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Old 05-23-2020, 04:54 PM   #15
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It will reduce understeer, and there might be applications that may beneficial for this method to add grip (imagining something like rallying on gravel/snow/ice), but why not fix actual issues before trying out hacks not without cons of their own?
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Old 05-23-2020, 05:09 PM   #16
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Zero front toe, -2 degrees front camber, they shouldn't have to touch the back and you should be able to get a cut rate on the alignment.

The factory alignment on Subarus seems to be universally understeer prone, it's a misery and why I have little interest in ever owning a WRX or STI.
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Old 05-23-2020, 05:11 PM   #17
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Am I missing something? coming out of a corner, under steer is usually balanced with increased throttle.
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Old 05-23-2020, 05:22 PM   #18
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Don't do this, he's joking. I think! It *would* reduce understeer tho...
I've driven without the front swaybar before, it's really not a joke! They are tuning tools. If it's causing your car to push, you unbolt it. Takes 15 min
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Old 05-23-2020, 05:24 PM   #19
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I've driven without the front swaybar before, it's really not a joke! They are tuning tools. If it's causing your car to push, you unbolt it. Takes 15 min
If you have to disconnect the front swaybar on a rwd car, something else is bad wrong with yer setup!
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Old 05-23-2020, 05:26 PM   #20
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Am I missing something? coming out of a corner, under steer is usually balanced with increased throttle.
You are missing something, because short of power-on oversteer, which isn't much of a thing with these cars, increased throttle induces UNDERsteer, not OVERsteer...
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Old 05-23-2020, 05:31 PM   #21
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Am I missing something? coming out of a corner, under steer is usually balanced with increased throttle.
You are. From driver inputs understeer can be reduced by mass/grip transfer to front .. by easing on throttle or light braking, not something opposite that on countrary reduces mass transfer/grip to front and further reduces front grip.
Well, one can reduce rear grip with adding gas even further to level of complete overcoming traction, and go sideways drifting. Skidding tires will certainly have less traction then still having grip fronts. But, it's not norm to drift through every turn on public roads, and drifting is slow way to go around track.
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Old 05-23-2020, 05:58 PM   #22
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If you have to disconnect the front swaybar on a rwd car, something else is bad wrong with yer setup!
I completely agree with that! Just making sure OP explored all options. I disconnect my rear sway for snow racing
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Old 05-23-2020, 11:21 PM   #23
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You are. From driver inputs understeer can be reduced by mass/grip transfer to front .. by easing on throttle or light braking, not something opposite that on countrary reduces mass transfer/grip to front and further reduces front grip.
Well, one can reduce rear grip with adding gas even further to level of complete overcoming traction, and go sideways drifting. Skidding tires will certainly have less traction then still having grip fronts. But, it's not norm to drift through every turn on public roads, and drifting is slow way to go around track.
Are you sure that it's increased mass transfer that increases grip? Then how does a larger swaybar work?



The reality is there are more than one possible outcome from applying throttle in a corner with a rwd car.

First is - more speed - more cornering force required from the front - front tires are already at a high slip angle - more understeer results

The other possibility - more rear slip angle due to both acceleration force and additional rear lateral weight transfer - reduced understeer

Third option - wheelspin - much more rear slip angle - reduced understeer. Maybe hard to do in a stock power brz especially with good tires.

However, the first two are both possibilities. Kind of depends on power and how well balanced the car is at steady state. We've setup cars to be fairly biased toward understeer to give the rear tires more ability to accelerate the car out of a corner.
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Old 05-24-2020, 02:54 AM   #24
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I went for another drive with my partner today with both this and our NB8A MX5.

The lug nuts were loose as soon as we'll took off. So I tighten them up. Lucky we checked as they were all a little looser then I would have thought.

Anyway, we hit a back road and noticed that felt the same as yesterday.
Basically very floaty up front and understeer.
TC light would come on very regularly, even when barely trying to corner fast or anything.

We played with the coilovers, going from stiff (9/12 front/back, then back to soft (2/12) front/back.
Having stiffer helped slightly but not really.

What we both noticed was that turning traction control off completely (left button held down for 10 seconds), that the car would feel a lot better. Not how the mx5 felt but a whole lot better. Much less under steer and much less floaty.
It gave you a lot more confidence.
What the car does still feel is that there is a bit of under steer and when you are putting the power down (even in longer, not sharp corners) that the car would float and push you over in the direction you pointed the wheel. The steering would also be light.
This was still a whole lot better and gave you more confidence then before.

Another reason too we believe the traction control is a part of the issue is that it seems to be very sensitive when driving normally around roundabouts or on high speed corners on bumpy back roads (driving normal to the speed limit not spirited).
With traction control off, you can go much faster around roundabouts without issue. There is more then enough grip in the tyres, and not enough power to blast them off.

So after driving the mx5 back to back, it seems that we have to get an alignment.


So I'm thinking something:

Front:
0 toe
Neg 2.5 degrees of camber (still is a daily)

Rear:
0.5mm toe each side (1mm total toe)
Hopefully 2 degrees of Negative camber (as stock rear control arms)

Also front spring rates are 6kg and rears are 4.5kg. When talking to MCA they recommended the upgraded spring rate.


Long story short:
Car with traction control off, the car feels better but still is slightly floaty and understeery.

Traction Control on, very floaty and under steer prone. No confidence and almost scary.



Pretty sure its just an alignment. Well I'm hoping so.

I appreciate all the replies and will be sure to update as soon as I can get it realigned.

Edit:
Also I don't want to remove any of the sway bars to fix the problem at this stage. I totally get you can use them to tune the car for over/under steer but the car is basically stock with slightly wider tyres (lighter wheels) and coilovers (which are a bit more premium then average).
Currently the car is on stock front and rear sway bars.

Edit 2:
I'm confident that I'm not going into corners with either too much speed or steering angle. Smooth inputs in and slightly more aggressive on the way out once the wheel is going back to straight.
Also I'm still on public roads and I like to make sure that there is a good safety margin and I'm inside the lines.

Last edited by NutGud; 05-24-2020 at 03:00 AM. Reason: Added text to the bottom
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Old 05-24-2020, 05:36 AM   #25
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Are you sure that it's increased mass transfer that increases grip? Then how does a larger swaybar work?
The reality is there are more than one possible outcome from applying throttle in a corner with a rwd car.
First is - more speed - more cornering force required from the front - front tires are already at a high slip angle - more understeer results
The other possibility - more rear slip angle due to both acceleration force and additional rear lateral weight transfer - reduced understeer
Third option - wheelspin - much more rear slip angle - reduced understeer. Maybe hard to do in a stock power brz especially with good tires.
However, the first two are both possibilities. Kind of depends on power and how well balanced the car is at steady state. We've setup cars to be fairly biased toward understeer to give the rear tires more ability to accelerate the car out of a corner.
Yes, increased mass transfer also transfers more grip. Hence why common way to fight with understeer is reduce transfer to rear if you were with under gas with throttle off (to what aswell in addition to opposite when you want reduce that for rear to have more grip, refer as playing with throttle), or with brakes increase transfer to add rotation, maybe less often mid curve, but commonly enough with trail braking on turn-in.
Larger swaybars work increasing effective spring rate for mass transfer from side to side. It results in less roll .. but also in less independent suspension and overloading tires on one side, so at one point of upping swaybar rates it has negative net effect of reducing available grip. Better to rely more on right stiffness springs and damping, but use swaybars more for balancing grip imho. Unless driver was limiting factor and less rolling car was required to bolster one's confidence to push more.
More speed to use up more grip while cornering .. it's not RWD specific, but any car's trait. Google on traction or grip circle. Well illustrates that your tires have limited amount of grip and it's up to you to what to "spend grip budget", and how one may use it most effectively without leaving unused grip on plate (namely - trailbraking and gradual increasing throttle proportional to unwinding steering wheel when accelerating out of corner).
Wheelspin i already mentioned in previous post. Drifting is not fastest way around track. And is easy to do .. if you already have used up lot of grip on something else, eg. cornering at high speed near limit, then many abrupt driver inputs can throw off balance and make car loose grip, including via getting rear sideways and wheelspining.
But! Theory aside, and all those specific ways to loose grip aside, purely from my limited track experience, driving on twins with square tire setup and NA power, i found myself overall much easier to drive/balance grip limit/fight less with car, when i moved grip balance to front, via more front camber then in rear, via less understeer biased then stock setup. It also reduced my mistakes count and upped lap speeds. Also similar alignment seems preferred and suggested alignment setup by many others, that do track their twins.
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Old 05-24-2020, 05:51 AM   #26
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NutGud: from your description there imho also another optioon (judging by turned traction control off) - not at right time and right extent interruption of electronic nannies, namely stability control, EBD as in electronic brake distribution and e-diff.
In your case imho it's EBD, and to lesser extent maybe e-diff that worsens things.
(long TC off btw switches only stability control off, EBD and e-diff is still on).
That's why many tracking twins prefer using so called "pedal dance", unofficial procedure, that leaves just basic ABS on, switching all the other nannies off. From my experience in ND miata, it's nannies were way less in way vs prerestyle twin's nannies. Have no own experience in restyle twin though to compare it's nannies. But on older ones PD may help in several cases on track.
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Old 05-24-2020, 06:57 AM   #27
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NutGud: from your description there imho also another optioon (judging by turned traction control off) - not at right time and right extent interruption of electronic nannies, namely stability control, EBD as in electronic brake distribution and e-diff.
In your case imho it's EBD, and to lesser extent maybe e-diff that worsens things.
(long TC off btw switches only stability control off, EBD and e-diff is still on).
That's why many tracking twins prefer using so called "pedal dance", unofficial procedure, that leaves just basic ABS on, switching all the other nannies off. From my experience in ND miata, it's nannies were way less in way vs prerestyle twin's nannies. Have no own experience in restyle twin though to compare it's nannies. But on older ones PD may help in several cases on track.

Funny you mention the pedal dance, as I was searching on the forums again today and found a couple of post talking about how their Traction Control was sensitive after coilover installation or different wheel/tyre setups, but what's more odd is that this was only for certain people. A shop owner mentioned they installed coilover and wheel/tyres for over 100 86/BRZs and never had these issues.


Regardless, I thought why not give this VSC reset a try.



https://www.ft86club.com/forums/showthread.php?t=121795 - Link to a post specifically about this.



But Basically, you need Techstream, a way to connect and just have the car on a flat ground.
I've just got a Tactrix OpenPort 2.0, so I used this.



I did this and it has helped a lot with the "regular" driving issue I had before, EG, roundabouts you can even safety push it and not have the traction control at all, or if pushing it, it'll only turn on as you begin to straighten up.
So for me, this helped a bit.

It still pushed/floaty/slides the front when pushing it around corners (Only really tried in 2nd/3rd (so above 80kms), but at least with Traction on, it was less serve.


So to summarise, issue is still there, but traction control was very sensitive before the VSC reset and now it operates when you expect it to. So I'm happy about that .

I'm still under the belief that I need another Alignment to actually eliminate the issue, as with TC off, obviously the issue is still prevalent.



But I thought that was very interesting.



Also I don't really want to be having to do the pedal dance when wanting to drive spirited.
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Old 05-24-2020, 07:15 AM   #28
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Another factor that can definitely impact the cars balance more than you might think is rake angle. A lot of people find that positive rake helps out and there are reasons that it does depending on your setup. For me, removing the rake to a nearly level, slightly negative rake helped the car balance out immensely. I just couldn't get it to work with positive rake. Just something to consider. I mention it since you said the front feels floaty. Maybe your dampers are blown? Do you have bump stops?

I am rambling at this point because it's almost certain that your lack of front camber is the vast majority of your problem.
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