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i think its only dangerous if they were drilled after manufacture.

If they were produced like that from the factory then they should be fine as they have taken the drill holes into consideration with the design.
(does that make sense? )

On the road it is purely for bling factor. On race cars, where brake temps can easily exceed double what you will see on the road, they can tend to promote cracking. But, as race cars replace rotors often and most don't even use drilled rotors anymore, it's nothing to be worried about for the road. If you stick it on the track, be careful to inspect them regularly - both rotor faces.

The only time I have heard of them failing is on Porsche GT3s doing several 250km/h-0km/h stops in a row. I can't see an MX5 ever replicating those conditions...

Boags

lil_mike wrote:

Boags'MX5 wrote:The only time I have heard of them failing is on Porsche GT3s doing several 250km/h-0km/h stops in a row. I can't see an MX5 ever replicating those conditions...

Boags

hmmmm, boags, its a rotary and its me driving i dont know about that?

it will be tracked and dríven hard fairly often. what should i look for specifically on the rotor faces?

I doubt there is enough room anywhere for you to get up to 250 more than a couple of times, and if you do, I doubt you'll be thinking "I wonder how long it'd take to stop from this speed."

You should be looking for hairline cracks, warping or anything other than clean straight surfaces I suppose.

Boags

PS - When are you going to invite me round for a beer so I can see the beast?

Boags'MX5 wrote:PS - When are you going to invite me round for a beer so I can see the beast?

X 2

If the holes are actually cast into the rotor, they are fine, but if they are drilled after the disc is cast, then they can start cracks as the drilling stresses the metal.
During expansion and contraction (heating up and cooling down) the holes get bigger then smaller, and this causes a lot of the stress.

Just stick to slotted rotors and forget about the holes.
They don't do all that much anyway.

dont go the wilwood
I have been told that all they do is upgrade the front brakes.
for the rears they just have a spacer for the calipers and put in a bigger rotor. so you get all this extra braking power at the front but pretty much exactly the same on the back.
If you are willing to wait a fewish weeks a member from the advan group (we call the place WHEELSPIN) has just made their own kit comprising of mainly RX-7 brakes which are as a matter of fact... bigger than the wilwood kits including bigger calipers and rotors for the back.
The front has 12\" rotors and 4 piston calipers while the real has the same rotor i think but big single piston calipers.
PM the guy, MX52NV
the kit is his and it is still prototype at the moment but he is hoping to put it into production really really soon.
Big Up for Wheelspin!

DOYLMX5 wrote:dont go the wilwood
I have been told that all they do is upgrade the front brakes.
for the rears they just have a spacer for the calipers and put in a bigger rotor. so you get all this extra braking power at the front but pretty much exactly the same on the back.
If you are willing to wait a fewish weeks a member from the advan group (we call the place WHEELSPIN) has just made their own kit comprising of mainly RX-7 brakes which are as a matter of fact... bigger than the wilwood kits including bigger calipers and rotors for the back.
The front has 12" rotors and 4 piston calipers while the real has the same rotor i think but big single piston calipers.
PM the guy, MX52NV
the kit is his and it is still prototype at the moment but he is hoping to put it into production really really soon.
Big Up for Wheelspin!

wouldnt they be heavy as buggery though??

i thought that was half the reason behind good brake kits... like willow and APR the fact that their calipers wiegh about 1/4 that of a standard caliper

i think the UK store has some good APR brake kits worth looking at... havent got a link but i do remember them looking the goods.. and should be lighter/better than a factory rx7 brake kit.

Boags'MX5 wrote:The only time I have heard of them failing is on Porsche GT3s doing several 250km/h-0km/h stops in a row. I can't see an MX5 ever replicating those conditions...

But it is about heat and not speed. A 380 mm Porsche rotor can dissipate enough heat to stop from 250 repeatedly. Secondly, the Porsche rotors are much better in quality than $150 DBAs. I saw new DBA cross drilled rotors crack on an S14 after 10 laps at QR, that was with stock power. The NA6 has tiny rotors, so while lil_mike should be OK on the street, I wouldn't go on a track.

You still need to sort out master cylinder and rear brakes with that kit. The one you want is the Goodwin brake kit.

Just to address the points raised on the weight issue.

The standard NA6CE single piston front caliper weighs 3 kg.
The FC/FD RX7 4 piston front caliper weighs 2.5 kg INCLUDING the adaptor brackets.

As mentioned, the kit is still under development - we are endeavouring to use readily available OFF THE SHELF parts.

Stay tuned for updates.

I had a mate with DBA Gold Cross drilled rotors on his EB XR6 and he managed to get about 100 cracks over the pair of front rotors just thru harsh treatment on the street.

Everyone I know with slotted rotors, regardless of the car, have not had similar problems.