Slant Six Forum :: Slotted rotors...

Most of you will be aware that Australian A-Bodies are basically the same as US models from 1962 to 1970.

DBA here in Oz makes slotted rotors in both solid disc (66-69) and ventilated (late 69-70).

It's my understanding that front suspension components for these years are close to identical,

The US rotors are 0.790" new, 0.760" minimum before discard.

Dan is very close. Those KH rotors are 0.810" fresh I am pretty sure, and have a min spec of, I think, 0.780".

Ehrenberg stated in MA that 0.750" was the factory min spec, but they were forced to print 0.780" spec on the rotors because of poor machining tolerances back in the day.

...but the disc brake systems are totally different.

OH NO DRILLING HOLES IN YOUR DRUMS or DISCS

Goggle CH TOPPINGS, they have a mail order service, you mail yours in, they drillem and mail them back. About $50 bucks a wheel.

Ive been PORTING drum brake surfaces for 40 odd years now. But IM THE CRAZY ONE.

drilled (actually cast) holes

Author:	james longhurst [ Sun Aug 26, 2007 12:54 pm ]
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When I went with drilled rotors on my Swinger I had a hard time finding ones that were even drilled properly. Quite often you'll find the holes drilled into the walls of the cooling vents. Can't be a good thing. Also read somewhere that (properly) drilled rotors resist warpage better than their solid counterparts. But that seems like a misnomer since many of the ricer cars I end up test driving have tons of noise and vibration from all the other "upgrades" the cars have suffered. -James

Author:	PiDstr [ Mon Aug 27, 2007 3:27 am ]
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Most of you will be aware that Australian A-Bodies are basically the same as US models from 1962 to 1970. DBA here in Oz makes slotted rotors in both solid disc (66-69) and ventilated (late 69-70). It's my understanding that front suspension components for these years are close to identical, so the DBA product "may" suit US vehicles. http://www.dba.com.au/2006/default.asp or check page 23 of catalogue for specs. http://www.dba.com.au/2006/PDF_CATALOGU ... 180607.pdf PiD v4.0

Author:	SlantSixDan [ Mon Aug 27, 2007 7:03 am ]
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Quote: Most of you will be aware that Australian A-Bodies are basically the same as US models from 1962 to 1970. DBA here in Oz makes slotted rotors in both solid disc (66-69) and ventilated (late 69-70). It's my understanding that front suspension components for these years are close to identical, ...but the disc brake systems are totally different. Both the solid (VE-VF) and ventillated (VF+) disc systems were locally sourced in Australia, not imported from the US. The US disc brakes were ventillated right from the start in '65. Looking at the DBA catalogue, the Australian early solid rotors are too thin (0.5") while the Australian later vented rotors are too thick (0.945"). The US rotors are 0.790" new, 0.760" minimum before discard.

Author:	DionR [ Mon Aug 27, 2007 9:35 am ]
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Quote: The US rotors are 0.790" new, 0.760" minimum before discard. You sure about those numbers? Sticks in my head that the later rotors are about an inch thick. I could be wrong, just seems like they are thicker than 3/4".

Author:	Dart270 [ Mon Aug 27, 2007 12:16 pm ]
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Dan is very close. Those KH rotors are 0.810" fresh I am pretty sure, and have a min spec of, I think, 0.780". Ehrenberg stated in MA that 0.750" was the factory min spec, but they were forced to print 0.780" spec on the rotors because of poor machining tolerances back in the day. Lou

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Author:	Pierre [ Mon Aug 27, 2007 12:28 pm ]
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I have bendix KH replacment rotors. I installed them a while back but I could of sworn max undersize was 0.020"

Author:	SlantSixDan [ Mon Aug 27, 2007 12:44 pm ]
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Quote: Dan is very close. Those KH rotors are 0.810" fresh I am pretty sure, and have a min spec of, I think, 0.780". Yep, I think you're right! Quote: Ehrenberg stated in MA that 0.750" was the factory min spec, but they were forced to print 0.780" spec on the rotors because of poor machining tolerances back in the day. I have a difficult time believing this without proof. Reads to me like one of Ehrenberg's campfire stories. Poor machining tolerances back in the day? Uhhhh...which poor machining tolerances would those be?

Author:	DionR [ Mon Aug 27, 2007 12:56 pm ]
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My mistake, it was just a gut reaction (must have been hunger).

Author:	PiDstr [ Mon Aug 27, 2007 8:34 pm ]
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Quote: ...but the disc brake systems are totally different. Well, doesn't that just bite,... and here I thought some of our performance kit might have found a home. PiD v4.0

Author:	andyf [ Mon Nov 26, 2007 7:03 pm ]
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I used drilled rotors from a Porsche on this B body car project. Actually I guess these aren't really drilled, rather the holes are cast into the rotor.

Author:	Eric Von Zipper [ Tue Nov 27, 2007 11:10 am ]
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OH NO DRILLING HOLES IN YOUR DRUMS or DISCS This must be absolutely crazy. Tho there are companies that do it. There are Hotrod mag articles on doing it. ITS INSANE Goggle CH TOPPINGS, they have a mail order service, you mail yours in, they drillem and mail them back. About $50 bucks a wheel. Ive been PORTING drum brake surfaces for 40 odd years now. But IM THE CRAZY ONE.

Author:	Matt Cramer [ Tue Nov 27, 2007 11:19 am ]
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Eric, There's also people selling magnets to install on the gas line, but that doesn't mean they work. It just means people can make money at it. People have it in their heads that this is how high performance brakes look, and there's a lot of other people out there who live by the saying, "A fool and his money are soon parted." But you see them a lot less often on brakes where it really counts. Have you had a look at the brakes on a NASCAR Nextel Cup car? It's hard to think of a more demanding application for iron rotors - the cars can hit 200 mph, have to be hauled down from these speeds repeatedly, and they're a lot heavier than most race cars. But you won't see these rotors drilled.

Author:	Joshie225 [ Tue Nov 27, 2007 1:34 pm ]
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Quote: OH NO DRILLING HOLES IN YOUR DRUMS or DISCS That's right. Those holes were not drilled. The rotor was designed and cast that way. Quote: Goggle CH TOPPINGS, they have a mail order service, you mail yours in, they drillem and mail them back. About $50 bucks a wheel. Just because you can mail order something doesn't mean I want or need it. I could order up an amputee Eastern European bride if I wanted, but... Quote: Ive been PORTING drum brake surfaces for 40 odd years now. But IM THE CRAZY ONE. Maybe not crazy. Probably just ignorant and certainly stubborn. My challengestill stands. I'll put my '67 Valiant with single piston discs against the best drum setup you can muster.

Author:	andyf [ Tue Nov 27, 2007 4:04 pm ]
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I use the Mercedes rotors on my B body and in the 13 inch kits that I sell. The Mercedes engineers decided to use drilled (actually cast) holes in their rotors so that is what I run. I figure if it is good enough for a $80,000 car it is good enough to run on my old '65 Coronet.

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Author:	SlantSixDan [ Tue Nov 27, 2007 4:26 pm ]
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Quote: drilled (actually cast) holes There's a very critical difference between rotors specifically engineered and manufactured with holes (cast holes) and rotors with holes added in the field (drilled holes).