Brake dust shields

RS2000 · Postby **RS2000** » Tue Jun 10, 2014 10:10 pm

Are there any positive reasons to retain the brake sheet metal dust covers on a track only NB ?

I'm about to replace rear wheel bearings, so it's a good time to remove them to allow more cooling.

Cheers

manga_blue · Postby **manga_blue** » Tue Jun 10, 2014 10:52 pm

They're shaped to direct air towards the centre of the rotors where all the rotor vanes start. The cold air gets flung out through the vanes from there. That's how the front brakes get cooled.

RS2000 · Postby **RS2000** » Tue Jun 10, 2014 11:03 pm

My car doesn't have any front dust covers ?? Must have been removed by a previous owner.

I don't think the rear covers would direct air anywhere.

Cheers

manga_blue · Postby **manga_blue** » Tue Jun 10, 2014 11:39 pm

It would cool a bit better if you had the front ones. Otherwise you can find shields to hook up to ducts.

e.g. http://www.flyinmiata.com/index.php?dep ... r=14-76300

RS2000 · Postby **RS2000** » Wed Jun 11, 2014 6:29 pm

Thanks Manga,

Ducts & special backing plates would certainly help cooling, but I'm not yet convinced the OE shields would cool better than no shields.

From what I've read, OE shields generally impede air flow to the discs. Perhaps the MX5 ones are shaped like they are to help improve reduced air flow.

Cheers

project.r.racing · Postby **project.r.racing** » Wed Jun 11, 2014 6:47 pm

first time i've ever heard that.

manga_blue · Postby **manga_blue** » Wed Jun 11, 2014 7:19 pm

Well there you go then. You learn something new every day.

Can't speak for other models but the OEM covers on my NA8 have big forward facing scoops to drag air down to the start of the vanes. Mazda did that to improve cooling - don't know how well it works but that was the idea.

project.r.racing · Postby **project.r.racing** » Wed Jun 11, 2014 7:58 pm

i can see why it only was on one model.

with a wheel, a tyre and a whole front bumper in front of it. how much airflow do you think that ywould actually catch?

i personally go with zero.

Postby **Boyracer** » Wed Jun 11, 2014 9:48 pm

I always remove them from my race cars, have never had a brake problem.

manga_blue · Postby **manga_blue** » Wed Jun 11, 2014 10:29 pm

Just googled this on miata.net. There are as many threads there as we have on gearbox oils. :shock:

There are two camps: the better cooling by scoop camp vs the weight/looks/better cooling by free air camp. Neither side wins. Pretty much anyone who's removed them says ultimately no difference.