OEM vs. Aftermarket Brake Rotors and Calipers

funny, I NEVER hear about rotors being machined out of billet tool steel warping or having extra runout. I doubt we can get our brakes hot enough to thin under the pads aside from a long, hard stop, say coming down a mountain, then having the brakes on full. If they are red hot and you stop and put the truck in park and get the foot off the brake, the brakes will not thin under the pad. Also, if the rotors are of stronger material, like tool steel, thinning is very unlikely. I live on a mountain, and drop 2k feet to town, and I have changed the rotor of my '11 taco ONCE. They also got new wheel bearings, pads, and calipers at the change, $400 in quality parts at the same time. While the vanes in the rotor are nice for a casting, since they save weight, they are not needed. I have been using solid rotors in high performance motorcycles for decades.

 

You measure the rotors to determine the thickness. You are not measuring runout. I can promise you that if you put a magnet in the shavings, you are going to pull metal and not leave behind a single speck of ceramic. I know this from having cut more than my fair share of rotors. If this warping was from some sort of build up, it would be consistent across the rotor and you would never have brake dust. There are probably a dozen or so other factors that disprove the nonsense that rotors don't warp. It simply doesn't make sense. It is one of those internet legends that keeps getting repeated to the point that people believe it because it is on the world wide web. This is no different that the myth that Toyota wheels are lug centric because that idiot Gadget put it on his website when he had zero knowledge of what he incorrectly stated.

 

Our factory brakes are pretty damn good. 4 piston front calipers, decent size. Not a sports car's brakes, but a surprising amount of money spent here given they still come with rear drums. Short of actually trying to take a Tacoma on the track (why?) I cant think of any typical use that the factory system isnt going to be more than adequate for.

 

The confusion got started because there is ample evidence that pad material transfer is a thing. It does exist and it's a problem when techs like us are dealing with repeat brake pulsations. Is it a poorly cast rotor? Sticky caliper? Bad driving habits like riding the brakes and holding them too hard while stopped?

Anybody that has put a rotor on a lathe and run the bits in knows that rotors can and do warp

Both conditions exist, both are caused by excess heat

 

If rotors were machined out of tool steel, you couldn't afford them. That's one of the reasons we use grey cast iron....aside from the fact that iron castings are basically free of stresses when compared to rolled materials and they iron castings are porous which makes them hold the friction transfer layer extremely well.

 

Have you ever put a dial indicator on the rotor before you pulled if off the hub, after you chucked it in the lathe, and again after you reinstalled that rotor on the hub? I have...lots of times. And I'll bet money that no 2 measurement will be the same when using a bench brake lathe unless you've recently indexed the adapters to the lathe arbor and faced them off with the outboard cutter.

 

why would I mount a dial indicator on a lathe when I can see the same thing by running the bits in? Ive used both on-car and bench lathes and you can clearly see runout .. not just high/low spots

 

I tried solid brake rotors on my mx race bikes when i did enduros, and hare scrambles. They work well in slow muddy events, but warp in hot dry ones. For me the laser cut slotted rotors worked as good overall as any.

 

Because if you measure it, you’ll realize that the lathe does not duplicate on-hub conditions…and many times, a lathe does more harm than good.
Next time you see the bit bouncing off the rotor on your bench lathe, and after you’ve “trued” it up…measure runout when that rotor goes back on the hub. I bet you’ll be surprised.

 

I have had success with on the car cuts, but usually on vehicles like a 98 Ram 2500 because the rotors are nearly impossible to remove without a hammer. A lathe should true the rotor, but if there is an issue with the hub, then truing the rotor to compensate for the hub is kind of shadetreeish. I do remember the Sterling 827 that if you didn't cut the rotors on the car, it was guaranteed to shake.

 

That would explain why a rotor for my BMW motorcycle, machined from tool steel, is expensive. But even at and extra 25/pound for material cost, the machining cost is higher than casting, but not that much. Cast iron is selected because it is cheap, and these are low cost wear parts. Yes, rotors are low cost wear parts, designed to be used up and replaced.

 

when procar brought us our first on-car lathe…their sales pitch was that it saves time. We only used it on land cruisers and 4x4 stuff, but we didn’t realize that we were screwing thing up since we didn’t bother taking it apart to repack and adjust the bearings first.

on car lathes are great to create zero installed runout, but gotta take things apart and clean rust first…then the time time savings goes out the door.

bench lathes ALL need to have the adapters indexed to the arbor/spindle and faced off on the lathe. Only then will they fixture a rotor straight. the claim has been made for years that “most rotors are warped right outta the box”…that came from bench brake lathes. Having been in the rotor manufacturing business for almost 20 years, I can guarantee that these little toy brake lathes are not more rigid or accurate than the 20,000lb machining centers used to produce them in the first place.

If you a rotor wobbling on a bench brake lathe more than 0.002” or so and it hasn’t been resurfaced before…the runout is in the adapters, not the rotor, and I’ll put money on that.

 

It might surprise you to know that many rotors (depending on friction material used) end up thicker than they start out after a dyno cycle…

the killer of rotors is rust, and European abrasive type pads.

Adherent pads don’t wear the rotor hardly at all.

 

The on-car lathe does. I've used both to do brake jobs on lots of different cars. Did they all leave the shop with poor brakes because I didn't use a dial indicator on each one? Guess I better call all those folks and tell them to bring their cars back in

 

You said "why would I mount a dial indicator on a lathe", and you were referring to a bench lathe. If an on-car lathe would have been the subject, you would have asked about mounting the indicator on the car. As such, I was also referring to a bench lathe. I assumed we were having an adult conversation without changing the subject to suit your argument or misunderstanding about the subject matter.

Never mind. Keep doing it the way you're doing it. I'm not sure why I try to educate people anymore.

 

Asking the tough questions now..

It's OK, your brake rotors are the straightest in the world, straighter than any of us mortals. Keep up the hard work

 

A couple thoughts after reading more posts on here: Cast iron has been the choice of designers for generations because it’s a tough material and a tremendous heat sink. It’s also easy to machine and resurface. Brake pad deposition is more talked about than seen in practice. I have seen it in racing but only on mismatched rotor pad combos when someone is trying something new/unproven. Not a real thing in passenger vehicles unless you have an exotic car from the 1990’s when they were experimenting with pad compounds. If you are machining parts and you aren’t using indication to measure the results of your machining you are winging it. Cast iron rotors warp, resulting in TIR, not variation in thickness. Fun stuff, thermodynamics and metal crystalline structure!

 

You used the LTS compound pad? Hawk has several listed for the Gen3 but the LTS does appear to be an excellent blend of properties and they're currently about the same cost as the TRD PTR09-89111 pads.

https://www.hawkperformance.com/compounds/street

I like the Brembo idea in view of value. I'm wondering how well the Brembo would work with the TRD performance Tacoma brake pads 2005-current: PTR09-89111 (these fit 3rd Gen, despite Toyota's parts catalog saying they don't. See post #554 from @crashnburn80 thread

https://www.tacomaworld.com/threads/brake-upgrade-stoptech-rotors-trd-performance-pads.523829/

regarding the StopTech cryo rotors and these TRD Performance pads.). I liked the information content of his thread but the StopTech cryo rotors cost in excess of $200/each now and I cannot make that happen. I expect to go with the Brembo but I'll wait to see if anyone has experience with these and either ceramic pad. I'll talk with Hawk or a local dealer in the meantime.

 

Do you have parts numbers for the Toyota "good" rotors and pads vs. the economy rotors and pads? Thanks

 

This is excellent information and I do appreciate the efforts you make here to educate people. You certainly have my attention and I must confess I have not treated disc brake work as specifically as this post indicates we should so I clearly need to improve my level of knowledge and behaviors. Indexing the rotor to the hub makes complete sense but I never thought of this before. I own a dial gauge but have never used it for this purpose but this practice must clearly change. I have lived in the rust belt my entire life and front end work seems to be impacted by this climate the worst. Undercarriage work of any type fits this phrase.

I have to interpret this as my need to disassemble the entire front end (always required), remove/reduce built up rust and paint w/POR15 to reduce the risk of its return but this is not so easy to do with a new hub bearing so I have to think about this carefully but their Metal Prep will help - we just can't access all the exterior surfaces - and I've always been told that choosing to press the bearing on the hub requires balancing afterward so I have refrained from buying the separate parts. I've also been giving strong consideration to building an electrolytic rust removal tank during the past few months and a plastic livestock watering could hold a lot of car parts that need this type of attention. The obvious problem is this method of rust removal is more time consuming than media blasting. I'm assuming light surface rust can be properly pre-treated with an appropriately sized diameter wire wheel followed by POR15.

If there is additional information to add to this please do.