S12 Howto database

OP: EightySix200SX

S12 Weld-on Coilover Conversion – Adjustable Suspension for the S12.
Written by Justin Carter

The following is a write-up of the coilover setup we have come up with here in SoCal. Engineered and tested by us of the Low.XII.Position crew, it is a for sure way to lower your S12 without converting to the S13 suspension. It is what I am running in addition to Andrew (demonic_s12) and Sterling (sterlingps12). The only difference between between our S12s and what Sterling did was that he used S13 tubes in the front. It can also be verified by Colin (draconis) who road passenger in Andrew’s car last year.

In the past many months there have been much interest and many emails inquiring as to our suspension setup so the following is the list of our suspension setup.
This setup allows one to retain the factory S12 tubes.

You will need a welder and a grinder as the front tubes must be sectioned 40mm shorter to accept a shorter SW20 shock. Also, once can use S13 camber plate and in doing so, inform Techno Toy Tuning that you will be running S13 camber plates with SW20 AGX socks and they will send you two small collars that will slip onto the camber plate to take up the slack. They are aware of the situation, so do not worry about their confusion. You will have to grind off the stock perch and weld the Ground Control perch in its place. Other than that, the necessary steps for the modifying the front suspension.

For the rear, the setup is easy and literally drop in straight out of the box. The Mustang Foxbody struts however will require some shimming. To do so, one will need four washers on each shock on the lower mounting bracket on both sides of the car to take up the slack.

Parts list ——————————————-

FRONT: (2026 update: Links are updated to the latest version from Techno Toy Tuning)
ROLL CENTER ADJUSTERS- http://technotoytuni…etail.php?p=815
S13 CAMBERPLATES- http://technotoytuni…etail.php?p=819
280ZX GC SLEEVES- http://technotoytuni…etail.php?p=802
MR2 SHOCKS- http://cgi.ebay.com/…=item255c19e4ab  (Link is dead in theory front shock inserts from the MR2 AW11 / SR20 should work, 280zx also works)

REAR:
SPRING PERCH [MUST USE SS-85500-A] Click for SPRING PERCH 
SPRINGS [MUST USE 5″X8″ SPRING] Click for REAR SPRINGS, various rates as high as 500 lb.
(These links no longer work and have redacted them.)

2026 update: I highly suggest to use the perches and springs wih the following

• Perches: https://www.speedwaymotors.com/AFCO-Adjustable-Spring-Spacer,49203.html with the part number for future refference: #10620187
• Springs: https://www.speedwaymotors.com/Eibach-Progressive-Pull-Bar-Springs,271.html  part number: 330675

FOXBODY SHOCKS- http://cgi.ebay.com/…=item4cf6ee146b
(dead link, just any rear Foxbody GT or even better 90’s ford E150 shocks too)

This is what to expect throughout the process

Creative given to Mod_mastaz and sterling of the old CS12 for providing this how to.

***The “///” denotes the alternative, meaning OR.***

If you want to stick to S12 suspension parts:

There are SSC/Canuck lowering/performance springs available for STOCK S12s. See http://club-s12.org/v3/index.php?topic=7848   for more details.  For shocks/struts to use with these springs, look further down in the Shock/Strut part of this post.

Those not wanting the S13 front conversion but still yearning for coilovers, you can use Ground Control front components and MR2 (SW20) struts with the stock S12 strut tubes. For details on the MR2 shocks, see the Shock/Strut part of this post.  There are universal collars/perches available that will work if you don’t like GC. I would recommend running a progressive spring or main spring/helper spring combo but just a main spring will be fine.  For the rear coilover setup, look here, page 2: http://club-s12.org/v3/index.php?topic=18579


If you want S13 coilovers, you have a few options:

Option 1:
S12 Setup
 -S13 balljoint
 -S13 spindle
 -S13 5-lug conversion hub /// -stock S13 4-lugs
 -S13 Brake caliper hoses (Optional, but recommended as the S12 hoses stretch a little tight)
 -S12 stock control arm/tension rods
 -S13 tie rods, and 1995 ford escort tie rod ends /// S12 tie rods, A1 tie rod ends (http://shop.a1racing.com/dgt100.aspx)
 
Option 2:
s12-S13 hybrid
 -S13 balljoint
 -S13 spindle
 -S13 5-lug conversion /// -stock S13 4-lugs
 -S13 Brake caliper hoses (Optional, but recommended as the S12 hoses stretch a little tight)
 -S12 stock control arm
 -S13 tie rods, and 1995 ford escort tie rod ends /// S12 tie rods, A1 tie rod ends (http://shop.a1racing.com/dgt100.aspx)

Option 3:
s12-S14 hybrid
   -S14 balljoint
   -S14 spindle
   -S14 SE hubs(5-lug) /// -s14 non SE 4-lugs
   -S14 Brake caliper hoses
   -S12 stock control arm

Option 4:
S13 setup
   -s13 control arm
   -s13 spindle
   -s13 Brake caliper hoses
   -s13 5-lug conversion hub  /// -stock S13 4-lug

Option 5:
S14 setup
   -S14 control arm
   -S14 SE spindle/hub(SE S14s are 5lug) /// -S14 non-SE 4-lugs
   -S14 spindle spacer(with S13 strut bolts) /// -drill out S13 coilovers to use accomodate larger S14 spindle
                 bolts

Option 6:
S13/14 hybrid
  -S13 control arm
  -S14 balljoint
  -S14 SE spindle/hubs  /// -S14 non-SE 4-lugs
  -S14 spindle spacers(with S13 strut bolts) /// -drilled s13 coils.

If you use S14 front spindles, might as well use S14 coilovers, if you can source it. If not, use S13 coilovers and mix and match S13/14 stuff for 5 lugs. You cannot use any S14 hubs(4/5-lug) on S13 spindles. S13 hubs go to S13 spindles and S14 hubs go to S14 spindles.


Megan Racing S12 SPECIFIC Coilover Kit
 Technically, its not 100% for an S12- you NEED to do the S13 front conversion, as detailed above.  The Megan kit is essentially a normal S13 Megan kit that has been modified in the rear for our suspension, but otherwise the S13 knuckle/spindle will need to be installed, as detailed in Options 1, 2, and 4.  This is the easiest and most convenient way to go if you are planning S13 front conversion. You can also adapt S13 rear coilover shocks to run a full S13 coilover set of your choice. You can use my rear suspension setup for ride height adjustment or just a spring length of your choice.  Check Megan’s website for the pics/details of the kit.


****OTHER REQUIRED ITEMS**** YOU ALSO NEED THESE TO CONVERT!!
-S14 tension rod brackets(you’ll need to slot out a hole to fit the S12 chassis)
-S13 tension rods(stock/aftermarket)
-A1 racing tie rod ends OR S13/s14 tie rod inner/outers combo, respectively.
-S13/S14 sway bar with endlinks/mounts /// -S12 swaybar with washers and two longer tension rod bolts(one for each side)



————————————————————–

Brake Upgrades

Brake upgrade for 5-lug with STOCK S12 suspension
– S12 MK2 SE V6 struts/springs

– Z31 87-89 turbo front hubs(for slip on rotors) and wheel bearing
– Z31 87-89 turbo front rotors
– Z31 87-89 turbo front calipers
– Z31/S12/S13 lines, SS or rubber

Alternative brakes for the SE V6 WITH Z31 hubs for slip on rotors
– S13/s14/q45/j30/z32 front Calipers
– matching rotors
– Z31/S13/stock brake lines /// -S13-Z32 front conversion lines for Z32 calipers
– washer to space calipers out .170″ to center the caliper to rotors


Brake info for S13/s14 front conversion(this applies AFTER you have converted)
If you use the Z32 4pots, you will need a Z32 master cylinder -and- Z32 front brake conversion lines for an S13. The z32 piston diameter is 1″ or 1 1/16″. If the stock S12 master cylinder size says 15/16″ on it(most are), then the Q45/J30 brakes will work fine. As for brake lines, stock S13 lines will bolt up to q45/j30 calipers. You can get Z31 SS lines (ebay ones don’t hold up too well) and they will bolt right up to the front and rears(make sure it is 6 pieces, 2 front 4 rears).

For the stock SE V6ers, they can run Z31 SS lines all around.

Brake option #1:
Z32 Front brakes
– Z32 Master cylinder 1″ or 1 1/16″(15/16″ is fine but will give a slightly mushier pedal feel)
– S13 Z32 front brake conversion line
– Z32 rotors(matching calipers)
– IF 4-LUG! — Redrill rotors

Brake option #2:
S13/S14 calipers
– S13 master cylinder 15/16″(if stock is 15/16″ not required)
– S12/S13/S14/Z31 front lines(stock rubber or SS)
– S13 rotors for 4lug /// -S14 SE rotors for 5 lug

Brake option #3:
Q45(90-96)/J30(93-97?, recheck before ordering) front calipers
– S13 master cylinder 15/16″(if stock is 15/16″ not required)
– S12/S13/S14/Z31 front lines(stock or SS)
– Q45(90-96) /// J30(93-97) front Calipers
– Q45/j30 rotors
– IF 4-LUG! — Redrill rotors



———————————————————————-

** Z31 Rear ** Conversion

+++Z31 vented REAR brake swap
– Z31 87-89(na/t) rear control arms
– Z31 87-89 axles(my stock 6-bolt s12[r180] axles bolt up to Z31 arms, R200 axles should too.)
– Z31 87-89 calipers/rotors
– Z31 SS/stock lines(2 front, 4 rear)
+++Try to get this as a set, it’ll make your life EASIER!

Ok Some background info. Before everyone though that Z31 87-89 arms and S12/Z31 84-86 arms were identical except the hubs. WRONG. The actual Z31 87-89 arm is different. It has been confirmed by 200sxkit car that the rear arms are infact different. The mount for the hubs are pushed out 10mm to accommodate for the taller vented rotors. The rear hubs used among the 84-89 Z31s are probably all the same. So if you want vented brakes on the rears, BUT wish to retain 4 lug, get your rear 4-lug hubs and swap them over to the 87-89 Z31 rear arm. Then redrill your Z31 vented rotors to fit on your 4-lug hubs. DONE!  Obviously, if you want 5 lug, just get the 87-89 Z31 arms, and bolt them on, no hub swapping needed.

If you find a way to get 87-89 Z31 vented rear rotors on stock S12/84-86 Z31 arms, please let me know. I have an idea, listed below…

Z31 vented brake info/tech:
!!USE AT YOUR OWN RISK!!
My theory to run the vented brake rotors/calipers on an S12/Z31(84-86) RCA is to get a hubcentric 10mm spacer(that fits inside the vented brake rotors and centers it) to space the rotor out 10MM and the vented brake calipers should bolt up to the S12/Z31 84-86 arm. If you’re 4-lug, just redrill the vented rotors to 4-lug.
!!THIS IS NOT CONFIRMED, USE AT YOUR OWN RISK!! If you have tried this and it does work, please let me know and post me some pictures so I can make sure. Thanks!



————————————————–

SHOCKS/STRUTS

I recommended to run all four of the same shocks because they are valved similarly. If you run Illuminas in the front and Konis in the rear, the Konis are going to have much better dampening characterstics so the rear is going to be much more stable over bumps. The car itself is going to be upset when going over bumps because the fronts won’t react the same as the rears. It’s not about how it FEELS, but how the car actually reacts. Remember that these adjustments are rebound and NOT bound. When you adjust the knob, you’re actually adjusting how it reacts to the bumps in the road. Think of it this way, bound prevents the spring from compressing and rebound prevents the spring from expanding. Bound is what makes a car feel JDM super rock hard solid. However you want the car to feel is all preference. Whether you actually gain some sort of performance enhancement* is another story.

*I meant this in a sense of actual faster lap times and/or faster speeds through a corner. This really all depends on what YOU want the car to do. A drag race setup is not the same as a road course setup. Same applies for drifting/street driving/etc.

That said…
For stock S12 front suspension…


– 280zx shocks in the front, Z31 in the rear is the general setup.  BUT that only limits you to Tokico Illuminas because there are no KONI Yellows or KYB AGX for that COMBO (there are KONI Z31s but no Koni 280zx, AGX neither.) 

– The next thing to do now is to run SW20 MR2 rear shocks (in the front S12 strut tube, according to Gerrybg) and Foxbody Mustang rears (in the rear of the S12). Then you’d have a selection of KONI and AGX shocks available.

– 1990’s ford van E150 rear shocks also work  
 
– Using SW20 MR2 front strut inserts in the front will require sectioning the strut tube but in return you get a shorter shock/stroke for the super lowered cars(good with GC/sleeve setup).  Less chance of hitting the bumpstops this way.  Foxbody Mustangs also have a shorter stroke and shock so that helps on lowered cars too.  One more thing, if you go Konis, run all 4 Konis, same applies to the AGXes.

– For the info on using the MR2 front strut insert and shortening the housing, check my suspension thread linked below and look on page 3, Gerrybg details the situation.