Does anyone know the approximate center of gravity of a Crossfire?

By that, I mean the point between the 2 jacking point receptacles on each frame rail at which point the car will be in balance.

I am looking at building a lift for my Crossfire, based somewhat on the example by Viny B (DIY Car Jack/Car Lift) on his youtube channel.
One of the key points on his design is that his vehicle will pivot just by moving it with his hands, so it goes nose-down on the floor, resting on the front tires, which leaves the fuel tank area at a height of about 50"off the floor. Or it will lift the nose and put the car's butt on the floor, with the front of the car about 50" off the floor. The level of fuel would have very little effect on the effort required to tilt the vehicle, if the CG point is carefully located, and the pivot point placed at that spot.
But crucial to this feature is determining accurately the Center of Gravity position of the vehicle. Logically, all the Coupes should be the same, and also all the Convertibles should be the same. I do not know if the SRT-6's have enough weight difference to be investigated or not. My question is, has anyone established what this dimension might be.
My intention is to establish this point, using the forward jackpoint receptable as the datum point, and locating the CG point a particular distance AFT of this point.
The advantages of this lift are tremendous.
Except for a massive weld failure, there is virtually no chance of collapse, as the lift is actuated by Acme screw thread rods. These will transmit lifting force, but even if they are completely released after turning them to a certain height, THEY CANNOT COLLAPSE BECAUSE THEY WILL NOT TRANSMIT FORCE in the reverse direction. They WILL NOT turn by themselves.
Acme screw threads are commonly used on airliners to position the flaps, horizontal stabilizer, etc, because even if the drive mechanism to the Acme shaft is severed or even broken off, the Acme shaft WILL NOT TURN. Thus, as a lift drive, they are perfect. It would not even be necessary to install stops on this lift, although I intend to install a set of locks as a secondary safety feature. (Even in an aircraft crash, with the stupendous crash forces, the Acme threads will NOT shift position at ALL. That is how they confirm flap setting positions after an aircraft accident, by physically looking at the flap drive screws and measuring them.)
I am going down tomorrow to see how much some Acme shafting will cost. I think a 8' length, cut into two 4 ft. pieces, will be adequate to operate the lift. I am also going to check into some angle gearboxes at a surplus place near me, as it is necessary to drive both shafts (one for each siderail lift) at the same time.
(The ides is to make two frame rails, one fitting into the lift points on each side, and then attach the center pivot at the correct point to both lift the car while it is balanced, and also allow the vehicle to be tipped forward or aft for full access to the front or rear end.)
If you watch Viny B's video, you will quickly grasp the concept.
I plan on doing a mockup out of wood first, to check the geometry of movement, and then make parts in steel.
Determining the CG point for a Coupe will be some effort, and I don't want to do it if someone already knows the CG point of the car.
Thanks to anyone who can provide information.

 

My best rough guess would be made using the weight distribution on the front and rear wheels.
Coupe % F/R 54/46
Roadster % F/R 53/47
Distance between wheels is 94.5 inches.
This would assume that the mass between the wheels was constant over 94.5”, which it isn’t.

Make a steel I beam that locates in the front and rear jack points on one side and then jack it up on one side to find at which point on the beam both the front and rear of the car lifted equally would be more accurate, do both sides and compare.

 

Yeah, I thought about doing that, but it seemed like a lot of work. I have worked on aircraft my whole life, and they have very closely defined CG,s that are known, and that can be easily computed, and when you do it on paper, it is exactly correct for the aircraft, and you can actually manipulate the balance point by tenths of an inch. I guess I will have to do the metal beam thing.
What I will probably do is fabricate the lift plates on each side, then jack it up using them, and move the contact point fore and aft until I get the best possible balance point, and then locate the lift point at that spot.
Thanks for the weight distribution figures!. That at least gives me a starting point, and it actually should be pretty close to that, based on how completely engineered modern cars are today.
I had thought about going ahead with the lift assembly driven by Acme screws, but I really want to complete the services on the car in the next week or so. I have two sets of ramps, so will just jack up each end, put it on a set of ramps, and then jack up the other end and put it on ramps, and do my work. Then take it down.
The lift can wait until I have more time this fall.
I am machining a jack point adapter out of aluminum, that fits the top of my hydraulic jack, and also fits the receptacle on the car side rails. I only have to make one piece for that to work just fine.

 

To get a little more technical you are in actuality I believe trying to locate the center of mass in the horizontal plane of the car. Using cartesian coordinates the horizontal center of mass would be somewhere at a point within the X & Y axis (X= length, Y= width). This is a plane that is parallel to the floor. The CG of the car would have to also include the center of mass in the vertical Z axis. Once the CG has been established the vehicle could then be revolved perfectly balanced about this single point in any direction.

 

You are correct. However, I really only want to find the point at which the car will pivot end-to-end, as in the "DIY Car Jack/Car Lift" video by Viny B on Youtube. I will not actually be making any attempt to rotate the vehicle horizontally around this axis, as the vehicle will actually be supported on the two body side rails, with the supports actually mounted on a hinged central point located at the to-be-established CG point, that crosses the vehicle from side to side on this CG centerline; Since I have a way of lifting the car now, using 2 sets of ramps to support it, this fulfills my need to complete the servicing of the car prior to my long car trip in June and July. I will re-visit this project when I get home from that trip.
I am also trying to locate two angle-drive 5:1 speed reducers, which will be used to drive the Acme threaded rods that lift and lower the vehicle, from a single driving point at one side of the car. Using the angle drives and the Acme threaded rods, a hand-drill can be placed on the drive, and spun to raise and lower the vehicle. After it is raised, my intention is to have safety lock bars that can be installed to prevent inadvertent descent due to weld failure. The Acme screw threads, even if something breaks or is disconnected, will NOT turn by themselves no matter what. (In fact, a separation of the drive would actually leave the problem of trying to get the car OFF the lift, as it is necessary to rotate both Acme drives at the same time to lower the lift.)

 

Here is how my 04 Coupe scaled out at last year before major modifications. Disclaimer here is that it was riding on SRT6 springs and had SRT6 brakes. The rest of the car was fairly close to stock, as far as weights go. The brakes would not materially change the way it scaled (perhaps by a few pounds at each corner for the bigger rotors). If I was to guess, probably 20# total for the car. Springs could change the corner weights, but not materially change the overall weight of the car. One of these days we'll put one of the dead stock cars onto the scales.

 

Thanks for the input! I will add it to my data stash!.

My current plan is to fabricate the lifting rails for each side, and then place the car on ramps at all 4 wheels, put the lifting rails in place, and then lift the car about an inch or so, via the lifting rails. I plan to put the lifting point at the spot I have calculated out, and see if the car is stable at that point. It shouldn't take long through trial and error to find out exactly where the lift points should actually be attached. I might have to move 1" one way or the other, but it should be pretty close. Once the perfect point is established, the lift rails and lift trunnion goes to the weld shop for final attachment. Then a practical test to make sure everything works. Assuming it works out, I will post information on here, so anyone can build their own verson.