- My model of MX-5 is: NC 2009 Roadster
- I’m based near: Stirling, Scotland
- I’m looking for technical help or recommendations on: __
I have a 2009 NC which I’ve had for about 4 years. The last MoT picked up corrosion, albeit non structural. So, I’ve clearly got some rust issues, like most MX owners in cars over 10 years old. It’s immaculate up top but underneath a different story. If you have rust problems check out the Dinitrol website, they have kits for different types of vehicles. I bought a kit which comprised RC900 rust converter, 4941 underseal protection and the ML for spraying into cavities. It took a while, several weeks, and I did need more of the RC900 converter. it’s very important to throughly remove surface scale and rust, which I did with wire brushes and scrapers. A dirty difficult job working on my back with the car up on ramps in the garage. I don’t believe you can ever really stop the ‘rust clock’ but you can delay it 5 years or so with the right treatment, depending on how bad it is initially. The trouble with these MXs is that there are so many cavities and areas which, with the best will in the world, you just can’t reach or miss. I’m hoping that my efforts and the Dinitrol will work, time will tell of course but I have to say that it was looking good underneath when I finished.
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some info here too
Did mine a few years ago (Aug 2020 issue of SoftTop HardTop). Will look at it agin the the warmer weather this year.
Hi, just read your article in the mag - nice one!
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It will need reapplying on a regular basis.
I’ve used Dinitrol and Bilt Hamber products on my previous NC. The Dinitrol coating was showing rust through after 18 months from application. All products used as seen in the links there.
Must admit I had to go over certain parts again using the Bilt Hamber (epoxy mastic) after grinding most down to bear metal.
Sold that car so I can’t say how it’s holding up 2 years on.
I have never injected anything into cavities, probably would on new cars. My theory is if rust is present you are only covering it up, past experiences are it just keeps on rusting under the coating.
Just my thoughts/opinion.
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[Hi Mick - did use use the RC900 epoxy rust converter followed by the 4941 underseal protection?
Dave
Hi Mick- Did you use the RC900 epoxy rust converter before applying the 4941 under sealant?
D
Used the products below from Dinitrol. I later bought Bilt Hamber rust converter and used their epoxy mastic as a underbody paint. Also around the wheel arch lip and up under the boot floor I applied Hammerite over the top of the epoxy paint.
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Took my car to MX5 Restorer in Pevensey for a full cavity wax and underseal. I would use them again rather than try myself because they know where MX5’s rust and have the equipment and experience to do a full job.
The also will carry out a 19 point inspection F.O.C.
Roy
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The car I bought last year has had the full treatment, underbody, cavities, even boot lid and bonnet cavities. Apart from getting it checked for any top up I hope not to have to grovel under there again, I’m past that now😩
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I’m past it as well, but I had to give it a go.
I did take the car into RPA near Falkirk for them to do a full Dinitrol treatment but they felt the corrosion had just gone too far. At least they were honest. So I’ve spent the last 3 weeks removing surface rust and replacing some bracings and apart from the two corners where the cill meets the wheel arch it wasn’t that bad. So, let’s see how effective the Dinitrol is over the coming years.
D
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Tail of two cars:
My 1996 Eunos Roadster. imported 2000 (so the rusting clock effectively started then). No additional rust proofing applied. Most of the time, not garaged. By 2017, both sides had rotted out, so 17 years from import.
My 1993 Eunos Roadster S-Limited, imported 2004. The original owner treated the car to cavity Dinitrol protection when imported. Until 2008, except for one trip to the Alps, the car was treated as a show car, winning trophies etc, garaged, covering barely 5000 miles. Then it was 5 years as a daily driver. I acquired it in 2013, with hail damage. Over the next few years, it was restored, including a respray. Dinitrol inside the doors was still wet. During the respray in 2015, some evidence of prior accident damage was uncovered. Sills and arches still looked good. I hardly used the car. By 2018, there was evidence that the sills were starting to go (bit of bubbling, but everything felt solid). A decision was taken to replace both sills and one arch (the arch from the side with the old damage). On one side, the inner sill had pretty much disintegrated, to an extent that the jacking point was compromised. So 14 years to reach fulled fat rot, with Dinitrol along the way.
I am not convinced these products will extend the life of a car. Where is the negative control (the MX5 equally cossetted but not treated)? Or, indeed, the positive control (the car that is treated, and then driven into the ground). It all seems to be anecdotes and rather unscientific “studies” involving bits of metal dipped into various liquids etc, in an attempt to simulate the factory finished panel.
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