Brake Rotor - Meyle or Zimmerman

[e30cabrio]

I had two piece drilled & slotted DBA rotors on the Z. I bought Centric rotors and EBC red pads for the front of the X.

[ard]

Originally Posted by TiAgX5

Ricer boi? Drilled rotors have been around for over 50 years, long before the '90s import drilled rotor craze.

As for the slotting, I use the X to tow a large trailer from time to time (in severe FL rain). The slots prevent vitrification of the pad surface caused by hauling 12,000 lbs down from 80 MPH. Water dissapation from between the rotor/pad surface is also reassuring. Nothing like hitting the brakes at hwy speed during a downpour and nothing happens for a second or two.

If you choose not to use them, DON'T. Just don't dismiss everyone who does as "poseur".

the issue is drilled ***AND** slotted.

You use one or the other.

But there is no application where both are an advantage...imo

Good article JCL

A

[shawndoh]

Zimmerman, imo.

[TiAgX5]

Originally Posted by JCL

I think that the primary benefit of drilling rotors decades ago was in reducing unsprung weight. There was a secondary issue related to pads outgassing, but we don't use those pad compositions any more, so that is moot.

You may want to look into SAE technical paper 2006-01-0691 "The Effect of Rotor Cross Drilling on Brake Performance". Some good info. While there was a benefit in cooling, the same test results showed the rotors can run hotter (due to less thermal mass), no impact of outgassing, no difference in wet weather performance, 25-30% more pad wear, and up to a 50% reduction in thermal fatigue life.

For the rotors you show, the anti-rust coating can be good (but it will quickly wear off the friction surface). I would be most interested in the thermal performance, and the vane design. OE rotors weren't designed to be drilled, so it is intriguing that they mention OE specs. Maybe they aren't using the OE vane design.

Read it back in '07, it was hardly a search for the truth in the solid vs drilled vs slotted rotor debate. Here's why.

All data collected by the 2 GM engineers was obtained using semi-metallic pads, the primary functional mechanism of this type of pad is abrasion rather than adhesion. By contrast, non-metallic pads (read-the correct pad for drilled or slotted) are more biased towards an adhesive mechanism relying upon a transfer layer of material deposited on the rotor. Just this fact SEVERELY limits the relevancy of their test results, only a total idiot would run a semi-metallic pad on slotted or drilled rotor in a test like they ran. Semi-metallic pads are designed to operate correctly up to around 550 deg F at the contact surface, once temps above that are reached, they are subjected to severe overheating and a cheese grater effect, caused by the holes/slots.

These guys work for GM, the auto manufacturer who designed the Vette rear brakes that have pads only contacting half the rotor friction surface.
Not someone I would consider the last word in rotor debate.

The only reason I would have that paper in my "reading room" would be for the event I run out of toilet paper.

Spoke with a tech twice before purchase and asked about vane design, was told it's similar to the Brembo design. Left and right discs have separate part #s due to vane config and directional machine pattern.

[JCL]

I understood that all pads rely on a combination of adhesion and abrasion. The weighting changes with pad composition, but both are in play.

Did the supplier tech advise the heat saturation limits of their rotor design, with and without drilling (ie, with and without the effects of the reduced thermal mass)?

[Gregory891]

Look at which rotors are factory OEM (E53 are Ate) and if you go aftermarket, to make sure that they are TUV approved. When you have the ability to drive anywhere from 120 or 140 km/hr (the Autobahn is limited in many areas) and "as you wish" - you want parts that work.

I'm not sure that many of the cross drilled rotors come (for long term use) with a TUV paper, Zimmermann and Ate certainly do.

[TiAgX5]

Originally Posted by JCL

I understood that all pads rely on a combination of adhesion and abrasion. The weighting changes with pad composition, but both are in play.

Did the supplier tech advise the heat saturation limits of their rotor design, with and without drilling (ie, with and without the effects of the reduced thermal mass)?

Agreed both are in play. Pointing out semi-metallics weigh more toward the rotor wear side, and overheat (+550 deg F) drastically accelerates the rotor failure vs carbon/brass/ceramic matrix pads.

Heat saturation #s were not discussed. Just verified they are produced from G3000 grade materal, with only 1 hole between each vane, slot position/angle leave 2 vane spaces undrilled between each holeset.

I was looking for rotors without a high void/mass ratio to keep the heat sink effect high, while still having the pad wiping effect for responsive inital bite in heavy rain. I've had pad hydroplaning in the past and this was the reason for voided rotors. BMW has addressed this issue on newer vehicles by lightly applying the brakes regularly to clear water from the pad/rotor surface (activated when the rain sensor "sees" water on the windshield).

[3Series]

Originally Posted by shawndoh

Zimmerman, imo.

Thanks I went with the Zimmermans.

[TiAgX5]

Installed the BrakeLab rotors with Cool Carbon pads (refinished pad carriers/calipers). Burnished/transferred pad materal.....

[TiAgX5]

Originally Posted by ard

the issue is drilled ***AND** slotted.

You use one or the other.

But there is no application where both are an advantage...imo

Good article JCL

A

Came across a car on the road today with drilled/slotted rotors.

You might want to cantact AMG and tell them the SRS GT is ricer, or there are NO advantages to doing both.

The CLA45 will have them too.