ND RF Rear Roof Corrosion

So I was sitting waiting in the vaccination centre car park the other day and, being a bit bored, started having a look around the seals and everything else while the RF roof was down.

I noticed two areas of seemingly surface corrosion, with possible bubbling underneath the paint, at the leading edge of the rear roof section where it sits on the rear seal of the mid-section.

Has anyone else noticed this? I’m going to see Mazda shortly anyway about the window squeak TSB and some bubbling corrosion under the paint on the alloys so I’ll mention this as well, just curious if anyone else has seen or heard of the same.

In other news I’ve realised I’ve seriously neglected the seals over the winter and they all need a good clean!




That’s disappointing isn’t it. How old is it?

I expect it’s where the roof moves a bit whilst driving, rubbing against the seal, the eventually goes through the paint.

Had a similar issue on the top edge of the tailgate on a car, where the rubber seal rubbed through the paint.

Sorry, I should have mentioned that to begin with.

Registered in Apr 2019 and used as a dealer demonstrator for 104 miles before I purchased it in Aug 2019. In fairness it’s a daily driver so mileage is on the high side (16k odd now) and has only ever been kept outside, it’s still disappointing to see :frowning:

I suspect you’re right about the reasons though, there are corresponding “rust” marks on the seal.

I don’t think it can be rust because none of the roof panels are made from steel. If the cars been kept outside you are probably cultivating an exotic fungus.

1 Like

I’ll check with a magnet tomorrow but I’m pretty sure this bit will be steel because it’s what holds the buttresses together when they lift.

This is on the leading edge of the joining part of 18, which has a plastic panel, 20, over the top of it.

Found a gap in the rain between showers to check. It’s ferrous metal, the magnet sticks as I thought it would. I’ve also confirmed it’s rust, it penetrates through the paint and there’s a bubbling underneath adjoining painted areas.

Before going to the dealer next week I’ve emailed pictures to Mazda UK to see their thoughts too.

2 Likes

I’d also check where the rear arches meet the bumper. I can see on mine (2019) that the paint has been rubbed off the arches by the plastic bumper and it will start to rust soon. Mine being white it was easy to spot, don’t think it’d be the case on other colours, so take a look.

3 Likes

See what you mean Dodger, I hadn’t noticed the piece of reinforcing steel under the panel. I have checked mine which appears to be rust free but I will get busy with the ACF50 just to be on the safe side.
Thanks for the info.

1 Like

No worries, I’ll report back if/when I hear from Mazda and the dealer.

1 Like

After reading this, I will have to check mine. I have a black 18 plate which is also stood outside on the drive. Maccy what is ACF50?
Cheers guys.

1 Like

ACF50 is an anti rust treatment, it was developed by the US military, I spray the underside of my ND each spring, very easy to use and can also be wiped on with a rag.

1 Like

ACF50 is lubricant/rust suppressor used in the aerospace industry. It is much used by motorcyclist to protect their machines through winter and can be applied to pretty much any surface. I give my engine bay a generous coating before winter. It works very well on plastics as well. I do all the exterior plastic trim on my Beemer with it.
Splash it on all over (avoiding the brakes obvs).
Available on eBay and any motorcycle shop.

1 Like

Correct me if I am wrong but I thought that the only external panels on the ND’s bodywork that are steel are the door skins. The rest of the external panels are aluminium.

Definitely showing signs of rust bleed and the paint has been rubbed off on the join

1 Like

This isn’t an external panel, it’s structural and covered by an external panel. In my case it’s a black plastic trim part, others may have body coloured parts.

Door skins and rear wings are steel. Nothing else is magnetic so its plastic or aluminium (probably).

You are indeed wrong … I believe it is the case that for the soft-top ND all the panels are aluminium apart from the doors, which are steel. I think this statement has led some to say that all the RF panels are aluminium, not steel.

I have a 2017 RF and I’ve been round it with a magnet, mainly because I have a tiny bit of rust on the side lip directly above the window glass on the smaller of the two metal roof panels. I can confirm that the LARGER of the two metal roof panels is not magnetic so it is presumably aluminium. The SMALLER one, which is only a few inches wide, is definitely magnetic. That’s a blow for me … I now know that the bubbling which I was hoping is not rust, must be rust. No idea what to do about it. It is barely visible above the passenger window at the moment but you can see it if you know it’s there. Anyone any ideas?