Thread: autoX spring rates

Just wondering if any of you have fully prepped sts/stc b13's and what spring rates are you running? Something that doesnt see the street and is only used for autox is what i'm after.

I own a pulsar gti-r but it has the same front suspension with a bit more weight to carry.
im currently on 392lb front 336lb rear with a whiteline adjustable sway bar at full stiff, and stock front bar

i almost feel like i need double the spring to try to be remotely competitive, perhaps at 750 front, 750 rear.
I of course will get revalved struts to match, but still interested in what u top guys are running for spring rate.

I drive a B14,daily and autocross,and I'm at 450 f,505 rear.If you go much stiffer,(I have) the chassis quickly starts to be the weak spot.Especially since you really can't do much in STS/STC to help that.If you want to find out how much flex a 20 year old econobox has,mount a GoPro on the rear 1/4 window looking forward looking down the side of the car.Then watch the gap at the top of the door when you turn left or right.It's unpretty.Luckily,with street tires you don't have enough grip to rip it apart Hopefully someone else can chime in about a B13 specifically.

I think spring rates that high would make the car nervous and loose under braking and transition, and maybe cause some forward traction issues from the skipping. I don't think even many B13/14 road racers are even running springs that stiff. In addition to the flexible B13 chassis, another limitation is that STC maxes out grip with 225 width street tires.

I could be wrong, but the last serious National-level Street Touring B13 SE-R efforts were roughly seven or eight years ago. Art Rinner took a stab with a really good co-driver named Will Kalman (see the non-dash sr20forum archives) before moving on. The prevailing spring rates with the guys back then were roughly 500 lbs, give or take.

The 225/45-15 BFG Rival didn't exist back then, which could make a STC SE-R more fun, though probably still short of beating the EF Civics.

Current spring levels are MUCH higher than that for circuit and auto-x racers. Some are even crazy enough to run them on the street. And although they may seem high, proper dampers and valving will take care of most of the issue people (incorrectly) perceive as being harsh. The OTS 8611/8610s are pretty good at handling in the 600-700lb rates just fine for example

With the chassis properly fortified with a cage (or even a half cage), the chassis benefits GFEATLY from rates in the 800+ lb range (as most people with said chassis are running nowadays). 800lb is on the lower limit of what a seasoned racer uses. With current dampers, a full cage and massive amounts of grip provided by current tire technology, it's not uncommon to see what I would call, "Honda" rates in use on these cars. I will try to look up the rates Mike Kojima's suspension based Dog 1 and Dog 2 run, but I am pretty sure it's up there!

To the OP, there was a pretty fast B15 in the midatlantic auto-x region (he is from Delaware) that ran 275 Hoosiers up front on 17x10 RPF1 wheels and 650lb springs front and back and was a pretty capable machine. He definitely placed high on several occassions, and if my memory serves me correctly, had a few FTDs as well. He has sinced moved on to an Evo

No argument about running stiff rates if you can stiffen the chassis.Unfortunately in STS/STC that can't happen.I still run 275 Hoosiers up front and was running 660f 550 rear,but with no chassis stiffening for me(my choice) in DSP,it was too much for the little feller.I've just gotten used to flex,and make it work.

Another thing to keep in mind about Honda rates is that they don't have the same motion ratio on the arms.

Never underestimate what real compression can do too. RUF75 rode in my car in grid/paddock during my last race and commented about how harsh it rode... but once I'm at speed it just soaks up every bump and never gets upset.

Oh Nate, the topic of motion ratio I do know a bit about and hence why I put Honda in quotation marks

I think the Honda's are 1:1 and us Nissan are at .75:1 if my memory serves me correctly (for anyone who cares anyways).

What setup was in your car when RUF75 rode in your car and which car was it??

I only point that out because people have said that Honda can run higher rates due to chassis stiffness in the past... Just making sure everybody else knows it is an apples and oil stain comparison.

Miata with my custom double Bilsteins with giant external reservoirs so I can get enough compression. 700F/450R (standard Miata rates) with super digressive 200lbs @ 1in/sec of compression (knee at 1 then flat at faster).

A Kojima-grade wheel-to-wheel car is a massively different animal than a ST-prep Solo car in build and application. Kudos to people still pushing the envelope. Dog 2's LCA geometry corrections alone are already blasting way beyond the scope of allowed modifications in Street Touring, though. A full-tilt STC car is going to ultimately going to be a little softer, likely softer than even our autocross cars on R-tires.

Final choices will come down to driving style, asphalt or concrete, tire choice, damper budget, etc. I have a feeling 750lbs won't make for a consistent-driving STC B13, though. You have to get it done in short order in novel conditions on narrow street tires, rather than dial in for a road course lap after lap on wide sticky tires.

Anyone been sizing 7.5" wheels on the back of a B13 Sentra with ST-legal suspensions? How much tire can we get back there legally without rubbing? If you land on 225 Rivals up front, and 205 Rivals in back, that might even drive your spring choices. So few of us are running Nationally-prepped STC cars that there's a lot of new tire choices to process and new testing to be done.

The Civic Si has a better power-to-weight ratio, runs lower CG, and works better in roll. Oh, and it has been developed to point where people are even bored with them. Get as light as you can, test-and-tune the crap out of the car, and enjoy having decent gearing and some sort of limited slip.