Brake caliper placement versus brake torque effect

[Scott_F]

I hope to get a good technical discussion going on this subject. The following are my current thoughts on the subject, and I would like to see other opinions.

Starting with front suspension (arms or beams), I don't think it matters where the caliper is placed, the torque effect will be the same. It will try to rotate the spindle upright forward. Placement would be based on protection, convenience, airflow, or opposite the steering arm.

Rear suspension is a different story, whether on a 3/4 link, or trailing arms on a buggy. If the caliper is placed to the rear, hard braking would compress the suspension and squat the rear, counteract front end dive due to weight transfer, and keep the chassis more level under hard braking. If it is in the front, the suspension would extend, increasing front end dive. If the caliper is on the top or bottom, the brake torque effect is in line with the arm or link, minimizing the effect on the suspension.

Post up if you agree or disagree with any of this, and tell us what your favorite or preferred caliper position is and why.

[johnnyweb]

i believe you are creating the same rotating force no matter were you put the caliper. i would put it on the back side to protect from rocks and debrie hitting it. that is were it is on my trucks and they work great and i have never damaged them. "yet"

[sickrick]

It does not matter where you place the caliper on the rear axle it will put the same forces on axle links.

What you may be thinking of is when stock car guys hook the brakes to the frame with a seperate strut to get weight transfer under braking. In that case the caliper would be allowed to spin around the axle if it was not for the sturt that transfers the braking load to the frame.

[Scott_F]

OK, maybe I was thinking too hard. What about a buggy trailing arm?

Floating drum brakes used to be common on dirt bike rear brakes, but I have never seen it on an off road car.

[ChuckH]

Some bikes in addition to floating brake arms also had a way to change the shock rebound dampening when you braked, yamaha called it BASS.

MX gave up on it because it really doesn't matter that much, i don't think its needed on a buggy, good theory but not necessary

[Scott_F]

Yeah, I remember how most riders disconnected the BASS. Brake Activated Suspension System.

[sickrick]

Originally Posted by Scott_F

OK, maybe I was thinking too hard. What about a buggy trailing arm?

Floating drum brakes used to be common on dirt bike rear brakes, but I have never seen it on an off road car.

It is the same.

[ibismojo]

you can go mclaren/mercedes forumla 1 style and mount the caliper at the bottom....heh, to bring down the center of gravity

[D.Mavis]

I agree that from a brake torque stand point it doesnt matter where the caliper is placed. From a force point of view in relation to upright strength it does matter, if only a bit. In the front for instance if the caliper is mounted behind the spindle it will unload the spindle during braking. it will tranfer force/ stress from the spindle (usually the weaker portion) to the upright. the direction will counteract the force/ stress on the spindle due to the weight of the vehicle. if the caliper is mounted forward of the spindle it will transfer force in the opposite direction adding it to the stress on the spidle due to the weight of the vehicle. The same goes for the rear. That being said I think its much more important to protect the caliper than to worry too much about the effect its placement has on the stress experienced by the spindle under braking.

[sickrick]

Originally Posted by D.Mavis

I agree that from a brake torque stand point it doesnt matter where the caliper is placed. From a force point of view in relation to upright strength it does matter, if only a bit. In the front for instance if the caliper is mounted behind the spindle it will unload the spindle during braking. it will tranfer force/ stress from the spindle (usually the weaker portion) to the upright. the direction will counteract the force/ stress on the spindle due to the weight of the vehicle. if the caliper is mounted forward of the spindle it will transfer force in the opposite direction adding it to the stress on the spidle due to the weight of the vehicle. The same goes for the rear. That being said I think its much more important to protect the caliper than to worry too much about the effect its placement has on the stress experienced by the spindle under braking.

What? The stress on the spindle varies with caliper placement? I believe you need to rethink this.