elmer fudd

what are people running for spring rates, race or street, I plan on making coil overs, I have done it on other cars before but I have no idea what a good spring rate would be. any one know what the aftermarket street kits equate too.

j9fd3s

iTrader: (3)

350F 175R here, my car is light, and if i had to street it id go with 300/150 or something

thunkrd

iTrader: (1)

i've got 275 150.. its commonly used and performs well..

elmer fudd

sweet i think i have some 350's and some 150's kicken around i will try those first and go from there.

thanks guys

probably a little high for the street. but its not going to cost anything to try them that high and if I need lower I can swap them out.

j9fd3s

iTrader: (3)

its not like 350 is way too high, and if your car is a little heavier than it'll be better

Jeezus

iTrader: (4)

425/200, I would go lower for street.

AcidAngel7477

iTrader: (16)

good stuff here..

:AA:

Kentetsu

275/150 here. Works great for everything from daily driving to killing Miatas in autocross. Put on 2,400 miles a couple of weeks ago when I went down to run the tail of the dragon.

You want to keep your rear spring rates roughly 50% of your front rates. 350f/150r will give you some aweful understeer tendencies.




.

elmer fudd

stripped to the bone. but Im used to a stiff ride. all my vws are real low. this is the first car that I don't plan on slamming, just a bit lower but stiffer.

my other cars are lookers, I want this to be a real driver.

Super82

iTrader: (1)

I'm curious as to why everyone runs relatively low spring rates on FBs. I'm also somewhat knowledgeable about miatas and on the for the street they commonly run 350+ in the front, with some people going up to 700lb springs for race cars. Miatas also weigh about the same as our cars. Is there something different about our suspensions that like lower spring rates?

As for me I'm running discontinued Eibach springs with are something like 200ish on the front (but progressive) and around 110 in the back.

RotaryRevn

325 front and either 150 or 175 rear (I forgot), koni red's. Car rides very nice, not harsh at all. I was surprised, I thought I went a little too high in the front but its great. I have an S model but with gslse suspension and series 4 turbo motor (so some extra weight added).

j9fd3s

iTrader: (3)

yes. the miata has a different motion ratio. with the FB the wheel and the strut (and spring) move about the same amount, 1" at the wheel = 1" at the strut.

the miata has the strut in the middle of the arm somewhere so the strut only moves like 1" for every TWO inches of wheel travel.

different motion ratio = different spring rate at the WHEEL (sometimes this is called wheel rate)

i did a search on the miata forum, and they don't seem to know what the motion ratio is, but their 700lbs spring might give the same wheel rate as our 350# spring

make sense?

bwaits

iTrader: (12)

Good post.

I would also add that many people (not knowing any better) think more is better when it comes to spring rate............... Hey if that guy used 500# I am going to run 600# and beat him............In the mean time I am going to sneak past both of them in the exit of turn 1 with my correct spring rate.


-billy

Kentetsu

Here's how I look at it, based on my own results and from watching some other 7s at the races with 450lb springs. If there is the slightest deformity in the surface, they look like they are sprung so hard that they "skip" across the surface in a turn. Their tires are not maintaining contact with the surface. Ever skip a flat rock across a pond before?

Meanwhile, with my 275 Lb springs, I'm absorbing a lot more of those bumps and keeping the rubber on the road. This, of course, makes for a lot more traction.

They use spring rates to control body roll, where I use swaybars to do it. My car corners flat, but I still have a controllable ride. And while my competitors freely admitted that their cars were not streetable (all came on trailers), I can honk my horn as I pass by them after the races. And run to the grocery store. And drive to work. And make a trip down to DGRRX.

If you want a pure track monster, then go for it. But if you still want to enjoy your 7 for anything other than all out racing, keep the springs on the lighter side and go with strong swaybars.

And if anybody in the relatively local area ever wants to see exactly what I mean, just stop by one of the events and I'll let you drive my car. Several have done so already, and they are total converts now...

mustanghammer

iTrader: (3)

I absolutely agree that it is extremely important that your car's tires are touching the ground all of the time. But stiff springs do not automatically equal an uncontrolable car or one that skips over bumps if it is properly prepared. This is an issue that can be solved with better shocks and struts.

Based on the description of how your car is setup, kentetsu - bushing materials, use of the stock rear suspension and a rear sway bar - I would say that your rear "spring" rate is actually higher than you think. But given the setup you are running a 150 spring is probably more than enough and a good choice.

I do club racing now - used to solo. I was shocked to find out that race tracks are not smooth by a long shot. All of the track I race on have turns with ripples in the braking zones and uneven pavement patches in the turn exits. You can't believe what the transition seam from the front straight into turn 1 at Gateway International is like. Or the pavement transitions at HPT where the track crosses over the drag strip. My car has stiff springs but with good shocks and struts these bumps aren't an issue.

Same was true with my old Solo Mustang. Some of the parking lots around here are pretty bad but they could be managed.

The key is in the shocks - I use Konis on front and Pro Racing shocks on the rear of my car. Spring rates on my RX7 are 400 - 450 front and 300-200 rear.

j9fd3s

iTrader: (3)

our race car (the honda in the sig) is on 750/1200 lbs springs. in sprint trim its full spherical bearings, enduro trim its poly/stock rubbers. we also run koni's...

it IS totally unstreetable, we tried.

Super82

iTrader: (1)

That makes perfect sense, thanks. I wasn't trying to advocate that stiffer springs are better, but I was just kinda curious as to why the proper rates for our cars are so low.

Sh00bs

iTrader: (8)

good info post.

Yeah i bumped a 6 year old thread, what of it lol

Carl

iTrader: (2)

Another way to think of "motion ratio" is leverage. The RX7 wheel has a lot less leverage on its associated spring than the Miata has on its. Thus the 700lb in the front of a spec miata is very similar to a 350-400lb spring on the front of an FB.

Carl

BeansNcornbread

Now, would 450f/335r be too stiff? I'm daily driving my 7, but I don't mind a stiff ride for daily use. Those are the spring rates on the coilovers I'm getting, and they have adjustable dampening. Should I be fine if I soften the dampening, or will I tripod either way?

hcaulfield57

iTrader: (1)

Good reading, how are people achieving these spring rates, with coilovers, since I can't find any springs for our cars that are that high

BeansNcornbread

https://coilover-store.com/product/stance-super-sport-coilovers-mazda-rx7-79-85-fb-race-spec/
This is where I'm getting mine. This company and Techno Toy are the only companies that still make coilovers for SA/FBs. That company just came out with coilovers for first gen 7's at the end of 2015, and the people that use that brand are pretty happy with them.

hcaulfield57

iTrader: (1)

Are RBs springs generally considered pretty soft? This car is my fun daily driver, so not sure how serious it needs to be. Not sure I can justify big dollars on a custom coilover setup if cheaper springs will get me something nice for the street.

chuyler1

iTrader: (1)

Racing Beat website says "rate increase of approximately 20% (front - 145 lb/in) and 20% (rear - 112 lb/in)". That seems soft compared to other reported rates in this thread, but I imagine with the sway bar package, they are sporty but not necessarily racy. I've been considering the Racing Beat setup for commuting and occasional auto-x events. I picked up this FB as a fun car. I don't need full road race prepped suspension, but I do want the feel of a more modern sports car.

hcaulfield57

iTrader: (1)

You basically summed up my thoughts. There seems to be a significant difference between the RB spring rates and it looks like what people are running on the street. My FB was purchased as a fun, cheap, reliable daily driver - all of which it fulfills. It feels great even on the 34 year old suspension, so I don't know if I'm the type of person that will really benefit from super high spring rates. Regardless I know I want to upgrade it to something stiffer, because I'm sure it can handle much better than on the old stock springs. My FB doesn't have to be a racecar, but I'd like to improve it in little ways where possible.