Sideways

I stopped by Porterfield yesterday and they want $40 per corner to drill the rotors. Is that reasonable? Also, how much is involved in removing the rotors (time and effort.)
I'm doing it mainly for looks...Thanks

mingster

didn't somebody say that drilling your stockers MAY result in cracked rotors? you may want to buy rotors with the holes that were cast in and not drilled.

Utah S2K

The holes in "holed" rotors are not cast in. These rotors are plate stock just like the O.E.M. The issue is that after machining the O.E.M. rotor, it is heat treated to gain tensile strength. If you drill them now they may definitely crack depending on how hard they are. Drilling high strength steel will induce what is known as "work hardening". Stress is built up in the material. This may result in stress corrosion cracking after a few heats and reheats..as in hard breaking. If you do choose to do this iffy procedure, make sure they bake the rotors (don't have time and temps in front of me cause I don't know the rotor material).....this will relieve some of the stress created by drilling.

I wouldn't recommend it unless the process is : anneal the rotor (soften it), drill, heat treat (reharden), then surface grind for flatness (as heat treat may cause warping). After all that they should me magnetic particle inspected for defects.

AusS2000

I've heard it said that many high end rotors are cast with holes. Can someon confirm this for the Spoons.

That said, the DBA LongLife Gold rotors are drilled during manufacturing then treated to reduce stress and hardened.

cdelena

I

mingster

how much are they?

AusS2000

About $US100 per corner plus shipping, BUT.....

As usual with Aus manufacturers they are alway just around the corner. We were supposed to have them last November, but now we're back to April, and I won't be surprised when April 1 comes about and they ring me and say "April Fool!"

ultimate lurker

Porsche and Ferrari both use cast in holes that are machined for final product. Drilling holes in a precast rotor is a recipe for problems, especially in race environments.

I've used drilled rotors before and didn't like them. We were able to record no measurable improvement in stopping distance, fade resistance, etc. In fact, in terms of thermal fade, a drilled rotor system _should_ run into problems sooner since a comparable non drilled rotor has more thermal mass.

Some people say that drilled rotors allow better air circulation for cooler running, but if you look at a modern vented rotor, you're not going to get much if any benefit from drilling holes because they are perpendicular to flow and remove surface area that is normally parallel to it.

The key benefit of drilling is to remove pad gasses and water. With good pads, gas build up is pretty rare (one of the reasons most Honda pads have a channel in the center). If you really want the venting function in a durable rotor, I recommend slotting. It's what CART uses (when they're using iron rotors) and is common in other forms of racing. I believe that Ferrari and Porsche vent their rotors to reduce rotating mass in their rather large rotors.

UL

Utah S2K

My mistake....the rotors are cast, checked mine this morning. Concerns about drilling (i.e. high strength steel stress) still apply whether cast or plate. $750 to $800 a set sounds like they know about annealing and re-heat treatment. $100 bucks a rotor is way too cheap and is probably a straight drill job. Find out what you get for your money...specifically. I think they look a lot better personally, the drilled ones that is. Maybe someday.....after all the other stuff on my wishlist. Anybody got pics installed?