Z31 rear conversion
 

For IRS models

Okay, so I'm sure many of you are aware of the fact you can swap in Z31 rear trailing arms and stuff into the S12. What is the advantage of this? Well, if you have access to a Turbo Z31 or the MKI Z31 N/A, they allow for vented rear discs. I will get pics of the trailing arm, but I dont see why it would be as needed.

For the MK2 Z31 NA model, it is the exact same as it would be for the S12 IRS setup. I do own a SE so was already stock 5 lug, but knowing that's only dealing with the hubs/brakes, there is virtually not difference between that I am aware of between a SE and non SE. If you have the NA setup, it should for the most part go right into the differential without issue as long as you have a R200. Once you obtain these parts, it is literally direct bolt in. Swap over the brake lines, as they are in the same place as in the S12 and Z31.

http://img.photobucket.com/albums/v6.../121209002.jpg
http://img.photobucket.com/albums/v6.../121209003.jpg
http://img.photobucket.com/albums/v6.../121209007.jpg
http://img.photobucket.com/albums/v6.../121209006.jpg

are the z31 calipers wider than the s12 items, as i don't think the s12 calipers would open up wide enough for the z31 discs, so in theory, i could re drill the z31 discs to 4 stud and use them on the s12 arms,but do i need z31 calipers ?

Ah yes, I did not realize that the point you said wasnt explained well. Thank you. Yes, the calipers are wider to be able to accommodate the thicker rotor since it is vented and not just a single disc. The other thing that will be needed are longer studs/hubs. They are designed so that the rotor slips on and fits into place correctly pushing out the hub just a bit so that everything lines up accordingly. As of the bare minimum of what you need would be Z31 hubs mentioned above and calipers.

I believe CiH would have better pictures since I do know discussing it with him and he obtained a set of rear arms with hubs from a Z31 for a conversion he's planning to do.

has anyone got a pic of an s12 hub and a z31 hub together ?

One interesting point is Z31 turbo and Z31 N/A don't appear to be inter-changeable. When I got my N/A arms we offered up N/A and turbo disks (parts that had been broken by the seller so of known origin). They were the same but the Turbo had deeper back spacing ie, if you lay them face-up, flat on the floor the Turbo was slightly taller.

could z31 turbo discs and calipers be fitted to the s12 hub though ?, i know i'd have to re drill them for 4 stud fitment, but would i need to space the caliper to centralize the disc ?

Yes, in theory you could but with the extra spacing for the rotor, it wouldnt work. Reason being, when trying to put on a wheel after putting the rotor on, there are virtually not threads on the lug studs and the caliper would not work due to different spacing of the bridge and the caliper itself needing to fit the extra width of the rotor. I'll get some better pics tomorrow.

ok matey, cheers.

presume I need the Z31 specific caliper carriers, as well as the calipers themselves ?

I do not know to be honest but would not be surprised if the carriers are different. Just the calipers themselves are different.

I'm also wondering how the z31 rear ARB/Sway bar compaires to S12....? ;)

edit:

TBH I'm hoping they're the same as IIRC the discs diameter is the same and I'll probably plump for refurbed calipers (rather than do it myself).

Hey peeps I'm still unting these damn brackets!

A mate suggested getting the s12 brackets machined to accept the wider Z31 vented discs. Can anyone se why this wouldn't work ?

quick blag; got the brake hardware and I got a z31 beam off ebay. save for a couple of bent brackets it looks in good shape and even came with handbrake cables attached (no doubt they're borked).

I'll start a proper project thread but I'm skint after buying that porker.

confused with mki and mkII Z31
 

I'm a bit confused with this thread. This is what I have 'seen' with Z31's.

MkI 84 to late 86 - non ventilated disc on rear 290mm dia. same calipers as s12 with the exception of mounting 'ears' which are longer to accomodate 290mm dia. rotor. (NB non turbo = 4 stud till 85, all others 5 stud)


MkII early 87 to 88 ventilated rear rotors,(both turbo and non turbo are all 5 stud) can't remember exact diameter, 282mm from memory. Calipers match rotors with wider opening to suit, (not interchangeable with earlier calipers). The trailing arms have a 10mm longer "bearing tube", to push the hubs out 10mm to suit the extra 10mm of rotor width. (I have a set of these later trailing arms complete and have compared it physically and measured the differences with earlier type Z31 setup)

So in closing if you want the ventilated setup you need the whole trailing arm with rotors and calipers and swap it onto your s12.

So does this mean you can use a whole rear end setup from a Z31 turbo (they have an LSD as standard) to get the vented brake upgrade and also and LSD.

Also if the LSD is bolt in can you just use the LSD and shafts from a Z31 turbo with the S12 subframe and hubs??? :confused:

I think the driveshafts would be different. Better to get the whole Z31 rear set-up but I'd expect the LSD to be fairly tired after 20-odd years.

i've got hold of a z31 turbo rear subframe and trailing arms, only thing that ive noticed is that where the shafts mount to the back of the hub they are 4 bolt instead of the s12 6 bolt set up, are the shafts the same spline set up as the s12 ones ?if so i could just change the ends.

Here

I hope this fella is wrong as I just dropped £100+ getting my spare z31 x-member prepaired :(

Not really sure what he means by "it has arc that hits the body" ?

hi mate, to me i think he's put it in upside down, if you turn it over, then it sits higher where the diff mounts, just a wild guess though.

fookin hope so. I sat on that thing for 6 months then see this less than a week after actually comitting some proper monies to my "project" lol (maybe). I'm 99% sure I've seen posts before that say they're identical.

how does your turbo subframe compaire to S12 regular ? I've never actually gotten a good look at the two together.

i'll put it under 2moz mate and let you know.:)

I've just pulled my N/S S12 half-shaft and trailing arm off and the hubs are different. Stock S12 has 6stud 3x2 but my Z31s are 4x1, same as yours. Also, the input shaft (diff end) is slightly larger and the (spider?) bearing is totally different.
So I'm a bit lost right now.

Can someone confirm a stock UK Turbo comes with the R200 diff ?

just measured the z31 and s12 shafts matey, they both measure 29.5mm and are 29 spline;) and the s12 is a r200 diff.

We tried to swap over the driveshaft bearing at the diff end and the Z31 input shaft is just slightly too wide to accept the stock S12 bearing ?
Granted I don't have a vernier to measure it though.

edit: did you notice the Z31 has symmetrical driveshafts too ?

i'am going to strip um down now, you got me worried.

Shaun where's that picture you put-up of your z31 sub assembley ?

on second thoughts i got them out and put all six shafts back, i don't think i can get my head round it until i've put the plenum back on and got it mapped.:(

Well I've done some digging and the 4-stud shaft is a "Double Offset Birfield" type" and the 6-stud is the "Tripod-Tripod" type. Other than the name I have no informatin on one or the other. However, the companion flange in the suspension arm looks to be specific to the driveshaft and the part is listed in the various US nissan parts websites. Looks like the s12 was only ever the T-T type.

http://i102.photobucket.com/albums/m...Y/HPIM1948.jpg

http://i102.photobucket.com/albums/m...Y/HPIM1951.jpg

ebay has thrown up an open turbo diff which will match with my driveshafts for £95 shipped. I always thought Turbos were LSD type ? Either case that may be my best bet.

hows draconis done it?

From S12Silvia.com;

I've half a mind to try fitting the 6-bolt flange to the z31 arm and useing the S12 driveshafts

Yay panic over lol. The driveshaft flange is indeed interchangeable and fits the outer flange perfectly. I'll chuck pctures up later.

good on ya matey,mine will have to be done later in the year.:)

http://i102.photobucket.com/albums/m...Y/HPIM1955.jpg

http://i102.photobucket.com/albums/m...Y/HPIM1954.jpg

Yeah, as far as I knew all Z31 Turbo's had a form of LSD. The late Turbos, MKII, had a clutch-type differential while the MKI I think had a viscous type.

In addition, my understanding, the turbo diff also has different splines in the axle. So if you go that route, the turbo Z31 axles are required.

I currently have my stock open differential with the NA MKII rear end. Because the NA MKII rear end is basically the same as the S12, the only difference is that the hub allows for a vented rear disc. It was literally plug and play. I dropped down my stock S12 rear and bolted up the Z31 NA MKII rear end. The bolts all matched up, the brake lines had to be slightly massaged for clearance spacing on the hub (not much at all) and the Z31 axles bolted right in. For this reason and simplicity, I suggest this route.

Turbo is ideal but has the possibility of containing more issues.

I imagine after 20 years they're likely all slipping like fook anyway. I was keen to keep the stock s12 axles/driveshafts so I could potentially upgrade to an S13/14 based LSD later. :)

yeah, thats what i was planing, i've got the s13 lsvd in mine, so at a later date i could go with a machanical one.

I set about compairing my two rear beams today.

http://i102.photobucket.com/albums/m.../Z31Beam08.jpg
-Turbo S12 Mk2 top, Z31 turbo lower. Using various mounting points as datum points they're identical to within +/- 5mm.

I offered up my Z31 arms to the S12 beam and they line-up spot-on. TBH I'm not sure if the arms are turbo or N/A, but they're 5-stud;

http://i102.photobucket.com/albums/m.../Z31Beam01.jpg

http://i102.photobucket.com/albums/m.../Z31Beam05.jpg

http://i102.photobucket.com/albums/m.../Z31Beam02.jpg

http://i102.photobucket.com/albums/m.../Z31Beam04.jpg

BEHOLD my brush painted arms!

I then offered-up the Z31 beam to my S12. I didn't fancy fitting my bushes to the beam incase I culdn't get them out again lol so this was a very rough mock-up;
http://i102.photobucket.com/albums/m.../Z31Beam03.jpg

http://i102.photobucket.com/albums/m.../Z31Beam07.jpg

I won't be using the Z31 beam as the machine work done to it is sloppy as fook but otherwise I see no reason why it wouldn't match up.

spot on, i din't think they would be different,good on ya for letting us know,;)

You are doing what I should have done. Very well done indeed. Mind if I use this in one of my write ups by chance?