Technical weight transfer question for smart guys

[MIKE SCHULZ]

Gentlemen: Simply put:If you put a bicycle on a stand and rotate the tire and put on the brake - the Action of the brake (Caliper) is to move in the direction of the tire while applying friction until the tire stops.In a Car most times I see that the Front calipers are behind the wheel (At the 3 Oclock position as you face the tire).I`d like to think that the manufacturers put these there to "Lift" the front end as the weight transfer shifts forward on braking while tendency for the caliper is to move upwards.Why though do I see some cars have the rear brake calipers at the rear (Same position) as the front?.My Jag calipers are where I would assume they do the most good - At the Front (9 Oclock) position (Looking from the side).I`m interested on some points of view!....I have already been told that an Automotive chassis doesn`t act the same way I picture that Bicycle wheel`s brakes do...But I think simply put - It`s exactly the same....

[mylesdw]

Mike: When the the brake is applied the caliper simply tries to rotate around the spindle. It pushes the upper ball joint forward and the the lower ball joint backward (assuming the car is travelling forward). It makes no difference where on the disc the caliper acts. Where a manufacturer mounts the calipers is probably much more to do with fitting in other stuff like steering arms and handbrake mechanisms etc.

[Big-Foot]

The question you ask does not match the topic, but I see where you are going.

Myles hit the nail on the head.

Typically front calipers are mounted towards the rear for a couple of reasons.
1) Most cars these days are called "Front Steer" cars - this is where the steering arm is - on the front of the spindle/knuckle assembly - There is more room for the caliper at the rear.
2) Placeing the caliper at the rear also allows the opening of the caliper to face forward where it can take a little more advantage of cooling air - although most backing plates will manage the air regardless.

Rear calipers - When you see right side calipers mounted in the 2 O'Clock position and the Left side calipers mounted in the 10 O'Clock position, it's usually because the manufacturer is getting away with one caliper casting to service both sides of the car - thereby putting the bleeder valve at the top of the chamber.

If you want to really get into the science (almost black art) of chassis forces in braking, take a look at Dirt Late Model braking technology (Stock Cars). I have worked on many of these that use a floating brake caliper bracket on the differential that has another link that joins to the chassis from the caliper. This will take the rotational force you have noted and impart it directly to the chassis via a link. They are a booger to get set up right..