Motion Ratio or Wheel Rate?

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hot_shoe

hot_shoe

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I was working on a setup for the Honda NSX-R when I saw that the front springs on the intial setup for the Racing suspension were actually a higher rate than the rears, at 13 kg/mm front vs. 10 kg/mm rear. This seems odd for a mid engine car, but I recall reading an issue of Sport Compact Car magazine where they said the front motion ratio of the NSX was lower than the rear, so the springs actually had to be stiffer in the front to get the desired wheel ratio. My question is, does GT4 model this or does it only give the spring rate as if the motion ratio was 100%?
 
First off, don't be impatient, it never works in getting you answers around here. :cool:

Secondly, never trust what the default settings give you. It may give you those settings when you fit the fully customisable suspension but it doesn't mean that they are the correct settings. That's why the tuners adjust the settings so it gives the car a better balance overall, be it lowering the spring rate, the dampers, ride height or whatever.
 
The racing suspension doesn't give you the stock settings for the initial settings. The sports are closer, but they're still firmer than the stock settings. Though the bias is usually the same as it is in real-life.

And they probably do model it in GT... though I don't know for sure.
 
hot_shoe, I don't have the ultimate answer either.

But if you set the rates on your NSX to 10 front / 13 rear, you find the car oversteers rather badly. So it is fair to suspect the rates were initially set to mitigate the inherent oversteering characteristics of this MR car.
 
I don't think I was impatient, seeing as there was almost 2 months between my original post and my thread bump.

Anyway,thanks for answering. I guess it doesn't really affect setup, because whether they model it or not you still have to tune the car based on its behavior, not just on numbers.
 
Sorry dude, I must've been tired when I looked at the post, as I must have only looking at the times not the dates. :embarrassed:
 
Softer springs at the rear mean only one thing - oversteer, if the difference in spring rates is big enough.
 
I tried for a very long time to determine if the game engine took into account such things as the angle of the suspension, with it's attendant effects in wheel-rate.

Sadly, I never got to prove it one way or the other but did confirm, as others have said above, that, other than perhaps the default spring rates showing the static weight distribution of the car, the 'stock' settings that a suspension came with are seldom anything like what is needed :D.
 
...hope it's ok for me to dig up an old thread...

I have a theory that the minimum possible spring rates represent the static weight distribution of the car. The NSX-R is 6.5/5.0 so I reckon the physics engine models the car as 57% / 43% F/R weight balance (slightly FR).

Even accounting for this, the stock spring rates are still unusually biased towards a softer rear compared with any other car I can remember. So is this to do with the motion ratio? No idea, sorry! If you were keen, you could try finding another car with similar mass, weight distribution etc and compare how they react on landing jumps when they are using the same spring rates. Or (just brainstorming...maybe this isn't possible), if you could somehow
- measure stopping rate using the data logger
- tweak the brake controller until you've got the same deceleration rate on 2 cars
- measure the dive during braking (perhaps using photoshop on a screenshot taken from an external camera angle)
then this could tell you if there's a multiplier involved in the spring rates

Personally, I've never found anything to suggest motion ratios exist in GT4 (although now that I think about it, maybe they could be influencing things and you'd have no way of knowing anyway). And like you said, tuning should be based on driving feel and not numbers.

Back to my tangent about the NSX, anyway I was thinking maybe Polyphony softened the rear to tame the car a bit so it wasn't too scary with the stock settings. But then playing with the spring rates, the effect on balance was very minimal. (I didn't play around with the brakes but it felt like the handling was being dominated by overly strong front brakes, which induced an understeer stance that remained right throughout the corner) But then maybe it was done so that when kiddies throw a Stage 4 turbo at the car with stock FC suspension settings, then having a soft rear meant the car wouldn't be totally undriveable. This is a lot of second guessing, though...

Sorry this doesn't answer your question, hope it is at least thought provoking!
 

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