Weight balance on early C3s
12-23-2008, 02:36 PM
#21
Pro
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Well... no. There isn't going to be that much of a difference.
So lets say the SB car is 3300 lbs, and has 50/50 distribution (I'm not claiming this is true, just using it as an example). That's 1650 front and 1650 rear. If a BB weighs 400lbs more (which I don't think is true, 400 lbs is a lot) and we put all of that weight on the front wheels (which again is not true, because the engine is primarily behind the front wheels - as a result some of that weight will go to the rear wheels) we are at 2050 and 1650 front and rear.
That's 55/45, and this is worst case. So there isn't too much of a difference between BB and SB in weight distribution.
So lets say the SB car is 3300 lbs, and has 50/50 distribution (I'm not claiming this is true, just using it as an example). That's 1650 front and 1650 rear. If a BB weighs 400lbs more (which I don't think is true, 400 lbs is a lot) and we put all of that weight on the front wheels (which again is not true, because the engine is primarily behind the front wheels - as a result some of that weight will go to the rear wheels) we are at 2050 and 1650 front and rear.
That's 55/45, and this is worst case. So there isn't too much of a difference between BB and SB in weight distribution.
12-24-2008, 06:02 AM
#24
Safety Car
What is the weight transfer to change the balance?
In the early 90s I set up a 70 Mach 1 w/a 351 Cleveland built to the 1970s Nascar specs,and set the car up to the 69/70 Bud Moore Boss 302 specs.The Mustang was/is 54% front,and 46 rear.For every 80lbs added to the rear of the car,the number rose a point for the rear,thus subtracting a point from the frontend.We hung ballast on the frame rails in the back on each corner,but only 160lbs to bring the car to 52/48.
The car handled great,but it is hard to compare it to my other stangs,cause this was a completely different setup,and feel.It was also,lowered per Boss Trans Am series specs.
I will say this tho'....being a Mustang guy for along time(still have them)..a stock C3 rides/handles in comparison to a modified Stang w/better front springs,and sway bars,so we are already ahead of the game.Plus,we have full frames that eleminates the frame/body flexing.
In the early 90s I set up a 70 Mach 1 w/a 351 Cleveland built to the 1970s Nascar specs,and set the car up to the 69/70 Bud Moore Boss 302 specs.The Mustang was/is 54% front,and 46 rear.For every 80lbs added to the rear of the car,the number rose a point for the rear,thus subtracting a point from the frontend.We hung ballast on the frame rails in the back on each corner,but only 160lbs to bring the car to 52/48.
The car handled great,but it is hard to compare it to my other stangs,cause this was a completely different setup,and feel.It was also,lowered per Boss Trans Am series specs.
I will say this tho'....being a Mustang guy for along time(still have them)..a stock C3 rides/handles in comparison to a modified Stang w/better front springs,and sway bars,so we are already ahead of the game.Plus,we have full frames that eleminates the frame/body flexing.
12-24-2008, 08:42 AM
#25
Team Owner
The four corner scales is the only way to go. From working on road racing machines I have learned that it it is very desirable to have rear heavy bias. More bite on the rear.
If you want to look at extreme machines like F1 they are 34% F and 66% rear. that is static and at speed the big rear wing puts even more on the rear. Porsche 935's adjust the rear wing for the races to just maintain steering on the front at high speed. it might be 10% F and 90% rear. That is why some extreme IMSA type cars suffered blow overs at higher speed tracks. The front end would lift and catch air.
I've only managed to attain 46% front and 54% rear. I'm considering moving my battery behind the passenger rear tire area down low.
If you want to look at extreme machines like F1 they are 34% F and 66% rear. that is static and at speed the big rear wing puts even more on the rear. Porsche 935's adjust the rear wing for the races to just maintain steering on the front at high speed. it might be 10% F and 90% rear. That is why some extreme IMSA type cars suffered blow overs at higher speed tracks. The front end would lift and catch air.
I've only managed to attain 46% front and 54% rear. I'm considering moving my battery behind the passenger rear tire area down low.
12-25-2008, 08:42 AM
#26
Le Mans Master
A completely stock 78's weight distribution is 48% Front and 52% rear which is the reason that C3's with the performance suspension had very small rear sway bars (7/16 in). The close to 50:50 weight distribuiton with a slight rear bias is the reason that many people mention "odd" handling when they push C3's on curves with high horsepower especially with rear sway bars and mention that you should not use a rear bar, which is completely untrue. Any car with high horspower and a 50:50 weight distribution will become more difficult to control IF you don't know what you are doing close to the limit. A front biased car is much easier to control at the limit since it will understeer but a evenly balanced car ultimately is much faster throught turns if driven properly and set up correctly, thus the reason GM installed a rear bar on the performance suspended cars.