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Rotors- how warm ?

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Old 05-26-2017, 02:05 AM
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Rotors- how warm ?

Long story short, I had a tire chain break & tear up brake pads & rotor on the front of my 93 f250. Went ahead & replace bearings, rotor, caliper & pads while I was at it. This was passenger side, only did pads on drivers side. I had replaced caliper & rotor last year. Anyway after test driving it for about 5 miles at 45mph I returned home and felt the hubs & rotors. Hubs were cool but rotors were fairly hot, almost too hot to touch on both sides. Did a couple test stops, pedal felt right. Wheels turn ok, just a tad of resistance. Never checked my rotors after driving, is that normal they get pretty warm with hardly any braking?
 
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Old 05-26-2017, 08:42 AM
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Yes, especially with new pads.

[The pads are always in contact with the rotors, even when you aren't braking. That light friction causes heat. It's why your rotor faces have a heat sink between them and your wheel rims have holes in them to disperse the heat.]
 
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Old 05-26-2017, 09:47 AM
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Originally Posted by one_bolt_short
.... It's why your rotor faces have a heat sink between them and your wheel rims have holes in them to disperse the heat.]
First I've ever heard of that. How do you explain solid brake rotors and steel wheels without holes?
 
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Old 05-26-2017, 12:22 PM
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I checked my son's truck, same year but a 350 this morning. His rotors got pretty hot (uncomfortable to touch) after a 15 minute drive, his were done by a local mechanic last fall.
 
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Old 05-26-2017, 12:44 PM
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I dunno....

https://motofaction.org/mechanical-101/what-is-the-difference-between-a-vented-and-solid-brake-disc-or-rotor/

Tech Article: Brake Cooling Singular Motorsports

More surface area (fins in rotor) = greater heat dispersal. That's just physics.

I heard long ago, like in the late '70s and '80s, when people used Cragar solid aluminum rims they had brake fade issues. Fine on Friday Night cruisers and dragsters with a parachute or three strapped on their butt. Problematic on daily drivers.

I'm cool with it though. Trust but verify. But just cuz you haven't heard of it, doesn't mean it isn't so.

 
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Old 05-26-2017, 12:44 PM
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I had a dragging drum (I adjusted it a touch too tight). Used an IR gun to check temperatures after a drive with minimal braking. If I recall correctly, the "normal" temps were in the neighborhood of 150F. That's a bit hot to touch for long, so it sounds like your truck is about the same. I'd consider it normal. I get around 60k miles to a set of pads.
 
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Old 05-26-2017, 12:54 PM
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Lol. Oh Lord. Everyone is gonna go out and feel their rotors now....
 
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Old 05-26-2017, 01:00 PM
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Originally Posted by one_bolt_short
Lol. Oh Lord. Everyone is gonna go out and feel their rotors now....
What makes you think that?
 
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Old 05-26-2017, 01:30 PM
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Originally Posted by My4Fordtrucks
First I've ever heard of that. How do you explain solid brake rotors and steel wheels without holes?
Brakes function by converting all of your vehicles kinetic energy (forward motion) into thermal energy (heat).

Your brake rotors will always be hot after a drive, especially a spirited drive where you're testing out your new brakes. The rotors have fins between the two surfaces to help dissipate heat. Wheels with holes aid this process. Solid rotors are generally only used in low speed, lightweight or rear-wheel applications where the braking load is low.
 
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Old 05-26-2017, 01:32 PM
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Originally Posted by Big_Al59
I checked my son's truck, same year but a 350 this morning. His rotors got pretty hot (uncomfortable to touch) after a 15 minute drive, his were done by a local mechanic last fall.
This, but then I saw it was the OP doing an analytic diagnostic check. My apologies.
 
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Old 05-26-2017, 01:32 PM
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Originally Posted by GoinBoarding
I had a dragging drum (I adjusted it a touch too tight). Used an IR gun to check temperatures after a drive with minimal braking. If I recall correctly, the "normal" temps were in the neighborhood of 150F. That's a bit hot to touch for long, so it sounds like your truck is about the same. I'd consider it normal. I get around 60k miles to a set of pads.
Drums I could see getting them too tight but there's no way to really adjust pad tightness that I know of?
 
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Old 05-26-2017, 06:28 PM
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Originally Posted by Big_Al59
Drums I could see getting them too tight but there's no way to really adjust pad tightness that I know of?
Right, they are self adjusting. I mentioned it because the incorrectly adjusted drum was the reason I was shooting my brakes (discs included) with the IR temp sensor.

And yes, the brakes need to dissipate a lot of energy as heat. Solid rotors are likely a cost saver used in certain applications only where performance isn't a primary objective.
 
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