why the 0.20 positive toe on rear suspension

[Racin510s]

Does anyone know why PD has put the 0.20 positive toe on the suspensions of all cars with full race suspension? In my own tuning I have been taking it down to 0.00 so it is neutral toe. Then I lower the car to the max and increase springs depending on the weight of the car. This makes a great starting point and sometimes I don't need to do anything else for the car to handle great for my style of driving.

I did a search for this before starting this thread and came up with no matches no matter how I worded the search. I also went to the tuning forum with the same result. Not a big deal to change just wondering why it was done. I was a SCCA racer thus the aka Racin510s and never used a positive rear toe on any setup on a real car on a real race track.

 

[Spagetti69]

Rear end stability perhaps. I often add toe in on rear wheels.

 

[Racin510s]

I often add toe as well but it is negative toe to compensate for the negative camber. Any time you use negative camber it toes out the wheels. It is the positive toe that I don't understand. I have had a lot of real world chassis set up experience. I wonder why some of my initial set ups weren't working until I noticed that the toe on the rear was positive. I took it out and no problems since.

 

[Spagetti69]

Toe in is for straight line stability as you know.
It sacrifices turn in response for a stable ride.

I often add toe out(negative) to my fronts for better turn in. The rear depends on how she handles.

If my arse is loose then positive toe can help.
Obviously differentials, camber, springs and dampers brake bias etc play a role too. Along with the situation that causes the end to break loose. Acceleration, deceleration, breaking, coasting.

Lots and lots of variables. All I would say is that if it works for you then all is good.

Tuning a car relys a lot on the individual's driving style also. A great tune for me might feel awful for someone else.
I like a bit of oversteer on acceleration myself. (I regulate the throttle manually to compensate but it's there if I need it).

 

[Racin510s]

No wanting to argue with you Spagetti69. Toe out is positive as it make the wheels go out. Negative toe makes the wheels go in. I wish I could draw you a picture. Mabey this will help. Positive \ , negative / with the slashes being the position of the wheels.

 

[Racin510s]

Got to quick with the fingers. You are absolutely right that tuning is per individual driving styles. What works for you is great and I'm glad you have found your edge when it comes to tuning your cars.

 

[Spagetti69]

From Wiki mate.

Positive toe, or toe in, is the front of the wheel pointing in towards the centreline of the vehicle. Negative toe, or toe out, is the front of the wheel pointing away from the centreline of the vehicle.[2] Toe can be measured in linear units, at the front of the tire, or as an angular deflection.

I'm not up to arguing either. We will have to draw a line under it but we both know what each other means.

Cheers.

Oh edited to add.

I haven't tuned in GT fot ages I'm tuning in another game but the principles should apply.

There was a thread around though related to spring values in GT working backwards. (don't ask lol).

Maybe there's some high jinx with the toe values too.

 

[ghsnu]

Positive toe: /......\
Negative toe: \...../

Took 3 years of auto mechanics at my school. Don't believe me? Google it.

Toe exists to center the wheels after a turn and keep the car stable. Its measured by distance between the back of the front tires or the back of the rear tires. Almost all cars come with positive toe on the rear tires. RWD cars usually have some positive toe at the front and FWD cars with some negative toe at the front.

Basic rule is: more positive toe for more stability and more negative toe for more maneuverability.

 

[iamsupernasty]

No wanting to argue with you Spagetti69. Toe out is positive as it make the wheels go out. Negative toe makes the wheels go in. I wish I could draw you a picture. Mabey this will help. Positive \ , negative / with the slashes being the position of the wheels.

You are wrong.

Negative toe is toe out.
Positive toe is toe in.

That is a fact.

 

[Vegard]

Because the car shifts weight to the outside tyres during cornering, rear toe effectively becomes fixed/passive rear steering.

If you have positive rear toe, the outside rear tyre will "steer" inwards, increasing stability whilst decreasing rotation. Helpful if your car is too loose.

If you have negative rear toe, the outside rear tyre will "steer" outwards, increasing rotation whilst decreasing stability. Helpful if your car is too pushy.

Note that toe angle increases tyre wear, even when you're going straight, as the rotational plane is not parallel to the surface.

 

[Racin510s]

I stand corrected.

 

[Morgoth_666]

No wanting to argue with you Spagetti69. Toe out is positive as it make the wheels go out. Negative toe makes the wheels go in. I wish I could draw you a picture. Mabey this will help. Positive \ , negative / with the slashes being the position of the wheels.

At least now I know I'm not the only person in the world who gets that backwards. I've finally learned that it is the other way around, but still for the life of me I simply cannot make my brain come up with a logical solution for why it is that way.

Maybe it's because I think of toe based on the front of the tire, and adding to the distance between the front of the tires seems positive. Maybe it's just because to me mathematically outward=farther=positive. Maybe it's because your toes are on the front of your feet and standing with your toes in means pointing your toes more towards one another. Who knows?

Perhaps it would be simpler if there was no +/- way of expressing it and it was simply out and in, because out and in make perfect sense(notice that without thinking I wrote it as "+/-" and as "out/in" which is of course still backwards).


Is there a scientific reason for toe out to be negative or is it just that whoever invented the idea thought it made sense? Perhaps carried over from a different field of application?

 

[grog]

Back on topic, These are all generic settings. I have a feeling most car makers didin't want to give up their true camber, toe, and other suspension settings. so we are stuck with alot of generic settings.

I wonder if behind these stock generic settings lie a hidden settup that is the real setup?

I feel they set the toe at .20 so all cars have consistent settings and some rotation (good turn in).

This gives me an idea (or has it been done), To find out stock cars true equivalent settings so as to experience them in a more pure state. Race cars would be near imposssible to find settings for.

 

[yanksmell]

I found this link and thought I could help somewhat.

A solid axle is "0" toe and camber and requires damage for that to change.
Independent rear axle design is anything you wish.

I have a Crossfire (SLK350) rear suspension and you can adjust it to any configuration you like (once I replaced all the solid links with adjustable links from a Hot Rod Supply House) however…

The unit came with -1 degree rear camber (huge tire wear issue) (the reason for the modifications) and +1 degree toe.

The -1 camber allows the rear tires to “bit” into a corner – which I understood.

The +1 degree toe however was not so straight forward so I contacted “Hot Rod” freaks that know most everything about this stuff.

I was told that an independent rear design is loaded with bushings and arms that flex and wear. When power is applied to the rear tires the force forces the tires to go negative (no axle tube keeping things at 0 degree toe and camber).

The positive toe goes to “0” under load as it picks up flex, busing wear and all the variables that can creep into an independent set up over time.

Simply put, it may be static + toe however it becomes “0” toe dynamically.

I suspect if you strapped the tires to the ground and pulled the chassis rearward would be the way to most accurately adjust the rear toe (to “0&#8221 thus neutralizing wear and dynamics of the rear links (sounds cool as I wrote that). I suspect the static toe would then be positive (physics).

I hope this helped.

Jon

 

[Racin510s]

I figured since I started this thread, I need to ask another question about toe. I was corrected about the difference between positive and negative toe

When adjusting toe on a real car it is measured in inch increments. On our 510's for every 2 degrees of negative camber we used 1/8" of positive toe. So in GT5 what is the toe measurement measured in? I know that is is a decimal amount thus the 0.20 of positve toe automatically added to the rear of the car when you use race suspension.

So the question is... The decimal is equivilent to inches or milimeters? Someone please let me know. Thank you.

 

[Machate-man]

I figured since I started this thread, I need to ask another question about toe. I was corrected about the difference between positive and negative toe

When adjusting toe on a real car it is measured in inch increments. On our 510's for every 2 degrees of negative camber we used 1/8" of positive toe. So in GT5 what is the toe measurement measured in? I know that is is a decimal amount thus the 0.20 of positve toe automatically added to the rear of the car when you use race suspension.

So the question is... The decimal is equivilent to inches or milimeters? Someone please let me know. Thank you.

It would likely be millimeters since the ride height is measured in mm and spring rate out of kg/mm. But the toe is measured in degrees, with 0.20 being 1/5" and 1/8" being 0.125 [closest in-game being 0.12]

These may be wrong for all I know though...

 

[Racin510s]

It would likely be millimeters since the ride height is measured in mm and spring rate out of kg/mm. But the toe is measured in degrees, with 0.20 being 1/5" and 1/8" being 0.125 [closest in-game being 0.12]

These may be wrong for all I know though...

:tup:Thanks for your response. I thought it was in mm just was trying to confirm it.

At this link
http://www.engineeringtoolbox.com/inches-mm-conversion-d_751.html

There is a conversion chart. According to the chart 0.2000mm = 0.0079 inches. In light of this info then the toe adjustments are actually negligible if this measurement really is decimal milimeters. 1/8" is 0.125" but that is equal to 3.175 mm. The slider bar for toe adjustment only goes to 1.0. So something is way off. It has to be a different scale of measurement or toe adjustments mean absolutely nothing.

Hopefully someone else has some better insight into what the measuremnt is. I will go and research decimal millimeters in degrees and see what I can find.

 

[NjLowrider]

The .20 is rubbish.

Start at 0

I only go as far as -.15 to +.08

Yellow bird= rear toe +.08
Any tvr= rear toe -.15

That's my extremes, everything else should be within them.