Are You Cracking Dba Rotors?

[Adz]

Oh o.

I have just put DBA 4000's on the front and rear with Hawk HT-10's front and rear. Might have to keep an eye on them. They cooked the fluid fisrst time at the track but thats my fault for not flushing and changing the fluid with some good stuff. So what does the paint on the rotor tell me. So the set up is a R32 GTSt with UAS adapter plate to run DBA 4000 GTR rotors with Hawk pads.

Cheers

[Duncan]

Gary from what I've seen the difference is simple.

slotted DBA 4000 crack.

unslotted 4000 and any 5000 series seem to be OK, I'm sure there are differences in design that is making the difference. there have been waaaay too many slotted 4000s crack in the last 18 months to be coincidence and dba are doing their business real damage in the enthusiast market by ignoring and denying the problem.

[dezz]

Interesting read.

I'm in the process of upgrading my brakes and was thinking, RDA or DBA slotted rotors front and rear, QFM KR750 pads, and braided lines all round.

Now having read all of this it sounds like thats a bad idea as they're just going to crack....So my question is, what options are available to me? Doesn't seem to be many...

Car is a S2 R33 GTS-T, 250~rwkw, daily driven so need a pad that will work on the street as well as take some track work.

[Brockas]

Another person here moving away from DBA 4000 slotted rotors.

2 track days, MASSIVE crack in one, hairline cracks all throughout the others.

Cool down laps + cool down afterwards didn't help.

[Kaido_RR]

they claim they are 'heat treated' I'll give them some fking heat treating. my next set will be project mu or endless. I have a new set of RDA sitting here and will give them a crack but I'm not putting too much hope out there.

+1 for endless, running their slotted disc with my ap's and they love the abuse

[Sydneykid]

Gary from what I've seen the difference is simple.

slotted DBA 4000 crack.

unslotted 4000 and any 5000 series seem to be OK, I'm sure there are differences in design that is making the difference. there have been waaaay too many slotted 4000s crack in the last 18 months to be coincidence and dba are doing their business real damage in the enthusiast market by ignoring and denying the problem.

You could be right, I am still using the 4000 series rear rotors that are at least 3 years old, compared to the third set of front rotors but they are 5000 series. Maybe the newer 4000's are the problem.

Cheers

Gary

[Roy]

But which car is it that is using DBA4000s and how many kms has it dont the last 3 years , including track days?

[GTR-N1]

Ok I recently became a victim of the dreaded cracked DBA 4000 rotor club. Wasn't overly impressed as they were near new. But with the rotors on the bench and inspecting the rotors with DBA it appears as though there could be a fault with the caliper and the use of the rotor…combined with the fact they were used for a hard stop from over 200km/h when cold at an airport run.

So looking at the rotor the outside face (the side that cracked) has obviously run hotter then the inside face. This is evident by the blue hue in the rotor face as well as the paint markings on the outside of the rotor where two of the three thermal paint stripes have been completely burnt off. All whilst the inside face is only on the middle temp paint with all three stripes still being visible and a shiny silver as you would expect.

So, differential expansion as a result of a big temperature gradient hasn't helped these rotors. Combined with the big hit of heat when cold. The rotors are off for some more testing and inspection. Will post up the feedback when I get it.

But some things we all may want to check. Make sure your pistons are not dragging the pads on the rotor. This is a possibility in my application even though the calipers have been rebuilt. Perhaps where was a bit if run out (doubt it) or the design of thw wheel limits airflow to the outer face (doubt it) Most likely pistons rubbing the pad on the rotor a little, or when I jump on the brakes the outer pad works a lot harder then the inner pistons.

Now finally, especially since its been a buzz topic lately. Be careful if you are going to be running brake ducts. I trialled some ages ago but took them off because I was not happy with them, and decided I would wait and do it properly when i get my new Brembos on. But if you are running DIY ducting ensure that the ducting is directed the centre of the rotor and the air then travels up through the vanes of the rotor. Simply ducting it towards the inner edge could lead to one side of the rotor (inner) running cooler then the outer face. This gives rise to differential expansion which is a known problem for stressing steel components. The main reason I removed my ducts was that I wasn't satisfied that in the wet they woudlnt be guiding water/mist onto the inner edge causing massive temperature differentials and thermal shock to the rotor. I had not really considered that air itself could have resulted in a 200degC temperature differential across the rotor.

Hi,

I've been reading all these posts with great interest up to page 4-5.

I'm due for front rotors soon and yes, learning along the way, I've decided to go for G4 or DBA5000 where the slots don't go up to the edge

Two Reasons

1) Being a chemist, I've noticed that tablets that are scored (ie slotted) across the middle are harder to break if the score doesn't reach the edge and

2) Having cut glass for leadlight many times, it's much easier to break the glass if I start the glasscutter from right over the burr of the edge - meaning it's hard to snap the glass panel unless I start from right at the edge.

Therefore the newer DBA4000 rotors are simply a very bad design - and they'll need to change it quick.

As they say in business: it takes 10 years to build up trust - and 10 minutes to lose it!!!

Chow

[Sydneykid]

Hi,

I've been reading all these posts with great interest up to page 4-5.

I'm due for front rotors soon and yes, learning along the way, I've decided to go for G4 or DBA5000 where the slots don't go up to the edge

Two Reasons

1) Being a chemist, I've noticed that tablets that are scored (ie slotted) across the middle are harder to break if the score doesn't reach the edge and

2) Having cut glass for leadlight many times, it's much easier to break the glass if I start the glasscutter from right over the burr of the edge - meaning it's hard to snap the glass panel unless I start from right at the edge.

Therefore the newer DBA4000 rotors are simply a very bad design - and they'll need to change it quick.

As they say in business: it takes 10 years to build up trust - and 10 minutes to lose it!!!

Chow

It's catch 22 with slots. If you don't take them to the edge, then they simply don't work as well in their wiping function. The trapped gas and loose material can't escape the slot, so it builds up under the outermost portion of the pad (the outer end of the slot). This decreases the braking performance and causes uneven pad wear.

Cheers

Gary

[MrStabby]

It's catch 22 with slots. If you don't take them to the edge, then they simply don't work as well in their wiping function. The trapped gas and loose material can't escape the slot, so it builds up under the outermost portion of the pad (the outer end of the slot). This decreases the braking performance and causes uneven pad wear.

Cheers

Gary

The G4 kit doesnt take the pad all the way to the edge, so it should avoid that problem. Also the radial direction of the DBA4000 slot seems to contribute to the stress build up. On other designs the slots are about 45 degrees to the tangent, rather than being almost 90 degrees.

[BOZ22N]

Hi,

Just got a price on getting some blank DBA heat treated rotors (4000's????) and getting SCBC to machine some wiper slots in them more like the project mu's for $630.00 a pair to suit the front 324mm brembos.

Do you think these will have a greater chance of not cracking or is the cast metal just not up to the task of hard braking?

Cheers,

Ryan

[djr81]

Hi,

Just got a price on getting some blank DBA heat treated rotors (4000's????) and getting SCBC to machine some wiper slots in them more like the project mu's for $630.00 a pair to suit the front 324mm brembos.

Do you think these will have a greater chance of not cracking or is the cast metal just not up to the task of hard braking?

Cheers,

Ryan

Well to be perfectly honest for the amount of messing about & the cost - why don't you just import some Project Mu rotors & be done with it?

As has been said it is not believed to be a metallurgical problem moreso a problem derived from the use of the small return slots around the outer circumference of the rotor.

[Roy]

Stoptech now do std replacement, single piece 324mm rotors. At least that way they are proper curved vane, not like the Project U etc whichg are just straight vanes or intermittent vanes (Depends on the ones you are looking at)

[djr81]

Well that is some good news. The Stoptech gear certainly move some air through the rotors.

Not exactly light weight, however.

But the big question is: How much?

The one disappointment of the Priject Mu 2 piece was the lack of proper vanes, although they are better in that regard that the DBA gear.

[djr81]

Justa quick aside: One of the best ways of moving more air is to get a larger diameter rotor.....

[BOZ22N]

I carnt run bigger rotors the calipers will foul on my rims(super advans). I will get on to stoptech on monday and get a price.

[Duncan]

rims are much cheaper than brakes aren't they?

[whitesky]

I can add my same experiences to this thread too.

I cracked 2 sets of 296 Dba's before I went to 324mm on the front of my 32GTR.

I have now cracked my second set of 324s. After cracking the first set, I ran ducting to the centre of the disks, and still cracked the disks.

So.... DJR81 like you I'm swaying towards the Project Mu's. How have you found them ?

And more importantly have you run them at barbagello more than once ? I can get a year of sprints out of a set of disks, but as soon as i take them to a long circuit where braking from a high speed is involved, they crack, (from the slots in the 4000's.)

Stoptechs are a second thought, but they seem to be about twice the price ?

The most annoying thing is, that if i had not given dba the benefit of the doubt I could have saved a lot of money or upgraded seriously with the same dollar amounts i have wasted.

Anyone else using Project Mu's ?? or will i crack them too ?

[GTRsean]

Got some advise regarding cracking/crazing rotors from a brake joint in Penrith.

He said that cryogenically treating them makes them less likely to go to crap out, but it doesn't make them last longer.

Might try it out on the next set of rotors.

[BOZ22N]

I think that i am going to get a set of RDA's and save the money i would have spent on custom DBA's or stoptechs. Then next set will be DBA 5000's or similar.