GR Yaris Geo fast road help and track set up

[Onehp]

Wow, -2.75° & toe out at front, together with added dynamic camber and, as you predicted, some understeer is still evident!

Don't be too afraid of some understeer! An adjustable car can have some, as long as it is not terminal!
3 deg is still too much imho for a pure road car, becomes too aggressive. Now running 2,4° (2°24') and neutral toe and 2° rear and it's plenty adjustble for a the range of tyres I use. Understeer to sense grip levels, and oversteer just a trail brake or aggressive added lock into the bend on throttle away. I.e running my original recommendation and it's plenty aggressive - but maybe your tyres like some more. And actually similar to @Michael Knight seen to camber difference front and rear, but he's going faster on Cup2 on track on stock suspension still. So yeah it depends....

Ref toe setting front for steering feel, it really depends on your tyre and tyre pressure also. One tip is to have zero toe and say seven minutes toe out marked out on the steering rods. Can even mark out individual minutes. And then just try out different toe settings. I'm currently happy with zero, with the aggresive neg cambers we're running it effectively becomes toe-in feeling which I think is the most darty feeling albeit not the most grippy on turn-in. Will probably change again as I run other tyres and pressures....

 

[Michael Knight]

Wow, -2.75° & toe out at front, together with added dynamic camber and, as you predicted, some understeer is still evident!

There goes my plan for a similar geo setting.

Not keen to start with learning about, paying for and the whole process for corner weighting, adjustable droplinks & top mounts that @Yaris San kindly mentioned.

So, I will probably be entering the -3° territory for front static camber (plus a bit more through the caster kit); another thing I wasn't too keen on for my road use, but probably easier to live with daily than the harshness that solid top mounts innevitably bring.

Front camber needed is definitely driver preference but given this is road car I feel 2’ 75” is quite enough. Yes it had minor understeer still in slow corners but it didnt bother much. Prefer having predictable car vs too darty which takes away confidence from fast corners. Car was very good on fast corners now.

I think the geo works well given its a stock suspension

edit. actually you can hear it from the tyres when oversteer is terminal vs when it is manageable - with this setup didn't get those terminal moments at all.
But best way is to test one setup and adjust based on your learnings.

 

[Spirited]

... oversteer just a trail brake or aggressive added lock into the bend on throttle away. I.e running my original recommendation and it's plenty aggressive - but maybe your tyres like some more.....

My tyres are Continental Sport Contact 7, OEM size, more than half way through their lifecycle.

With "aggressive added lock into the bend on throttle", you get oversteer, I get understeer. I go on throttle mid-corner and the car washes out, opening up the trajectory.

That's with -2.5° front & -2.2° rear camber. And toe per side at -0°03' front & +0°06' rear.

Increasing the front-rear difference and reducing the rear toe in are two of my next steps for less understeer (together with adding 0.5° caster through the relevant bushing kit). I just don't know how far to go with front camber, especially as I have never experienced anything beyond -2.5°.

3 deg is still too much imho for a pure road car, becomes too aggressive...

Too aggressive in the sense that the car may surprise you if not 100% focused as it changes direction unexpectedly during evasive maneuvers or if one side hits a pothole (a case when I understand @Yaris San may expect it to be less forgiving, probably in a similar way of the car abruptly changing direction)?

 

[Onehp]

With "aggressive added lock into the bend on throttle", you get oversteer, I get understeer. I go on throttle mid-corner and the car washes out, opening up the trajectory.

Maybe my description was inaccurate on the timing.
If already on throttle (=accelerating) and then turning in, you will get understeer as weight transfer has unloaded the front. If you turn in extra in a bend so you're just on the edge of the grip circle and at that point add throttle, with that geo the whole car should come around and as you keep steering lock in the rear comes around more = oversteer - more accurate description moving away from geo to driving technique. Mine does it on any tyres incl. one close to SC7 in grip levels, as demonstrated in a touge run with a friendly GRY on SC7 where I had no big issue staying in front which would have been the case if there was a large grip gap.

There is a vid of a driving instructor doing 4 wheel drifts in the dry with a competely stock GRY in up to 3rd gear, he uses mid turn left foot braking to set the car up for oversteer. This video humbly opened up my eyes that I cannot blame the car for any chronic understeer and I've already made it a lot easier with geo which helps in a road setting which tends to be more slow in, fast out than driving on track where it's easier to use the brakes to set up the car. Still, (re)learning to master left foot braking (many modern cars don't allow it at all) has really improved my driving with this car. Just to say it's maybe not all geo and, as indeed as my warning goes, once the car is tail happy it might be even harder to tame, harder to go the other way in driving skills when you want stability in an emergency evasive action.

That's with -2.5° front & -2.2° rear camber. And toe per side at -0°03' front & +0°06' rear.

Increasing the front-rear difference and reducing the rear toe in are two of my next steps for less understeer (together with adding 0.5° caster through the relevant bushing kit). I just don't know how far to go with front camber, especially as I have never experienced anything beyond -2.5°.

My emphasis, if you still decide to increase the difference, I would say reduce rear camber to - 2° or so, no real need to run more the - 2° rear unless you're driving so hard you're wearing the outer edges a lot more.... Since you have quite some tyre wear (acquired with the current geo setting?), maybe accurate analysis of wear pattern front and rear can tell you more there.

 

[Michael Knight]

Maybe my description was inaccurate on the timing.
If already on throttle (=accelerating) and then turning in, you will get understeer as weight transfer has unloaded the front. If you turn in extra in a bend so you're just on the edge of the grip circle and at that point add throttle, with that geo the whole car should come around and as you keep steering lock in the rear comes around more = oversteer - more accurate description moving away from geo to driving technique. Mine does it on any tyres incl. one close to SC7 in grip levels, as demonstrated in a touge run with a friendly GRY on SC7 where I had no big issue staying in front which would have been the case if there was a large grip gap.

There is a vid of a driving instructor doing 4 wheel drifts in the dry with a competely stock GRY in up to 3rd gear, he uses mid turn left foot braking to set the car up for oversteer. This video humbly opened up my eyes that I cannot blame the car for any chronic understeer and I've already made it a lot easier with geo which helps in a road setting which tends to be more slow in, fast out than driving on track where it's easier to use the brakes to set up the car. Still, (re)learning to master left foot braking (many modern cars don't allow it at all) has really improved my driving with this car. Just to say it's maybe not all geo and, as indeed as my warning goes, once the car is tail happy it might be even harder to tame, harder to go the other way in driving skills when you want stability in an emergency evasive action.

My emphasis, if you still decide to increase the difference, I would say reduce rear camber to - 2° or so, no real need to run more the - 2° rear unless you're driving so hard you're wearing the outer edges a lot more.... Since you have quite some tyre wear (acquired with the current geo setting?), maybe accurate analysis of wear pattern front and rear can tell you more there.

And its different driving to unselttle the car and drift vs. try go fast. maybe pros can combine this for going fast.
But I feel car is quite adjustable in corner with this setup so no need to do any big changes atm.

 

[Michael Knight]

btw started lifting wheel off the ground in corners when going fast. wonder what would happen with stiffer suspension - likely the same?
So torsen diffs do not really help here. friction ones work even wheels off the ground.

 

[Onehp]

And its different driving to unselttle the car and drift vs. try go fast. maybe pros can combine this for going fast.

Well basically my point is still valid, with our changed geo and especially added front camber, if you first sit on the grip circle before accelerating, you won't get massive understeer once you start accelerating as both axles will slide more or less equally (grip balance due to changed camber). However if you are not on the grip circle and first accelerate and then adding lock, you will still get understeer due to weight transfer to the rear happening first, so reducing front end grip.

 

[Onehp]

btw started lifting wheel off the ground in corners when going fast. wonder what would happen with stiffer suspension - likely the same?
So torsen diffs do not really help here. friction ones work even wheels off the ground.

Mk2 is slightly stiffer in front, also the the front arb is stiffer. This makes front roll stiffness higher, meaning it will tend to lift the front inside sooner then the rear relative the MK1. This matters when accelerating out of corners and can help rear traction which is most important out of corners. So you could add a front adjustable arb and see what that does.

Another way to avoid this is to have very good damping also in droop and perhaps an active valve that makes sure the suspension extends as quickly (by removing damping force) as it can in case it senses the wheel is lifting from the ground. So maximising inner wheel contact. This is the rally way.

Ultimately however with high grip tyres on track, you will need to get plated diffs if you want to go really fast because you'll be going so fast you're lifting both inner tyres...

 

[Michael Knight]

Mk2 is slightly stiffer in front, also the the front arb is stiffer. This makes front roll stiffness higher, meaning it will tend to lift the front inside sooner then the rear relative the MK1. This matters when accelerating out of corners and can help rear traction which is most important out of corners. So you could add a front adjustable arb and see what that does.

Another way to avoid this is to have very good damping also in droop and perhaps an active valve that makes sure the suspension extends as quickly (by removing damping force) as it can in case it senses the wheel is lifting from the ground. So maximising inner wheel contact. This is the rally way.

Ultimately however with high grip tyres on track, you will need to get plated diffs if you want to go really fast because you'll be going so fast you're lifting both inner tyres...

good points. not sure what wheel was lifting but would assume it was rear. but should investigate more in detail how it goes.
Car was not loosing lateral traction when liftoff so not easy to say if it was front or rear.

 

[Spirited]

New setup.
Not sure if that toe is good (50%) what it used to be but lets see.
Front camber now -2 3/4 and rear -2 1/2

View attachment 25833

So, how are these settings feeling after a year?

 

[Michael Knight]

So, how are these settings feeling after a year?

its quite ok. need to see how it goes on track now. First session end of April at Kymiring.

 

[Spirited]

Have I gone too aggressive?

After enjoying stock for a start, I went for:

• -2.5º front & -2º10' rear camber,
• - 0º03' front & +0º06' rear toe.

The difference was positive, but understeer was still annoying & rotation not really as much or playfull as I would like it.

I moved on to:

• -3º front & -2º24' rear camber,
• - 0º05' front & +0º04' rear toe.

This gave me welcome playfulness from the rear, and directness & grip from the front.

However, the rear now also rotates when I don't want it to. I get lift-off oversteer to the point that I don't dare go hard on the brakes while turning, over crests, etc. It's as if the car switches from precise to vague while I try to tame the unwanted oversteer. And while I'm managing everything calmly & safely, time goes by and I don't seem to get comfortable with this behaviour; it's holding me back.

Is it a case of "run out of talent" or have I gone too aggressive with geo? More importantly, what should be the next step? I was thinking -2º75' front camber, - 0º05' front & +0º05' rear toe, unsure about rear camber & try to add a bit of caster (6º target).

Any thoughts welcome. Thanks!

 

[Michael Knight]

maybe its matter of balance. as a driver I prefer light understeer setup as it easier to build confidence, and in practice that is managed with driving technique using trail in braking etc. maybe you could try adding slightly rear toe to get more stability there.

I'm not certain how rear toe acts in suspension movement but its possible that it adds toe out when suspension extracts ? It could explain your sensation of vagueness there (ie. goes to toe out in certain points).

 

[GRgrampa]

Have I gone too aggressive?

After enjoying stock for a start, I went for:

• -2.5º front & -2º10' rear camber,
• - 0º03' front & +0º06' rear toe.

The difference was positive, but understeer was still annoying & rotation not really as much or playfull as I would like it.

I moved on to:

• -3º front & -2º24' rear camber,
• - 0º05' front & +0º04' rear toe.

This gave me welcome playfulness from the rear, and directness & grip from the front.

However, the rear now also rotates when I don't want it to. I get lift-off oversteer to the point that I don't dare go hard on the brakes while turning, over crests, etc. It's as if the car switches from precise to vague while I try to tame the unwanted oversteer. And while I'm managing everything calmly & safely, time goes by and I don't seem to get comfortable with this behaviour; it's holding me back.

Is it a case of "run out of talent" or have I gone too aggressive with geo? More importantly, what should be the next step? I was thinking -2º75' front camber, - 0º05' front & +0º05' rear toe, unsure about rear camber & try to add a bit of caster (6º target).

Any thoughts welcome. Thanks!

I wouldn't say that you've gone 'too aggessive' as I am running a very similar set up and find the car to be very well balanced.

@Michael Knight makes a good point in relation to your rear toe and adding a bit more (I run 0.10') will help stabilize the rear.

Are you using adjustable dampers/ride height? If so, then around 10mm positive rake will assist in reducing understeer.

 

[Spirited]

I wouldn't say that you've gone 'too aggessive' as I am running a very similar set up and find the car to be very well balanced.

@Michael Knight makes a good point in relation to your rear toe and adding a bit more (I run 0.10') will help stabilize the rear.

Are you using adjustable dampers/ride height? If so, then around 10mm positive rake will assist in reducing understeer.

Thank you!

No adjustable dampers/ride height here.

Does +0º10 toe at the rear:

- cause premature wear on any part of those tyres with no track use, some fast road but also motorway miles?

- mean less fun? With my current setting, while on Sport & with the tyre shop having left tyre pressures at the same level all around, I felt I could get a RWD-like keeness for oversteer on throttle at corner exit. I wasn't getting that feeling with my previous settings. (settings details on https://www.gr-zoo.com/threads/geo-fast-road-help-and-track-set-up.555/post-118753)

 

[GRgrampa]

Thank you!

No adjustable dampers/ride height here.

Does +0º10 toe at the rear:

- cause premature wear on any part of those tyres with no track use, some fast road but also motorway miles?

- mean less fun? With my current setting, while on Sport & with the tyre shop having left tyre pressures at the same level all around, I felt I could get a RWD-like keeness for oversteer on throttle at corner exit. I wasn't getting that feeling with my previous settings. (settings details on https://www.gr-zoo.com/threads/geo-fast-road-help-and-track-set-up.555/post-118753)

There's no premature wear as iirc the factory setting is 0.15'.

Given that I use mine in sprints and hillclimbs, I'm obviously looking for what gives me the fastest times and a stable set up is what works for me.
So yes, you could argue that it's 'less fun' but that may not be the case depending upon your driving style. I don't and haven't experimented with mid-corner lift off so can't tell you what it would do with this set up.

 

[Onehp]

@Spirited you do mean you have toe in now in the rear? Yeah add some more, the rear will communicate better with you then. I would also go neutral toe in front, with that camber that effectively feels like toe in and gives more immediate front axle feedback and you don't need the toe out for turn in grip anyway with that camber.

 

[Spirited]

@Spirited you do mean you have toe in now in the rear? Yeah add some more, the rear will communicate better with you then. I would also go neutral toe in front, with that camber that effectively feels like toe in and gives more immediate front axle feedback and you don't need the toe out for turn in grip anyway with that camber.

Thank you!

Yes, toe in at the rear currently. What do you think I should I set it to (from current +0º04')?

Regarding fron toe, I went 5-6 minutes out, because I found 3 minutes out to be... well, not direct enough and I wanted to eliminate understeer. I remember everyone was opting for out (front toe) for the first couple of years these cars became available. Then I think I started seeing posts like @Phil1291 's, if I remember correctly, suggesting a move towards toe in for non-track applications. But without being aware of the logic behind it, I'm concerned it will give me understeer. I get your logic, though, about camber being so great that soon takes over (once you start turning) as the key factor (for grip), as opposed to toe out.

 

[Onehp]

Thank you!

Yes, toe in at the rear currently. What do you think I should I set it to (from current +0º04')?

Regarding fron toe, I went 5-6 minutes out, because I found 3 minutes out to be... well, not direct enough and I wanted to eliminate understeer. I remember everyone was opting for out (front toe) for the first couple of years these cars became available. Then I think I started seeing posts like @Phil1291 's, if I remember correctly, suggesting a move towards toe in for non-track applications. But without being aware of the logic behind it, I'm concerned it will give me understeer. I get your logic, though, about camber being so great that soon takes over (once you start turning) as the key factor (for grip), as opposed to toe out.

What tyres (size tyre, wheel and model) are you running? What pressures?

 

[Spirited]

What tyres (size tyre, wheel and model) are you running? What pressures?

Stock BBS forged wheels; so, 225/40 R18 with Continental SportContact7.

Pressures are:

• front 32 psi;
• rear have been anything between 29 & 31 psi with no material difference to that problematic behaviour; or none that I could notice, anyway.