GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL
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Race Director
Joined: Sep 1999
Posts: 12,439
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From: CONCORD NC
GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL
Although I think they are a great bargain for a street application, do NOT use these rotors for track events. I tried one of these with one OEM rotor on the opposite side, and the slotted/drilled rotor CRACKED while BARELY BROKEN IN. I had actually just returned from bedding a 2nd set of pads on the rotors, maybe 30 min of track time on the original set, when I heard "pinging" from the brake area. Sure enough, the outermost hole on several of the 'rows' of holes cracked out to the edge of the rotor.
I was hoping for better metalurgy, but I guess that it is not to be.
Dave
I was hoping for better metalurgy, but I guess that it is not to be.
Dave
Melting Slicks
Joined: Feb 2001
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From: DFW TX
Senior Member
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Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Oh well, I won't waste my money on those. Thanks David. :cheers:
-Jeremy
-Jeremy
Team Owner
Joined: Mar 1999
Posts: 28,753
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From: San Jose/Bear Valley CA
CA Events Coordinator
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Thanks for the info... I am not buying any more stock or stock looking brake rotors or any stock brake stuff for my car anymore!!! Everything I have ever had that resembles the stock stuff has broken, cracked or wore out very fast!! :(
vetterdstr :cheers:
vetterdstr :cheers:
Safety Car
Joined: Nov 2000
Posts: 4,039
Likes: 2,606
From: Northern VA, USA
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Well, hopefully your problems will finally be example for people who don't understand. Drilled rotors are for looks, not racing. :nonod: Drilled rotors are much more prone to cracking under stress, and you won't see many hard core racers using drilled rotors. Outgassing is no longer a problem with new pad technology, so the holes are just for looks.
Thanks for posting your results! :)
Thanks for posting your results! :)
Drifting
Joined: Apr 2000
Posts: 1,390
Likes: 36
From: INDIANA
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Thats the problem, pro's know the holes are not a good thing on stock style rotors, but then big companies, GM included now offer drilled ones for sale!! Heck, I ordered the Durastop perf rotors for my Blazer, and was WAY disappointed when they came and were not drilled/slotted as advertised and told by the dealer. Guess really I am glad now though.
Drifting
Joined: Feb 1999
Posts: 1,481
Likes: 1
From: San Diego CA
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Come on Dave, don't tell me you were surprised?
As far as the stock braking system goes, I don't think you're really going to see an overall improvement with aftermarket rotors on the track. They cost a bundle more, and even though they might last longer, you end up behind in the end since the stock (or HD) rotors are so inexpensive. If you're sticking with stock calipers, you're not going to see an improvement in braking anyway. I guess you might get better heat disipation with a premium rotor though (not sure if aluminium hats are an improvment in heat transfer to the hubs or not).
Hmmm... let me see... dang! I've gotten 12 track days so far on my original stock rotors! I was using stock pads, now I'm testing EBC's Green Stuff compound (not good enough for a heavy car like the C5 on the track) so my pads aren't all that agressive (although I do run race rubber).
Maybe I just need to brake more... naw!
Mike :flag
As far as the stock braking system goes, I don't think you're really going to see an overall improvement with aftermarket rotors on the track. They cost a bundle more, and even though they might last longer, you end up behind in the end since the stock (or HD) rotors are so inexpensive. If you're sticking with stock calipers, you're not going to see an improvement in braking anyway. I guess you might get better heat disipation with a premium rotor though (not sure if aluminium hats are an improvment in heat transfer to the hubs or not).
Hmmm... let me see... dang! I've gotten 12 track days so far on my original stock rotors! I was using stock pads, now I'm testing EBC's Green Stuff compound (not good enough for a heavy car like the C5 on the track) so my pads aren't all that agressive (although I do run race rubber).
Maybe I just need to brake more... naw!
Mike :flag
Racer
Joined: Oct 2001
Posts: 442
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From: San Clemente CA
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (y2khardtop)
Hi,
Do you think rounding the edges of the holes would help the cracking problem? Certainly it would reduce the local stress level in the metal.
Steve
Do you think rounding the edges of the holes would help the cracking problem? Certainly it would reduce the local stress level in the metal.
Steve
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Michael S. Palmer
Team Owner
Joined: Mar 1999
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From: San Jose/Bear Valley CA
CA Events Coordinator
Re: GM slotted/drilled rotor DISSAPOINTMENT-TECHNICAL (SNW Vette)
I think the only thing that would help these rotors is to be thrown in the trash. Drilling of the holes after the casting is part of the problem... the other part is that the metal is sub standard for extreme usage. (not that I ever drive my car like that) ;)
vetterdstr :cheers:
vetterdstr :cheers:
