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Old 05-23-2020, 04:55 AM   #1
NutGud
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Understeer Issues - Toe Alignment Issues?

Hi All,

1) Toe Alignment Spec - Do I Have to much Toe?
2) Is there any other reason I'm understeering

Car - MY14 Toyota GTS.

I've bought some of the TS STI Wheels (17x7.5) and had the tyre shop install 4x brand new Pilot Sport 4 (Not 4s just 4) 225/45/17 as well as align the car.
I didn't ask for any specific alignment specs... See attached.


I've currently running MCA Sport Essentials (Brand New - 2 months been installed by me. Their specification sheet mention it should be 350mm front/rear from of wheel to guard and measuring now, its pretty much even.
Although the driver's side (Right - RHD) was 350 and the Left side was about 345mm....
I've checked tyre pressure after the car had 2 hours to cool down (Also note it's cold outside) and all 4x tyres were about 33-34 PSI. So I'm confident that the pressure isn't the problem.



Now my problem and question.

I've always noticed this with the car, but they had pretty old/worn PS4 on the Stock 17s.

Basically, when going around a corner, when you accelerate the car feels like the front tyres "Slide" and understeers. The steering doesn't feel precise at all. It becomes very light.


There's basically no oversteer at all and just feels crap.

Really you just have to remove throttle input and wait for the car to settle.


The coilovers dampening adjustment (0-12) was 2 from Soft in the front and rear.

I put the rear to 9 and it makes it feel better, but still understeers and "slides" (The front slides - Steering light).


Obviously this feels crap!

It doesn't give me any confidence in the car at all.


This happens with or without traction control on... seems to be better with it off, but still happens.

The TC sometimes come on usually coming out of the corner, not at the start.

Note: I have an NB MX5 and it does not feel or understeer like this.





Question 1) My Alignment.....
Is there too much toe in general?
Everywhere I read has pretty much 0 toe front/rear.
I didn't bother asking for a specific alignment and they just gave me I would assume a standard alignment.
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Old 05-23-2020, 05:52 AM   #2
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+0.7 front, and +1.2 rear toe-in .. that's in what measurement unit?

If in degrees, way too much.
If in inches, according to this (with 24.62" tire diameter) even worse, +2.65dg front, +5.59dg rear, but i doubt something THAT off may go unnoticed or even set that much.
If in mm, +0.12dg front, +0.22dg rear. A bit too much in front, normal in back.

Understeer or oversteer balance is about which car end has more grip vs other. There are several ways of skinning cat, as in - to add or remove grip to one end of car, to change car grip bias.
For example, to add grip - softer springs, more toe-in, softer rollbars, less air pressure in tires, more negative camber. For less grip - stiffer springs, stiffer rollbar, higher tire pressure, less camber.

Just toe-wise i usually aim/ask to dial on twin for zero front toe, and slight toe-in rear (+0.15dg to +0.25dg total toe in (halve that if per wheel. "+" means toe-in, "-" - toe-out)).

Stock alignment for these cars: at front each wheel 0dg camber, 0.0 toe, rear each wheel -1.2dg camber, +0.2dg toe-in. It's a bit understeer-ish bias.
Most "fix" it by adding front negative camber (which also makes better tire wear on track instead of just ripping outer side as if on stock alignment), extent to how much camber optimal depends on use type (DD only or track), with dialing toe close to "stock" of zero front toe and slight rear toe-in (for some stability under accelerating out of corners, or to ease handling when accelerating in straight if/with wheels spinning (eg. if low grip such as wet/snow/ice)).
Simple to aim camber values for closer to neutral/less understeer-y grip balance might be - by 0.5dg more front camber then rear.

What use your car sees? (just daily driving? pushing a bit more? track driving?)
What camber adjustment means your car has? (twins as stock have only toe adjustment. Aftermarket coilovers may have front camberplates. For rear camber adjustment aftermarket LCA might be needed).

P.S. Also remember that "hard" to get rear out might not be just because of grip balance .. but also because if tires may have more grip in general. PS4 have much much more grip then stock Primacies. You really have to push them to loose grip .. not so easy when driving within speed limits and not hooning dangerously, just driving together with rest of traffic. Need to push more (eg. on track), or loose grip in other ways (driving in wet, or do driver inputs to overcome available grip). Understeer or oversteer .. it's more about when one pushes to limit, which end of car looses grip first. With grippier tires you have overall grip limits much higher, not just rear but also front.

Last edited by churchx; 05-23-2020 at 06:03 AM.
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Old 05-23-2020, 07:24 AM   #3
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Power-on understeer is a normal phenomenon. Despite Fast & Furious "physics"... Get on the gas, load up the rears and unload the fronts, the car is going to push. Up to a point anyway, but given 2.0 liters of n.a. fury, for us power-on OVERsteer isn't so much an issue usually...

Proper driving technique is to trail-brake on corner entry, maximum steering input near apex, on the gas at exit while unwinding steering with enough turning already done that you don't have to get OFF the gas to point the car.

That said, your toe numbers look fine (assuming millimeters!), but you could run less. Could run zero toe all around and that would generally reduce understeer a bit, particularly knocking the rear toe down from 2.4mm. Which isn't excessive but from zero to half that is the range I like to be in for rear toe, with zero front toe.

You could run a lot more front camber (assuming coilovers have camber adjustment). Street-only and desiring less understeer I'd try at least -2 degrees front camber, could run more than that and still be streetable, up to, say, -3 degrees.

AS for damping adjustments, go by manufacturer recommendations, but usually you adjust from full *stiff*, not full soft. I.e., the reference point is to screw the adjustment needle all the way in (clockwise), and then count clicks out from that point. Usually the steps between the first clicks out result in bigger changes in damping, towards the soft end you get to a point where more clicks out doesn't do much.

But again, technique is possibly a reason for what you're experiencing. If you're in a corner in anything higher than first gear and just smash the throttle, you're gonna get understeer in general, unless in low-grip conditions.

Last edited by ZDan; 05-23-2020 at 07:47 AM.
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Old 05-23-2020, 07:50 AM   #4
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Quote:
Originally Posted by churchx View Post
+0.7 front, and +1.2 rear toe-in .. that's in what measurement unit?

If in degrees, way too much.
If in inches, according to this (with 24.62" tire diameter) even worse, +2.65dg front, +5.59dg rear, but i doubt something THAT off may go unnoticed or even set that much.
If in mm, +0.12dg front, +0.22dg rear. A bit too much in front, normal in back.








Understeer or oversteer balance is about which car end has more grip vs other. There are several ways of skinning cat, as in - to add or remove grip to one end of car, to change car grip bias.
For example, to add grip - softer springs, more toe-in, softer rollbars, less air pressure in tires, more negative camber. For less grip - stiffer springs, stiffer rollbar, higher tire pressure, less camber.

Just toe-wise i usually aim/ask to dial on twin for zero front toe, and slight toe-in rear (+0.15dg to +0.25dg total toe in (halve that if per wheel. "+" means toe-in, "-" - toe-out)).

Stock alignment for these cars: at front each wheel 0dg camber, 0.0 toe, rear each wheel -1.2dg camber, +0.2dg toe-in. It's a bit understeer-ish bias.
Most "fix" it by adding front negative camber (which also makes better tire wear on track instead of just ripping outer side as if on stock alignment), extent to how much camber optimal depends on use type (DD only or track), with dialing toe close to "stock" of zero front toe and slight rear toe-in (for some stability under accelerating out of corners, or to ease handling when accelerating in straight if/with wheels spinning (eg. if low grip such as wet/snow/ice)).
Simple to aim camber values for closer to neutral/less understeer-y grip balance might be - by 0.5dg more front camber then rear.

What use your car sees? (just daily driving? pushing a bit more? track driving?)
What camber adjustment means your car has? (twins as stock have only toe adjustment. Aftermarket coilovers may have front camberplates. For rear camber adjustment aftermarket LCA might be needed).

P.S. Also remember that "hard" to get rear out might not be just because of grip balance .. but also because if tires may have more grip in general. PS4 have much much more grip then stock Primacies. You really have to push them to loose grip .. not so easy when driving within speed limits and not hooning dangerously, just driving together with rest of traffic. Need to push more (eg. on track), or loose grip in other ways (driving in wet, or do driver inputs to overcome available grip). Understeer or oversteer .. it's more about when one pushes to limit, which end of car looses grip first. With grippier tires you have overall grip limits much higher, not just rear but also front.
I assume the measurement is in mm.

So good to know that the toe isn't ridiculous.


Car is a daily, but I still want it to have some fun on some back roads.

Yes, the front coilovers have camber adjustment. Perhaps on my next alignment, I'll get more negative camber and less toe.



I've only experienced the car with Pilot Sport 4 (The older tyres on the stockies were PS4, but obviously much more worn).

I'm not really sure how though that I'm getting to the end of the grip level of the 86 so quickly.

I've been on track twice now (with my other car) and never had this issue, as well as in a honda on back roads.


Quote:
Originally Posted by ZDan
Power-on understeer is a normal phenomenon. Despite Fast & Furious "physics"... Get on the gas, load up the rears and unload the fronts, the car is going to push. Up to a point anyway, but given 2.0 liters of n.a. fury, for us power-on OVERsteer isn't so much an issue usually...

Proper driving technique is to trail-brake on corner entry, maximum steering input near apex, on the gas at exit with enough turning already done that you don't have to get OFF the gas to point the car.

That said, your toe numbers look fine (assuming millimeters!), but you could run less. Could run zero toe all around and that would generally reduce understeer a bit, particularly knocking the rear toe down from 2.4mm. Which isn't excessive but from zero to half that is the range I like to be in for rear toe, with zero front toe.

You could run a lot more front camber (assuming coilovers have camber adjustment). Street-only and desiring less understeer I'd try at least -2 degrees front camber, could run more than that and still be streetable, up to, say, -3 degrees.

AS for damping adjustments, go by manufacturer recommendations, but usually you adjust from full *stiff*, not full soft. I.e., the reference point is to screw the adjustment needle all the way in (clockwise), and then count clicks out from that point. Usually the steps between the first clicks out result in bigger changes in damping, and you get to a point where more clicks out doesn't do much.

But again, technique is probably a big reason. If you're in a corner in anything higher than first gear and just smash the throttle, you're gonna get understeer in general, unless in low-grip conditions.



Yeah, I'm just surprised that the car is able to over grip the front tires and "slide" so easily.
My old honda with a K24A3, never felt like this and it was one Bridgetone Re003s on 225/45/17s.

Obviously different setup and what not, but being FWD the way it understeered during a corner still didn't "slide" out or anything.
Especially seeing as the 86 is a RWD, I just don't really understand why it's doing this.


In my NB MX5 it's a completely different beast. Yes, obviously a lot less power, but it's actually not that far off when you look at power to weight figures.




I might have to meet with some local 86 owners to get them to feel it.

Just something that I thought was quite odd.





And also it just feels weirder then usual understeer. Like the front "slides".

Perhaps I'm overthinking this a bit too much.
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Old 05-23-2020, 08:13 AM   #5
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Remember that stock alignment is 0 camber front and -1.2 camber rear.
So you do track car. Then i guess worth increasing front camber to ~ -3dg front, rear to -2.5dg. That should both add grip and even out track tire wear and change grip bias to more neutral.
As to why manufacturers usually do stock alignment to more understeer-ish bias in modern cars, because it's supposed to be "safer". People driving cars have very varied skill level, and more often then not lack skill driving on limit, knowing little how to deal with oversteer, but understeer is easier to handle for them, as they can always do usual thing - ease on gas or press brakes "to fix". Countersteer? Hah, if for them car doesn't turn enough due front pushing out, they turn wheel even more . No manufacturer would want to face any liability or have reputational damage for one of it's cars labeled as death trap just because 9/10 of average drivers have lacking skills.
Remembering MR2..
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Old 05-23-2020, 10:20 AM   #6
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It could just be "new tires", although I just had brand new Conti ECS mounted and they were grip monsters right away...

I also just redid my suspension setup last weekend, re-installed camber plates and went from ~-0.5 to -1ish degrees to -3.3, and during test drive, the difference in over/understeer balance was profound, even driving well below the limit!

You have the adustability, so get you some negative front camber, at least -2 degrees and up to as much as -3 degrees. You might have rear camber bumped up to about -2 degrees as well for general handling balance.
For toe, have them dial front toe to 0.0 and rear toe to zero up to 1.2mm (about 0.1 degrees) total or half that per side. Might be paying for a second alignment if they don't want to redo for free, but IMO it will be worth it to you
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Old 05-23-2020, 12:05 PM   #7
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My personal experience has been that toe in up front, or positive toe, does cause the car to push pretty badly. 0 toe would probably help out a lot. However, I think more front camber would help you more. These cars need a lot of front camber due to the strut style suspension. 2-3 degrees of negative camber in the front would help a lot. Also, I'd zero out the rear toe as well. I have tried several alignment setups on my car and I have more or less settled for zero toe front and rear to give the car good handling on the street and autocrossing. That's how I like it anyway.
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Old 05-23-2020, 12:30 PM   #8
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With zero rear toe i find much harder in case of limited grip. Much more mini corrections needed, instead of more or less just driving. Rear toe-in also simplified on track accelerating out of corners. Imho it's worth having some, but to extent when pros outweight cons.
I'm not familiar with auto-x specifics though, maybe there is something to be had from zero also rear toe, did only trackdays + daily driving on different grip surfaces in different seasons. But about some rear toe-in for RWD cars i see suggested by most people, and it's there in even stock alignment for most RWD cars.
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Old 05-23-2020, 02:50 PM   #9
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With zero rear toe i find much harder in case of limited grip. Much more mini corrections needed, instead of more or less just driving. Rear toe-in also simplified on track accelerating out of corners. Imho it's worth having some, but to extent when pros outweight cons.
I'm not familiar with auto-x specifics though, maybe there is something to be had from zero also rear toe, did only trackdays + daily driving on different grip surfaces in different seasons. But about some rear toe-in for RWD cars i see suggested by most people, and it's there in even stock alignment for most RWD cars.
That is in line with the differences between track and street/autox in my opinion. I prefer some rear toe in for track driving too but in autox i prefer zero toe to get the car to point faster. You are right you will be making more quick corrections with zero toe but the other side is that it is helping you control rotation rather than having to try to rotate it and then risking over doing it. Again, this is my experience experimenting with alignments on the twins.
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Old 05-23-2020, 03:51 PM   #10
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Quote:
Originally Posted by churchx View Post
Remember that stock alignment is 0 camber front and -1.2 camber rear.
So you do track car. Then i guess worth increasing front camber to ~ -3dg front, rear to -2.5dg. That should both add grip and even out track tire wear and change grip bias to more neutral.
As to why manufacturers usually do stock alignment to more understeer-ish bias in modern cars, because it's supposed to be "safer". People driving cars have very varied skill level, and more often then not lack skill driving on limit, knowing little how to deal with oversteer, but understeer is easier to handle for them, as they can always do usual thing - ease on gas or press brakes "to fix". Countersteer? Hah, if for them car doesn't turn enough due front pushing out, they turn wheel even more . No manufacturer would want to face any liability or have reputational damage for one of it's cars labeled as death trap just because 9/10 of average drivers have lacking skills.
Remembering MR2..

OP just follow what this guys said


I would throw in that you want atleast -2dg up front.




oh and tires, my PSS understeer like a dog when it was old so i throw that in the dumpster.
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Old 05-23-2020, 03:58 PM   #11
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Try removing the front swaybar
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Old 05-23-2020, 04:24 PM   #12
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Lack of negative front camber is what stands out to me.

Also knowing your spring rates and swaybar sizes/settings would be helpful.
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Old 05-23-2020, 04:33 PM   #13
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Start by adding another degree of neg camber up front and soften the front bar if it isn’t stock
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Old 05-23-2020, 04:40 PM   #14
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Quote:
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Try removing the front swaybar
Don't do this, he's joking. I think! It *would* reduce understeer tho...
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