I'm track prepping my street car for HPDE. Swapping to the 1.8 brakes all around. Intended use will be mostly street driving with 5-6HPDE's per year.

Anyway, the brake dust shields are in the way. I'm not a fan of bashing and cutting. Bashing is a good way to make press-fit components loose. Cutting is a good way to create razor blades on the car.

So, thought I would just remove the things completely. Common practice in the Spec Miata world. Is there any real downside to this on a street car in a dry-ish climate that will be getting frequent brake inspections?

I did search. Surprisingly, not much turned up.

 

you dont have to remove the fronts (and shouldn't), you need to more or less remove the rears.

 

That^
You can actually trim them if you want and they will still clear. Easy if you have a plasma cutter. But an angle grinder would work.

 

Curious why? I've been tracking my car without them and others in the past that had aftermarket BBK's.

 

I thought these help vent air around the rotors to aid in cooling them. If spec guys remove them do they add a more efficient brake duct system to replace them? Or are they just not necessary period.

 

they scavenge airflow and dump a little bit onto the brakes.

 

Man, I'm seeing all kinds of stuff out there in the ether.

Pros:
1. Splash shield. Prevent rotor warping if you splash water on them while hot.
2. Heat shield. Protects your ball joints and tie rod ends from heat.
3. Dust shield. Either keeps dust/debris off the brakes or keeps brake dust from your suspension/engine compartment. About a 50/50 split in the ether.
4. Brake cooling (assuming it's able to capture air). Obviously, ducted plates connected to high-pressure air with a hose (like Andrew's prawns) offer significant cooling. I've noticed that with slightly wider than OEM wheels, the cooling "scoop" on our OEM shields seems pretty well blocked.

Cons:
1. They get in the way if you do a lot of front-end/brake work (i.e., track car).
2. Unsprung weight (a tiny bit).
3. Inhibit cooling if they can't scoop air. Seems a lot of tracked M3's with mega-wide wheels pull them.
4. Get in the way of BBK's.

Usual. Conflicting opinions. Little data. They must do something, because cars could be built more cheaply without them.

Think I'll just take Brainey's advice. Chisel off the rears and slightly bend the bottom of the fronts. Looks like the quickest and easiest thing to do that doesn't create a future OSHA hazard.

 

Brake ducting is not allowed in Spec Miata.

 

Don't they just unbolt?

 

IIRC I just bent mine a little bit to fit 1.8 brakes. Worked fine.

 

Thing that make your car harder, better, faster, stronger are not allowing Spec Miata.

 

The fronts unbolt after removing the hub. The rears are press-fit.

Bending in the bottom a bit on the fronts will work fine. After scoping how close the tie rod end is to the brake disc, definitely seems worthwhile keeping as a heat shield.

Rears seem to require either a lot more bending, a lot of cutting (leaving behind the aforemention OSHA hazard) or removal.

 

Good point.. I only have 1.8 fronts on my car ATM until I buy some rotors/pads for the rear. Let us know what you decide on!

 

Removing them properly in the rear requires pulling the hub off the axle splines -- something that they are reluctant to do. I wound up cutting them off as close as possible to the hub. So yes, it makes razor blades but fortunately razor blades that are buried pretty deeply in mechanical bits and unlikely to catch fingers.

Removing them in the front is easy, and replacing them with TSE prawns is a good idea.

--Ian

 

In the Wheeler book, he says they are not needed. Spec Miata rules are not made to make the fastest Miata, they're made to make 4 variations of Miata close to the same speed.

 

yes, so never copy a slow spec miata.

 

For what its worth, I took them off my car when I did the 1.8 brakes. Car is daily driven.

 

Took them off my '91 when I put on sport brakes, never regretted it. Rears can be removed by splitting the shield at the smallest dimension on the hub with a cold chisel and "unwrapping" them with channel locks.

 

Rears are gone. Did exactly what you suggested. They even had a little notch at that location to get the chisel started -- as if the Mazda design engineer didn't really want those things on his rear suspension.

 

On my street car the fronts were so rusted I ripped them off by hand.