What are they?

[fstsven]

Maybe a stupid question...   s:oops: :oops: s:oops:  

I recently saw a Ferrari 360 and a Lamborghini Gallardo parked up (drool, drool)    s:shock: :shock: s:shock:    s:D s:D  
After, of course (and much to girlfriend's disapproval), long and thorough observation, I noticed that both have, on the rear brake disks, something that looks like a second, smaller brake calliper, on the opposite side of the (BIG!) main one.  Anyone have an idea what they are and what they do?

Cheers!

[aaronjb]

on the rear brake disks, something that looks like a second, smaller brake calliper, on the opposite side of the (BIG!) main one

At a guess - that's the handbrake.

There's three ways of putting a handbrake on a car with disks all round:

Brake shoes in the 'bell' of the rear disk (Nissan 300ZX, 200SX and others use this) - handbrake works well, but makes the 'bell' area quite large.

Handbrake cable operates a lever which pushes the rear pads onto the disk independantly of the caliper piston - Renault 5, 19 and many other cars of that era used this - you end up with a really poor handbrake!

Secondary caliper operated by cable only - the two you saw obviously use this - it means you can have a hurfing great disk and enormous swept area while keeping a really good handbrake action. The Ultima GTR also comes with that as an optional setup - essentially because racing calipers don't have any provision for a handbrake  s:) s:)

[Tem]

Handbrake cable operates a lever which pushes the rear pads onto the disk independantly of the caliper piston - Renault 5, 19 and many other cars of that era used this - you end up with a really poor handbrake!

The '2 has basically that. The lever just pushes the piston, not the pads. The handbrake action itself is quite poor, but the good side is the saved weight.

[Anonymous]

Am I right in thinking that some high-performance cars that use the brake-by-wire system also have a secondary redundant mechanical set of calipers, just in case the electronic ones fail?

I'm sure I read that somewhere... On a Merc I think.

[dreambackup]

wouldn't it be the system to dry the disks / keep the ceramic disks warm?