An Easier Winter - Front Suspension Modification

 As I am still exhausted from swapping the RX8 engine and transmission into BB, I chose a much simpler project for this winter: improving the front suspension.  The plan is to raise the roll center, add adjustable, negative camber, and convert to adjustable coil overs.  I'll also add an air dam which will likely only have cosmetic benefit but maybe it will make me faster because I'll feel faster!

Let's start with roll centers.  As a teenage Road and Track reader and would be tuner, it was clear: Lower the car until the rocker panels touch the street and then raise 1/4" for best cornering.  As usual in engineering this is only half of the truth.  Low Center of Gravity is great for reducing weight transfer in turns, thereby letting the inside tires continue to do some work.  However, if you only lower the car, you also change the roll center.  The roll center is a function of the angle of all the links in the suspension but the dominant variable is the angle of the lower A-arm in an MGB.  If one lowers the ride height by an inch, the roll center drops by around 2 inches, due to the steep angles in the triangles formed by the links.  So, you have lowered the CoG by an inch but the torque that rolls the car when cornering has increased its advantage by two inches.  You can see the angles involved here:

So flat lower A-arms lead to a roll center just above the ground.  When one lowers the car, it sinks below the ground.  The next time you are following an SUV down the highway, look at the rear A-arms.  They likely look like this:

Since an SUV has a naturally high CoG, the roll center must be raised to reduce roll-over moment so the A-arms slope downwards.  Rolling over in BB is not really possible without assistance from dyno mite or a steep hill but the physics are the same!

The next area which needs brought up to code (meaning modern tech) is the camber.  Camber is the angle of the wheel to the road.  For aggressive cornering, at least a few degrees of negative camber (top of the wheels sloped in toward the body) is needed.  Like a Model T which could be had in any color as long as it was black, an MG comes with a wide range of camber options as long as they are zero degrees!  I think I need more.  Maybe not this much but more:

So, I will be designing and fabricating a set of three brackets for the front suspension.  These will hold coil-overs with adjustable damping, replacing the venerable lever shocks and allowing damping adjustment.  As always, this won't bring perfection but BB and I will learn a lot and will get, hopefully in contrast to last season, a bit faster!

Thanks for reading and keep having #funwithcars !