Braineack

iTrader: (62)

off the top of my head 550 / 335

Braineack

iTrader: (62)

calculated 560 / 335

Eraser-X

I have the datalogs of 2 session driven by Hustler @ H2R going CW one is on the wet track and one was in the dry. These were logged with MaxQData and a 10hz GPS. I also have a CCW log of a slow guy in a late 80s 911 those Porsche guys are mostly just rolling traffic on this track.

Savington

iTrader: (31)

Camber will help you, but stop listening to SM setup guys. They are very good at what they do, but our cars are totally different. More weight, triple the power, way more rear spring/less front spring, better shocks. What works for an SM probably won't work on your car.

I am at 2.8 front, 2.5 rear, zero toe, 3.5* caster, 700/450 rates, ~12" ride height with 1/4" rake front to rear.

+1 on rear bar. The people who say to remove it haven't got the car set up properly (or they are running an FCM Bilstein setup that's designed for use without a rear bar). The car handles better with a rear bar, period.

MicaCeli

iTrader: (1)

What front bar are you using?

Tim Broughton

iTrader: (3)

What would be a good rear spring for a car running a 550lb front, racing beat 1.125 frog sway, and stock rear?

Braineack

iTrader: (62)

I'm running a 300 lb rear spring with the 550s on the front. 7/8" front on stiffest setting, no rear bar. I've only autoxed the setup and liked it, but I'm a suspension n00b peon and have much to learn and experiment.

hustler

iTrader: (6)

email me please. I didn't know you had max-q on. Its too bad it didn't record all of the session for whatever reason.

spoolin2bars

iTrader: (1)

your right about that. but, hustlers car is just as different to a spec, as yours is to his. your car's lighter, more spring, diff. shocks, wing, splitter, cage, are you still on torsen?

i think he's already going with the consensus. lower + more camber. with his spring rates and veh. weight, i would go with a little less static camber than you have. maybe 2.25frt./2.0 rr, 3.5-4.5 caster, 0 toe, zero rake on height, and try the oem rear bar. if it's tail happy, he can try a bigger split on the shock valving (settings) stiffening the frt. more compared to rear. ultimately he just needs to get it close, and do some work at the track. a tire pyrometer, good air gauge, (what psi he running hot?) and some data aq. will go a long way towards getting his proper settings.

hustler

iTrader: (6)

31psi hot.

Emilio specifically said that I want .25-.5" of rake. I'll get this car moving, its just taking too much work. Once I try suspension, if that goes south, then I'll coinsider something else.

Rennkafer

iTrader: (3)

Emilio's right on with that... all the cars we set up at work have some amount of forward rake whether they're winged or not. The amount varies car to car but it's generally .25" to .75"

Shaihk also agrees with Emilio on this btw as he told me to run ~.25 of rake with my FCM's.

Sav pretty much repeated what I'd said earlier about your car not setting up like an SM, and it's true. I'd argue that Sav's car is a closer match from a setup point of view than an SM is.

Savington

iTrader: (31)

~325, then align to taste

Savington

iTrader: (31)

Same diff, same wheels and tires, same power. Spring rate ratio in the same neighborhood - 9/6 vs 12/7.

Why? I've run 2.2/2.0 in the past, now I run 2.8/2.5.

Why? Nearly everyone runs at least a quarter inch of front rake.

ZX-Tex

iTrader: (15)

Just want to say for those of us (me) about to align their Miata for the track, this thread is

Tim Broughton

iTrader: (3)

Word. Is 300 close enough or would I want to go with a bigger rear bar (14mm+) with that? I'm at 425/300 right now and the rear bias is a little bit of a pain in the ***, but if I could bump up to 550s in the front and handle better while retaining the rest of my current set-up I may jump on that.

Braineack

iTrader: (62)

Can we discuss the rear bar more?

While I don't track much (at all), I found that on my FM springs (318/233) with a 7/8" F sway and stock R bar that the rear would let go unpredictably and the inside rear tire would lift (55% FRC). Once I pulled it I found the handling and traction in the rear to be much more predictable. However, I did notice I lost a lot of turn in and it was hard to toss the car about tight autox courses (58% FRC).

But once I fit my 550/300 springs I felt the handling improved dramatically, and felt the turn in improved ten fold even without a rear bar (62% FRC). It was suggested that the spring ratio would just make the car push, but it hasn't been the case. Is this just a factor of the roll stiffness? I can step the rear out with the go fast pedal if inclined.

Since I have a ***** multi-purpose street car, I'm going back down to 400/250 rates for comfort. But should I try experimenting with the rear bar reattached?

hustler

iTrader: (6)

Yes, you should do this. I'm going to get this car set-up properly then possibly unhook the rear. I find that more rear brake bias = less rear sway. I've been compromising corner exit to get the car to turn on turn-in. However, all my experience is invalid because I have the car set-up like a Buick right now.

bellwilliam

iTrader: (1)

for camber settings. just buy a pyrometer, THAT determines your camber and many others (including sway bar setting somewhat).

$105
IO Port Racing Supplies: AccuTech™ Economy Pyrometer

ScottFW

iTrader: (4)

The stiffer your spring rate, the less contribution the bar will make to the FRC% (over/understeer balance). On mushy stock springs my car handled fine with both FM bars installed. When I upgraded to 450/300 I left the FM bars in place, and promptly spun the car at the first track event I did with that setup. A little oversteer is fine but it was a bit much with the rear that stiff. The FM rear bar is 5/8" or ~16mm. I put the stock rear bar (12mm) back in and have been really happy with the setup. It's still throttle-steerable but much more neutral and predictable, and when it does lose grip there's not nearly as much tendency for the car to swap ends. You're only running 25# less front spring than me so if you find the oversteer objectionable with the stock rear bar, then your 300# springs paired with 550# fronts might give a balance more to your liking. Spring swaps are cheap and easy so try it and see, then change what you don't like.

Any RWD car with enough horsepressure is going to be able to break rear traction coming out of a corner if you intentionally make it do so by stomping the go pedal. That's not quite the same thing as when you're mid-corner near the limit of grip and an oversteery setup has the rears break loose first.
Also, the stiffer your rear springs, the less you will notice the absence of a rear bar but at rates like 550/300 it still makes a significant difference at least for track use.

Part of the rear bar discussion will be what you're doing with the car, i.e. track vs. autox. In autox where you're throwing the car into tight corners and want to get the power down immediately, pulling the rear bar can help alleviate inside rear tire spin. But on track where the transitions are generally smoother and you want better mid-corner handling, it's going to push with no rear bar unless you're running some really high spring rates.

spoolin2bars

iTrader: (1)

oops! i'm running a 1/4 inch of rake. forgot i changed it when i put my new coilovers on! lol, i figured with the bigger spread in rates i would do that to make sure i didn't get too much understeer.