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Inboard disk brakes?

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TEG

Teslafanatic
Moderator
Aug 20, 2006
22,100
9,483
Good idea or not? Less unsprung weight!

Inboard%20Disc%20Brakes_tif.jpg

4WD_with_DS_suspension_6.jpg

rear_jag_72dpi.jpg

peter02.jpg


Used on some Jaguar, Citroen, Rover, Alfa Romeo, custom hotrods, race cars, etc.
 
In configuration on the last picture there realy is not much less unsprung weight but in the configuration on the first there is.
Brake disks are located near differential which is fixed to the chassies. They do not go up and down with wheels.
 
GreenSpeed said:
I don't get it, don't the discs still turn like on normal car? If so how would there be less unsprung weight?

Yes they turn so the rotating mass is the same, but they don't have to move with up and down wheel motion (as WarpedOne said) so it is easier for the wheels to bounce up and down quickly without transmitting as much motion to the rest of the vehicle.

Personally I think they seem like a good idea, but I don't understand why they haven't been more popular. Perhaps the intrusion into cabin space is too much of a downside.
 
GreenSpeed said:
Another downside is that it would be harder to check your brake pads.
Also in terms of looks, many love to see the brake calipers and disks ;D

Yes, cars that have been "upgraded" to 22" wheels, but retain stock brakes do look funny to me. Looks like something's missing.
 
I think the reason they're not more popular is due to cost, complexity, and space concerns.

Cost - Any non-driving wheels will need another CV joint and bearing to hold the brake. Cooling ducts will probably be necessary, impacting the design of the whole vehicle.
Complexity - The above parts aren't free.
Space concerns - Two of the brakes are going to take space away from the engine compartment, which is usually cramped already.

The result does lower unsprung weight (improving grip), but also raises overall weight (reducing acceleration) and may hurt aerodynamics for the cooling ducts (reducing acceleration, top speed, and efficiency).

Everyone loves low unsprung weight but one has to ask if all the consequences of this particular technique are worth it.

-Ryan / Kardax
 
Yeah - I had mentioned the joints & half shafts and space issues in other postings before.

So, yes, for non-driven wheels it adds extra weight, cost and complexity.

*But* for driven wheels where you already need a half-shaft and something inboard (e.g.: motor or differential) then why not put the discs inboard as well?

The Alfetta GT where I first encountered inboard brakes had inboard discs on the driven rear wheels only. The front wheels used in-wheel discs so there were no half shafts in front.
 
Ceramic discs is the HOT set up, similar to carbon fibre. There isn't a single F1 car that uses inboard brakes, and if there is a car that is very sensative to weight, its an F1 car. They all have outboard mounted ceramic discs.