Offset vs. Spacers - Scrub radius affected?

**Phil 'The Guy'** · 28-06-2012 21:31

Lee, Mitto is a very good friend of mine, and a lot of other people posting in this thread. There's nothing subjective about this question though, and if this site is to be used as resource such a load of bollocks should never be given air time as it may confuse those that can't think it through for themselves.

**mitto** · 28-06-2012 21:33

Originally Posted by Phil 'The Guy'

leeturbo387, the only reason you would get more camber with more offset is because you're changing the motion ratio of the suspension, effectively reducing spring rate and lowering the car, which if the suspension cambers in under load would then change the camber.

So by that statement, if you move the spokes of the wheel away from the hub, irelevant of the wheel offset,
You alter the camber and therefore the contact patch of the tyre, since the axis is moved away from the hub.

So basically, you've just made my point valid again and the answer to the original post should be "it depends on the wheel"

**leeturbo387** · 28-06-2012 21:35

no comment i dont want another bollocking from phil lol

**Munkul** · 28-06-2012 21:37

Originally Posted by mitto

So by that statement, if you move the spokes of the wheel away from the hub, irelevant of the wheel offset,
You alter the camber and therefore the contact patch of the tyre, since the axis is moved away from the hub.

So basically, you've just made my point valid again and the answer to the original post should be "it depends on the wheel"

No. it DEPENDS on the offset. THINK about it.

Ach i give up. Bury this thread deep where no-one will ever see it ever again please

**mitto** · 28-06-2012 21:38

^^^ dont worry about that, as long as the input is constructive then it's all good!

**akinadan79** · 28-06-2012 21:38

too much....too much...too much....sooooo confused!!

**leeturbo387** · 28-06-2012 21:39

good night all lol ffs

**mitto** · 28-06-2012 21:44

Originally Posted by Munkul

No. it DEPENDS on the offset. THINK about it.

Ach i give up. Bury this thread deep where no-one will ever see it ever again please

Phil just mentioned the exact principal I am talking about, so I'm asking. The load on the hub to wheel are different things relative to the load between the hub and the wheel rim mounting / aka spoke. So different wheels will have different effects on the geometry, because the load / hinge / axis moves. Is that not a true statement?

**superclarkey** · 28-06-2012 21:57

No because it don't matter if it one solid wheel or cut into a 1000 slices the distance from the pivot is the same, so the force have to be the same simpe as that.

Otherwise you would be able to cheat physics..

Only difference would be in structural loading within the wheel but that's stress factors and is about wheel load capability and if it can take the load, it however doesn't change the pivoting points.

**Andy_F** · 28-06-2012 22:05

What the fucking fuck happened in here.

From what I can decipher from this thread, Mitto, it looks like you are mainly comparing the difference in gemoetries between fitting a lower or higher offset wheel. My understanding on Phil's last post is just pointing out the obvious that spacing a wheel out further (compared to not spacing it) changes the way the suspension behaves since there is more leverage compressing the suspension - 'lowering the spring rate'. This will also obviously cause more suspension travel too, and thus more changes in the dynamic camber, castor, scrub radius and bump steer. Seems this is what you are mostly taking about, leverage etc, is obviously makes a difference.

However, that's totally not what I was trying to clarify.

Logic dictated to me that if 'effective offset' is achieved by spacing a higher offset wheel to match the specs of a lower offset wheel, that the scrub radius should be the same. Seems pretty much everyone is clear on that being correct now.

Spacing a wheel compared to not spacing it is a whole other can of worms which initially had nothing to do with my scenario.

**James** · 28-06-2012 22:26

So the original question's answered and dealt with

Mitto, the only way I can possibly make sense of what you're saying is that based on spoke design, a dished low offset wheel will likely have the majority of it's spoke weight towards the hub, whereas a high offset wheel with flatter spokes, plus spacers is more likely to have it's spoke weight further outboard and this potentially further outboard unsprung weight will have more leverage on the suspension. Is that what you're saying?

**mitto** · 29-06-2012 06:43

Originally Posted by James

a high offset wheel with flatter spokes, plus spacers is more likely to have it's spoke weight further outboard and this potentially further outboard unsprung weight will have more leverage on the suspension. Is that what you're saying?

Yes, thus having an effect even on static camber meaning the scrub radius is changed since camber has a bearing on the scrub radius... that's been said several times on the thread already.

I don't understand how the position of the spokes, the point at which the wheel rim connects to the hub has no bearing on the scrub radius at all, since it changes static geometry. Even if it only changes the angle at which force is driven into the tyre.

With this difference in offset and the huge variation in wheel choice, in my mind it MUST make a difference, because the points of leverage are being changed. This is totally irellevant of changing the wheel's position.

I'm talking static, once the wheel starts turning and going onto lock it all goes more out of sorts again.

For the sake of making an example, fit a ET50 wheel with a 50mm spacer and spokes on the outer lip, then fit an ET0 wheel with a 5" dish... what you are all telling me is that the scrub won't be changed at all by the change, however minimal, in geometry. Even though this change has been mentioned more than once by other people on this thread?

We all know the example I made would drive VERY differently and thats the point I'm trying to make.

If scrub radius is fixed and solely determined by the kingpin, then I'll shut up, because it then it can't be changed no matter what you do right?

**mitto** · 29-06-2012 06:50

Originally Posted by superclarkey

No because it don't matter if it one solid wheel or cut into a 1000 slices the distance from the pivot is the same, so the force have to be the same simpe as that.

So the wheel makes no difference...

Originally Posted by superclarkey

Only difference would be in structural loading within the wheel but that's stress factors and is about wheel load capability and if it can take the load, it however doesn't change the pivoting points.

Oh wait it can.

Of course the pivot points change if you move the position at which the wheel hub connects to the wheel rim, because it has a direct effect on the angle at which force is put into the tyre. Look at the above example ET50 / ET0... you are saying the load on the tyre would be identical? BOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOSACK.

**superclarkey** · 29-06-2012 07:21

You are actually retarded.

**mitto** · 29-06-2012 07:29

You didn't answer the question, thats more retarded...

**Phil 'The Guy'** · 29-06-2012 08:22

Mitto, you are really really wrong! There is literally no explaining this any clearer than has already been explained at least ten times in this thread. This isn't a discusion any more, as it seems you have a very special brain that can't understand a very simple bit of physics. So on that note I herby close this dumb thread, and banish it to the archives where I hope to never see it again

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