924Board.org

epsylon · Guest

Is there a company that sells drilled front rotors for the 924 N/A? Mine are in pretty bad shape and need replacing, thought I would upgrade if possible. Are the front rotors on my car from anther car (ie volkswagon or audi )? Or should I go to to the 944 braking system, seems like a lot of work when all I really need is some new rotors. How about a company that drills rotors for any application?

Lizard · Guest

go to http://www.performanceproducts.com

epsylon · Guest

checked out the site and all they had for the 4 bolt 924 N/A application are the "Frozen Rotors" which are not drilled. are these any better than the stock rotors?

epsylon · Guest

cool found some:

http://www.pelicanparts.com/catalog/shopcart/944M/POR_944M_brakes_pg5.htm

Lizard · Guest

just to let you know those are for the 5 bolt pattern (M471) if you get the performance products catalog I am sure I have found some in there or you can call them if you wish

924RACR · Posted: Thu Oct 10, 2002 5:45 am Post subject:

Drilled aren't any better, just make more noise, wear more quickly, and will eat pads. Furthermore you will lose braking effectiveness, not gain cooling.

Some people think they look cool, though.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

epsylon · Guest

not really going for looks, although my scored rotors look like crap right now. maybe i should be looking for vented and not drilled.

Zuffen · Posted: Thu Oct 10, 2002 6:15 am Post subject:

Vaughn how cum Porsche offers drilled totors for thier cars if they aren't effective.

I haven't noticed an increase in noise or diminished braking form having them on the front..
What gives?

_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

Smoothie · Guest

I'd think they'd at least improve wet braking.

Lizard · Guest

that is what they do they make wet braking more efficent and also they DO help to disperse heat which in turn helps to stop pedal fade as for the rest I don't know

924RACR · Posted: Thu Oct 10, 2002 9:15 am Post subject:

They do not help disperse heat, they will actually have more of an impact (as a result of lost surface area and mass) to make braking worse (loss of what we call Cp, specific brake torque, expressed as Newton-meters/bar). They will not help fade.

They will hepl clear water from the pad surface, which helps high-speed wet braking - autobahn.

Otherwise they suck. Listen to the brake engineer. I was working on a project, they wanted to put in cross-drilled rotors for looks/marketing, and had to ditch them because the performance wasn't there.

Vented is another story, they are good and do work. Want vented rotors? Get the M471/944/5-lug brake conversion.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Lizard · Guest

ok we gotcha I was going by what they claim I have never tried them

numbers · Guest

Vaughan, what about sloted rotors? Same story?

924 turbo · Guest

One thing drilled rotors definately do is reduce weight!

Everything else (cooling, braking power, gas/dust scavenging) seems to be up to debate. Drilled rotors definately crack more often than non-drilled rotors, especially if they're truly drilled and not cast into the rotor when it's made. I wouldn't use them, as I've heard too many cracked rotor stories, even on the cast-in holes. I'm definately interested in hearing Vaughan's opinion of slotted rotors, though!

924RACR · Posted: Thu Oct 10, 2002 10:36 pm Post subject:

Even cast cross-"drilled" rotors crack. Slotted are definitely better for durability, not the cracking issue, less of a loss of surface area, and do enough to clean the pad surface of water - not to mention more evenly. However still no advantage, really, in hot braking.

Drilled - weight? Yes on motorcycles, but not enough of an improvement on cars to be worth the loss of braking performance.

If you've got a brake fade problem, most likely you're using an incorrect/inferior brake pad. Get a semi-metallic, I highly recommend and use the Axxis Metal Masters for street cars. Performance Friction makes some nice stuff too, have them on my tow vehicle (Chev Suburban), but haven't run them on a 924. For track use, get a track pad, and consider the 5-lug brake upgrade.

I wouldn't have a problem running slotted rotors, but I wouldn't spend any extra money on them personally. For me, it's a moot point, since I am not allowed to run any drilled or slotted rotors on the racecar per the rulebook. Of course, I don't need them either.

_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype