Z32/S13/S14 - multi-link rear suspension swap

[Butter]

My opinion is still that the S13 would be the best choice for Z31 as I believe the ease of the swap and the lower overall cost is a larger benefit than the small subframe differences. This is only my personal opinion though, so take that for what it's worth

Take it as fact. I find that post from Hybridz not too credible. Most s30 owners swap in R33??? Why? Because maybe the first guy to do it used that? He didn't even mention the differences in the the control arm pickup points which effect your roll center and camber change.

The bottom line is that most of the improvements over the S13 get thrown out the window when you put these things into the Z31. Unless you make modifications to the floor aft of the pumpkin (or install it tard style), your subframe will be have a 15* nose up attitude which gives you anti squat but decreases traction.

USE S13.

[Butter]

I got my full S14 subframe and S14 front suspension with brakes for $200. I put the FLCA's on my S13. I didn't need the brakes and front spindles and sold them for $200, enough to fund 5 lug hubs. I was actually mad that I paid $200. Luck has nothing to do with it, you just have to not be lazy and search internets.

If you can't figure out simple logistics of parting out cars, then maybe this is something you shouldn't try. Worst case scenario, you rent a storage shed which costs @$30/month.

Things you can strip off the subframe and leave at the junkyard.
-Brakes, kinda small for a Z and it's a good time to upgrade to Z32's.
-Upper control arms, upgrade.
-Toe links, upgrade.
-Traction links, upgrade.
-LCA's, upgrade but be aware they are $$$.
-HICAS(if equipped), put eliminator.
Don't leave the 4 lug hubs. You'll leave the bearings behind and they are expensive. If you have a press and know what you're doing, you can reuse them. Most people change the whole assembly and pay twice as much.

[Racinjitter]

1SickZ wrote: whats the difference in the actual rear subframe from s13-s14.. and can you use s13 arms and etcc on the s14 subframe?

basically i have a free s14 i can go pick up or i can go buy a local s13 for 75$. so im just asking my options.
If you use aftermarket stuff, it all interchanges. I am unsure if the factory stuff is all the same. Anybody have FAST to look it up?

Butter wrote: The bottom line is that most of the improvements over the S13 get thrown out the window when you put these things into the Z31. Unless you make modifications to the floor aft of the pumpkin (or install it tard style), your subframe will be have a 15* nose up attitude which gives you anti squat but decreases traction.

USE S13.

Butter wrote: S14-Track is a little wider (20mm?) than S13. I believe some arm mounts were moved during design. Nissan used the higher mounted rear struts, I think, to increase stroke. When you drive an S13 and then drive an S14, the S14 just feels more stable when cornering over dips, etc. probably because of this. Even so, I wouldn't recommend doing what I did. Too much trouble. Again, use the shorter S13 coilovers with an S14 lower section in back.

[1SickZ]

i only ask because there is little diff. in pictures i see..
first thing i see right off the bat is the s13 has the little pieces hanging off the end of the mounts and s14 doesn't.
just wonder if the measurment are the same or maybe a tad diff.


S14:
http://s205.photobucket.com/albums/bb7/ ... C09952.jpg


S13:
http://s205.photobucket.com/albums/bb7/ ... C00010.jpg


the difference of 20mm track isn't much and could be wanted in some apps.. am i dumb to assume u can use s13 coilovers on s14 rear subframe?

[Butter]

Get the S14 subframe. Use S13 coilovers with S14 lower mounts. You will mant to use s13 coils with any subframe unless you want to kill yourself with strut tower mods. It is a shorter unit.

The S14 uses rubber isolators at the diff, which is what I think you are referring to. I just picked up the new aluminum bushings from Stance last night to replace them. While there, I found out that the Y33 Q45 subframe is nearly identical to S14. This may change the game up a bit as it uses that healthy R230 right, and I suspect it has S13-like track.

[1SickZ]

Butter wrote: Get the S14 subframe. Use S13 coilovers with S14 lower mounts. You will mant to use s13 coils with any subframe unless you want to kill yourself with strut tower mods. It is a shorter unit.

The S14 uses rubber isolators at the diff, which is what I think you are referring to. I just picked up the new aluminum bushings from Stance last night to replace them. While there, I found out that the Y33 Q45 subframe is nearly identical to S14. This may change the game up a bit as it uses that healthy R230 right, and I suspect it has S13-like track.

the y33 uses a short nosed r200 which bolts in the s13 frame with the use of one 300tt shaft and one 45 shaft. This is what i am doing.

[OK85ZX]

1SickZ wrote:
the difference of 20mm track isn't much and could be wanted in some apps.. am i dumb to assume u can use s13 coilovers on s14 rear subframe?

The only real difference for our application is going to be the track width, since everything else is swappable including the coilovers (like butter said use S13 simple because of the height allowing you to keep the stock shock towers).

Use whatever you can get... if you can have an S14 for cheaper and don't mind the additional width then go for it. S13 is just much closer, if not the same as stock width. Not a huge deal.

Definitely interested in pics of the y33 frankensetup.

[1SickZ]

went and compared the 2 frame side by side today, the s14 rear mount are 1/2 inch wider. front is nothing to write about. the s13 is a 4 bolt diff s14 is 2 bolt mounting. s14 lca's are a bit longer than the 13's. The traction arm mount on the s14 curves out where 13 is striaght up so by looks s14 looked easier as far as notching our car. That was until I measured and realized its bowed in because its 1/2 inch higher than the 13. The 14's lca mounting is ideal but I went with the 13 frame and instantly picked up mazworkz rear support plate for the diff mounting surface as the torque from the z will prolly shred this thing in half (my buddies sr did so u know the vg will) I got picks of my progress so far not much but the project has offically began. Oh and some might ask me why am I all over it. Well last wed I broke both z stubs at the track first pass and they didn't break at the narrow part either. Time to move on!!!

[1SickZ]

Measurments are not exact!!

Q45 subframe(used z32 pic)





i went and got all my q45 parts today.. what im curious is can i use all the arms from the q45 on my s13 frame i measured them out to what seems to be identical.. i also purchased the spindlesand hubs as they are the aluminum z32 style units.. and the hub is the 5lug big spline units.


Also if all these arms are interchangable.. like s13 s14 j30 and possibly q45... what i noticed for fitment reasons is that the j30 upper arm curves way out to clear the shocks as i read somewhere someone said the reg. s13 is real close... im babbling cuz im tired and just wanting to get you guys some info. its more drastic that the s13 but with the same mounting points.

[1SickZ]

S13 required cutting/notching:



the main difference with the s13 from the s14 is lca's mounting location.


Its mounted i just gotta snap some pics. on the other hand i've sourced every other part needed except im still awaiting a shipment from stance.

[Rat1314]

the best write up you will find is on the first page of this thread. http://www.ziptied.com/forums/index.php?topic=6734.0

[OK85ZX]

Rat1314 wrote: the best write up you will find is on the first page of this thread. http://www.ziptied.com/forums/index.php?topic=6734.0

right, between that and this found on the second page of this thread (http://www.300zxclub.com/showthread.php?t=55042)

it wont' be handed to you on any more of a silver platter.

[1SickZ]

DeleriousZ wrote: so who wants to copy paste the 300zx club one so i don't have to sign up for that lame site? lol.

87Kevin;665037 wrote: OK – I havent been here for a while, I have all the pics, so might as well explain what I did. Keep in mind that this was a s13 240sx subframe I used. I used it because the track width is the same as stock (87). I had to modify a few things that I may not have had to if I used a z32 subframe since it is wider. For this reason, I’d suggest starting with the z32 subframe since it already has the right uprights. You could keep the stock s13 uprights, but you’d be stuck with worse rear brakes than you started with and 4-bolt hubs. The rotors and calipers are smaller. That’s why I used the z32 knuckles because the rear brakes are way better than stock. So my setup is:

240sx subframe
240sx arms
240sx springs
300zx knuckles
300zx shocks
solid aluminum subframe bushings

This seems to get me close to stock ride height. I am in the process of switching to s14 rear upper control arms to clear the shock. The s13 arms go around the shock on both sides, and I had to cut a bit of metal away from one side since the shock is leaning rearward more on my car than it would on a stock s13. The s14 arms are one sided and a little longer which should give me more camber adjustment.

So you ask why change the rear subframe? Well - if you do what I did or similar but with a z32 or skyline subframe (all of these are similar designs with similar geometry and interchangeable parts) these are the benefits:

Better rear brakes – similar rotor size, but dual piston aluminum calipers and drum ebrake although I don’t know exactly why that it’s better

VLSD – yes I know that vlsd is not that great, but it’s better than open and is upgradable with numerous bolt in aftermarket diffs.

Better geometry – way more anti-squat which is good for road racing and handling. While not the best for drag racing, I’ve found that with my laggy turbo, I get better launches due to less bogging.

Upgradability – almost every arm in this setup has an adjustable aftermarket replacement, not to mention endless coilover and big brake options.

Solid bushings – This is not neccesary, but if you do this, you can think of the whole subframe as a meaty re-inforcement to the ass end of your car since it is now bolted solidly to your unibody. This made my car feel like a totally different car. Easily the best handling mod I’ve done.



OK – so here’s how I did it:

1 – unbolt brake lines where they go through the little metal tab underneath the car and remove old subframe completely.

2 - fab up some metal plates that look like this:
(see attachments)

mine were 5/16” mild steel and were waterjetted. Buy 4 grade8 ¾” bolts about 4” long. Put them through the holes in the plates and weld the heads onto the plates so they cant turn.

3 – you will have to use a hole-saw slightly larger than the heads of these bolts to cut through the sheet metal on the rear crossmember where the old diff used to mount. You need to cut two holes to make room for the heads of the bolts so the plate can sit flush.
(see attachments)

4 – prep and paint the plates to prevent rust and rip off the undercoating where they weld to the car. An angle grinder with a wire wheel works well for this.

5 – bolt the plates to the new subframe loosely and slide it under the car without the shocks.

6 – using multiple jacks and jackstands or blocks of wood lift the subframe into position.

7 - if you use a 240sx subframe like I did, you will notice that the front mounting point of the lower control arm is preventing you from lifting the subframe all the way up. Notch out the unibody and weld it up like this:
(see attachments)

not sure if the 300zx subframe will eliminate this problem.

8 – now comes the time to break out the measuring tape. Measure every thing 10 times. Measure from the old stock mounting studs, measure from any reliable points under the car to make sure the subframe is centered and straight. You will notice that there is a gap in the center of the rear plate between the old stock plate because the stock c-member is curved. Make a spacer to bolt in between.

9 – once everything is straight and square, weld the plates onto your car. Take your time beacuse you are welding thick plate to thin sheet metal.
(see attachments)

10 – remove subframe and use wax spray to seal where you cant get to and undercoat everything to make it last.

11 – attach your subframe to the new mounting points. To make it sit level, use ½” of spacer on the front mounting points, or even better, use ½” thicker plate in the front than in the rear.

12 – enlarge one of the stock bolt holes for the shocks in the rear until they bolt in.
13 – you will need a custom driveshaft made. You could get the rear yoke that is meant to bolt to the diff you now have, or do what I did and just drill new holes in the diff flange for your 300zx rear yoke. There is plenty of meat there for that, and the bolt holes don’t align the drive shaft, the little metal ring does that.

14 – ebrake – either leave it off, make some frankenstien cables, or go to home depot and buy 8’ of 1/8” aircraft cable along with 2 u-clamps. Cut the ebrake lines that come out of the drums about 6” out. Clamp one side onto one end of the cable, run it through the loop that comes out of the car and pull it tight as a mofo and clamp the other side on and cut off the extra. This sounds ghetto, but it has worked for me better than the stock ebrake did.

Now just make some new exhaust and you are good to go. I take no responsibility for anything that might happen here – take this info at your own risk.

[Butter]

Again, do not use a z32 subframe. It's rediculous. Z32 brakes on a 240 sub is a simple upgrade.

11 – attach your subframe to the new mounting points. To make it sit level, use ½” of spacer on the front mounting points, or even better, use ½” thicker plate in the front than in the rear.
Don't do this, it's more important to get the subframe up close then to make it sit level.

13 – you will need a custom driveshaft made. You could get the rear yoke that is meant to bolt to the diff you now have, or do what I did and just drill new holes in the diff flange for your 300zx rear yoke. There is plenty of meat there for that, and the bolt holes don’t align the drive shaft, the little metal ring does that.

I don't see how you can use the stock z31 in this manner since 240sx has a short nose carrier and you need a much longer dshaft. I can't see any of the pics.

[ZFast88Z]

1SickZ wrote: Well I got the s13 frame in.

Let's just say I'm not happy with what I had to cut out of this car for it to fit !!

What did you have to cut off the car that didnt make you happy? I only had to lightly notch in a few places to get my S13 subframe to fit. Im confused as to what your talking about.