You're correct with both of your comments.redandwhitE wrote: ↑Fri Jul 31, 2020 10:53 pmForgive the ignorance but for my edification: the front brace is across the top of the suspension (under bonnet) and the anti roll bar is somewhere under the engine across the 'axle'?
I know it's not an axle but the word suits my purpose and you hardly hear it these days so felt it needed resurrecting!!
A body brace tries to keep 2 parts body the same distance apart of putting a strut between them. In this case it's the 2 front damper top mounts which, on a Macphereson strut front suspension such as R8 and R3 (but not HH-R), has a major controlling affect on the camber (the in/out lean) of the wheels.
The best design of any strut is straight but unfortunately most enginebay struts have to be cranked slightly to miss the engine.
An anti roll bar (or ARB) is basically a torsion bar between suspension members on the the two sides of the car. Your car can have none, one (usually at the front) or 2 - one front, one rear. They join a suspension member on one side of the car to the same one on the otherside. They are usually cranked to miss the big bits inbetween.
They are used to redistribute the vertical load between the more heavily loaded outer wheel and the less loaded inner wheel during cornering and are basically used to 'trim' the under/over- steer balance of the car.
As the name, suggests the effect is to reduce body-roll which has the beneficial affect of keeping the roadwheels more upright and improving their limit of grip.
The downside is that they make an independent suspension system less independent, as what's happening at one side affects the other. Basically, if the wheel at one side of the car hits a bump or pothole that wheel is less free to move to cushion the input due to the higher combined spring-rate of the road-spring plus the ARB.
If you want your car to understeer less you put an ARB on the front, or increase the stiffness of the one already there. This is usually done by increasing its diameter.
For interest, most R3s don't have a separate RARB as the rear suspension's H-frame performs that function. The cross-section acts as a torsion bar between the two trailing arms and the thicker of the two Maestro/Montego sections was chosen as it has the desired stiffness characteristics. It was the one from the Montego Estate.