Are brake rotors different through the years? I am lookin at some on ebay and they don't have 924S or 944 rear rotors for the early years. Here is what I am looking at would these work?
Fronts
http://cgi.ebay.com/ebaymotors/PORSC...Q5fAccessories

Rears
http://cgi.ebay.com/ebaymotors/Porsc...Q5fAccessories

http://cgi.ebay.com/ebaymotors/PORSC...Q5fAccessories

Or would there be another place to get some cheap rotors.

 

Try brakeswap.com.

The site is a little primative, but if you follow the links for 944 Cup, you'll get there. I just bought a set of Zimmermans. $160/pair for the fronts, arrived quickly.

 

I just bought a set of slotted rotors from them for my Explorer. Haven't received them yet, but I haven't seen any negative info on them. Everyone seems to love them. Why get the blanks when you can get their drilled/slotted edition? I'll give a report when I get them on the Exploder and are broken in. Most people pair them up with Hawk pads. I'm trying Wagner Thermoquiets.

 

[QUOTE=Lizard944;6658489Why get the blanks when you can get their drilled/slotted edition?[/QUOTE]

Because drilled crack sooner, and both wear out pads sooner.

It's a cosmetic upgrade with a price to pay.

Unless you are racing the car and don't care about the consumable costs, you get "blanks". Because they work. And on a DD, you won't (CAN'T) notice a difference, unless you are deluding yourself.

 

Ahh, so that's why Porsche now places them on every vehicle that comes off the production line; because it "won't make a difference." Granted, they are casted with the holes, but millions are using post-drilled rotors with only a rare incidence of cracks. Perhaps Porsche fills their vehicles with synthetic oil too, because it won't make a difference? Incidentally, the well-worn blanks that I'm replacing on my Explorer have small cracks in them.

 

If they were cross-drilled, they would be BIG cracks.


It's actually normal for a rotor to develop surface cracks (hairline) due to the expansion of the surface. It's not a problem as long as they're tiny and do not connect.

It's all folklore but I've also heard that cross-drilled rotors are more likely to crack. My "common sense" conclusions is that both camps are correct. Cross-drilled rotors DO offer more surface area and voids for airflow, and probably do provide better cooling. You can't find a race car without drilled or slotted rotors; and they don't care about cosmetics.

Better cooling is good in extreme conditions (racing), but irrelevant (or even a negative) when stopping on cold brakes.

But if you drill holes in something, you make it weaker and more prone to cracking. You also reduce the friction surface.

For street cars, the benefits of cross-drilling will never be used. But they do look cool.