Drilled and Slotted Rotors

[wardy1]

Whilst having my D2a serviced a few weeks ago it was noted that my front rotors were a bit sus. Went with the AMV recommendation to replace with drilled and slotted ones and WOW! My brakes were always good, and I'd always thought this upgrade was a bit of a **** but I'm a convert!
Stopping is stronger than ever.
Going to go for drilled rears at the next service.
Oh yes, they were only $174/pair.....plus new pads.

[eckolsim]

Yep,

Did the same and fitted TRW pads on the front. Very happy.

[Disco Muppet]

Just a heads up, Drilled rotors can cause stress fractures around the holes, not sure how common it is but it does happen.
Hope you enjoy them, about to go through the same process myself :)

[walker]

I think slotted rotors are a good thing and do make a difference. However I am not convinced on the drilled part

As Mr Muppet said, they are prone to stress fractures but on a 4wd they also fill up with mud very quickly.

The TRW pads made more difference than anything to my brakes, they are great.

[twr7cx]

Cross drilled rotors are generally only suitable for a street road car. Most track cars will avoid them due to the fractures that occur. Likewise on 4WD's going off road there can often be issues with stuff getting in there.

RDA have taken an interesting approach to this. Instead of using drilled out holes they use a combination of the slots and dimples, thus retaining more of the strength. I have these on the rear of my D2a in the gold coating and have a set in the garage for the front. The gold coating helps to prevent corrosion which can be an issue with how often my vehicle is in salt water.

[OffTrack]

I have DBA T2 slotted discs all round on mine with LR pads. I like them a lot but have noticed that they are a bit noisy under heavy braking. From what I've read this is a pretty common trait of slotted rotors.

Brakes Direct - DBA528S DBA Street Series T2 Slotted Brake Rotor (http://brakesdirect.com.au/aus/dba528s-dba-street-series-t2-slotted-brake-rotor.html)

The fronts have the "kangaroo paw venting".
DBA Kangaroo Paw Disc Rotor Ventilation Design - YouTube

cheers
Paul

[Slunnie]

X2 for the dba slots, they are excellent and are quiet for me, these work very well with Bendix pads.

[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

[Slunnie]

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

It's all straight forward, but I would recommend not getting drilled dur to cracking of the rotor. If you really want that type of thing look at dimpled instead.

[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 :twisted::twisted::twisted::twisted::twisted::twis ted::twisted::twisted::twisted::twisted::twisted:: twisted:
Love that TC light on the dash;););););););)
Andrew

[Disco Muppet]

I got told mine were "marginal" in passing last years road worthy.
I'd hate to be in the car in fully upgraded brakes :p

[Slunnie]

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 :twisted::twisted::twisted::twisted::twisted::twis ted::twisted::twisted::twisted::twisted::twisted:: twisted:
Love that TC light on the dash;););););););)
Andrew

You hoon you! :lol2:

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.

[Disco Muppet]

You hoon you! :lol2:

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 **** :p

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 :burnrubber: :p

[Steve Td5 130]

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.

[LandyAndy]

I went for genuine pads for the same reason.
Andrew

[3-Gees]

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:o
Cheers Gregg;)

[CraigE]

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.

[justinc]

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

[Disco Muppet]

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.

[Tombie]

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.

The out gassing of modern brake pads is huge muppet... The benefits are much greater now.

X drilled haven't cracked for years (was an early DBA issue and long since sorted.)

But agree slotted is all that's needed on our 4wd most of the time.

[Disco Muppet]

Compared to the effect of outgassing on older brake systems, I'd say the effect of outgassing on modern brakes is hardly an issue. One of the reasons we progressed to disk brakes was because they don't suffer from brake fade anywhere near as much drum brakes. For modern brake pads and rotors to be suffering from outgassing, they need to be getting rather hot, hot to the point where your pads are just about catching fire. At which point, I'm of the belief that having xdrilled rotors is going to make SFA difference :p
Each to their own though.

[LandyAndy]

Job ALMOST done.
2 pads to put in the last overhauled caliper,bleed/flush that caliper then roadtest.
Using genuine pads,the info sheet has a diagram which basicaly translates to dont brake heavily in the first 200km.
Any thoughts on bedding the rotors/pads in.
Andrew

[justinc]

Job ALMOST done.
2 pads to put in the last overhauled caliper,bleed/flush that caliper then roadtest.
Using genuine pads,the info sheet has a diagram which basicaly translates to dont brake heavily in the first 200km.
Any thoughts on bedding the rotors/pads in.
Andrew

Good work Andy.

accelerate to about 80kmh, firmly brake down to about 30, then repeat 4 to 5 times, allowing cooling off between stops.

jc:)

[LandyAndy]

Job completed:cool::cool::cool::cool::cool::cool::cool :
The first few brake applications at low speed were interesting,almost felt like I had greased the rotors:eek::eek::eek::eek::eek::eek:
4 or 5 applications from 80kmh sorted it out.Good pedal and a rough feling thru the steering is gone.3 amigoes didnt raise their ugly heads either:cool::cool::cool::cool::cool::cool:
Andrew