Quote:
Originally Posted by funf
Hello,
First of all, let me introduce myself as I have only recently joined this forum. My name is Stuart and I am in England living in a ill age called Olveston which is just north of Bristol. Last year I bought a 1930 two door Tudor with the large engine, left hand drive. And was originally registered in Denmark so it has it's speedometer and odometer in kilometres. I have had to do some re-commissioning work on the car but am very pleased with it and really enjoy driving it.
But I would like to tap into the huge knowledge base here at the Barn; It has been accepted wisdom ( at least over here) that all cars have the maximum braking effort on the front axle, what with the weight of the engine over the axle (considerable for a model A) and the forward weight shift as cars decelerate, dictates that in the order of 75% of braking is done by the front wheels. The weight clamping the tyres to the road thus allowing a lot of braking effort.
However with A's, all the wisdom I can find tells owners to adjust the brakes so that the rear brakes come on first and that the fronts should only start to work when the reas are at or near maximum effort. (as per the books by Les Andrews).
So my should A owners not adjust the brakes to favour the fronts?
Be gentle with me!
Stuart
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Even on a modern car, the rear brakes engage first, then the fronts. This sets up a balance effect. The bias changes from rear to front very early in braking, so early, you will not notice it. It is done by different size wheel cylinders and load sharing spring inside the master cylinder. Of course this cylinder ratio thing means nothing on a stock model A with its mechanical brakes.
The ratios are set up on the model A brakes by changing the angle of spread through out the travel of the operating cams inside the brake drums. The change causes the fronts to be applied slightly quicker than the rears as the pedal is pushed down, so when the rears engage first, the fronts will apply slightly later, but then increase pressure quicker and then pass the rears as the pedal gets pushed down further. This is also why it is very important to follow the service bulletins when adjusting brakes. When done correctly, your brakes will be excellent for a car eighty years old.