I'm building a Group 12 Saloon which has no centre section except for a piano wire spine. I am putting a sliding weight on the spine which will have about 45mm of movement with a damper at each end. The theory behind this is that under acceleration the weight goes towards the back wheels to improve traction. Under braking the weight will move forward to give more weight to the front to keep the guide in the slot. I will experiment with the amount of weight so it won't lift the front or loosen the back end. Well That's the theory.