Problem with Suspension and Tranny on 0-400m Runs

[darkwind]

I was toying around with my Viper GTS, trying to get it below it's already record time(for me) of 0'08.856 when I came acrossed something puzzling. Whenever I put in the Racing Suspension or the Full-Customize Tranny, my time went from 8.856, to 8.9-9.3s. It may be a conflict between weight balancing and the suspension and tranny, but I don't think thats it.

Anyway, heres the setup for my fastest time. If anyone can take a look into this and/or explain the problem, that would be a great help.

Exhaust: Racing
Racing Chip: Yes
NA Tuning: Stage 3
Tire: Racing Super-Softs
Nitrous: 50
Clutch: Triple-Plate
Flywheel: Racing
Carbon Driveshaft: Yes
Driving Aids: TCS-2
ASM- 0/0
Downforce: 30/30
Weight Ballance: Ballast- 96
F/R Balance- 50

Suspension and Transmission are Standard.

 

[djaft3rb3ats]

it maybe that ur too low and that ur bottoming out, also, orignal suspension takes away shock bound and rebound, so that may pose an issue too. ur ballact is 96 back..u need some major hard ass suspension in the back, or just take it off, and like duck said, u need like 20-30 mm higher in the back for chassis downforce, try that and maybe ull improve ur laptimes. post it whe u do



djaft3rb3ats

 

[doormeister]

Try 1)setting your front springs all the way left (soft)
2) Front rebound to 1
3) rear springs full right (hard)
4) rear bound 10

I'm not saying it will work. Just try it. I would like to hear what it does to your times.

Also, you might try backing off on your down force. I'm not sure why you are using it. Just asking you to try it an let us know what it does.

 

[darkwind]

It's seems that so far only FR cars, ok only the Viper as far as I know, suffer from the racing suspension. I ran a 9.6 with a Ford RS200 with a semi-racing suspension and I got the Mines Skyline to do a 9.056 with everything on it including the racing suspension and full custom tranny, both essentially are set up about the same as the Viper. Anyway, I tested the set up you suggested and here are my times:

With Downforce:
0'08.776

Without Downforce:
0'08.822 - Major tire spin

+30 in the back with best time from above runs:
0'08.769

Best setup + just installing the FC Tranny:
0'08.958

If I keep the car at the suspensions normal height of 113, the times are faster than lowering the car. I could always do what I did with the ballast. I added 5 to the ballast until it start to hinder the run, then went back 5 and added 1 until I got the most help out of the ballast.

I'm still not sure about putting in the Tranny. I've run several setups of the tranny and short of adjusting the individual gears, I can't get it any faster. Maybe if I kept it at auto 13 and adjusted the final?

I'm going to try and get the RS200 below 9.5 later, but once I get a final setup for the Viper, my next project is a BUICK Special. It shouldn't be to hard to get mid-low 9s. It runs a '10.120 without nitrous and no tuning to any of the parts.

EDIT:for all the runs, I set front/rear camber to 0.0 and set rear toe to +4

EDIT EDIT: making the front toe -4 seemed to help lower my time with the buick so I'm gunna go see how it affects the Viper.

Yep, it does help. The Vipers new best time is '08.752

 

[Eric.]

It's seems that so far only FR cars, ok only the Viper as far as I know, suffer from the racing suspension. I ran a 9.6 with a Ford RS200 with a semi-racing suspension and I got the Mines Skyline to do a 9.056 with everything on it including the racing suspension and full custom tranny, both essentially are set up about the same as the Viper. Anyway, I tested the set up you suggested and here are my times:

With Downforce:
0'08.776

Without Downforce:
0'08.822 - Major tire spin

+30 in the back with best time from above runs:
0'08.769

Best setup + just installing the FC Tranny:
0'08.958

If I keep the car at the suspensions normal height of 113, the times are faster than lowering the car. I could always do what I did with the ballast. I added 5 to the ballast until it start to hinder the run, then went back 5 and added 1 until I got the most help out of the ballast.

I'm still not sure about putting in the Tranny. I've run several setups of the tranny and short of adjusting the individual gears, I can't get it any faster. Maybe if I kept it at auto 13 and adjusted the final?

I'm going to try and get the RS200 below 9.5 later, but once I get a final setup for the Viper, my next project is a BUICK Special. It shouldn't be to hard to get mid-low 9s. It runs a '10.120 without nitrous and no tuning to any of the parts.

EDIT:for all the runs, I set front/rear camber to 0.0 and set rear toe to +4

EDIT EDIT: making the front toe -4 seemed to help lower my time with the buick so I'm gunna go see how it affects the Viper.

Yep, it does help. The Vipers new best time is '08.752

Now, I'm not very skilled at tuning, but it just seems wrong to have any toe on a 400M setup. You want those tires to have maximum forward grip.

Are you using TCS?

 

[djaft3rb3ats]

make camber back to default and no toe, 20-30 rear ride hieght might help u, then just spam the df, otherwise change gear ratios independently

 

[darkwind]

My Current Setup: 8.752

Default Camber & No Toe: 8.820

No Toe & No Camber: 8.813

Default Camber & Toe: 8.753

Amazingly enough, the toe and the camber provide faster times. When camber is set at 0.0, the tires are perpendicular to the road. Since the 0.0 camber provides the tires with the most area coverage of the road, this allows the tires to get grip faster than the default camber. Toe on the other hand… I can’t explain that. Maybe it’s because the front and back are at opposite ends it provides a better straight line run?

Now, I'm not very skilled at tuning, but it just seems wrong to have any toe on a 400M setup. You want those tires to have maximum forward grip.

Are you using TCS?

Yes, I’m using TCS. Try racing the Viper at full horsepower without it. The car won’t go forward until you hit 4th gear.

New fastest time: 8.633

Modifications made to the setup: Changed TCS from 3 to 5.

Just for extra fun, I ran a max speed test and the results are that this Viper, with this EXACT setup, runs 9.121 without Nitrous, and does 263.49 mph without topping out. I estimate that it'll top out between 265 and 270 mph.

 

[djaft3rb3ats]

My Current Setup: 8.752

Default Camber & No Toe: 8.820

No Toe & No Camber: 8.813

Default Camber & Toe: 8.753

Amazingly enough, the toe and the camber provide faster times. When camber is set at 0.0, the tires are perpendicular to the road. Since the 0.0 camber provides the tires with the most area coverage of the road, this allows the tires to get grip faster than the default camber. Toe on the other hand… I can’t explain that. Maybe it’s because the front and back are at opposite ends it provides a better straight line run?

not really, according to my knowledge, though its perpendicular, its not necessarily the most area on the floor,thats why, like me, i make my camber 2.7/1.3.


maybe its me



djaft3rb3ats

 

[Wild Cobra Z28]

I never tried it, but most likely a Sport Suspension is best for 400 an 1000 meter times. Semi-Racing I doubt is better than Full custiom.

In the real world, the entire suspension geometry is set up differently betweem circuit racing and 1/4 mile racing.

As for your transmission, you want full custom, but you need to reset your gears so you finish the race at your peak power RPM. Chances are for your best times, start in 2nd gear and finish in 5th. Unless you have a real narrow powerband on your engine, this will work best for your transmissions and 400 meter racing:
1) Set the Final Gear ner the right end. Most cars will work all the way right, but I usually go 0.5 away from the end.
2) Set the autoset to 1. If it is already at 1 or 2, mowe it right first, then back to 1.
3) Set the sliders for 2nd all the way left
4) Set the slider for 5th all the way right. If driving a lower powered car and need 1st, set it to the right also.
5) adjust 3rd, 4th, and 6th to make a strait horizontal line at the botton of their appropriate diagonal lines on the graph. May as well set 6th too, you may want to tray racing this way! If you have a scientic calculator, this is easier: divide 2nd gear number into 5th gear number. Find the 3rd root (x^(1/3)) of 5th/2nd 3rd = 2nd divided by root number. 4th = 3rd divided by root number, or 5th times root number. 6th = 5th divided by root number.
6) Once the gears are set, never touch autoset. Only use the final drive ratio for your top speed. In the case of 400 meter, find the point where you finish the race at your peak HP RPM in 5th, or in some cases 6th. As you make other adjustments, it may be optimum to adjust again.

Math Example:

2nd = 2.156
5th = 1.332

2.156/1.332 = 1.618....

3rd root of 1.618..... = 1.1741

3rd = 2.156 / 1.1741 = 1.836

4th = 1.836 / 1.1741 = 1.564

6th = 1.332 / 1.1741 = 1.134

TCS makes a difference. I found normally 6-8 works best for cars above 500HP. Weight over the drive axle often helps too. Set your suspension near or at the max height as well. 1/4 mile racing is entirely different than track racing.

Zero's on camber and toe are optimum in a perfect world, but since there is flex in the real world, -1 is likely best for toe on the drive axle only (or both 4WD.) Now that is of course, if the GT4 simulator addresses that concept... This is not an issue on real 1/4 mile race cars as they have a solid axle and little or no flex!

An untested thought.... camber might actually help on the non-drive tires as it reduces the tire footpring on the tarmac....

Ballast helps times for most cars when placed over the drive axle because it increases the friction between the tire and the tarmac. Finding the magic amount is a trick since at the same time, it reduces your acceleration at non-slip times of the tires. Most cars I testes used between 60 and 120 KG, but I used the full 200 for the TVR Speed 12. I also launched the Speed 12 in 3rd gear rather than 2nd for its best times.

Have fun, good luck....

 

[djaft3rb3ats]

wow mathwhiz, thanks for all that, maybe we'll try it out. thanks


djaft3rb3ats

 

[jmillheiser]

when setting up for drag racing with a RWD car you want to maximize weight transfer to the rear. With my CLK-GTR I was able to get an 8.538 out of it by setting the rear to be a bit higher than the front in ride height but keeping the rear suspension a bit softer than typical. Set the front up to 9 bound and 1 rebound, this effectively replicates the effect of 90:10 shocks that are commonly used on the front of drag cars. Another help is RSS tires, not as good as drag slicks but as close as we can get in GT4.

Keeping the rear as hard as possible is what you do with a FWD drag car. with FWD you want to prevent weight transfer to the rear which is why you still see wheelie bars on FWD drag cars (not to keep it on the ground but to keep the front wheels hooked up).

 

[djaft3rb3ats]

so thats in addition to the higher rear and way low front am i correct, since theres no braing theres no need to fear bottoming out, rite?



djaft3rb3ats