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E21, E30General discussion and technical help for 1975-1991 3 series cars.
Your Ride: 1) Alpinweiss 1989 M3 2) Diamondswartz 1989 M3
Nope...
Quote:
Originally Posted by GreenTourer
Ah, I see...........I think what you call rotors in the U.S. is we call vented and drilled discs in the UK, thus my confusion. Never heard them called that before.
...vented points to the area in between the inside disc surface (where the inner pads touch) of the rotor and the outside (where the outer pads touch) surface.
If you stand a rotor on end and look at it as if it were a "blade", the vented area is the space in between the inner and outer surfaces.
Non-drilled rotors can be vented (space in between surfaces with vanes to guide the air through) or non-vented (solid). Either of these then can be cross-drilled or slotted.
Your Ride: 1) Alpinweiss 1989 M3 2) Diamondswartz 1989 M3
Actually...
Quote:
Originally Posted by xsperf
i had zimmerman on my older bmw, and i have brembos on this one, they are both great. and about the cracking, thtas if the holes are DRILLED, usually they are drilled if its like a 'made in Taiwan' deal where they are a knockoff, replica, but the real deal is not actually drilled, the holes are molded
...that is not exactly the way it is.
Cross-drilled rotors are machined, drilled, and the holes are double chamfered (beveled edges to reduce wear on pads). The inner (lower) bevel will act as a wear indicator and once reached you should change out the rotors.
Rotors are cast & machined and only a very few rotors are made with "holes-in" (some Porsche and other exotic car rotors). They still must be drilled out and chamfered because the "hole-in" casting is really just a dimpled casting and each "hole" (dimple) does not go totally through the rotor.
There is no easy cost effective way to make holes totally through a casting other that drilling them out because of the vented area between the inside and outside and the vanes within. To attempt do so would most certainly be hugely labor intensive and cost prohibitive.
...vented points to the area in between the inside disc surface (where the inner pads touch) of the rotor and the outside (where the outer pads touch) surface.
If you stand a rotor on end and look at it as if it were a "blade", the vented area is the space in between the inner and outer surfaces.
Non-drilled rotors can be vented (space in between surfaces with vanes to guide the air through) or non-vented (solid). Either of these then can be cross-drilled or slotted.
That is all...
Correct. Contrary to popular belief, the holes or slots on the surface are not for cooling the rotors. They are for dissipating the boundary layer of gases that build up between the pad and rotor, hence maximizing braking power.
10-23-2007, 11:37 PM
Nope...
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