@oinojo Im not, at least not during mid and low speed corners, where the problem is more present, at high aero loads maybe. I will know for sure at Tremblant, since corner 1 is an uphill 110-120mph flat out corner. But so far no indication that I am.
@CSG Mike Both videos were with pedal dance on. He drives an na miata that has nothing (not even ABS), and he commented how the only thing he could perceived electronics wise was the ABS being very intrusive, so much so that he encouraged me to search for a way to disable it without destroying brake bias, of course. Tires were 245/45R17 Nittos NT01 on 17x9 wheels, pads were Stoptech SR33 (on the C43 kit) on the front, DTC-60 on stock calipers on the rears.
@soundman98 The car is not very low at all, at around 20-25mm lower than stock at the front, and at around stock height in the rear. Springs are very stiff, 12k all around, but are a necessity for aero, its an evil I need to live with basically. The car is not running "for show" aero, its really loading the shit out of those springs, I would not go lower, even after facing all of these problems, the car is still faster than last year with less aero and softer springs.
@Racecomp Engineering After that day at the track I came to the same conclusion, not as simple as a diff swap. The coilovers are rebound ajustable only, so I think like you that maybe the compression may not be up to par for the job here. Im getting adjustable sway bars to try and have a bit more control over how the car reacts. At least, if anything, I should have more tools to play with, as so far, playing with the tools I have seems to not be enough.


Thanks for your input guys, its really appretiated. Also I would like to say that the car is by no means slow, its still clocking times about 1 to 2 seconds faster (in 1:45 to 2:20 minute long laps) than last years, its just that we feel we are leaving even more time on the table with the setup of it. Of course more power would be an easy way to go faster, but I want to sort out the suspension for the level of aero Im running now before touching the engine.

@icecreamtruk The BBK would explain the ABS intrusion; it messes with mechanical bias unless you band-aid with pads. You will be able to stop faster without pedal dancing, but lose the ability to trail brake.

I wouldn't call 12k square a necessity for aero. I run 6k square with aero, at a 33mm drop, and don't bottom out. There's more to suspension tuning than just spring rates.

Check out this video. Do note that I'm on 300TW Michelins, rather than a more typical 40-200TW.

[ame]https://www.youtube.com/watch?v=z6VTYT0Wsh4[/ame]

Any reason for such a large amount of rake?? That's definitely not helping keep the rear end stable.

Aero benefits mainly, and also my bad attemps at curing corner entry understeer.

I will lower it down to 10mm front-rear rake next, correct the toe a little bit and camber, since that will change it as well. Also install adjustable sway bars, its not so much that the car needs bigger bars, but that sometimes I run out of tools to easily/quickly dial the setup of the car.

Yeah Im starting to guess the brake bias is not ideal, altho when I started trailing with less pedal pressure it worked better. It just seems that if I engage the abs, even once, during trail, the car just washes out entry/mid corner.

While 12k is not a necessity, I had 8k springs before, with a bit less aero than I do now, and the car felt as soft as a noodle on turns and transitions. I wanted to overdo it rather than underdo it in case I wanted to run stickier tires (looking at you, Hoo$$$iers). Im also trying to limit the amount of bumpy tracks I run at, Im really enjoying less and less the short and low speed bumpy tracks and enjoying more the very high speed flowing stuff.

But yeah, I really cant do much more than select a spring rate and hope that the shocks are up to par and that I didnt hit too far from the mark, I dont have a team doing R&D for me, im just an enthusiast trying to go big, little bit by little bit. Input from knowleageble sources helps tons, as it saves time and money from testing things on my own at the track, altho sometimes you do have to test to find out (I've had tests that invalidate opinions of so called experts, so im more skeptical lately).

I'll start by reducing rake, by suggestion of many others here, to a 10mm and correct rear alignment after that and see where that leaves me. Adjustable sway bars are also on the way, to be able to do quick balance changes at the track (while shock adjustment also changes the balance, it doesnt create huge changes, but rather small ones, for example a car that understeers to the moon and back, will still understeer regardless of how much you play with the rebound.

It sounds like you need some good dampers; the better your car absorbs the road, the better grip and stability you have. I happen to particularly enjoy bumpier tracks (like Buttonwillow) because my suspension advantage only grows larger relatively to the people competing with me.

Explain "as soft as a noodle". A datalog of your driving to correlate with your descriptions would be great as well.

What have you tested that you've crossed off?

Tires and aero. I have bought tires based on recommendation/reviews of drivers with more experience/faster than me (at least on their car) and I have been massively let down, no need to hide the info, the R888R is a big pile of s**t when it comes to setting fast times. Good tire for endurance and for learning car control (very forgiving), very slow as well, slower than most 200TW fast tires out there. Aero, I've been led to believe that at NA power levels aero was going to be a waste and only make me slower, good thing my bullshit detector was on and I took the time to research more rather than take it for granted.

By as soft as a noodle I mean the car was rolling like it was on stock suspension on transitions. I was "waiting for it" to settle everytime rather than just turn one way or the other. It made me remeber when I started tracking the car completly stock on semi-slicks, slow to react to inputs. That was on previous 8k supension, after adding a "real" splitter, that I had to make myself, because basically almost every splitter out there is for looks rather than function, very little chassis mounted, properly sealed and sized splitters, lets not even talk about diffusers and enplates on them either.

Its not like this now, but the loss of traction on corner exit was there before either, so one thing fixed, another came up. Maybe I just needed bigger bars on the previous setup to control lateral roll and let the car keep a bigger dive/squat attitude.

Like I said before, im not really "unhappy" with the car, its plenty fast, faster than it has ever been. I just feel like it could be even faster. Like there are times where Im sliding sideways where I just wish it would slide a tiny bit less, or stay at a shallower slip angle, but every drift lately is a big blown out of proportions drift rather than a subtle, more rotation like drift.

You keep dancing around dampers, I get it, the ones everybody likes are $$$ but it sounds like you're lacking the compression to control even the 8k springs the way that you needed and that the 12k springs are a band-aid.

Looks like you're on Koni inserts from Ground Control right now? If you've got single adjustable Yellow derivatives then you've been outside their operating range for a long time, upgrade.

There's a lot of "works for me, will work for you" type of advice out there. Sometimes it's right, but more often than not, it's wrong, because the scope of experience is usually rather narrow for the person making that statement.

You're absolutely correct about the tire thing. People love to talk about how they did XYZ on a "200tw street tire" because the tires are stamped 200TW and that somehow magically makes it a street tire, but the reality is many tires are only stamped 200TW for competition legality purposes. The 100TW tires are much more accurate in describing the wear rate of the tires; I don't think anyone worth their salt would try to argue 71Rs last 2x longer than R888R, even though the stamped rating claims that.

Aero is absolutely effective, regardless of power level, unless you go into a power level so low that you're already WOT everywhere. Then, you actually hit the diminishing returns point of aero. That just simply isn't the case unless you're racing sub 100 hp cars. Even then, 100hp cars benefit from aero, just in a different form.

That "waiting to settle" time is a damper problem. Now you're effectively just riding on relatively uncontrolled spring, because you're so oversprung relative to the force your damper can exert.

I seriously need a datalog to try to determine why you're getting unwanted rotation. It keeps coming back to "i need a datalog", because this is something beyond what you can communicate to me verbally.

It sounds to me like you need to fix your damping situation first, before diving into a LSD. You've thrown a lot of money at trying to make your car faster with a lot of band-aid solutions. Lets attack the cause of the issue, not try to cover it up.

Thanks Mike, I will try to fix the datalogger and actually get real and precise data going, its on the plans, I also need it to analyse my driving see where im giving up time. I'll shoot you a message when I get some tangible data we could work with.

No, im on fortune autos 510. They were 6k front, 8 k rears originally and I sent them for rebuild and spring rate change to 12k square. The front feels fine but Im starting to suspect they botched the rears, or at the very least the rears are a bigger problem than the fronts.

Rear damping on this car had me struggling for awhile too, hopefully you can find a solution, it's a tough nut to crack on a budget and the easy button is 'buy this for $xxxx!' from a lot of people. Seems like most dampers can nail the front pretty well but missing the rear seems to happen. Good Luck!

No ones mentioned it so I thought I would ask, what alignment specs are you running? front and rear please. any other suspension work done besides the springs/dampers? adjustable LCA?


You went to stiffer springs in order to fight the rear end being twitchy? A slightly stiffer rear sway bar might of been a better option to try first


Lowering the front more than the rear will also shift the COG forward, so I'm thinking you might want to even out the ride height some as well.


It's a balancing act for sure but all these things add up

Alignment specs are dialed in using pyro measurements, so im not doubting those, except maybe the toe. Its -4.7 camber up front, 0 toe, -2.8 camber rear and a pinch of toe-in (0.05 I think). Stiffer springs were added to allow me to run the car with the splitter closer to the ground without scrapping all the time. Its a compromise to gain aero dependant grip, giving up some mechanical compliance in the process. I will lower the rear to see if it helps.