Many a car has ran fine with disks and no dust shields. As the name implies, they help shield the disks from dust, rocks, and leaking fluid that may degrade braking and potentially damage the rotors or other components. The choice is, “what are you comfortable with?”
All factory built cars come with them. Few hot rods have them. You can decided yourself, what you want to do.
I have never added dust shields on any disc brake conversion that did not come with the dust shields. However, if the disc brakes were donations from a vehicle that already had the dust shields, I did not remove them unless the shields were damaged. I have never replaced a damaged shield, and if one side was removed, both sides were removed. Guess maybe I was too lazy to create dust shields for disc brake conversion kits that did not come with the shields. I tend to put a ton of miles on the stuff I build, never had a problem with missing disc brake dust shields.
The Willys in my Avatar has narrowed Econoline axle with a GM metric disc conversion and no shields. I don't know about dust, but in a heavy rain, my brakes are for ****! I think the splash from one wheel floods the opposite disc.
I think they're more about keeping brake dust in than road dust out. I've always thought that that's the Good Reason to go with the Real Reason of finding more uses for open-loop recycled plastic.
I did not add dust shields when I converted to disks on my ‘54 country squire, same when I upsized the brakes on my mustang. On my tundra, the dust shields turned to dust themselves years ago. all of these have been fine and I don’t miss the shields in any way.
That's what I thought too, especially for alloy wheels. Keeps the wheels clean. Brake dust can be hell on alloy wheels. Some wheels seem to need them, some not. It has to do with air flow direction through the wheel when it is rotating.
all the OEM dust shields I've seen cover the inside of the rotor, not the outside, so they do nothing for brake dust on wheels.
It seems we are talking about different things. Some cars here in Australia have a shield between the rotor and the wheel to keep brake dust off the wheel.
I suggest the inside dust shields help prevent road trash from getting picked up and wrapped around the rotor.
I'd guess that they kept trash out but also shielded the ball joints from radiated heat under extreme use.
I never use them. And actual that vast majority of factory disc applications had no dust shields. Like my 97 Monte Carlo for example
just for fun I looked at a 1998 Monte Carlo on bat, which has nice pictures of everything, and no dust shields. Interesting. I've never noticed any other modern cars not having them.
I can say I have never seen any factory dust shields between the rotor and the wheel, but then again, I don't mess with too much modern stuff. I have seen aftermarket pieces that were intended to be installed between the rotor and the wheel, but those were mostly designed to keep the brake dust off the wheels. I would think that the dust shields would reduce the rotor cooling to some extent, having both sides of the rotors covered would be 2x as bad. I have also seen a lot of older cars with messed up dust shields that someone had poorly attempted to straightened, or had been removed. I could see where the rotors could be covered with splashed water under certain conditions, but a touch of dragging the brakes before you needed them would solve that problem. I suspect the entire reason they have been installed on new vehicles for years was because some bureaucrat, sitting in some office, with no understanding of anything automotive, thought they needed to be there.
or they do what will be necessary to prevent lawsuits that would cost them more than the cost of adding the parts, more likely.
It seems counterintuitive, but industry is set up actively to generate the most expensive practical methodologies. The reasons for this are complex, and elaborating them will take us into serious OT territory. But for this to work industry players have to be prevented from breaking ranks and undercutting the rest, very often through legislation.
From one of the brake gurus on Gr***roots Motorsports “from the OE side, consider this: if i could eliminate two part numbers from the bill of materials for my vehicle, plus the ***ociated cost and weight savings from deleting those parts, i'd be a berkeleying hero. the reasons OE's use them have all been touched on by previous posts. it's a combination of splash and gravel /dirt protection, thermal protection for suspension parts (don't want to liquidate all the ball joint / tie rod end grease or burn off the boots), and airflow management.” Dan
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