Position of brake callipers?

[ChevronB19]

Most (all?) cars with discs have the callipers on the front wheels at the rear, but on the back wheels at the front (if you know what I mean).

Is there any reason for this? Something to do with the majority of braking being by the front wheels so it’s a ‘drag’ rather than a ‘push’?

[Lotobear]

..My S2 Elise has the fronts and the rears at the back and my 1968 Elan has exactly the same arrangement so there doesn't seem to be a rule per se (or else Lotus know best).

I think it's perhaps more dictated by things like suspension configuration and available space than what's pure from and engineering perspective but I'm no expert.

[HelldogBE]

ChevronB19 said:

Most (all?) cars with discs have the callipers on the front wheels at the rear, but on the back wheels at the front (if you know what I mean).

Is there any reason for this? Something to do with the majority of braking being by the front wheels so it’s a ‘drag’ rather than a ‘push’?

[anonymous-user]

It's because on most cars the steering rack is low and forward and the engine sits over the top of that rack. With this layout, to get the correct geometry the steering arm on the upright/strut ends up at the front middle and hence the brake caliper has to go at the rearwards side. At the rear, without any steering rack and much freer options for suspension links, the brake caliper can go on front or rear side of the upright. Polar moment and CofG considerations drive towards an "inside" and low arrangement for sporting cars

[Limpet]

Just noticed my i30N has the front calipers mounted forward of the wheel.

It's never occurred to me whether this could even make a difference, and it's certainly beyond my remedial level engineering knowledge as to what that difference might be.

[nismo48]

very informative thankyou..

Max_Torque said:

It's because on most cars the steering rack is low and forward and the engine sits over the top of that rack. With this layout, to get the correct geometry the steering arm on the upright/strut ends up at the front middle and hence the brake caliper has to go at the rearwards side. At the rear, without any steering rack and much freer options for suspension links, the brake caliper can go on front or rear side of the upright. Polar moment and CofG considerations drive towards an "inside" and low arrangement for sporting cars

[InitialDave]

I did once ask someone at Aston Martin why they'd designed a concept car o was looking at with the brake caliper at the bottom of the wheel, as it seemed very odd, and I'd have thought it'd be hard to fit around the suspension optimally.

Turns out it was just a fake caliper permanently attached to the disc, and they'd forgotten to rotate it to the right position after moving the car on the display stand!

[Burgerbob]

I think, generally, FWD cars tend to have the front caliper at the front of the wheel. RWD at the back.

For the rear wheels, calipers tend to be at the back for both FWD and RWD

[The Rotrex Kid]

Burgerbob said:

I think, generally, FWD cars tend to have the front caliper at the front of the wheel. RWD at the back.

For the rear wheels, calipers tend to be at the back for both FWD and RWD

This is what I’d agree with.

I’ve always thought it odd that the front brakes on my car are on the rear of the hub…

[Panamax]

The Rotrex Kid said:

Burgerbob said:

For the rear wheels, calipers tend to be at the back for both FWD and RWD

This is what I’d agree with.

Well, I wouldn't agree.

Look at almost any sports car and the rear calipers will be towards the front of the rear wheels. Porsche, Ferrari, Lamborghini etc.

I've always assumed the manufacturer's objective is to get the weight of big, heavy calipers as far inside the wheelbase as possible. Moment of inertia and all that physics stuff.

[fozzy280472]

My rear brake calipers are at 12 'o' clock , well it is a TVR so always going to be weird .....

[The spinner of plates]

As already highlighted, it’s all about packaging limitations, CoG and containing mass within the wheelbase where possible.

Whereabouts, in the 360 degrees of options, a disc is ‘grabbed’ from makes no real difference to the actual retardation forces applied.

[anonymous-user]

fozzy280472 said:

My rear brake calipers are at 12 'o' clock , well it is a TVR so always going to be weird .....

I spotted brake calipers mounted at 12 'o' clock on some crappy Korean SUV the other day, only time I've seen it!

[Triumph Man]

My E34 has the front calipers positioned frontwards, and my E39 had the calipers positioned rearwards. The E34 has a recirculating ball steering system, with the box and draglink/track rods rear of the hub, and the E39 had a steering rack, positioned forwards of the hub.

[2Btoo]

nismo48 said:

very informative thankyou..

Max_Torque said:

It's because on most cars the steering rack is low and forward and the engine sits over the top of that rack. With this layout, to get the correct geometry the steering arm on the upright/strut ends up at the front middle and hence the brake caliper has to go at the rearwards side. At the rear, without any steering rack and much freer options for suspension links, the brake caliper can go on front or rear side of the upright. Polar moment and CofG considerations drive towards an "inside" and low arrangement for sporting cars

Yup, I'll go with that.

Max_Torque, your posts on here are almost always worth reading. Thanks. Keep at it!

[Pica-Pica]

It’s just about packaging the other components in the vicinity, steering suspension, engine etc.