Inboard Brakes, what they are and how they work.
What are they?
Inboard not mounted to any external component ie wheels, this type of braking system is mounted to the differential or a brakeshaft on the front of the vehicle.
What are they?
Inboard not mounted to any external component ie wheels, this type of braking system is mounted to the differential or a brakeshaft on the front of the vehicle.
Why?
The purpose of inboard brakes is to reduce unsprung mass within the suspension system on the vehicle, alot of old English sports cars used to have this arrangement, most noteworthy older JAAAGGs. And subsequently used in the back of hotrods, as they came on a subframe of sorts.
The lotus F1 car above car uses inboard brakes to improve centre of mass and inertia, as well as cooling, this is a compromise as it means running a small driveshaft to the brakes on the car.
Advantages
PACKAGING, a larger brake disc can be used without it being inside the wheel as a result less rotating mass as the wheel can be smaller.
Heat: brake dust and higher temps can be separate from the tires
improved roll centers, improved inertia, improved front brake cooling
solid fixed brake lines can be used.
SPRUNG MASS is lowered meaning ride can be softer, less time is spent overcoming inertia of the suspension and more is put on the tires.
Disadvantages of this system
HEAT: rear brakes where notoriously bad at cooling, not aided by poor aero of the time as well as the fact that it is mounted in a confined space under the vehicle
PACKAGING, area around the rear differential will need to be bigger.
TORQUE: the distance from the tire to the brake disc has significantly increased, meaning that any force will cause distortion in the drive/half shafts,however we are talking Nm here so there is a difference so the drive shafts need to be stronger
SERVICE: lower a diff to just do the brakes, hahahaha NO.
#GiveMeABrake #builtnotbought , #inboardbrakes . #oldstillgold
why not now? on modern cars?
I genuinely have no answer, well other than the diff thing.
Comments
Engineering Explained is pissed off
is he now?well he should have finished all of his suspension playlist with this, not that i don’t like the bloke but he could make sure he has finished everything or do an advanced series of playlists
reminds me of Alfasud, Alfetta and Alfa 75, which is a pain in the ass to work on the brake.
Alfa make brilliant cars, briefly, and then they need to be fixed.
I genuinely didn’t know these existed. I recently designed a system like this but didn’t gave much thought to the axle stresses. Very nice article. This will be very useful to me. Thanks :)
Edit: I actually do have the answer to your question. The materials and the mechanical complexity together with added cost wouldn’t be ideal to make a large volume production car. It MAYBE possible with a small volume car company.
You’re welcome
Ok, so hypothetically we are in a world where this system is in mass production, would there be a reason to change to the outboard brakes?
i think the main problem with these might be oscillation… the long “driveshafts” are an elastic component, and together with an inconstant friction moment, this is going to start oscillating easily… which results in a lot of problems, like an increase of the braking distance, more wear and more stress on the mechanical components.
oscillation and harmonic frequencies as well as rigidity of the chassis mounts are going to be a large factor in wear of these components, as there is an inconstant friction moment the harmonic frequencies will change so the wear will be increased, however if this was on a front driveshaft, the hub and steering can be mounted after them meaning that there is less wear on the hub. if you have the brakes at the end of the driveshaft, you will minimise wear, if you mount the brakes at one end of the driveshaft, you will remove a large portion of the distortion and wear.
for reference
go to https://sky-brakes.blogspot.com/2017/07/inboard-braking-system.html
Hey,
We are making a electric atv and we are thinking to use inboard brakes in the rear but we do not have any idea of how to fix the brake disc to the shaft.one idea we have is to use a spline kind of thing to fix it.
Please do comment of any other idea.
In hub motors or not? because if you are using in hub motors put the brake rotors where the diff would be in a nomal car atleast it gives you a space/location to work on them and duct air to.
If like a normal car, then its the same as below just enjoy even more clearnace problems.
The way of building a system like this is thinking, I have a driveshaft of same shaft splines at both ends, i need a flanged plate to bolt the disc to and i need a holder to build the caliper and prevent the shaft from moving in 3d space.
IF all else fails take another wheel hub and machine down what you don’t need. and try to copy the picture for the lotus F1 car