- My model of MX-5 is: __NC
- I’m based near: __Bradford on Avon
- I’m looking for technical help or recommendations on: __Does anyone know if the rear brake dust shields are really necessary? The car is a 2012 Sport Tech PRHT and I bought it a couple of years ago with 38k on the clock. As far as I know it had been well looked after and according to service records it hadn’t had any major work - just regular servicing - and no mention of rear hub replacements. This year I completely refurbished the brakes (calipers, discs, pads, braided hoses) and at the same time I did the usual thing of tidying up the tatty front shields. I then noticed that the rears didn’t have any at all! Is this normal for a 2012 Sport Tech?
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No. They should have them too.
Oh, that’s a bit worrying! I’ve no idea why they’re not there.
What do the dust covers actually do? As far as I can see you will have better rear brake cooling at the expense of brake dust being blown inwards. Hardly the end of the world so I would not get too concerned.
What do the racing fraternity do, with or without?
they shield dust 
From what I remember , the backplates can’t be replaced without taking the hub off, which looks like a big job.
So the question I’d like to know is, who took them off, how and why.
Well blow me down with a feather, I never knew that!!!
So would I!
Would be my guess that the old ones corroded away and the owner realised how much work fitting new ones would be
front is more important in comparison but rear or front dont worry too much unless you drive extremely spirited and you are heavy on brakes.
they arent dust shields, they are there to provide cooling to the disks by directing the air underneath the car.
If you track the car I’d replace them or even add additional cooling to reduce the heat and prolong the pad life,
I think id be even more concerned if they’d rotted away.
Mines 19 years old this year and the back plates are still in good condition.
I’ve replaced the calipers, pads and discs and am pretty sure I would have noticed the ragged edges of a rotten bit of tin. Might have another look at the weekend. The car isn’t tracked so I’m not too worried - just wondering what’s been going on.
Mine were still mostly intact but very crumbly, it wouldn’t have taken much more rust before I’d just go **** it and rip them off.
But I think more likely the car’s had rear bearings done and they’ve just not bothered to replace them afterwards.
Depends how far up the tree you go, below 1989 Lotus 101
I suspect MX-5 racers would rather have them fitted than not.
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Perhaps they were removed because they make it really difficult to get a brush past them to clean the wheel barrels!
I wouldn’t dream of removing them, but I do curse them every time I wash my car.
Surely the bearings wouldn’t have packed up given such a small mileage? And why both? I’ll investigate further……
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38K is really too low for bearings but 12 years isn’t necessarily, especially if the car’s ever had wet feet
As far as cooling goes, the fronts have a bit of shape to them but the rears, not so much, I doubt they’re doing anything useful and tbf they could easily be counterprodictive. Some people reckon they shield the bushings etc a bit from radient heat from the discs but I doubt that too, there’s a decent air gap and flow. Maybe at the pointiest end of things
They also shield other road debris etc from getting thrown onto the disc face. I removed mine on my NB, haven’t had any issues. I doubt their presence or lack thereof on the rear impacts brake cooling that much, if at all.
I’ve just had a look on Mazda’s Approved Used website…and they all have dust shields.
When I sold mine after 9 yrs from new, the dust shields were as good as new-just looked back at my photos. I’d suggest this needs following up to find out what’s been going on.