- 83
- daveyules
Welcome to my Ride Compliance Suspension Tuning Guide. This post contains my entire breadth of tuning knowledge regarding shock and spring rates and how they are related in GT4. It’s intended to be a clear and accurate guide to help you tune your cars to perfection. Let’s get started.
An Introduction
In my opinion the absolute fastest racing suspension is not necessarily the stiffest, but the most compliant. By compliant I mean that the suspension fully absorbs the impact of any bump at any speed in order to keep all tires in contact with the road. Doing so minimizes undesired momentum that can cause you to lose control.
Ride Compliance
The best way to figure out if you’ve nailed the most compliant suspension settings for any given car is by watching the way it bounds over bumps. If you can see or feel that the car is reacting multiple times per bump (bouncing) then you know that your springs and shock absorbers are not in sync. To elaborate, when you hit a bump, you want to see your car have two reactions:
First, the car should absorb the impact of the bump. The distance that your car moves vertically is directly related to the stiffness of your suspension, your speed, and the trajectory of the bump. At high speeds it's easy to leap off the pavement if your springs and shocks are not soft enough. Remember that a tire that is not in contact with the road is not affording you any stability, acceleration, or deceleration.
Once your suspension fully absorbs the bump, its second reaction works to reestablish your car’s ride height to its prior level. This is where shock rebound comes into play. If your shocks are too soft or too hard the car will bounce. Bouncing is never ideal because it can cause inconsistent responses from your car's suspension. If your car reaches another bump before it has settled from the prior one, your suspension geometry will be different and you may not be prepared to react sufficiently to maintain control. This is what we are trying to avoid by tuning a car for ride compliance.
I have an M5. Here are its suspension settings:
Component: front/rear
Spring Rate: 11.8/13.6
Shock Bound: 8/9
Shock Rebound: 8/9
I use this tuning at the Nurburging but consider it to be a blanket setting for all tracks in the game. I’m not claiming that these settings will make the car easy to drive; the inherent dynamics of any BMW require surgical accuracy to keep the car on the road at high speed. What I will claim however is that these shock and spring settings will give you an excellent compromise between compliance and cornering grip regardless of tire type, horsepower, or additional (but evenly distributed) downforce. I do use a custom limited-slip differential to stabilize the car during throttle liftoff and braking, but that conversation is for another day.
Spring Rate
The M5 is heavy, but fast. Its weight commands increased spring rates, but its ability to generate higher speeds mostly negates any benefit in doing so because you don't want to fly off the road. I use its spring rate as a benchmark when setting springs on other cars in the game, though I do take into account other vehicles’ differences in weight and speed. If another vehicle is lighter or heavier, I will decrease or increase the spring rate at the same percentage as the ratio between the two cars’ weights. If another vehicle is slower or faster, I would adjust the spring rate accordingly to achieve a compliant ride at top speed.
Weight Distribution
Because the Bimmer has a near 50%/50% weight distribution you’ll see that I set the front and rear suspension settings very similarly. From there, any difference is due to suspension geometry. If it were a front wheel drive, mid, or rear engine car I would adjust the ratio between front and rear spring rates to account for the difference in weight over each axle. In most cases this is 60%/40% or 40%/60%.
I hope that this guide has been quick, concise, and that you've learned or reaffirmed some of the wisdom included. Feedback is appreciated.
Cheers
Check out my Gran Turismo Tuning Guide App for the iPhone at http://www.gttuningguide.com
An Introduction
In my opinion the absolute fastest racing suspension is not necessarily the stiffest, but the most compliant. By compliant I mean that the suspension fully absorbs the impact of any bump at any speed in order to keep all tires in contact with the road. Doing so minimizes undesired momentum that can cause you to lose control.
Ride Compliance
The best way to figure out if you’ve nailed the most compliant suspension settings for any given car is by watching the way it bounds over bumps. If you can see or feel that the car is reacting multiple times per bump (bouncing) then you know that your springs and shock absorbers are not in sync. To elaborate, when you hit a bump, you want to see your car have two reactions:
First, the car should absorb the impact of the bump. The distance that your car moves vertically is directly related to the stiffness of your suspension, your speed, and the trajectory of the bump. At high speeds it's easy to leap off the pavement if your springs and shocks are not soft enough. Remember that a tire that is not in contact with the road is not affording you any stability, acceleration, or deceleration.
Once your suspension fully absorbs the bump, its second reaction works to reestablish your car’s ride height to its prior level. This is where shock rebound comes into play. If your shocks are too soft or too hard the car will bounce. Bouncing is never ideal because it can cause inconsistent responses from your car's suspension. If your car reaches another bump before it has settled from the prior one, your suspension geometry will be different and you may not be prepared to react sufficiently to maintain control. This is what we are trying to avoid by tuning a car for ride compliance.
I have an M5. Here are its suspension settings:
Component: front/rear
Spring Rate: 11.8/13.6
Shock Bound: 8/9
Shock Rebound: 8/9
I use this tuning at the Nurburging but consider it to be a blanket setting for all tracks in the game. I’m not claiming that these settings will make the car easy to drive; the inherent dynamics of any BMW require surgical accuracy to keep the car on the road at high speed. What I will claim however is that these shock and spring settings will give you an excellent compromise between compliance and cornering grip regardless of tire type, horsepower, or additional (but evenly distributed) downforce. I do use a custom limited-slip differential to stabilize the car during throttle liftoff and braking, but that conversation is for another day.
Spring Rate
The M5 is heavy, but fast. Its weight commands increased spring rates, but its ability to generate higher speeds mostly negates any benefit in doing so because you don't want to fly off the road. I use its spring rate as a benchmark when setting springs on other cars in the game, though I do take into account other vehicles’ differences in weight and speed. If another vehicle is lighter or heavier, I will decrease or increase the spring rate at the same percentage as the ratio between the two cars’ weights. If another vehicle is slower or faster, I would adjust the spring rate accordingly to achieve a compliant ride at top speed.
Weight Distribution
Because the Bimmer has a near 50%/50% weight distribution you’ll see that I set the front and rear suspension settings very similarly. From there, any difference is due to suspension geometry. If it were a front wheel drive, mid, or rear engine car I would adjust the ratio between front and rear spring rates to account for the difference in weight over each axle. In most cases this is 60%/40% or 40%/60%.
I hope that this guide has been quick, concise, and that you've learned or reaffirmed some of the wisdom included. Feedback is appreciated.
Cheers
Check out my Gran Turismo Tuning Guide App for the iPhone at http://www.gttuningguide.com
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In GT4, it's possible to make a car bottom-out (hence all the sparks when rolling over bumps and rumble strips) but there is barely as much of a speed penalty in this game like there was in the original GT. 
) because that's what I've been known as for many years on and offline. 
