Hey guys, as this is a subject that a lot of new owners can find scary I thought I’d try and make a thread that hopefully a desperate Googler will find and know that not all hope is lost!
I bought my first 5 about 6 months ago, a 1998 1.8 mk2 with 90k on the clock for £1000. I did a lot of research about them before buying, but you can never do enough it seems. Embarrassingly mine didn’t even have an undertray on it when I bought it so I should have seen the rust, but alas I didn’t and a health-check at a specialist garage showed up the horrendous state of my chassis rails just in front of the front wheels, the classic location of the dreaded rot. The anti-roll bar mounts were flimsy and the main chassis section in front of that could be holed easily with a screwdriver. The guy at this place quoted roughly 2 grand for sorting it and said it’d take a week or more, which was of course heartbreaking news after feeling like I’d hit the jackpot buying such an amazing car for so cheap.
But after some Googling of my own and talking to some friends, I decided to attack the job myself with the help of a friend who is a dab hand at welding. I should preface this by saying I’m a practical guy who has done everything mechanical to the car themself, I’m by no means an expert but I’ve learnt a lot and will always feel confident when tackling a new problem with the car, so if you consider yourself confident with a spanner then you’re on the right track!
I bought some chassis repair section from the mx5restorer, which are fantastic quality! 2mm thick steel with bolt holes and new bolts for everything that needs to bolt to the chassis.
The main thing people ask is what exactly is involved with getting to the area to comfortably cut and weld?. The total score was the wheels, front wings, bumper, radiator, air box, anti roll bar mounts, and upper suspension control arm/wishbone. The only thing that gave us problems were the anti-roll bar mounts, which are tack welded to the chassis, so you need to drill those out and prize the mounts off, which wasn’t that bad in the end. You don’t actually need to remove the anti-roll bar completely, and you just unbolt the upper control arm and drop it down so your alignment/tracking isn’t effected. We also disconnected the ECU as my friend has heard of ECUs getting fried when you’re welding something major like the chassis. You also need to un-tether and tuck any wires that lie on the metal above the chassis rail, headlight wires etc, as the welding will likely melt them!.
After you’ve got the section exposed, simply trace around the replacement sections, cut out the old rusted metal and weld in the new pieces! If you weld or know someone who does, it’s not as bank-breakingly expensive as you might first think. My friend charged me £150 for the job as I’d done all the stripping and labour myself. Obviously that depends on who you know, but it’s gonna be cheaper than garage rates.
It’s also worth noting that this car passed an MOT with flying colours 3 days later!.
This is the car with all the front end off, note the tremendous amount of foliage that came out of the front wing!
This shows the area we had to work with, again this is only the upper control arm, anti-roll bar mounts and radiator disconnected.
And this shows the extent of the damage, this particular piece took a mild battering from the removal of the tack welded anti-roll bar mount, but it wasn’t much prettier before.
So if you find yourself with the chassis rot, don’t fear! ask around, find someone who can weld and if you can’t, someone who knows their way around a car and it doesn’t have to be the highly professional, intensive and expensive job that you first imagine!
Good luck!