Anyone have experience or thoughts about these?
http://www.ebay.com/itm/Brake-Calipe...item1c20ad1ff0

 

The Big Reds and standard brakes, both great brake systems. My car NB 993 originally had Big Reds. Where I Club Race, they were licking me up a class, not good....so I traded my Big Reds for standard brakes. At the track, couldn't tell the difference.

If you are building a 993 RS clone, you'll of course want 993 Big Reds, the rears have slightly larger pistons for more bite. They may also have a slightly different brake bias valve/proportioning valve.

IMHO, an upgrade to Big Reds gets you little for your money...I have had both, wouldn't go back to Bug Reds:
1. No measurable difference in performance in a 25 - 30 minute race. Big Reds will run cooler longer, BUT, eventually they will heat up too,
2. Rotors cost more
3. Brake pads cost more
4. Rotors are a bit heavier and are rotating mass that needs to be spun up, AND slowed down,
5. The stock brakes are lighter, improves the unsprung weight.

But for pure cosmetics, they look great!

 

"Question: If you install larger brakes, will you stop quicker? Answer: Not really.

Upgrading a major system, like your brakes, is not a trivial or inexpensive decision."

Source: Written by Bill Gregory for the "Challenge", monthly publication of the Connecticut Valley
Region, Porsche Club of America.

 

Cosmetically, for similar money, actual Porsche brakes:

http://www.ebay.com/itm/Porsche-911-...90f5e1&vxp=mtr

http://www.ebay.com/itm/Porsche-911-...8db44f&vxp=mtr

 

Remember the Performance Triangle.... the same applies to Brakes.

Cheap. Reliable. Fast.

Pick 2 any 2 but only 2.

Simon.

 

Somebody correct me if I'm wrong, but brakes are simply a method of applying force to tyres, aren't they? I am given to understand that bigger and better brakes are easier for the driver to modulate at the limit, but that all other things being equal, more adhesive tyres will stop a car quicker than bigger brakes.

 

The ebay ones in the OP are Dansk items, many USA resellers list them, Automotion for one

 

Everything you ever wanted to know about 993 brakes


the bigger brakes can apply a bit more brake torque, they do run cooler and last longer, the RS bias is beneficial on a track car set up for it, ideally a 25mm m/c would be used but that's a complicated process

the above #s are w/o any p/v, the stock 993 55bar p/v would usually be used for all but the tt brakes, there is a lot of sub-threshold braking below the 55bar knee

at the limit tire slip is the ultimate limiting factor, which is why alignment, suspension, aero and wheels/tires are also important

 

Exactly. Plus larger brakes have more surface area for heat dissipation.

 

...then close the book, you'll have what you want to know, no BS. These two guys, plus a cast of lots more, are why I have been to Rennlist nearly every days since it was created, way back in the day.

I can see a Verburg Cupcar book one of these days soon.

 

One thing to keep in mind is the change in friction coefficient with brake pad compound and change with temperature for a given compound.

Friction coefficient (Mu) versus temperature for various Ferodo racing pads below is shown in graph below. Mu is proportional so the brake torque from .36 Mu to .48 Mu for example is ~33% increase in brake torque.

The brake torque is only shifted ~+12% to the rear with RS brakes, but note one can vary the pad compounds front to rear and effect a much larger change than 12% in brake torque.

Note there can even be a greater change than 12% in Mu between front and rear pad coefficients due to temperature running the same pads.

This is why pro teams change brake ducting and/or pads track to track to keep the coefficient curves in control front to rear as matched to the heat dissipation requirements of the track.

 

i'v experimented a little w/ differing brake pads f/r but am leery of it, even w/ pads as close together as Pagid 19 and 29 are is terms of their friction curves I came away w/ the distinct impression that the ABS was not always 100% happy.

I've settled on a pad w/ as flat a curve as possible and use the same pads f/r w/ caliper/rotor combinations that have as close to the bias wanted as is possible. In Cupcar's graph w/o knowing any thing else I'd take the DSNO because it has the flattest curve, of course there are other things to consider too

 

Pervy got to the question. Sorry I was so abstruse. What I meant was the DesignTek vs OEM. These seem less expensive.

http://www.design911.co.uk/fu/prod13...93--DesignTek/

 

...the question was great, the answers were even better...

 

Yeah, I had the same thought - pretty much over my head.