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Cross Drilling Brake Disc's

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tang0 Proficient

tang0

Posted
Posted

cross drilling and slotting will do a couple of things to a disk, a pro being that you'd be getting rid of heat quicker, and big con being that you are weakening the disks a LOT .. obviously the choice if yours but i dont think i'd like relying on weakened disks for my life !

|PRESA| Proficient

|PRESA|

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cross drilling and slotting will do a couple of things to a disk, a pro being that you'd be getting rid of heat quicker, and big con being that you are weakening the disks a LOT .. obviously the choice if yours but i dont think i'd like relying on weakened disks for my life !

So are you saying that any cross drilled disc are weak? or are the ones you buy already cross drilled/slotted made of a stronger material?

leech_ Grand Master

leech_

Posted
Posted

crossed drilled are meant to be weaker on the whole and many people have seen them crack after extensive use (not just on the track to i might add). Personally i would keep them standard and go buy some dba 4000 + get some better brake pads then the standards.

|PRESA| Proficient

|PRESA|

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crossed drilled are meant to be weaker on the whole and many people have seen them crack after extensive use (not just on the track to i might add). Personally i would keep them standard and go buy some dba 4000 + get some better brake pads then the standards.

What is dba 4000 +?

I'm using some Motul Rb70 (I think it is) brake fluid and I got a set of Bendix Advance pads going into it. Do you think I'm going about it the right way so far?

And would this brake set up be suitable for some hard laps at a track?

drifto Collaborator

drifto

Posted
Posted

Just my experience so i'll share it

Bought my car runnning standard rotors and Bendix Ultimate pads. It was good on the road but under extreme conditions like Mt Bulladelah or Mq Pass they struggled.

The stock rotors where to worn to skim again so i needed to replace them. Standard replacement cost the same as EBC half drilled and slotted of the same size so i got em.

Matched with EBC red stuff in the front and green stuff in the back plus 5.1 race/rally fluid i hit the Eastern Creek with high expectations.

It never had alot of bite under hard breaking or feel but i was still running ABS. After 5 laps the breaking distance increased slightly but the car became unstable breaking into turn 2 and the hairpin.

After driving Duncans 32 with big rotors and a pad combo put together by RACE BRAKES in Sydney i was even more dissapointed with my set up. The difference was unbelieveable.

Returned the car to the workshop that set it up. Rear brakes at some stage had been on fire. Fronts had not been up to temp in time and caused rears to over heat which then put all the effort back to the front whilst the rears kept cooking and doing little breaking.

Changed to Endless street spec "Y"pads in the front and standard Bendix Advance in the rear for street driving.

After hard breaking massive shuddering was occuring.

The hotter they got the worse it got.

Had the disc skimmed and it was fine until i got them really hot again at Wakefield and they again shuddered.

Examined the rotors and noticed tiny 3mm-5mmcurved hairline cracks all the way around the face of the rotors.

Had them replace with DBA slotted rotors and Bendix ultimate pads.

So far so good.

Bass Junky Grand Master

Bass Junky

Posted
Posted

The cross drilling weakens the surface of the disk more than slotting.

If you read through the DBA website they don't recommend the Cross Drilled for circuit.

The problem is that when they cool down, the area around the drill cools at a different rate to the rest of the disk as there is more surface area to radiate heat.

That area cools faster and hairline cracks form.

I had an 88 VN Commodore with Slotted and Cross Drilled on front and rear and the fronts had cracks all over them.

BASS OUT

Roy Grand Master

Roy

Posted
Posted
 

After driving Duncans 32 with big rotors and a pad combo put together by RACE BRAKES in Sydney i was even more dissapointed with my set up. The difference was unbelieveable.

Bugger, Duncans stealing my car and letting lunatics from the deep south drive my car again:)

Funny enough im about 1wk away from finishing another reco of my brake setup with now Comp 9 pads...see Here for the Tutorial i just posted.

Drifto...did you get the seat in ok... ive finally got my rails spot on now, so if you need piccies or help let me know:thumbsup:

blind_elk Grand Master

blind_elk

Posted
Posted
I'm coming up to a pad change soon (Putting in some Bendix Advances) and naturally I'm going to get the guys to machine the disc, is it possible to cross drill or slot standard disks?
Yes, they can be slotted (I'm tracking down the name of a guy who can do them for you). What I have found is that slotted rotors are virtually "self-cleaning", ie if you glaze up the pads and rotors, the slots clean the pads, and the clean pads clean the disk.

Meantime, I'd be fitting Ultimates, rather than Advances. My reading of the Bendix info is that they are for a Joe Average driver in a family sedan; they are not a performance pad (someone correct me?).

GTRgeoff Grand Master

GTRgeoff

Posted
Posted

While you can spend a fortune on DBA's, for a little over $500 you can get the RDA stuff with slotted fronts. Irecommend the Racebrakes products. RB74 front and Comp 2 rear with motul DOT 5.1 fluid. Haven't had a brake fade yet.

drifto Collaborator

drifto

Posted
Posted

SH?T

Sorry Troy, i meant you

How's Duncan anyway i don't think i've even met him.

The seat is megga!

Got Sparco rails to fit up perfect, I now have a good two inches head clearance and my arms can steer instead of trying to stop me falling out of the seat. Although getting in and out is an art form.

tang0 Proficient

tang0

Posted
Posted

just that i would not personally like to drill standard rotors and rely on them to save my life when i need it ..

however, i'm all for installing some drilled and slotted rotors that have been designed for the job ..

So are you saying that any cross drilled disc are weak? or are the ones you buy already cross drilled/slotted made of a stronger material?
Duncan Grand Master

Duncan

Posted
Posted

haha I did what? Dorifto we must have crossed paths one day but I'm not sure, where you at OP on Sat? Kel and I were there in the 350z

Anyway....some people have had trouble with cracked cross drilled rotors so probably give them a miss.

You can most certainly have your rotors slotted though, this shouldnt have an impact on strength if done properly....DBA 4000 for instance start life as a blank rotor and have the slots machined into them later. check out www.dba.com.au

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