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Mazda MX5 NC Rear Shock Change & Wipers

The MX5 came with two options of shock absorbers. The Sport model (RS) got flashy Bilsteins and all the other models got boring Mazda made shocks (US models low-end shocks were Tokico, but I can’t see anything on my JDM shocks to indicate the same). I wasn’t lucky, my car isn’t technically Sport spec, so no Bilsteins from factory. Can’t have everything eh?

My car is also no spring chicken, having done just shy of 200,000km at time of posting. Since getting the car, the first thing I noticed was just how much softer and un-sporty the suspension was compared to the RS I test drove previously.

Add to that the KM and you have a recipe for some rather bothersome handling “quirks”. In the case of my car, the rear shocks didn’t so much dampen, as kind of just make a half arsed effort to reduce how many big oscillations happen after going over a bump. It didn’t do so well. I was left with a car that had a soft, bouncy and squishy back-end. Going over a large bump would often leave the car feeling unsettled as it bounced its way down the road, using all the available suspension travel.

I’d had enough and i started to look at what i could do. A quick call to the local suspension supplier and i managed to get a great deal on a pair of proper Bilstein B6 Sport shocks. These are proper aftermarket models and far superior to the OEM Mazda Bilsteins.

Some new bump stops were arranged from Japan, as I didn’t know what state mine were in and I had seen the horror stories of people pouring bump stop colored powder out of their dust covers.

First things first though, I took the Roadster for a trip to the supermarket, the long way, yesterday in the pouring rain and was almost driven insane by the horrible squeaking from the wipers. Not to mention their streaking and shuddering. They were done.

At work today I grabbed a pair of 450mm J Hook style wipers. Both wipers are the same length, and pretty short. Yeah, Genuine Mitsubishi…. made by Bosch.

Fitting is easy, standard J Hook stuff. Just make sure to release the locking tab on the underside of the clip, and make sure it locks in on the new ones.

The old wipers were ugly. Discolored, hard rubber.

Good timing too, it starting to bucket down whilst i was changing the shocks, so the new wipers got a trial by rain on the test drive. Passed with flying water, silent and clear. Lovely.

Next was what I came here to do. The rear shocks.

Now, I did use a guide to help me. There are a couple of ways to do this job and one of the more common ones is to leave the top hats in place, and just remove the shock and spring. This is the guide I used, that elaborates a bit more on the process.

First step is to pull all the lining out of the boot.

With a slight tip, there is a clip hidden on each side, behind the panel that has the boot light. You need to pull that panel forward, or in my case, out, to get to them.

Once all that’s gone, it’s pretty easy to find the top hats.

The LH side one is behind a metal plate that protects the fuel filler pipes. You DO NOT need to remove this, but you can count on it making a mess of your gloves, or your skin.

One of the major tools that will stop you wanting to stab yourself, is a ratcheting 17mm wrench. Thankfully I have one of these, or you will literally be there all week undoing the nut on the top hats, and then doing it back up again later. Do not proceed without one. You also need a small allen key to hold the shock shaft. I found mine didn’t turn much, but you will need it.

Another tool that is crucial, is a small jack. You will use this to jack up the bottom of the shock, to both aid in removal and refitting. You can’t really do it this way without it. Mine was old, shitty and hadn’t been used in about 5 years…. and I lost the handle, but a power bar and screwdriver came to my rescue.

While the car is on the ground you need to undo the nut on the top of the top hat. I didn’t remove it completely until the car was in the air, but I don’t know if it matters. Once that’s off, you need to remove the lower shock mount bolt.

Once that’s off, you need to use the small jack to gently and only slightly lift the shock up. It’s to take the pressure off the shaft the shock is sitting on. Once you have the pressure taken off you need to lever the shock off that shaft with a pry bar.

Then the fun begins, you need to wrestle the shock out. The first one I did I also took the spring out, but I noticed on the second that it was actually easier to leave it in the car.

Heres a non-sport shock, and an AutoEXE lowering spring.

Amazingly I still had decent bump stops. They were heavily discolored, hard as a rock, and compressed shorter than the new ones, but they were still in one piece.

I chose to replace them anyway, as the NC uses the bump stops as some sort of secondary shock (apparently), and the old ones were, well, old.

Anyway, here’s a flash, new, beautiful Bilstein next to the cruddy old thing.

Tested at the ‘Ring, ya know.

So the next part of the game is to reassemble everything and put it back in the car. This bit sucks. A lot. But it can be done.

Another thing to note is the Bilstein circlip style lower spring mount. I had some issues with this. The O-Ring is meant to go in the recess in the spring mount, and then it’s slipped down the shaft and sits on TOP of the Circlip. The circlip doesn’t clip into the mount. The O-Ring is a real pain in the arse and a lost a lot of time trying to get the mount to slide down. I found the best method was to lubricate the oring with dishwashing liquid (it’s very slippery but will wash away easily with water) and then use forceful rocking pressure until it slides on. P. I. T. A.

Now, one quick note about the top hat nut. Initially I chose to use the Nyloc nut that came with the Bilstein. This is designed to have a washer under it, but IMO it’s not as good as the original nut with integrated washer. The Original nut has a larger surface area. I even went so far as to have fitted the Bilstein nuts, removed them and then refitted the original nuts. The thread is the same and they are both 17mm.

I haven’t had a chance to give it a real test, but I took it for a quick drive down a twisty road, in the rain. The results were immediately obvious, the body roll is far less, and the rear is now no longer bouncing along and doesn’t feel like its being dampened by a pair of old pillows. I cant wait to take it for a drive in the dry.

It did show up the imbalance of the fronts being crap now too, so i’ll need to keep that in mind. I can get some Bilstein B4 struts for that, but B6 aren’t available anymore. It’s also a lot more work to do them and i’ll need spring compressors. Might just get some RX8 sway bars instead.

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