Hey folks, my 2012 NC2 has developed some rear underbody rust in the last year. Mostly just surface at the moment, but it’s all over the rear suspension components, diff, etc.
I was wondering if anyone had any recommendations for:
a) DIY treatment (removal of rust and protection against future rust issues). Including: is it worth it, or should I just take it to a pro?
b) Workshops in the South West who do a reliable job. I’ve seen ‘doctormx5’ online and they seem decent chaps, with good reviews.
Cheers!
My model of MX-5 is: NC2/mk3.5
I’m based near: Bath
I’m looking for technical help or recommendations on: Underbody rust.
The hardest bit (for me anyway) was getting the car raised up adequately and safely, to get at the underside components. Wire brush and wire brush drill attachments soon sorted the loose surface rust then. I used Bilt Hamber hydrate 80 to convert the rusty areas leaving a nice surface to treat with another Bilt Hamber underseal product. Lasting very well and it’s quite pleasing to know you’ve helped prolong the cars life a bit! not sure that a pro treatment would be much different? DIY tends to do a thorough job as if you’re not sure, you do more? Can’t help with a garage in your neck of the woods as I’m up in Yorkshire. Worth a go though if you feel up to it
As Barrie really did my own but it’s a pig getting under and actually doing it, especially when you are the wrong side of 60 yrs old.
Used the Bilt Hamber stuff too and those small flap wheels on my Dremmel to get the rust off. Treated with epoxy black mastic from Bilt Hamber. As a double dose then went over it with some smooth black Hammerite in the places where it gets the most muck thrown at it.
Another vote for Bilt Hamber. Dynax UB for exposed bits and S50 for the box sections and behind wheel arch liners. Around £80 to do mine a couple of years ago. Their big spray cans come with a long wand and diffuser for box sections and very easy to apply with minimum preparation. Took a few days and it’s messy. I’m also 60+ but doable up on ramps at one end and axle stands at the other.
And a vote for Dynax S50 and UB from me as well.
Also worth a look is Lanoguard as I am presently experimenting with both on my 99 NB.
S50 just installed in the front chassis rails box sections and main chassis rails box sections with the fab lance. Put something under the car to protect the drive though as its
runny so gets everywhere especially in the box sections which is the whole idea!!!
Personally have found 2 pack mastic paints and Hammer finish paints crack and split so prefere stonechip and a spray wax coating after surface prep.
This is only my opinion having used on a few classic cars.
I am rapidly approaching 60.
I am tackling mine at the moment. Using Corroless Glass Reinforced Black Rust Killer Chassis Paint and then over topping with BH products as above. Its a bit time consuming and messy.
not sure that a pro treatment would be much different? DIY tends to do a thorough job as if you’re not sure, you do more? Can’t help with a garage in your neck of the woods as I’m up in Yorkshire. Worth a go though if you feel up to it 
