FAO: Martin.. (brake related)

["Dan" <danielpwillis@xxxx>]

We've chatted about this and I have dug up some info on why SOLID 
disks are currently the "way forward" and all that grooved/drilled 
stuff is dying off. YES I do have drilled discs on the Porsche but 
she's 8 years old this year ;oP

Basically a thread (on a Porsche forum) was talking about how drilled 
discs suffer badly from cracks that originate from the holes under 
heavy track use...

"1) Cryogenically frozen rotors are less prone to cracking but will 
eventually experience the same problem. Some say frozen rotors make 
little difference in terms of warping or cracks or disc life. 

2) Solid rotors do not have this problem. Also, modern brake pads do 
not create gases upon heavy application as they once did many years 
ago. Thus, the vent holes are unnecessary in relieving these gases and 
are designed more for dissipating water when running in the rain. I 
have read conflicting opinions on the true purpose of the vent holes."

Basically... grooves just kill the pads. I have spoken with some 
motorcycle enthusiasts about it too.
Holes were used as stated above - for gas venting. No longer an issue. 
Water CAN be drained off but to be honest... well... I don't think 
it's an issue.

SO for good braking you need:

1. BIG discs
2. The further the caliper from the hub the more effective they will 
be (all about torque/rotational force and gearing)
3. Nice solid discs are good. No drilling (affects strength of disc) 
or grooving (looks nice but that's it)
4. Venting... old school now and kinda obvious.

The Delorean had a nice system for it's day. Four discs was pretty 
much unheard of in the late 70's (except for Martin's French thingy - 
they loved em).
Now however there are a few things letting the car's system down:

1. Size of disc. It's tiny. My mother's Fiesta has bigger discs.
2. Venting. There is none. While I VERY much doubt I'll be seeing any 
high speed braking manouvers from you guys it changes nothing. Brakes 
need vents ;o)
3. Size of wheels. Okay so I'm putting on a flame retardant suit here 
but I'm really in to performance cars (duh) and as such the wheels are 
quite important - they are the ONLY thing connecting you to the floor 
(yes Martin, I know it's the tyres ;oP). To increase braking 
efficiency here we need to ditch the wheels. For a start you can't get 
anything bigger behind the wheels; second they allow very little 
cooling; third they are heavy (I won't get in to that) and forth... 
you want big brakes... and you want to show them off (I'll admit that 
one is just me).

Ceramics are being offered on the big expensive cars (Porsche GT2/Merc 
CL etc) but they are dogged with problems. I'm told one set should 
last 130k but so far they are experiencing far less!

Dan
Porsche 911
Delorean (Vin#5284 - just got my running number for the Great South 
Run and it's 5824.. pretty close!)
Calibra Turbo