Hey all you autocrossers and road racers running coilovers I need your guys advice on front and rear spring rates for my FB. I plan to start tracking my car but I would also like to be able to drive it on the street without my teeth chattering too much. I plan on ordering a set of Respeed's front race coilovers and rear adjustable collars. If it helps, I all ready have a full set of Tokico 5 way adjustable Illumina shocks, polyurethane bushings, and RacingBeat front and rear swaybars. I was thinking about going for 250 – 275 lbs springs for the front and 150 – 175 lbs springs for the back. What do you guys think? Thanks in advance for the advice.

 

i just put on my respeed street coil over kit on last week with 250 front and 150 rear and its a pretty ruff ride with my tokico hp's. it wouldn't be so bad if Missouri took care of there crappy roads.

 

Kentetsu is running 250's up front and 150's out back. He reports that the car is decent on the road and still sits flat in auto-X. I've seen evidence of that in his videos. The Illuminas play a big part in that, but if you plan to drive on the street as well than that is the setup for you. You could also ask Billy at RE-Speed. He knows his stuff and he can certainly point you in the right direction.

 

correction* kentetsu is running 275 up front, not that much of a difference, but meh.

I wanted to have a great handling car. When I saw Kentetsu's car, I knew that was what i wanted to go for. So I ordered the rear kit 150in/# when it was on sale. Bought the race coilover kit, along with 275in/# springs. my teachers were pretty surprised with how stiff it is. but remarkably it is comfortable even on the stiffest setting. i have the illuminas, awesome product they are.

Actually for racing these are pretty soft... or so people say. The thing that you really need are performance sway bars. The combination of a good front and rear sway bar, along with the front and rear coil over kit make a car that will handle very well. the sway bars help the car to not roll. instead of using ultra stiff springs to banish roll, you use a mixture of a semi stiff spring and a good sway bar.

Most of you already know all of this information, but some people are noobs and it might help them to understand o.O

 

i run 300/200. Do yourself a favor and read Jim Susko's book. www.gforceengineering.com. It's the best 75 anyone on this forum could spend. Too many people make suggestions without actually running or driving other cars with other setups.

 

This is the video that was referred to. Kinda tells the story on spring rates and swaybars.
The Illuminas will be important if you want some comfort on the streets while using high performance springs like this. The softest setting is Cadillac Comfy...

Hit me up if you have any questions man, and good luck with the build...

http://www.youtube.com/watch?v=N9cmv...e=channel_page




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Yeah sway bars.

See, that's how I contribute. I'd go with the RE-Speed bar. The RB front bar is too heavy.

I know your probably all over this since you do autocross, but if you want good times and good performance from your suspension, don't skimp on tires. They are the most important part of the suspension.

 

+1 on the book. and Jim has been at the rx7 game for along time . tech support is great just call and he is willing to share his knowlage.
btw I was running 450# front and stock front bar and 300# rear no bar.
I am changing some stuff around this year keeping the #450 fronts and changing to an Re-Speed front bar the rear is going down in spring rate to 250# with a stock bar with urathan bushings.
still running the Advanced Design shock/struts.
I don't drive the car on the street very often, trailered to most events.

 

Thanks for the great input guys. I think I'm leaning towards 275 lbs springs for the front and 175 lbs springs for the rears, but I’m still a little unsure. Since I only drive my car on the weekends I would prefer it to handle rather than feel comfortable, but not so uncomfortable to where it’s unbearable to drive on the streets.

Hey Kentetsu I watched the video you posted of your car, your car looks like it handles great man. If you don’t mine me asking, if were to buy your coilovers again knowing what you know now, would you go for some stiffer spring rates?

Hey for those of you guys that have read the Jim Susko book, what do you guys think of it? I'm really thinking about getting that Jim Susko book before I buy my coilovers from Respeed.

Thanks again guys I really appreciate the input.

 

Chon, if I had it to do all over again, I wouldn't change a thing.

Well, scratch that because I do miss having the Illuminas in the rear of the car. Being able to adjust them down to a 1 or 2 setting made the ride very comfortable. With the Bilsteins on the rear (non adjustable) I'm sort of stuck in "race mode" all the time. I don't mind this too much, but in a couple of weeks I'll be taking the wife to North Carolina in the car, and she bitches about the ride even going across town. Of course, she's been spoiled with our BMW for a couple of years now too.


Also, if you are unsure of what to do, then send Billy a PM (Bwaits) or go to his forum and ask him what he thinks www.re-speed.com He is very knowledgeable, and has always been will to give advice prior to purchase. He held my hand through this entire process, and I could not be happier with the results...

 

Yep - buy the book

400# fronts and 250# rears on my IT racecar. I have a racing beat front bar and no rear bar. I have a Susko tri-link and Peterson Racing panhard bar on the back. For struts I have Koni 2810's in front and PRO shocks in the back. This is a racecar setup - too stiff for the street.

Keep in mind that tires make a HUGE difference. If you use real race rubber or Kumho/Hoosier R Comps you need stiff springs to control the increased cornering forces. Street tires - no matter how good or expensive do not approach the grip levels generated by racing/R Comp rubber.

 

You have to remember that there is a huge difference between racing on a track, and autocrossing. Tracks tend to be very smooth, well maintained surfaces. Autocrosses take place on whatever parking lot you can find, and they tend to be very rough and have "dimples" sunken into the pavement from tires pressing down in the same location all the time.

One of the guys that I've raced against for a few years now has 400+ springs on the front, and even with race rubber, due to the rough surfaces, you can watch his car "skip" across the surface in hard corners. This is what led to my belief that you should only go as stiff as you need to in order to control roll (along with proper swaybars). Any stiffer than that, and you start losing contact with the surface in rough conditions. Not to mention that spring rates of that nature make if highly impractical, and even dangerous, to drive on the road anymore.

As my car progresses over the years, and I make progress as a driver, I may eventually end up with a track-only car. In that case, I will certainly be running spring rates in the neighborhood of 400 Lbs. But in the mean time, I still like to be able to hop in my car and shoot off to work everyday...

 

Chon, Billy reccomended That I go with 325 front and 150 back but I have a piston car so its a little heavier up front... I told him I wanted it to be fun, didn't need to handle like a Caddy. Dunno if that helps you out at all.

Oh, Kentetsu, You mentioned you guys have a BMW. Assuming it's the family car... 3 series? 5 series?

The big question is, how much better does the RX-7 handle?!

 

mine's an ex-pro7 car, so its 350/175 it rides fine for what it is. GC front bar, no rear.

actually cause its got a cage, and small racing seat and its LOUD the ride isnt noticeable

 

ive got 350lb springs up front. i think theyre just a lil too stiff for a DD but awesome on the track. im looking forward to getting some 275s soon

 

Mojave-

Its a '98 328i and it handles like a pregnant yak. Nice cruising on the freeway, very comfortable, and actually handles really well in long sweepers. But she is not quick, and tight turns make you feel like you should have called ahead for reservations... But, she's also got 130k on her, and most likely is all original suspension. New shocks would probably help a lot, but its an automatic so I kinda hate to put much money into it. Shoulda held out for a 5speed S model, but it was such a good deal...

I enjoy the 7 so much more. Even though she can be a bit of a rough ride sometimes (during pothole season) and smells like gas, and the wind noise is terrible.... Its just so much more fun...

 

BMW needs all the bushings too, they were prolly bad in 99...

wind noise might be an easy fix, the window frame on the door straightens out over time. check it if its bent out at the top = wind noise. the fix is just to bend it back.

 

Those rates are low for a dedicated track car. Those rates look good for a street/autox setup. It is much easier to have a AutoX car that handles well and is still street driven than a track car.

Question for you. What percentages would you give for each (street - autox - track) in terms of usage for the vehicle.

Is that pointed at anyone in particular?

Agreed, as well as street driving.

-billy

 

Not picking on you here but in my experience there isn't allot of difference between Autox and Roadrace spring rates. The balance of the spring/sway bar package will tend to tune a car differently between these two sports - more over steer/low speed car rotation for Autox and more understeer for a racetrack. But still the rates can be very similar.

Case in point my Autox Mustang had the following rates - 1650lb fronts and 780lb rears. These springs were mounted in the stock locations on the car so the actual wheel rates were less than the spring rates. However these kinds of rates were required to control the tires - 25X11x16 Hoosier/Goodyear slicks on 16x12 wheels. On a couple of occassions I ran the car on the track - the spring rates remained the same - the alignment was changed.

As far as pavement quality - there is pently of bad pavement on race tracks. They suffer from the same maladies as the street - hot/cold - freeze/thaw. Old race tracks can be pretty bad, just like old parking lots. The key to a bumpy surface is in the shocks and struts that you use. My Mustang had custom valved DA Konis on front and PRO Shocks on the rear. I never felt bumps....never lost traction.

BTW, I Autox'd for 15 yrs before switching to club racing and RX7's. Below are pics of my old Mustang and my current RX7 Note that in the RX7 picture the spring rates are 450 front and 300 rear with Tokico Illumina all the way around - the tires are Hoosiers. The car still had body roll!

 

Not at all. This type of thread pops up twice a month and people give out some shoddy suggestions sometimes, and it's just become an annoyance of mine. Spring rates and exhuast questions bug me because there is so much parroted bad knowlege out there.

 

if you are going to be doing more street driving then racing, which to me seems like most people would, i would tend to side more along having the softer rates of about 250-275 up front and 150-175 in the rear. i would talk to Bwaits and take his advice. once im ready to switch out to front coil-overs and camber plates, thats what i plan to do. also i have driven Kentetsu's car, and i can say with confidence that it handles better and is more predictable than anything ive ever driven.

but take my advice with a grain of salt as you would with most because my experience is limited, im only 21

 

MustangHammer: first of all, let me say that your car is beautiful! I've always admired it. Also, I only have a few years of autoX experience, and I'm still learning.

One thing I find interesting is that you still have body roll even though you are running those higher spring rates, but I have almost zero body roll running the softer spring rates. This would lead me to believe that we are both trying to solve a problem (body roll/handling) but going about it by using different methods. The question then would be, which method is better?

Now, looking at this problem from my own limited experience, if I have managed to control the body roll and can still daily drive my car (which might not be a goal for everyone), doesn't that suggest that my solution has an advantage over the use of higher spring rates? Not trying to argue here, just trying to broaden my horizons and understanding of suspension setup.

 

im running 300 up front 350 rear....lol

THANKS AGAIN BILLY!

 

I'll bet that works just great for drifting. lol. Talk about oversteer!!!

 

yup i guess we'll find out, should have the car back on the ground here in the next few weeks. Hopefully be road tripping out to denver for a drift event...only time will tell!!