Wheels Poking Through My Car's Body

[XSquareStickIt]

Hi all. Recently, I've been devoting a large amount of time to tuning a 1985 Mazda RX-7 GT Limited (FC) in preparation for the Japanese 80s Seasonal Event. However, when I took my car to the Mt. Aso race, this happened.

As you can see, the front left tyre has penetrated the body of the car. While the game does not give you any ill effects such as... oh I dunno, shredded tyres and busted bodies, I play Gran Turismo for it's realism, so I sought to tune my car at the Nurburgring to eliminate this problem.

Of course, since the event has a 420 PP and Comfort Soft tyres cap, I have to make sure my car doesn't exceed those performance limits. I used the Carousel as a reference point in trying to eliminate this problem, since the elevation change and the time said change takes place is insane. I figure, if I could prevent the wheels from hitting the body upon hard braking into the corner, I should be safe everywhere else.

My car already has 418 PP when I first brought it to the Seasonal Event. I beefed up the engine output via removable parts such as racing air filters and cat converters. I had not performed any non undo-able parts. And as such, the mass of the car is at it's stock 1280KG. The final power was 232 HP, although I have yet to check the torque figures. I'll update it here if anyone deems the torque figure necessary.

I conducted the test overspeeding into the Carousel just as a safety measure. I'd brake a little too late, such that my car shoots out of the embankment of the Carousel, but not hitting the guardrail. I have almost succeeded in not allowing the tyre to hit the car's body, although in doing so, I've ran into a new problem.

Said problem is my car being WAY too hard for handling's sake. It's still driveable on a high speed circuit like the Nurburgring where the Gs are huge, but I'm pretty sure it's just going to piss me off at Tsukuba where it's just hairpin after hairpin. Anyway, here's a quick overview of my parts settings for my FC:

Ride Height Adjustment (F/R): 0/-1mm
Spring Rate (F/R): 4.8/5.3 KG/mm
Dampers (Extension) (F/R): 1/7
Dampers (Compression) (F/R): 7/2
Anti-Roll Bars (F/R): 7/4
Camber Angle (F/R): 0.2/0.2
Toe Angle (F/R): 0/0.21

Brake Balance (F/R): 8/8
Power: 232 HP
Mass: 1280 KG
PP: 418

Aside from a few other tranny mods not worth mentioning, everything else is stock. With these settings, I braked for the Carousel at 137KM/h (around 91MPH), and the tyre was barely touching the body, but still touching nevertheless.

Like I said, I find that this suspension setup is way too hard, even for the Nurburgring, resulting in a very numb feeling. When braking for the Aremberg turn for example, I could hardly feel anything from my Dualshock controller. I have a feeling I'm doing this completely wrong. Is stiffening the suspension not the way to go? Or am I not doing it enough? Or is the whole "tyres through the body" a graphical glitch? I've tried the same experiment with the car in it's stock form, and there was no such problem. I don't even think I've increased the power THAT much. All in all, I'm just really confused and I would appreciate it a lot if someone could point of what I'm doing wrong, if I'm doing anything wrong at all. Thanks in advance.

For reference, here's the ground clearance of my FC, vs a 1998 FD with the exact same weight, but more power at over 280 HP and Sports Hard tyres:

RX-7 Type RS Stock Suspension settings:

Spring Rate (F/R): 4.8/3.6 KG/mm
Dampers (Extension) (F/R): 1/1
Dampers (Compression) (F/R): 1/1
Anti Roll Bars (F/R): 1/1
Camber Angle (F/R): 0/0
Toe Angle (F/R): 0/0.20

 

[Rotary Junkie]

I'd actually consider that setup to be more than a bit on the soft side and quite a bit low on camber.

The softer your suspension is, generally speaking, the more camber angle you need.

Ride Height Adjustment (F/R): 0/0mm
Spring Rate (F/R): 10.5/10.5 KG/mm
Dampers (Extension) (F/R): 9/9
Dampers (Compression) (F/R): 6/6
Anti-Roll Bars (F/R): 3/2
Camber Angle (F/R): 1.6/1.4
Toe Angle (F/R): -0.05/0.21

Try using that as a basis, I can't guarantee it'll feel good straight off but report back with what it does right/wrong and I'll suggest changes to try, report back, etc etc and we'll get it behaving properly.

 

[DigitalBaka]

RJ "phoning in" a tune for a rotary...nice.

My two cents would have been to raise it up a couple clicks and tweak your original tune but I will let the master work.

Does it do this on the stock suspension by the way?

 

[HaylRayzor]

Worst Ive seen for this is the corvette grand sport.

 

[VTiRoj]

Personally I think you shouldn't pay too much attention to it happening in-game and get yourself a decent image editing program.



This is also known as the lazy way to solve the problem.

 

[XSquareStickIt]

I'd actually consider that setup to be more than a bit on the soft side and quite a bit low on camber.

The softer your suspension is, generally speaking, the more camber angle you need.

Ride Height Adjustment (F/R): 0/0mm
Spring Rate (F/R): 10.5/10.5 KG/mm
Dampers (Extension) (F/R): 9/9
Dampers (Compression) (F/R): 6/6
Anti-Roll Bars (F/R): 3/2
Camber Angle (F/R): 1.6/1.4
Toe Angle (F/R): -0.05/0.21

Try using that as a basis, I can't guarantee it'll feel good straight off but report back with what it does right/wrong and I'll suggest changes to try, report back, etc etc and we'll get it behaving properly.

To be honest, when I saw that setup, I thought you either didn't see the "Comfort Soft" tyres part, or you were crazy. I thought there was no way such a race car like setup would work on a car with Comfort Tyres. Regardless, I tried your setup, and when I dove into the first corner, I went:

http://i82.photobucket.com/albums/j266/the_showstopper_2006/*****.jpg

Now, admittedly I know nothing about tuning cars. I thought that only cars on racing tyres or the like could use a suspension setup so hard, hence why I was so reluctant to stiffen my suspension on my FC, especially considering the FD has higher grip tyres, and what little reviews I could find for it criticised it for almost being too hard for the mountain roads. But the setup you suggested worked brilliantly: not only did it solve the original problem of the wheels hitting the body, but it was almost surgical knife sharp. The speed that I braked for the Carousel rose from 137 to 140 KM/h as well.

My only slight complaint is that the rear breaks out a bit too much on hard braking into a corner. Given that the 1985 FC has a weight distribution of 55/45 F/R, I lowered the rear a little in my original setup to put more weight on the rear and make it more responsive. And, for some reason, the car was a bit prone to understeer as well on corner exit. Not to mention, I wish I could lower the thing more: it's Centre of Gravity felt pretty atrocious for a Rotary.

I think I ought to mention as well that in both cases, I've tried to keep the LSD as inactive as I can. Initial torque is set to the maximum of 60, and both sensitivities have been set to their minimum of 5. This is probably not a very smart move on my part, but as I've said, I'm quite new to tuning, so any advice is greatly appreciated.

Either way, my lap time for the Nurburgring Nordschleife was 8:38.6 with no assists other than ABS. I didn't drive that well to be honest. But I wanted to get back to you as soon as possible, so I didn't give it a second go.

My two cents would have been to raise it up a couple clicks and tweak your original tune but I will let the master work.

Does it do this on the stock suspension by the way?

Yeah, I did consider raising the car to counteract this. But raising a car is morally wrong in my books, not to mention, I think the FC is already pretty high off the ground on it's own. And, no, the car does not have that problem in stock trim.

 

[Rotary Junkie]

To be honest, when I saw that setup, I thought you either didn't see the "Comfort Soft" tyres part, or you were crazy. I thought there was no way such a race car like setup would work on a car with Comfort Tyres. Regardless, I tried your setup, and when I dove into the first corner, I went:

I read it, but I'm definitely a bit nuts.

Now, admittedly I know nothing about tuning cars. I thought that only cars on racing tyres or the like could use a suspension setup so hard, hence why I was so reluctant to stiffen my suspension on my FC, especially considering the FD has higher grip tyres, and what little reviews I could find for it criticised it for almost being too hard for the mountain roads. But the setup you suggested worked brilliantly: not only did it solve the original problem of the wheels hitting the body, but it was almost surgical knife sharp. The speed that I braked for the Carousel rose from 137 to 140 KM/h as well.

I've found that you can run almost ridiculously stiff spring rates if you tune the dampers correctly and keep anti-roll bar stiffness down; a softer setup will usually be a bit easier on tires but might not deliver quite the same grip (more roll = needs more camber = less straight line traction).

My only slight complaint is that the rear breaks out a bit too much on hard braking into a corner. Given that the 1985 FC has a weight distribution of 55/45 F/R, I lowered the rear a little in my original setup to put more weight on the rear and make it more responsive. And, for some reason, the car was a bit prone to understeer as well on corner exit. Not to mention, I wish I could lower the thing more: it's Centre of Gravity felt pretty atrocious for a Rotary.

You probably can lower it a bit while avoiding the issue you started the thread about thanks to how much stiffer it now is; it's worth a try at least. I'll get to both of your issues in a second though, I think I see where the problem with the two are.

I think I ought to mention as well that in both cases, I've tried to keep the LSD as inactive as I can. Initial torque is set to the maximum of 60, and both sensitivities have been set to their minimum of 5. This is probably not a very smart move on my part, but as I've said, I'm quite new to tuning, so any advice is greatly appreciated.

7/35/5. If it's too loose on exit, drop to 30, then 25, etc. Too loose on entry, increase decel to 10/15/20 etc. In fact, experiment around with a lower IT and just toy with accel/decel values until you find something that feels right.

Yeah, I did consider raising the car to counteract this. But raising a car is morally wrong in my books, not to mention, I think the FC is already pretty high off the ground on it's own. And, no, the car does not have that problem in stock trim.

Well, in completely stock form, the car sits higher than it does with FC suspension, so there's that.

Depending on the car I'll run anywhere from pretty mild spring rates (my FD for example) to extremely stiff (my pre-Spec II NSX was fairly stiff, my touge Evora is extremely stiff), just going off whatever feels best... Same for ride height. Even in GT4 the FD never liked being low (in fact I got my best results with 135/135mm ride heights, the same as the very slightly adjustable stock suspension for the Spirit R used) or being particularly stiff. FC on the other hand seemed to like quite a bit stiffer spring rates and a bit of a drop.

 

[XSquareStickIt]

I read it, but I'm definitely a bit nuts.

I've found that you can run almost ridiculously stiff spring rates if you tune the dampers correctly and keep anti-roll bar stiffness down; a softer setup will usually be a bit easier on tires but might not deliver quite the same grip (more roll = needs more camber = less straight line traction).

I see your point. The thing is, I'm under the impression that the FD RX-7 was a completely no compromise sports car, and hence it's suspension is as hard as it should and could be. Of course, since I'm still new to tuning, I was pretty impressionable and thought that a spring rate in the 4 KG/mm territory was hard as balls. And when I compared the spring rates of other RWD cars with around the same mass (like the NSX or MR-2 for example), I was led to believe the FD had the hardest spring rates advisable.

How well does a car with springs as stiff as you suggested for my FC perform in the rain? I've yet to be able to test it in the rain, although it wasn't in my list of requirements when I started this thread. I'm just curious.

7/35/5. If it's too loose on exit, drop to 30, then 25, etc. Too loose on entry, increase decel to 10/15/20 etc. In fact, experiment around with a lower IT and just toy with accel/decel values until you find something that feels right.

Thanks! I'll give it a try when I have the opportunity to. I'll keep you posted.

Well, in completely stock form, the car sits higher than it does with FC suspension, so there's that.

I'm afraid I don't get what you're trying to say here. Could you please elaborate further?

the FD never liked being low (in fact I got my best results with 135/135mm ride heights, the same as the very slightly adjustable stock suspension for the Spirit R used) or being particularly stiff. FC on the other hand seemed to like quite a bit stiffer spring rates and a bit of a drop.

I'm afraid I don't understand this either. I was under the impression that the lower a car is, the better it performs, unless you're not getting enough stroke in your suspension and any more stroke would cause the body of the car to hit the ground. That said, what is the FD's stock ground clearance, and is there a way to check for it in GT5?

 

[Rotary Junkie]

I see your point. The thing is, I'm under the impression that the FD RX-7 was a completely no compromise sports car, and hence it's suspension is as hard as it should and could be. Of course, since I'm still new to tuning, I was pretty impressionable and thought that a spring rate in the 4 KG/mm territory was hard as balls. And when I compared the spring rates of other RWD cars with around the same mass (like the NSX or MR-2 for example), I was led to believe the FD had the hardest spring rates advisable.

Well, the NSX Type R would like a word. The FD is likely about as stiff as you'd ever want to go for having a car be moderately comfortable in daily driving, but for track performance it could stand to be a bit stiffer.

How well does a car with springs as stiff as you suggested for my FC perform in the rain? I've yet to be able to test it in the rain, although it wasn't in my list of requirements when I started this thread. I'm just curious.

I couldn't say good/bad/ugly. Wet traction in a RWD car absolutely sucks unless you're on rain tires but that's pretty much regardless of setup. If planning to run in the rain I'd suggest lowering camber values and possibly raising the rear ride height 5-15mm (GT5 is more than slightly odd with ride height vs traction, rear ride height seems to decide traction).

I'm afraid I don't get what you're trying to say here. Could you please elaborate further?

Take a picture of a car with the factory suspension. Then take one at the same angle with the fully customizable suspension. "0" ride height, for whatever reason, simply means "default" rather than "stock", and default is lower than stock.

I'm afraid I don't understand this either. I was under the impression that the lower a car is, the better it performs, unless you're not getting enough stroke in your suspension and any more stroke would cause the body of the car to hit the ground. That said, what is the FD's stock ground clearance, and is there a way to check for it in GT5?

Generally speaking, lower is better... In the real world. GT5 has some peculiarities with ride height meaning it's not always true (though I've found a few cars that actually do like being slammed), GT4 may have. What I was trying to say was mostly that different cars need/want different things; the FD seemingly prefers a more mild setup to the FC.

 

[DigitalBaka]

Well, in completely stock form, the car sits higher than it does with FC suspension, so there's that.

I'm afraid I don't get what you're trying to say here. Could you please elaborate further?

Take a picture of a car with the factory suspension. Then take one at the same angle with the fully customizable suspension. "0" ride height, for whatever reason, simply means "default" rather than "stock", and default is lower than stock.

Basically, "0" on the fully adjustable suspension is lower than "0" on the default. I would assume it varies from car to car but once I have noticed have been probably in the neighborhood of a 20 "tick" difference....whatever 20 measures in PD-land. You'll notice it in bumper cam view and from outside the car. If you can get two side by side that should prove it pretty well.