Dreaming of upgrades for my 914 was wondering about the advantages of slotted brake rotors and also are there any manufacturers who build them for our cars. I have read that the 914-6's had them. Does anyone know a source or have opinions?

The Sixes did not have slotted rotors. The Sixes had vented rotors, which are a whole 'nother kettle of fish.

A slotted rotor is a stock rotor (in our case, a solid rotor) that someone cut grooves into the wear surface of the rotor. This can help wipe water away from the face of the pad, and can also help get hot material away from the face of the pad. With modern pad compounds, it is not usually a whole lot of help. In the Olden Days, pads used to out-gas more when heated up and it could cause a problem where the pedal was nice and firm and yet the brakes didn't slow you down. Pads are much better today.

A vented rotor is kind of like two solid rotors next to each other, with an air space in between. Some of that space is bridged by metal, in order to hold everything together. The rotor is much thicker (over 1" thick, usually), and has more thermal mass (due to having more mass!) and has that air passage so that air can travel through the rotor taking heat with it. It helps keep brake temperatures down when the brakes are used hard.

You can run vented rotors on the front of a 914, but this is generally done by swapping in a 911 front suspension. If you want to keep the four-bolt wheels, you may be able to find some of the billet hubs that were made a while back. You'll still have to swap out the calipers, as they won't fit over the vented rotors with enough room for a real brake pad.

--DD

If your car is a street car only...then slotted or vented rotors will get you nothing but a thinner wallet

All my street vehicles have slotted rotors.

I like them, especially in the rain. The water film is wiped off instantly.
I think it also helps keep sand and grit from getting trapped under the pads. In my experience, the slotted rotors develop fewer wear grooves.

That said, I don't know about availability of off-the-shelf slotted rotors for /4 applications, which also contain the bearing carriers (front). Any competent machine shop should be able to do it but there's an art to it (how many? how deep? spaced regularly or nonsymmetrically?) and this is _no_ place to be experimenting. They'll need to be balanced after machining. And there is no getting around the fact that any machining is removing mass of which 914's have no surplus...

Despite my initial reservations, I'm also a convert to cryo-treated rotors.

A full shipset of cryo treated slotted rotors and good pads is expensive and as DanT observes, probably substantial overkill for the average street 914. If it doesn't rain much where you live, you'll probably never notice any benefit.

(Pads and rotors for the Titan was around $1k and I got group-buy pricing on the pads. But the Titan has a reputation for undersized brakes and I felt an upgrade was in order. For the Subie it was about $800.)

Since I use my car for DE's I have cyro/slotted rotors all around. Am using Carrera rotors F & R with C2 front calipers and C2 Turbo calipers on the rear. I have used drilled rotors in the past, but they will start to crack around the holes when they get older....

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Thanks for the responses and feedback!
I love this site

...nothing but bling on a street car

Probably not adviseable for solid 914-4 rotors, there's not enough thickness for slotting or drilling.

Your user profile doesn't specify the year of your car. Anyway these guys sell vented/slotted for 4 lug 914s. I have purchased electric window motors from these guys for my 911 and they were brand new and excellent: http://www.partsgeek.com/catalog/1975/pors...rake_rotor.html

hijack warning, achtung!
rules...points...non stock brakes
FG bumpers, fg deck lids.
"every gram must be accelerated, cornered and braked"
less weight creates less brake heat
less weight accelerate faster
less weight wears tires less
less weight corners faster
less weight uses less fuel

Thanks Sean! great advice as always . Now if I can Just figure out where I sit in this new points system

trophies for 2011 will be classed same as last year. new rules dont apply till 2012