the JIC springs. One though is to put the 10k springs in the back but I still think that may be too stiff. I think the range will be 300 - 450.


Thanks.

ninjabones

I have JICs with 8 fr / 11 rr that I purchased this time last year. The ride is firm, but tolerable on the street at about 4 settings from full soft. I wouldn't do it for a daily driver, but for spirited weekend romps, it's not too bad. I might be willing to trade springs with you as my car is now a dedicated track car. However, I'd have to check with JIC to be sure that swapping springs does not require revalving.

Glen

Ag02M5

I'd say get lower spring rate springs from JIC directly though you should be able to use H&R or maybe Hypercoil. Just depends on the spring ID. Not sure what it is off hand.

I am still playing with mine but I went with 7/11 for my 965. I still need to dial it in but it seems like a pretty good compromise between street and track.

I'm pretty sure you won't need to revalve.

I think the front may be a bit soft compared to rear but I haven't driven it enough to know for sure. I'm thinking 7/10 or 8/11.

Cheers.

RT

Stealth 993

Call JIC & ask what spring rates they would suggest. It will be fine with lower rates, but you will need to dial in the compression & rebound to match.

jaholmes

I was only going to swap JIC springs. The HR option was to completely swap the JIC's with Bilstein HD's or get OE M030 springs.

jaholmes

Ahem. I have talked to them several times. They did offer to swap mine for a custom set if I wanted but I went with what I had. They are an older set which they said the valving is more track biased then street. I think the one's now have a more street biased.

jaholmes

Mine are set zero, softest setting. Maybe I need to fiddle with the settings to dial out some of the bounce.

I'm pretty sure that springs can be swapped without a re-valve.

Ag02M5

I also found the ride was super bouncy on the lowest setting, esp in front. Dialing it up a few really helped out. I think I will still dial up the front another couple notches to get it evened out.

993_Pilot

Subscribed ! I have 8k fronts and 11k rears on mine, but I haven't gotten around to installing them yet, so I can't comment. But I am interested in what others have done, and their impressions.

Bull

JIC springs can easily be changed without re-valving (unless you go above 1000lb spring rate). The last time I checked with JIC, the springs were only $80 ea. When JIC offers "custom" suspension set-ups on there website, rather than their kits, all they are doing is selecting custom springs to put on the same shocks.

CornerCarver

I recently purchased a set and believe I have 9k and 12k. What identifies the spring rates; color, part #?

Bill Verburg

The JIC springs are marked on the ends w/ the spring rate in kg/mm


They use seeveral fiifferent comos
7/10, 8/12 seem to be the most common,

raising the rear relative to the front tunes in more over/less under steer and vice versa

7/10 is 392/560 lb/in and very useable for a street/track combo
8/12 is 448/672 obviously more track oriented

to the best of my knowledge here are some others
RoW M030 is 150/300
993RS is 246/457
993Cup is 600/800
GT2Evo uses several combos from ~1500 to ~ 2000

CornerCarver

Thanks, Bill. With the 9 and 12, it seems like the occasional fun run meets and driving to track may be a little too harsh.

Did you figure out a fix for the moving camber plates? I met up with an owner of a Mitsubishi EVO with same setup. He installed lock washers in between washers and bolts. He tracks often and fast on r compounds without any movement.

jaholmes

Sorry Bill, should there be another zero for the RoW numbers.

It looks like 7/10 would be close to RS specs.

Bill Verburg

The interem fix is bigger washers and longer bolts(go all the way through the plate also grade 12.9 vs 10.9, and vigilance. Been good for the past 3 track days.

I'm looking into using Mode monoball/camber plates