I’ve just had my MOT and my MX5 NA passed! However the mechanic who did it took me under the car to show me the state of the rust underneath. He said at the moment it is just surface rust on the underside, subframe and sills but leaving the rust one more year it’ll become a problem. He suggested rubbing off the surface rust and wax oil sealing the car; also drilling holes in the sills and putting a cork in there.
What are peoples suggestion on dealing with the rust/ a long term solution for preserving the underside. I’ve heard of the sill drilling before so if anyone could show me a photo of what is done/ opinion on it that would be appreciated.
If you are going to pressure wash, scrape, treat and reseal the underside, now is the best time to do it. You want to get it clean and dry,
As for drilling the sills and putting in a grommit, if the sills have been recently repaired, maybe worth doing. But if the sills are original, probably a waste of time. They’re already rusting, and you just can’t get the inside of those sills properly treated.
I last undersealed a car about 20 years ago. It was a dirty disgusting job trying to do it in a 18" gap. 20 years on, I’m going to pay someone to do it, who can do a much better job than me, and who can reach spots I can’t (like up around the top of the rear subframe).
Surface rust on suspension components, wishbones, subframes, etc is commonplace and rarely terminal.
I have almost finished refurbing my MK1, last done in 2003, scraping/wire brushing off rust, hydrate 80 rust killing and then black smoothrite. One rear corner left as used a litre of smoothrite and ran out - waiting for another litre to arrive. As the car not in use in the winter or bad weather will not bother with the underseal containing waxoil to finish as used on our Eunos. Eunos used all year round and parked outside.
The worry with your post is the sill rust. I assume this is on the visible surface of the sill at the rear just in front of the rear wheels? If so this will be advanced corrosion from the inside out and will likely, eventually require welded repair. As mentioned preventative treatment of the rear sill section that characteristically corrodes is difficult because the metal layers run very close together and existing rust will likely have bridged that gap and will effectively stop penetration of any injected waxes, etc. Perhaps put up photos of the sill corrosion for further comment.
Anyway well done on passing the MOT and enjoy the car. It is the best time of the year for doing this sort of work but most would rather drive the car than be stuck underneath it
On the very odd chance that the inner sills are not rusty and that would be very odd, you can get creeping cavity wax in there using this idea but I assume like the majority of these cars there will be rusting. In that case it is a cut and weld job.
If you are doing underneath yourself and it is a horrid job but someone has to do it,
Lidl are selling 400 mil aerosols of Powerfix Profi Under body protection for £2 a can if you buy 2. That stuff is not for getting inside the sills. Inside the sills I would use either Bilthamber Dynax 50 or a simiar product for inside sills.
Is anyone able to share ballpark costs? Got my NC back from with a advisory, but also have some paint issues and need a new clutch master cylinder and trying to decide if its time to move on or really commit to it for the three next few years.
We don’t have any info to what the advisory is. I could guess it’s rust on the undersides being as you post ref an underseal thread?
I’ve seen various thread come up with posters saying I’ve had an advisory for rust, the NC’s rust for fun (as do other model of course) it’s at what level yours is?
For a guide my current NC had underseal treatment carried out including cavity waxing around 5-6 years ago, that cost pretty much £800 then. A proper job taking days to complete, well it’s going to be expensive.
Having said the above you can pretty much deal with such things yourself, I have in the past, if you have the room/garage, the tools and materials.
BTW your clutch master cylinder does also combine with the brake master cylinder, could it be the clutch slave at fault or just an adjustment of the clutch pedal required? What are the symptoms?
So, i am not mechanically minded and trying to get my head around as lot of this, half to be corrected on a lot of this as it’s a mix of advice from a mechanic, a mate who is more into beatles and some googling.
MoT was front and rear sub frames showing signs of corrosion. Tried to have a look myself but no access to a ramp so it was the fashioned inspection pit from a high curb at the side of the road but looks similar to some of the pics above.
Clutch pedal starts to stick to the floor after it’s been used for a while. Stop start traffic seems to really do it. When the last service was done it was dry so steer I got was probably the master but might worth getting the slave done at the same time to saclce on labour of it needs done separately (car is 2009 and has done 80k so from what i have read would probably need replaced at some point? ).
Sometimes a rub over in the worst areas with a wire brush and paint of Kurust then underseal can fix the MOT advisories. Only trouble is if you find really crusty stuff and holes a different job altogether.
Maybe you have air in the clutch system, could be the slave at fault, a few have had the fluid bled to find they have a better feeling on the clutch pedal, worth a look.
Today we had our 5 into Guildford Tyre Company Ltd for wheel alignment. In a separate post I explained how I had some reservations over them, due to recent online feedback. But nothing they did today gave me cause for concern and they seemed quite honest about the state of the alignment, saying it was only on the cusp of needing doing on the rear. Which isn’t surprising having had two new rear shocks fitted this week.
Anyway as we were getting into our 5 in their car park to leave, one of their mechanics came over and asked where we had our underseal done on our 5? Rather taken aback, I asked why? He explained he had an MX5 (currently in pieces) himself and he thought the underseal job on ours had been done very well. He said it was very neat and if the car had come to them for an MOT, they wouldn’t have looked twice at it. I’m assuming some MOT stations must consider underseal a red flag?
Anyway, I told him it was done by the MX5 Restorer near Eastbourne in July 22, which he seemed to note.
I said it cost us £560 (now £600) and we had to wait several months before they could do it. He said the price seemed about right and he wasn’t in a hurry to do his, given it was off the road right now. But he told us it was important to use someone who did a good job, hence why he came to speak with us.
This was interesting and pleasing feedback to receive. We chose MX5 Restorer on the basis of their reputation here and online. But until today I wasn’t sure if they deserved the reputation, given how easy it is to sway online feedback with friends, relatives and Asian feedback farms. But it seems they did a good job at a fair price, so I thought I’d share the experience.
