the other day while I had the under tray off I checked I checked, for the first time since I got the car 2 years ago, the chasis rails. found an area bit bigger than a 50p piece on the driver side. The inner skin is exposed but solid with surface rust.
I took it to a local specialist and he said, bearing in mind the cost of fiving it (£480 for one side) it was not bad enough to do yet but to keep an eye on it.
I’d appreciate any opinions on this based upon the pics below. Hopefully will be inserted OK!
Clean off as much rust as possible and treat with one of these rust converters (the best ones, the names escape me atm) then paint over. I wouldn’t inject any cavity wax into the inner sections, I guess it will only cover up and make things worse. You are only slowing down the rust, cutting it out is better but as said a bit premature as yet.
Sounds fairly positive! I can treat the rust with a converter (FE-123 I already have) then maybe seal with something like Hammerite Underseal. Does that sound like a plan?
Else is it worth getting a patch welded over it then sealing it? Not sure how much dismantling would be required to do the welding?
Either way as you guys say It’s only going to slow it down never stop it!
As far as the wax injection is concerned would it do any harm? I understand that it’s the double skinning that’s the problem and so the wax possibly wouldn’t penetrate into the right places but happy to have it done so long as it won’t make it worse? Every little helps as they say!!
These front chassis legs rust from the inside out, so the idea of injecting product into the legs is to address the largely unseen corrosion. A layer of dinitrol or even waxoil will stop the rust process continuing.
I would scrape and wire brush the loose rust off the outside and apply something like Hydrate 80 from Bilt hamber to neutralise the rust. You can then paint on top - I would use Hammerite smoothrite metal paint followed by Finnegans waxoyl underseal.
Sorry posted a reply a while back but it seems to have gone AWOL!!
I live in Hampshire my nearest specialist is DoctorMX5. He charges £840 for both sides, £350 - £400 seems very reasonable as I understand that there is a lot of dismantling involved.
What I’ll do is brush/scrape the rust and use the Hydrate 80. I already have some smoothrite and the Waxoyl underseal so I’ll slap those on.
I don’t have the gear to do the wax injection but I can get my local village garage to do it reasonably with whatever I ask them to use. There seems to be plenty of ventilation/drainage holes in the bottom and top in the rails already to get the wax injection in without having to drill any more. So fairly easy to do I guess.
If you have been to DoctorMX5 or any reputable MX5 specialist they would not advise full blown repair on those chassis legs. Bear in mind that welded repairs have a place but unnecessary welding will create weakness on the weld margin.
Do a google on ‘rusted MX5 chassis leg’ images - you will see how bad they can get. A lot of these cars were passing MOT’s as garages were not aware of the problem and in sum cases unable to fully inspect.
Your car shows a small area of penetrating rust but none of the distortion, cracking and material loss associated with a lot of situations where a proper welded repair is required.
In fact DoctorMX5 did say it wasn’t necessary to do any welding at this stage and suggested sealing the area and checking it every so often. Didn’t specify what to seal it with and there seems to be a few options!
I was already aware of the chassis rail issue on the MK2 and when I saw some of the horror pictures you mention I was really pleased that mine were relatively OK. I certainly don’t want to cut out any original metal before I really have to.
Lots of different opinions on products so I’ll do some research and decide. I’ve heard of or used some of them so sure they are all capable of doing the job.
