I think I found a suspension / geometry guru !

[ibizacupra]

That waxing of the 'lyrical' is deliberate...geometry is a boring read for most.... voice a picture then things become more palatable.

From that link i read Mr 'S' may bring you a Digital Geometry Gauge, from that i assume some..... setting-up will be explored... i would love to be part of the conversation but i need to know 'How adjustable' have you made the car? with any set-up 'direct' adjustment needs little maths...... in-direct takes... an age...
On that note... often even within racing still the importance of CASTOR/KPI/ TOOT is miss understood....... this area is 'very relevant' to you and the cars wider track and flat wishbones....i feel?

I have played with basic camber and tracking previously..
I now want to add caster adjustment via hubs and top mounts (pending regs allowing me to do both)
Achieving the flatter wishbone and ball joint should correct the roll centres previously changed by default of ride height being lowered.

Hoping for increased caster going some ways to helping turn in and corner traction. 400+bhp and fwd is asking a lot of traction.

digital gauge for camber, worked well up to now.

Got my tyres on order now so will get the 8x17 rims mounted onto the car and see what fits from what does'nt and decide on parts vs what I am going to be allowed to do in the regs.. Its all a grey area at the moment so nothing I suspect you can assist on at this time.

 

[wheels-inmotion]

Its all a grey area at the moment so nothing I suspect you can assist on at this time.

Indeed not... seems like you have things very much under control and have a very complete vision with the car......although race set-up in argument was not my intention here seemingly we do own interests that explore our pursuits.

One area to 'explore' with Mr Xmas's Digital Camber Gauge is 'TOOT' (toe out on turns) Directly not adjustable...... very relevant to race...... totally dismisses rack ratio.... very miss-understood... and Castor related.

 

[ibizacupra]

Indeed not... seems like you have things very much under control and have a very complete vision with the car......although race set-up in argument was not my intention here seemingly we do own interests that explore our pursuits.

One area to 'explore' with Mr Xmas's Digital Camber Gauge is 'TOOT' (toe out on turns) Directly not adjustable...... very relevant to race...... totally dismisses rack ratio.... very miss-understood... and Castor related.

Does TOOT (not come across this before) also have ackerman included in there.
I am restricted by regs on what I am allowed to move and by how much, not allowed to run spherical joints, so wishbone arms are bushed instead.

When I have the setup built I may contact you for setup and suggested geo to suit.

 

[wheels-inmotion]

Does TOOT (not come across this before) also have ackerman included in there.
I am restricted by regs on what I am allowed to move and by how much, not allowed to run spherical joints, so wishbone arms are bushed instead.

When I have the setup built I may contact you for setup and suggested geo to suit.

Yes indeed the good old Ackerman theory.. well read but seemingly miss-understood in the pure mechanics, rack ratio and TOOT can be very good friends in most forms of race.

On that note, i was approached by a Drift school here in the UK to write and set-up the geometry on their lead car......... 'Drifting' whats this? never heard of it!
So on with the cap i hit the maths.......... wrote the geometry........set the geometry.....displayed all the set-up on my site........ and it was utter 'PANTS' drifted sort of OK..... little tight......(words of the driver)
Anyhoo i was wrong.... the set-up was designed to be 'safe'.. my lack of understanding for the specific art of drift was flawed..

Some of the positions and explanation's in WIM are wrong but i decided to leave them there!!!! 'WHY' some may think?..... the information opened a debate between all manner of forums, many people slated me with corrective positions and explanations and all was on display for all to share, (that's good)

My point is this 'no one' person knows everything, to expand in knowledge maybe there is a need for a bloody nose every now and again.

'Licking of wounds' expands the mind.....
Taken from the book of Bones....

 

[ibizacupra]

and all this means what exactly in english. (plain english )

 

[wheels-inmotion]

and all this means what exactly in english. (plain english )

'Willing to help' and not scared to be 'wrong'

Debate within any field is only as good as the argument.....

Can we start again ..... i think I/WE are getting drawn into an area not beneficial to anyone....

My field is geometry and theoretical geometry..... i work for the common man not any dealers or race teams UK/World....

WIM is a free site designed for information and offers free one to one help if needed. 'Muddyboots' was a perfect example.

I am definitely not the absolute law within geometry but i do have an absolute desire to help those in distress at £0 so this is not a money making venture.

Away from this race topic maybe i can contribute advice here, and i would welcome a guiding hand here since i am a 'newbie' you know....

 

[ibizacupra]

'Willing to help' and not scared to be 'wrong'

Debate within any field is only as good as the argument.....

Can we start again ..... i think I/WE are getting drawn into an area not beneficial to anyone....

I think chap, you are reading a lot into this thread thats not there.... not even between the lines that are'nt there.

no debate no arguement going on here to my knowledge, unless there's subtext I have completely missed

I think I know what I want to achieve and will start from there. From track testing this can be developed if needs be as the season progresses, so I will come back and ask questions if I need to.

Agreeing my spec is not joe public road car spec any more so not relevant to most who may read this.

anyhow...
BTT

 

[RobT]

Doode, I have no idea what you are talking about, you may do but that isn't obvious to me.

I have done a bit of racing and have experimented with tyre pressures, toe, camber and damping rates. Largely I have left spring rates alone. These are the things that can reasonably be altered on a saloon car. My experiments have been measured by laptimes, confidence in the feel of the car, and tire temperatures across the tread width. I am a very experienced scientist so keep very thorough records.

Lets assume a theoretical situation - a 200hp front wheel drive car, a hatchback, that has mcpherson strut front suspension. The car runs perhaps 0.5 degree of negative camber and the merest hint of toe out to help turn-in. Like most modern hatchbacks, the car has little castor, maybe 1.5 degrees. The scrub radius is approx 45mm-ve. What would be the affect on handling, all else being equal, of moving the SR towards, and ultimately to, zero ?

 

[wheels-inmotion]

I think chap, you are reading a lot into this thread thats not there.... not even between the lines that are'nt there.

no debate no arguement going on here to my knowledge, unless there's subtext I have completely missed

I think I know what I want to achieve and will start from there. From track testing this can be developed if needs be as the season progresses, so I will come back and ask questions if I need to.

Agreeing my spec is not joe public road car spec any more so not relevant to most who may read this.

anyhow...
BTT

I think you are very right...
Time to sit and stroke the cat me-thinks

 

[wheels-inmotion]

Doode, I have no idea what you are talking about, you may do but that isn't obvious to me.

I have done a bit of racing and have experimented with tyre pressures, toe, camber and damping rates. Largely I have left spring rates alone. These are the things that can reasonably be altered on a saloon car. My experiments have been measured by laptimes, confidence in the feel of the car, and tire temperatures across the tread width. I am a very experienced scientist so keep very thorough records.

Lets assume a theoretical situation - a 200hp front wheel drive car, a hatchback, that has mcpherson strut front suspension. The car runs perhaps 0.5 degree of negative camber and the merest hint of toe out to help turn-in. Like most modern hatchbacks, the car has little castor, maybe 1.5 degrees. The scrub radius is approx 45mm-ve. What would be the affect on handling, all else being equal, of moving the SR towards, and ultimately to, zero ?

Be gentale 'What is SR'

 

[RobT]

Be gentale 'What is SR'

The clue is in the preceeding sentence - SR=scrub radius

 

[wheels-inmotion]

Be gentale 'What is SR'

'Oh that SR'
First the incriment of measurment shown for the Camber is that
60'/1
or
100'/1
as 0.5 could read as 30' or 50'

Also you have shown the radius without the tyre width or the KPI inclination... no one could calculate the 'scrub radius' without the actual camber position/ King pin inclination.. wheel off-set and the King-pin off-set, then a possible 'SC' could be realized......
.
.
.
FWD desires Negative SR...
.
.
.
.
Feeling like this is some sort of test, i conclude. You 'Cannot' have a Zero 'SR'

 

[RobT]

Thanks for the units lesson, I know what a degree is and whichever way it was described, it would still be half, that is 0.5, 1 part divided by 2 parts, of a degree.

I am not asking you how to calculate the scrub radius, I am telling you what it is, and all I have asked is a very simple question.....care to enlighten us with an answer or even a theory ?

I ask again, on a fwd car (and yes I know they are -ve), what would be the apparent effect, to the driver, of steadily increasing the value from -45mm towards zero ? (and you can have zero SR.....but what would the car feel like if you did ?)

 

[ibizacupra]

I am intrigued by the impending answer for Mr Guru. Dr RobT being the man who has doen the exact thing I am edging towards (but not allowed to do the same due to regs)

 

[wheels-inmotion]

Thanks for the units lesson, I know what a degree is and whichever way it was described, it would still be half, that is 0.5, 1 part divided by 2 parts, of a degree.

I am not asking you how to calculate the scrub radius, I am telling you what it is, and all I have asked is a very simple question.....care to enlighten us with an answer or even a theory ?

I ask again, on a fwd car (and yes I know they are -ve), what would be the apparent effect, to the driver, of steadily increasing the value from -45mm towards zero ? (and you can have zero SR.....but what would the car feel like if you did ?)

The increment of measurement is relevant....

Yes you can have a zero SR..... on a horse and cart?

Since the radius is born by the camber and the kpi.. then 0 SR would mean 0 camber and 0 kpi with a wheel off-set equal to the kingpin off-set, or a camber position - equal to the sum of the kpi //

In answer to your question lower the SR would make the car stable.. very stable.... but is detrimental to the Castor position.... i assume with such a low Castor value the camber and even more so the kpi are designed into the overall geometry....

The 'flatter' wishbones described earlier what increment would you allow for the kpi... and since there is a swapping of values between kpi camber and the steering arm dynamically if only by their radii, the camber positions dynamically
belay this interest in SR.

Other than that i have no idea!..... simply very 'flued' up and in love with my 'day nurse'.....

Since this whole evolution evolved from a simple question regarding toe from 'Muddy boots'........ shall we lay this one to rest (for now).....?