Offset vs. Spacers - Scrub radius affected?

[Stavros]

Basically, don't use spacers when you don't absolutley have to, because it's a shit idea

So low you're saying offset wheels are a bad idea too? As in geometry terms the centre of the wheel and the tyre are in the same place wether the wheels are pushed out with a spacer or lower offset. It's the same thing.

What's the perfect offset? Stock? Higher?

Either I'm missing something, people are taking the piss, or some people are spastics (possibly me).

[mitto]

The perfect offset is 0. That's fairly obvious isn't it? The problem is when you move the hub face of the wheel away from the hub of the car. Doing this with spacers is the worst possible situation. Surely you grasp that? How do you not understand the difference? Unless you assume that low offset means that you have the "spacer" as part of the wheel, which is not normally the case with good quality wheels.

[Munkul]

Mitto, sorry but you are either completely wrong, or complicating this so much inside your head that it just doesnt make sense. To anyone.

The perfect offset is NOT 0, because your knuckle, hub and brake disc setup cause the hub face to be offset from the axis of the kingpin angle. This is why cars come with positive offset wheels in the first place. To reduce the scrub radius from what it would be naturally with ET0 wheels.

[Stavros]

The perfect offset is 0. That's fairly obvious isn't it? The problem is when you move the hub face of the wheel away from the hub of the car. Doing this with spacers is the worst possible situation. Surely you grasp that? How do you not understand the difference? Unless you assume that low offset means that you have the "spacer" as part of the wheel, which is not normally the case with good quality wheels.

So zero offset is perfect? This is what wasnt mentioned, and no, I didnt understand why that is perfect? Why is zero offset perfect? Hardly any cars have a zero offset?

So I'm still confused why a spacer is any different, from a suspension point of view, than a lower offset?? Heavier yes, but beyond that, what am I missing? Both push the hub face away from the centre line of the wheel.

Maths and suspension are not my stongpoints, but this is spinning me out.

[Andy_F]

Perfect offset is going to differ on every car depending on how the suspension geometry has been engineered on each individual car, IE, how the factory suspension engineers intended the car to utilise scrub radius. 0 offset is only ever going to be perfect on a vehicle that has its suspension engineered to utilise that offset to obtain the desired factory scrub radius.

Take a factory super car, fit a set of 0 offset wheels to it (no other changes) and I'd be willing to bet that it would handle shitter.

Dunno why this is getting so complicated now, my question literally needed a one word answer.

[Clark3y]

Mitto, sorry but you are either completely wrong, or complicating this so much inside your head that it just doesnt make sense. To anyone.

The perfect offset is NOT 0, because your knuckle, hub and brake disc setup cause the hub face to be offset from the axis of the kingpin angle. This is why cars come with positive offset wheels in the first place. To reduce the scrub radius from what it would be naturally with ET0 wheels.

This, absolutely.

[mitto]

Mitto, sorry but you are either completely wrong, or complicating this so much inside your head that it just doesnt make sense. To anyone.

The perfect offset is NOT 0, because your knuckle, hub and brake disc setup cause the hub face to be offset from the axis of the kingpin angle. This is why cars come with positive offset wheels in the first place. To reduce the scrub radius from what it would be naturally with ET0 wheels.

I realise that, but since you cannot usually run your wheel in absolute paralell with your kingpin, then for the purposes of getting the point across the perfect offset is 0. Unless you run ET38 (or whatever it may be) with extended lower arms and shifter suspension pick up points, thus running closer to paralell, both in steering and geometry terms.

Actually an offset of 0 is perfect, assuming it is in total paralell with the kingpin.

Of course in real terms, that would drive like ass.

so in short, it's better to have a lower offset wheel without a spacer. Assuming the thickness of the wheel hub is the same and the actual position of the wheel hub is moved closed to the hub face of the car. Does a high offset wheel and a spacer effect scrub radius... yes.

[kam]

Are we talking 1/10 or full scale drifting?

[Munkul]

... and back in circles again.

PLEASE explain how, in PRACTICAL purposes without the aid of irrelevant diagrams etc, that a 9j ET0 wheel has a lower scrub radius than a 9j ET30 wheel with a 30mm spacer. Lets assume the design of the wheel itself is exactly the same in each case.

[mitto]

Anything. You move an object further away from an axis point the change in angle becomes more dramatic.

[kam]

... and back in circles again.

PLEASE explain how, in PRACTICAL purposes without the aid of irrelevant diagrams etc, that a 9j ET0 wheel has a lower scrub radius than a 9j ET30 wheel with a 30mm spacer. Lets assume the design of the wheel itself is exactly the same in each case.

The scrub radius is exactly the same.

[Stavros]

... and back in circles again.

PLEASE explain how, in PRACTICAL purposes without the aid of irrelevant diagrams etc, that a 9j ET0 wheel has a lower scrub radius than a 9j ET30 wheel with a 30mm spacer. Lets assume the design of the wheel itself is exactly the same in each case.

This is what I was thinking was correct too. Common sense even.
I thought I was being thick?
Mitto is wrong?

Yes no answers to the above would be fine.

Thanks.

[mitto]

Lets assume the design of the wheel itself is exactly the same in each case.

Then you bought shit wheels that have a "built in" spacer, rather than proper wheels that have the same hub thickness and actually move the hub inside the wheel.

Sorry did you think i'd fall for that? Let's assume you bought proper wheels where the actual hub offset is changed rather than just machining off less alloy... what now?

[kam]

This is funny.

On a macpherson setup, the scrub radius is measured from the angle between:

Camber plate (top of strut) to bottom ball joint axis.
Centreline of wheel.

Explain to me how the centreline of the wheel is different between an ET10 wheel, or an ET30 wheel with a 20mm spacer.

[mitto]

Explain to me how the centreline of the wheel is different between an ET10 wheel, or an ET30 wheel with a 20mm spacer.

It's not, the position of the hub face "should" be different relative to the centreline of the wheel. Now turn the wheel.

[Munkul]

in a further effort to try and understand what you're saying, I have studied this diagram again...



Did you put that spacer on there yourself? Cos its on the wrong side of the wheel

Its ok to be wrong, even if you're old and wise and experienced etc etc,

[Robbs]

I still cant get my head around what mitto is trying to say

regardless of whether the offset is gained by a thick hub or by spacers or by a thin hub with more dish, wheel design etc, with a certain offset (or effective offset) the centre line of the wheel will always be in the same place .

I dont see what difference wheel design or hub thickness or spacers would make.

[Munkul]

oops, bad diagram. back in a min.

[Mr Bizzle]

Talking utter and complete poop

[mitto]

^^^ what Bizzle said.