Thread: Drilled and Slotted Rotors

Originally Posted by LandyAndy

Already here and ready to fit Slunnie.
Isnt the cracking caused by quenching of the red hot rotor in water???
Unlikely to happen unless one drives like a rally star off-road.
Not a hard on the brakes man myself,was told my rotors were close to being needing replacing when I first bought the D2,only needing to do it now at around 80000ks 7 years later.
The most wear is since chiping/intercooler/exhaust modifications
Love that TC light on the dash
Andrew

You hoon you!

If you have them then! But, quenching isn't related to the cracking, I suspect it has more to do with stresses in the rotor when hot and the Xdrilling being stress raisers(concentrator) in the rotor, so the cracking radiates from all of the Xdrills.

Originally Posted by Slunnie

You hoon you!

If you have them then! But, quenching isn't related to the cracking, I suspect it has more to do with stresses in the rotor when hot and the Xdrilling being stress raisers(concentrator) in the rotor, so the cracking radiates from all of the Xdrills.

Spot on.
Slotted rotors are good in that they help pull brake dust away from the pads. Less debris = better contact area.
Flip side of that is you're still taking bits off your rotor so they're not quite as strong as just blank rotors.

Cross drilled rotors were born out of asbestos brake pads that created gasses that would force the pads away from the rotors, so the holes were drilled to allow the gasses to escape. Relevant in the 50s, not so much now.
Other than that drilled rotors are just a bit of bling ****

As Slunnie says, the drilling of the holes creates stress patterns. With the constant heating up and cooling down of the discs, cracking occurs.
Rotors that are made with the holes cast in them as opposed to drilled are a bit better, but there's still really no performance benefit to drilled rotors. That said, it's unlikely that a D2 will crack a good drilled rotor, unless you're really giving it a hammering

I have had slotted rotors on my wife's D2 for 2years very happy with them,
I choose to go with a softer pad to help preserve the life of the rotor.

I went for genuine pads for the same reason.
Andrew

Hi Andy,
I fitted DBA slotted rotors all round last year and very happy, quiet ,smooth braking and little dust, I used TRW pads as recommended by brake dudes. Disco breaks are fantastic, I drive other 4wd's at work and some are dam dangerous with their brakes
Cheers Gregg

Originally Posted by LandyAndy

About to upgrade to slotted/cross drilled rotors all round this weekend.
Any pitfalls to watch for or any tips greatly appreciated.
Thanks
Andrew

I fitted Gold cross drilled and slotted rotors to my 84RR when I had it. Not a difficult task. Greatly improved braking and brake temps greatly reduced, less brake fade when used hard, I had no problem with any cracking and did use them hot in mud and water.
When I replace the Defender rotors it will be with slotted and dimpled rotors, same for the Statesman and BMW.
Look at dirt bike rotors they are effectively the same and have no trouble with cracking.

Fitted plenty of slotted and drilled too over the years. Some were fitted due to anticipated hard use towing vans and horse floats etc.

Not 1 case of cracking or anything.

JC

Like I said, only if you REALLY hammer them.
Most of the accounts of cracking I read were on Ricer forums and often after track days.
Doesn't change the fact that there's no benefit from xdrilled rotors.