Coilovers: Illumina's vs. Koni's, spring rates, please help!

[zredbaron]

Okay, guys. I really feel like I'm getting the runaround here. I am getting 20 different stories from 10 different people...maybe some of you can share some of your experience/setups and, of course, your infinite wisdom!

 

The short question is this: What spring rates can the Illumina's handle?

 

My car will be a streetable weekend warrior (~250hp) for the next few years, and I intend to be very competitive with autocross. (I am looking for a stiff ride, but not too ridiculous for the street.) Down the road (2-5 yrs), the car will not be on the street much and I will want to move toward road racing. I aim to get a setup that I won't have to redo when I move to road racing!

 

I am currently working with Ross Corrigan (who has been immensely helpful) to get a set of coilovers, shocks, and brakes. I am having a hard time choosing spring rates, and appropriate struts. I have decided the car will ride on 225/50R16 all the way around, 15lb wheels.

 

He wants to set me up with 250fr/225r with the Koni's. He mentioned the limited spring rate capability of the Tokico Illumina's. I like the idea of the Koni's, but I have to admit that the car is currently in Arkansas and finding a set of 280z strut braces is approaching impossible.

 

So I'm thinking I might be willing to sacrifice a wee bit of spring for convenience of installation and of course the screwdriver-click adjustments with the Illumina's.

 

I call Tokico and they say the strut the have paired with the 240Z can handle spring rates of 160fr/190r. According to them, anything above that and the Illumina's "are just along for the ride, it's all spring at that point." I trust their engineers, but perhaps people are installing a different model number than they have in their system.

 

I call MSA, their MSA springs are 173fr/243r, which they use with Tokico's and say work great!

 

I call Top End [insert verbal bashing here] and they say that the Illumina's can handle the 250fr/225r setup just fine.

 

What gives? I've read in these forums that the Illumina's are limited, but just how limited are they? If anyone can share their setups or offer some advice I would really appreciate the help.

 

Thanks!

[JMortensen]

Do a search and you'll find the answers to all of your questions.

 

Here's a quick answer from my experience. First, you'd be better off IMO running the 225's in front and the 250's in back. I am running 200fr/250rear and Illuminas, and I've blown 1 shock in 5 years and 40K miles. I think I blew it going over a bumper on the track.

 

The Illuminas can handle 250 in/lb springs, any higher than 275 and it gets a little iffy. John Coffey says that Konis can fit into the 240 housings, Ross says you need 280 housings. I trust John on that one. He has a FAQ about strut sectioning that will help you out.

 

There are a couple of guys running the stiffer springs in front, but the vast majority run stiffer in the rear.

 

I'd go with the Konis because if you do get serious about the track you will want to up the spring rate substantially. On the flip side, the Illuminas are nice because you can turn them down for street driving. I think but I'm not sure that you can do the same with the Konis, but I know that I drive my Illuminas on the street at 1 or 2, and they don't beat the crap outta you.

 

Jon

[johnc]

The issue with Tokico (and most other single adjsutable shocks) is that rebound and compression damping are tied together. Rebound damping controls spring rebound (spring extension) which is all the stored energy in the spring as a result of a hitting a bump.

 

The Tokico engineer's figures are a bit conservative but they are essentially right, but remember, the Illumina application we use (for shortened struts) are Toyota MR2s in front and 240Z fronts in the rear. If you crank up the Tokicos to 5 to control rebound from 250 to 300 lb. in. springs the compression damping becomes stiff enough to reduce grip. The Tokico Illuminas have a real adjustment range on our cars of from 2 to 4.

 

I have run 300 lb. in. rear springs with the Illuminas but that was only for a smooth surface autocross setup. I would not exceed 250lb. in. in spring rate for the Tokico Illuminas and would try to run a bit softer if I could.

 

The Koni 8610s do fit in the 240Z strut tubes and I've done an installation recently for a customer. These are more track oriented shocks and require spring rates over 200 lb. in. depending on what valving you specify when ordering.

 

For a compromise street/autox/track car I would run the Illuminas with 200 f and 225 r springs and a 1" (25mm) front and 3/4" rear anti-roll bar.

[Guest DISCUS]

My car is designed specifically for Autocross and Street as you suggest. However my conversion is lighter than stock so I have gone with 175 front and 225 rear. I am very happy with those spring rates. My car is approx 100 lbs. lighter than stock, balanced front to rear and corners. I would also agree that it makes more sense to have the heavier spring rate rearward. If your car is about stock or a bit heavier than 200/250 should give you a pretty good balance and well within the Illumina range.

I run #1 rate for long distance Highway, # 2 for street and for autocross I run #3 up front and #5 on the rear. Remember their is lots of room for individual taste and thus different reccomendations.

[Forrest]

I used a spring rate spreadsheet a little while ago and it recommended 175F/225R for my car assuming a weight of 2650 (which is close) and the axel weights and estimated unsprung weights that the guy who wrote the sheet (who had a 2650lb s30.) I was going for a pretty rough ride but not full out race scenario. It was curious though that no matter how rough I set it, the front spring rate never got up to 200 - it seemed that for my weights 175 was best in the front in most of the scenarios.

 

I don't have the link anymore, but I'm sure someone else does. It was a good spreadsheet.

[TexasNissanDude]

John Coffey says that Konis can fit into the 240 housings, Ross says you need 280 housings. I trust John on that one. He has a FAQ about strut sectioning that will help you out.

 

Would someone happen to have a link for this FAQ? I have searched but was not able to find a link.

[Here comes trouble]

Coffey's advice seems to be reasonable. I would not put heavier springs in the frontthan the rear.........nor would I go no more than 250 in the rear... You will have the set-up for very fast spring removal and installation. Buy 3 sets of springs or two 180#------two 200# and------------two 225 # with 225# the maximum limit in the rear

[zguitar71]

I have 186F and 200R Arizona Zcar springs and Illuminas. I use #1 on the street and at the last autocross I used #3 on the front and #4 on the back and the car was very balanced. This course has a driveway transition to navigate that launches the car. The Illuminas absorbed the launch very well with the spring rates I have. I had KYB's last year and the same dirveway was terrible, to the point I was going to avoid that course in the future. I am much happier with the suspension now and do not feel the need to change anything except the settings of the shocks depending on the track type and speed. I think the Illuminas and my spring rates are a good match, they do not overpower the shocks. The ride in town is much better now than the KYB's, I bought them for Autox but the improved street ride is and added bonus and was surprising to me.

[Mikelly]

Go with the Konis Ross and John recommend... they will serve you well... And will be a better compromise when you decide to move beyond cone shagging, and start HPDEs...

 

Mike

[Drax240z]

I'm running 200f/250r 1-1/8" front bar, no rear bar, and illumina's all around. I haven't had any issues with the illuminas. Still playing with settings on the track, but on the street I run 3 in the front, 4 in the rear.

 

I'll probably go with a smaller front bar and a rear bar once I get my LSD installed.

[260DET]

Just an observation on apparent North American spring and roll bar rates.

 

The average NA setup uses relatively heavy roll bars and light springs to what we in Oz tend to use, although of course there is plenty of variety here.

My front bar is 22mm thick, not many use thicker than that, while the rear is 18mm which is a bit thicker than average.

 

Most springs would be in the mid 200s, depending on shocks and body stiffness, there may be a trend to use heavier shock settings with lighter springs though. Mine are 250F 300R with a half cage, went up from 275R before the half cage.

[randy 77zt]

i run 250lb rear and 225 front-car is daily driver.springs are 12" .shocks are illuminas.front sway bar is 15/16.rear is 7/8.car drives good on the street and can run good on the track.might try 300s in rear and 250s in front.track tires are kumho v700 225/50-15.the illumunas will wear fast(40000 miles)with stiff springs.

[Guest JAMIE T]

It's actually kind of interesting, all this. It seems like there is even a differance between east coast and west coast set-ups. Like, east coast racers seem to prefer to use heavy spring rates and moderate anti-roll bars, while the west coast guys like softer spring rates and stiffer anti-roll bars. Each set-up works fine as the ITS cars on both coasts are very fast. Even though I'm and East Coaster, I prefer the west coasts soft spring, stiff anti-sway bar technique for controlling body roll. I'm using 300lb rear and 225lb front. I will likely use the Koni's when that time comes around.

[johnc]

Don't compare spring rates for a SCCA ITS prepared 240Z (regardless of coast) with those for a 240Z that does not have an 8 point cage installed. The 240Z chassis will start flexing with spring rates around 300 lb. in. unless efforts are made to significantly reinforce the chassis. A series 1 240Z will flex more then a late 240Z and 260/280Zs will flex even less.

 

A welded in roll bar with a strut tower brace will allow 300 lb. in. in the rear. A full cage with a front strut tower brace will allow 300 lb. in. in the front. I know Keith ran front spring rates upwards of 350 lb. in. on Chet Whittle's ITS 240Z but I'm not sure how he got away with it. Maybe great cage design, maybe something else?

[katman]

The last season season we ran "Big Orange" in ITS used 400#/in front and 350 rear, with the equivalent of a 15/16 bar up front, no bar in the back. John's structural assessment is right on all accounts as usual. We got away with it because we had a very effective front strut bar, very efficient cage, no structural compromises to the basic unibody (dents, rust, corrosion, etc.), and custom adjustable remote reservior shocks. We also had very light wheels and tires (Hoosiers) and overall front end weight was less than stock. The low unsprung weight is important because is reduces your shock loads.

[gramercyjam]

Another .02 here on tokicos and spring rates. I run 300# 6" springs front and rear for the last 2 years with the illuminas usually on 2 in front and 3 in the rear. The car also has exremely light weight 16" Real wheels and Hooser bias ply slicks and a 1" front roll bar and a 7/8" rear bar and weighs less than 2000# with stock brakes and very good racing pads and shoes, deleted brake booster and adjustable bias. No cage, but it has a 4 point roll bar, the chassis is reinforced and seam welded, with a welded in rear strut bar. It is a dedicated autox car. It wouldn't last 5 minutes on the street with those spring rates and the ground clearance. Co-drivers have told me the car is extremely twitchy. I don't know, it seems normal to me and it is OK for me. The car handles a lot differently with this setup with added chassis ballast or even heavier tires like radials. I probably would make some changes with the springs a shocks sooner than I plan. As it is, I plan on going to stiffer springs and better shocks at some point for even better transition handling.

[Guest ufoautocross]

OK guys. I've been Autocrossing for about 8 years now and I am running 450f 500r with msa's 1"f 3/4"r sb with no problems. I took the championship in VSP last year and am in 2nd place this year. I also teach a performance driving school at Thunderhill and Buttonwillow and drive Laguna Seca And Sears Point with no problems. The Tokico adjustables will hold up to a 600 pound spring. advanced designs double adjustables are recommended for over 600 #s. Always Stiffer by 50 #'s in back though which seems weird but works very well.

[johnc]

For the typical 240Z installation using BZ3099, BZ3015, and/or BZ3016 the maximum spring rate the rebound valving was designed to control is 250 to 275 lb. in. per three different Tokico engineers that I've talked with. Maybe you folks are using a different shock part number?

[evildky]

I'm running 440 lb fron and 250 rears with tokiko's, I was hesitant but the guys at GC swore they illuminas could take it, so far so good, the car is a frotn runner at local events

[EMWHYR0HEN]

It's mentioned alot here that stiffer rear spring rates than fronts is the way to go. I'm curious to know, WHY?

 

In gerenral, What are the basic handling chararteristics of an S30 with a stiffer rear spring setup?

 

What about a stiffer front spring setup?