Mazda MX5 NB, Getting a Butt Lift

Not to be outdone by the Rover, the MX5 got some time spent on it too

I have most of the things on the MX5 sorted now, and it’s running and driving good. The one part that really stood out and made me go “eugh” was the rear end panels.

The boot lid has taped over rusty holes, and damaged paint

And the rear bumper was an aftermarket fibreglass thing that was cracked and the paint was falling off it. It also didn’t suit the rest of the standard body, as it flares out at the bottom and makes the standard wheels look a bit weak

The guy I got the soft top from had wrecked a black NB, and wanted to sell the rear panels, so as luck as it, he had everything I needed to tidy it up.

The one “gotcha” was that the dual exit aftermarket Primasport exhaust won’t fit a standard bumper without cutting it. I didn’t want to cut the replacement bumper, but it just so happened he also had a standard muffler, so I picked that up too. Plus, the super loud boy racer exhaust wasnt quite my style.

Into the garage we go

This is what I was dealing with on the boot lid. UGLY.

Open the boot. Pop out the number plate lights (should be a push to the right and then pull out the LH side, but mine were broken)

Unclip the loom from the metal

There are two of these weird clip screw things on the back of the high stop lamp. I removed them using two little screwdrivers to lever the tabs away from the screw thread, and then pulled them free

Remove the loom from the boot lid, remove the four nuts holding the lid to the hinges and off it comes. Super easy

Refitting is the reverse. Boot lid onto hinges, loom onto boot lid and through holes for lights. Lights on, align the gaps, tighten it all up and bam, done.

I could have stopped there as that already made a great improvement, but I needed to rid myself of that bumper.

Number plate off, it exposes two torx screws

Tail lights need to come out too. There is a screw on top of each, and two 10mm nuts inside the boot (one hidden behind the loom), and then they wiggle free

There are a couple of plastic clips in the rear guard liners that need to come out so you can access a screw at the top leading edge of the bumper

There will also be a series of clips under the bottom edge of the bumper on a standard one, but in my case I had two metal straps riveted to the bumper on the bottom, and a rivnut on each side bolted to the sides. The straps were easy enough to remove with a drill, but the rivnuts were horrible. They had come free from the fibreglass and were spinning with the rusted bolt. The fibreglass was broken on one side so that made it easy, that side just came away but the other side I actually had to break the fibreglass tab off as there is zero room to access the spinning rivnut with the bumper on.

With that sorted, off came the bumper

There were a couple of small patches of rust in the rear panel, which I ground back and rust treated to stop it getting worse. Nothing structural, just some surface rust that had been left too long.

The next mission was to remove the muffler. The hangers were easy, they just slipped off. The two bolts on the flange made me want to rage at Mazda. Normal car manufacturers would just use a nut and a bolt, but not Mazda. They use a pressed in stud in the flange, and a nut.

I managed to get the top nut off with lots of penetrating fluid and a rattlegun, but the bottom one just would not budge. In the end I had to cut it off with the angle grinder, but this also ruined the stud

In the end I had to drill a new hole through the stud and replace it with a nut and bolt. What a pain though. I learnt a valuable lesson about drill bits too. Make sure you have a good quality set of HSS (High Speed Steel) drill bits if you’re trying to drill a bolt. Start with a punch to make a starting dent, and then use a small drill bit for the pilot hole. Work up in size until you get to the size you need. Use LOTS of lubrication, in my case WD40 worked a treat. I don’t know if it’s good practice or not but it worked; I used the fastest speed my drill would do, and lots of pressure.

With the stud sorted, off came the old muffler

And on went the original single outlet muffler

I installed the replacement rear reinforcement, and fit the original bumper.

The car is in dire need of a good clean and maybe a cut/polish, but already I’m much happier with how it looks.

I took it for a quick run for some photos. The original exhaust with the stainless headers makes for a nice deep rumble instead of the higher pitch buzz the other muffler makes. Its more refined, but still makes a great sound if you give it beans.

This is a (rubbish) video of the old Primasport dual exit exhaust

I tried to get a video of the replacement standard exhaust but the camera just made a horrible rattling noise over everything, so I’ll need to sort that and try again later.

And that concludes the butt lift. Once it has a new warrant on it, I will list it for sale and see if I can pass it onto a new loving owner. Its come so far from the crap box it was when I got it, and now it’s actually a nice little car that someone will be proud to own (and I’m proud to say I owned).