this post was submitted on 14 Aug 2023
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For now its a daily driver, but I do intend to slowly build it out to be a drift car. I've heard that drilled rotors can form micro-cracks around the holes and need to be replaced every so often. What yall think?

Slotted and drilled: https://www.rockauto.com/en/moreinfo.php?pk=11610153&cc=1431309&pt=1896&jsn=3866

High carbon: https://www.rockauto.com/en/moreinfo.php?pk=1023160&cc=1431309&pt=1896&jsn=3875&jsn=3875

2005 mustang in case that matters.

ty :)

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[–] empireOfLove@lemmy.one 5 points 1 year ago* (last edited 1 year ago) (2 children)

Your rockauto links got truncated and don't work.

Let's think for a bit about why we slot and drill rotors. Slotted/drilled rotors do little to nothing for cooling- the surface area they add is minimal and the airflow passages tiny. They are instead designed to allow wear debris and any gas released from the brake pads during hard, super hot stops to be vented away from the friction surface, effectively "cleaning" the pads with every wheel rotation and allowing more consistent brake performance.
Their downside is this cleaning action tends to pull pad material off too, so your pads wear faster. Not too big a deal for track tho since you should be inspecting pads and changing them frequently during track use.

Generally these features are more important for non-asbestos organic brake pads which can offgas a lot, and when this gas becomes trapped between the pad and the rotor it acts like a lubricant and reduces braking efficiency. Ceramic and metallic pads do offgas and will sew some benefit, but not to the same extreme since they handle heat better anyway.

Yes, they can crack around the holes. Any feature like that can be a stress riser and propagation point for cracks when under high thermal stress. However you'll be able to see the cracks in the polished rotor surface before your rotors are likely to fail- that cast high-carbon steel is surprisingly strong and resilient. And lets be real- Rotors aren't that expensive. If replacing a $250 set of rockauto rotors every year or two is an undue expense... uh, no offense- but you probably shouldn't be tracking your fucking daily. This game is pay to play.

So where does that leave you? The honest answer is "you won't notice". The drilled rotors will improve pad performance a bit, and while cracking is possible it won't be dangerous. They will not improve cooling enough to see a noticable improvement, and frankly you will far and away be limited by the calipers piston size and hydraulic system force long before you'll reach the pad and rotor's limitations, and when you do hit your heat limit, holes and slots won't help.

Honestly, I'd get the normal high-carbon rotors for now. You can get fancy later on when you want to do a proper brake system upgrade with significantly larger rotors, calipers and pad area, which will see real improvements in brake performance and where the pad cleaning action of slots will start to matter.

[–] strawberry@artemis.camp 3 points 1 year ago

alright thanks so much :)

[–] strawberry@artemis.camp 1 points 1 year ago (1 children)

and i imagine getting cheap "perfomance" rotors is worse than just getting normal ones right?

[–] empireOfLove@lemmy.one 2 points 1 year ago* (last edited 1 year ago)

Maybe. Maybe not. Rotors are pretty simple and hard to fuck up the metallurgy on, they're the one thing I don't actually mind going cheaper on. It's not like you're buying OEM carbon ceramic rotors for your Lamborghini.

The biggest issue with cheaper rotors is poor runout tolerance (how flat they are). Sometimes you get a wiggly one and it'll have poor performance 'cause the pad doesn't make full contact, plus makes your car vibrate weird when you stop. They can be turned down backnto flat by a shop though, or just warrantied.

[–] RightHandOfIkaros@lemmy.world 2 points 1 year ago

I have drilled slotted rotors on the fronts of my 1968 Ford that came with the Wilwood disc conversion kit. There isnt really a huge noticeable difference from the drums that were on there before, for regular street driving that is.

If your car never goes to a race track, the only reason you'd really consider anything other than OEM style rotors is looks or price. But youll probably be replacing pads and rotors faster with drilled slotted rotors than OEM style.