S13 Suspension Coilover Installation

S13 Suspension Coilover Installation (Thanks to Brian “DoriSlutM30”)

S13 coilovers

S13 inner and outer tierods

S13 control arms

the tension rods are m30 and so is the thing that goes from the control arm to the sway bar

S13 knuckle (i think its called). it has the hub on it. and you need the two bolts that go from the knuckle to the coilover.

the caliper and rotor are M30

do what you want with these (ABS & dampening control)

you have to gut the back to get to where the strut tower mount is and drill a hole

here’s what i started with

Here’s the finished product


Drew’s step by step

Project S13 Coilovers – completed 9/24/2006


Having a crappy suspension with 15 year old shocks is not good. The OEM replacement sonar suspension shocks are about $2500 a set and really aren’t that good anyway. A nice set of coilovers can be had for about $1,000. I opted for that. In order to get coilovers in your M30 you need to do a few tricks. For the fronts, you need to obtain the inner and outer tie rods, lower control arm and spindles/hubs assembly from a S13 240sx (89-94?). The rest of your M30 stuff can be used and its quite a simple swap, just requires some time and patience. Installing the rear coilovers requires some minor customization and is also quite simple. Getting to the rear shocks on a convertible, well that�s a bit more tricky but we will cover that.


I purchased a set of KTS coilovers for an S13. They are pretty reputable, have good support in the US and can be refreshed with new dampers for about $400 for all four. Not bad. They come with a 6/8 kg spring set and will set you back about $1,100.



For the fronts, the parts list from Dorislut on www.f31club.com is perfect. I had everything I needed.


Remove the stock parts – easiest way is to remove the two nuts for the sway bar end link, remove the two nuts to the tension rod, remove the INNER control arm from the rack (don’t bother with the outer link, you won’t be using any of this so remove as an assembly), remove the ABS sensor from the M30 spindle assembly and get it out of the way. You won’t have antilock brakes anymore. Remove the brake caliper� and hang out of the way with wire, remove the rotor, remove the bolt for the lower control arm, remove the three nuts under the hood holding the top of the strut, stand back as it is going to all drop at once. Throw this shit out.




This is the S13 lower control arm, tension rod (I used the M30 tension rods) and spindle/hub assembly. Install this.



The coilover will pop right in and bolt up to the s13 parts. Reinstall the caliper and disk, note that the caliper will be on the opposite side of the wheel now. No problems, just bolt it on.


Fronts took about 6 hours, including pulling the parts at the junkyard. I think I could probably do it in half that time now that I have done it once. Not easy, but not really hard either. I had problems with some bolts on the M being very difficult to remove. The rest was straightforward.


For the rears – the convertible M30 is not so clean when it comes to accessing the rear struts. This will get it done:


First, put the top down. Remove the bottom of the rear seat, just pull on it and it pops out. Now put the top up, and remove the four nuts that hold that back seat in. You will need a long extension and a u-joint adaptor to reach the ones on the bottom. You will need to crawl into the trunk like a dead guy in New Jersey. I could not even get a picture of them. They are black nuts and 14mm. Once you have these out remove the rear seat, you should now have this:



Remove these screws from the plastic cover:



Now go crawl back into the trunk and remove the same screws from the other side. The plastic piece should come loose and you can slide it down the seatbelts out of the way. You could remove it entirely by removing the seat belts, but I didn’t bother. Just get it out of the way.


Now you can access the struts – there is some funky rubber foam covering them up – move it out of the way:



Remove the screws from the actuator and remove the actuator.



At this point you can work with the top up or down. It’s easier with the top down for me. Just tuck the headliner out of the way around the strut tower. See the ears that the actuator was screwed to – if you want to reuse the struts, you need to remove the nut and pull this off in order to get the strut out. If you don’t care, just take vice grips and bend them up.


Now you want to jack up the rear of the car and put it on jack stands, remove the rear wheels. Undo the lower strut (17mm one bolt). Remove the three nuts up top and remove the strut.


Here is the side by side on your new v. old:


As you see, the s13 strut uses only two bolts. Also, the bolts are smaller for the s13 so your M30 nuts won’t fit. I used 4 nissan 12MM nuts that I found lying around in my box of bolts.


Measuring the new strut, you will find that bolt center to bolt center is about 3 1/8″. You need to make the new holes to meet with this width.

Use one of the existing holes, and drill a new hole on the other side. You can see where I marked it up.

Use a round bastard file to slot the existing hole towards the other hole until it meets with your mark. You can now install the strut. I removed the lower strut mount from each of the struts and measured two inches up to the locknut, so that both struts would be at the same height relative to eachother. Then tighten the lower locknut. Jack up the control arm and install the strut bolt, complete torquing the top nuts. You are done. Put the wheels back on and go about adjusting your ride height.


  • s13 coilovers
  • s14 modded knuckles
  • s14 adjustable lower control arms
  • Powered by max s14 extended inner tie rods
  • Moog s14 outer tie rods
  • using q45 rotors
  • dual piston calipers. Z31 rear