Understeer

Hey

Do most experience understeer under WOT, she just wants to squat and go straight ?

Maybe its my tyres or pressures , I am running BPU, TRD rollbars, 33 psi all round, Falken 452 upfront , Goodyear Eagle F1 Asymmetric 2 Rear , Toyota OEM Suspension alignment settings

It definitely shouldn't understeer in a straight line ? Do you mean oversteer I.e the back end steps out ? I can't see how you can understeer in a rwd car in a straight line ? Understeer and oversteer can only happen in corners though.

Haven't you just fitted a plate LSD? These can give some under steer effects. That tyre combination probably isn't helping as the 452's aren't bad but won't be as good as the F1's so making under steer more likely. I'm not sure how uprated the anti roll bars are but I do know the comparative stiffness of these front to back can be used to promote under or oversteer so maybe your setup is neutral to under steer and fitting a stock front or rear (need to check which) bar may improve things.

May be lot of causes but if you want less understeer do this: sticky tires upfront, less so on the back. You could also play wirh tire pressures and if you have adjustable suspension, you could also try that too.

Mine was set up towards lots of oversteer - yokohama advan neova ad08 upfront and skinny eco tires on back 265. Lots of pressure in those too. Also, the rear dumpers are set to the stiffest position and I just can't imagine it understeering. Back gets loose even under slightly more accelerator pedal contact. This kind of setup is not for street, more like for drifting, but you could apply some of these principles to a lesser degree to make yours a bit more neutral

It definitely shouldn't understeer in a straight line ? Do you mean oversteer I.e the back end steps out ? I can't see how you can understeer in a rwd car in a straight line ? Understeer and oversteer can only happen in corners though.

More so in corners she understeers

Haven't you just fitted a plate LSD? These can give some under steer effects. That tyre combination probably isn't helping as the 452's aren't bad but won't be as good as the F1's so making under steer more likely. I'm not sure how uprated the anti roll bars are but I do know the comparative stiffness of these front to back can be used to promote under or oversteer so maybe your setup is neutral to under steer and fitting a stock front or rear (need to check which) bar may improve things.

Thanks, yeah have the LSD in there, I think its the grippy tyres on the rear

May be lot of causes but if you want less understeer do this: sticky tires upfront, less so on the back. You could also play wirh tire pressures and if you have adjustable suspension, you could also try that too.

Mine was set up towards lots of oversteer - yokohama advan neova ad08 upfront and skinny eco tires on back 265. Lots of pressure in those too. Also, the rear dumpers are set to the stiffest position and I just can't imagine it understeering. Back gets loose even under slightly more accelerator pedal contact. This kind of setup is not for street, more like for drifting, but you could apply some of these principles to a lesser degree to make yours a bit more neutral

Suspension is fixed Rate TRD Bilsteins , I think my only options are tyres and pressures , think I will mess with the pressures ; I think a 30-31 psi might help things

Looks like I need to

http://www.thesmokingtire.com/2012/massive-list-of-solutions-to-understeeroversteer/

Raise front tire pressure.

Lower rear tire pressure.

It's defo your tyre combination. I used to think Falkens were ok, until I put Vreds on the rear of my TT. Lots of understeer, especially in the wet.

H.

FAR TOO VAGUE!!! Corner entry understeer? Steady state cornering understeer? Corner exit understeer? Power on understeer? Trailing throttle understeer?

Fred Puhn, "How to Make Your Car Handle" (I give this author and title from memory, but Google it, it's a good beginners book on chassis dynamics). Then move on to the Carroll Smith stuff.

Any front engined road car will understeer without some fairly major suspension kinematic changes, the makers wouldn't dare have it any other way. Before people cry "But my car's tail happy", this is the difference between steady state cornering and power on corner exit understeer. As Havard says, tyres will make a difference. Ill conceived wheel and tyre changes can make drastic changes to the balance.

A plate type LSD, apart from trick ones like Giken, WILL cause corner increased entry understeer, given an inherently already understeering chassis, especially in the wet.

It CERTAINLY won't be too much rear downforce, I can guarantee you that

34psi front 32psi rear mate

Sorry Chris , I was tired last nite

Corner entry it is most prevalent, steady state it's there and exit , on exit for me to invoke oversteer I would have to push the car too aggressively for it to be safe on a public road and it would be considered wild driving on a track , I use a touch of trailing throttle to get her pointing the way a want, push through the directional change

she was sitting up last few months so taught maybe the tyres needed to be scrubbed in, before I could get her to an air pump I drove her on roughly 30 psi , and she felt gripper but I didn't push her through any twisty stuff till I checked pressures

Pumped her up to 33 psi all round , she feels a bit skatish on the surface, as though the car is on ice, but not a serve , maybe too much pressure and I am not getting a full contact patch off the tyre

If I am going through a sweeping bend, is just a gradual directions change, the more throttle you use , the more she wants to keep going straight, you have to modulate the throttle to keep her turning in

It's probably too low... Side view photo? Plus the odd mix of tyres won't help. What LSD is in it?

Tyre temp' readings are the only sensible way to set pressures, and road pressures will be different to track pressures, as will geo'.

If the ARBs are adjustable stiffen the back and/or soften the front will reduce understeer.

Improved front tyres will reduce understeer.

If the dampers have adjustable rate harden rear and/or soften fronts will reduce understeer.

Increase rear tyre pressure and/or reduce front tyre pressure will reduce understeer. Try 32 front, 36 rear.

Get rid of the LSD as it seriously increases understeer.

I'd agree with that apart from the LSD, as the drive out of the corners from the lsd is worth working around the understeer it induces IMO (especially with a modded high power car)

Thanks Guys

She has more characteristics to induce understeer , will try the tyre pressures as its cheap , I got her setup by a competent suspension guy and a piece of string so she is as close as you will get her to OEM settings, for safety reasons will be geared towards understeer by Toyota, its only now after all new suspension I can really push her and highlight what would be suited better to my driving style, at least I have a good platform to work off now

Bilsteins are fixed rate, rollbars are fixed adjustment, unless I get her realigned again , looks like I am stuck with tyre pressures

LSD is the Carbonetic unit

And yes Chris , she is too low lol has big wheels and tyres, everything you dont like but it looks cool; Blame me for the wheels but Toyota messed up everything else

If the ARBs are adjustable stiffen the back and/or soften the front will reduce understeer.

 

Improved front tyres will reduce understeer.

 

If the dampers have adjustable rate harden rear and/or soften fronts will reduce understeer.

 

Increase rear tyre pressure and/or reduce front tyre pressure will reduce understeer. Try 32 front, 36 rear.

 

Get rid of the LSD as it seriously increases understeer.

Tyre pressures ----- Wrong!

LSD ----- Maybe!

Dampers ----- Depends on whether it's corner entry, fixed state, or exit, very complex subject, depends on what valving is in the dampers to a large extent.

Commonest mistake people make is thinking a lowered car will necessarily handle better than one at stock ride height, or near stock.

Understeer is safer than oversteer, that's how most road cars are set up for normal daily driving

She is a GT car , I am just trying to work with what I got and make her handle as best I can

Completely agree Chris , Stock ride height & wheels I am sure would make her 100% better through the twisty's , but she is a hell of alot better than she was, I think if I just tweak her, it will make her that bit more fun to drive

Put the stock front roll bar on and see what difference that makes, the TRD bars are something like 25% stiffer

After Chris at Centre gravity set my car up I had no issues at all in any situation in my car, perhaps your stock alignment

needs a little tweeking

Put the stock front roll bar on and see what difference that makes, the TRD bars are something like 25% stiffer

 

After Chris at Centre gravity set my car up I had no issues at all in any situation in my car, perhaps your stock alignment

needs a little tweeking

TRD bars may not help, from what I remember she did feel more neutral when I last drove her (TRD bars are new additions)

What tyre pressures did you run Dunk?

My car had understeer but only when really pushing the car hard at Silverstone did I find it, other than that on the road

the car was very neutral and I was very happy how it drove.

My car had the trd roll bars front and rear, lowered 30 mm front, 25 mm rear using Eibach pro sport springs and

new OE dampers. We also fitted complete new suspension at the same time, lower arms upper arms etc

duncan+shaw+toyota+supra+mkiv+160908+table.pdf

Thanks Dunk

She got pushed hard on the B roads the other nite , she is very neutral otherwise

I would just like her to feel more planted, regards every day driving , I reckon tyre pressures may be too high, she feels like she is sitting on top of the road rather than sitting on the road, felt more planted, better tyre contact in corners at 30psi

Thanks Dunk

 

She got pushed hard on the B roads the other nite , she is very neutral otherwise

 

I would just like her to feel more planted, regards every day driving , I reckon tyre pressures may be too high, she feels like she is sitting on top of the road rather than sitting on the road, felt more planted, better tyre contact in corners at 30psi

Mine were set at 32 psi front and rear,

Mine were set at 32 psi front and rear,

Might try a 32 front , 30 rear mix to see if she feels more planted and reduces understeer