Z32 / M30 2 pot rear brake conversion

edited by draconis due to change of content of inappropriate material and slander.

Ah yes, I remember looking into this. Badass setup btw. Z32 rear calipers + m30 drum brakes haha. Way overkill for our car weight, but it will fit, because the Z31 guys have experimented with this. To use the m30 rear drums, you need the 87-89 hubs(vented brake hubs, its 10mm further out). To use this on a regular s12/84-86 z31 hub, you would need to custom fab a 10mm hubcentric spacer for the ROTOR, not hubcentric type for your wheels. If you look closely at the hub with the rotor off, there is a slight lip for it. You just have to get a wheelspacer with that OD to fit the ID of the rotor and you're set.


It sucks but I just took it RIGHT now.

87-89 Z31 guys have ran z32 rear brakes without an e-brake. Some have even thought about using a driveshaft brake as an e-brake. It's basically a small rotor and caliper on the driveshaft to prevent the wheels from moving.

m30

It's a Phillips head. A lot of S12 fasteners are phillips for some damn reason. Quick trip to the hardware store would fix that haha. I guess it's only used to hold the dust shield anyway. Getting new hardware and highest grade bolts for it would be perfect for the m30 back plate.

Edit: Hrm e-brake cable locations are way different, but it shouldn't be hard to use either m30 or z31/s12 e-brake lines with a custom mount for it.

easy

Can you measure the bolt pattern of the backing plate for me later? I'll measure these when I'm not lazy as fuck haha. A rough estimate is fine cool though cuz I'm probably just gonna bust out a ruler or something to see if it'll fit for a fact, or at least really close. How easily sourced are these M30 e-brake assembly? I don't think I've ever seen one in the junkyard before. If I ever want to go back to 4-lug and if these parts are easily sourced, I'd go this route instead of stock s12 stuff.

Edit: After looking at the Z32 backing plates, I think they might be the same too. They have that same 4 bolt pattern. I need to get a set of S13 rear dust shields to find out. I don't know about the rear hubs, but they look similar also and we could possibly change to the newer style axles. Maybe make VLSD swaps easier too? Who knows. I need to look at the FSM to compare Z32/S13/S14 rear hubs for similarities.

i think we'd have to do a whole contrl arm swap or something, whats the back look like?

control arm

I've got the parts on the way to convert to Z32 2 pot rear calipers. Here's what I'm going to use:

87-89 Z31 rear arms, (got a pair for $20!! without hubs, I already have the hubs here).

R33 turbo skyline - calipers,rotors, backing plate and shoes

HR31 skyline turbo handbrake cables. These have the same rear cables as an M30.

I've worked out that I'll need a 5mm spacer behind the rotor, as Z31 rotors are 57.2mm from rear face to the front top hat face where as Z32/R33 are 63mm. I already have 5mm spacers here so it all should be pretty much a bolt up.

It will make my track 15mm wider per side, so I may have to roll the inside lip on the guards a little.

I've figured the key to this conversion is having enough space behind the hub so that the brake shoes don't foul on the hub.

I've been able to find out that the extra 10mm of width in the 87-89 Z31 trailing arms is in the arms themselves, the tube that the hubs/axles go into is 10mm further out to make space for the extra 10mm in the ventilated rotors, hopefully this will help to clear the brake shoes for the hbrake. The hubs/axles are the same length for all the Z31's. So I can use my current hub/axles in these arms.

The S12 arm doesn't use a backing plate, it only has a caliper plate that's welded to the axle tube.

There might be enough meat to drill and tap or use bolts on the caliper bracket, but it would be much safer to torch or cut off the bracket that's there and weld a new one on.

#4?

dust/water shield, it only has phillips head screws holding it in, if you used that for holding a brake setup it would be a death wish.

You might be able to drill and tap it for a larger bolt, but honestly I don't believe there is enough material to make it safe enough for a street car.

I did go onto Z31 that's where I got the information from after much abuse I might add. One or two there aren't the friendliest of people, (understatement).
I asked several times for someone that had actually physically compared the bits and could confirm first hand whether the difference was in the arms or the hubs. Someone responded who said they had and that it was the arms that were different and the hubs were the same across models, (except for the obvious 4 and 5 stud differences).He's a well known mod on that site and supposedly one of the experts and also all round rude grumpy bastard I must say!!(Worse than me, and that is bad!)

Sorry i can't give a link to the thread as the dickhead then proceeded to delete it, whether this was because he wasn't sure of his supposed expert knowledge and didn't want the thread read or not, I can't say.

Of course without actually doing the comparison myself it's still second hand info.

As soon as I get a chance I will measure the distance from where the hub slides in to the caliper mount plate on both my trailing arms, (S12 and the 87-89 Z31 ones), and this should confirm it for me first hand. By looking at the trailing arms I can see how this could be achieved quite easily when making them without redoing all the parts that weld together. There is a 'tube' that is welded in the arms, you'd call it the bearing and hub carrier tube I guess. All they would have to do is weld it in 10mm further out and you've got the extra 10mm, it would be the cheapest way to do it to from a manufacturing point of view.I'm pretty sure the CV shafts could cope with an extra 10mm of outward movement. Anyway I will check with my tape measure next week, can't now as I'm way behind with some work I have to finish.

Also the 'screws' that hold on the backing plate on an s12 have a bolt type thread,10mm from memory I have taken them out a while back .I'm pretty sure that R30 skyline rear arms use the same thing to hold the backing plate on and I have seen pics of a Z32 backing plate and brake shoes bolted to an R30 arm using hex head bolts in place of the philips head ones. I can't confirm that he drilled out the threads and retapped them to a bigger size or not, or just used hex head bolts of the same size, I suspect the second.

Here the guys with live axle, (which are the common s12's here), unbolt the whole axle and backing plate and hbrake drum setup and discs and calipers etc from 910 bluebirds to do a rear disc conversion. They go straight in in place of the s12 rear drum brake axle setup and the 4 bolts are the same except they have 10mm longer threads to attach to the axle housing, so you just use the bluebird ones. They are only pissy little 10mm bastards and it all works great.

I have done this conversion myself previously on a 4 link s12 so know first hand.

This is a pic of the S12 V6 rear control arm,



and this is a pic of the 87 or so Z31 rear control arm.

So I guess anyone can run vented rear brakes(with a spacer), but not the M30 backing plate + z32 rear brakes with full functionality. At least this clears up A LOT of misinformation.

hubs

I mean the z32 brakes it'll work with the 87-89 control arms, but not the S12 or 84-86 z31 arms because the arm itself is actually different. That tube that holds the hub is pushed out. The hubs could be different, but if you use m30 backing plates on an 84-86 z31/s12 arm, wouldn't the hub hit the backing plate stuff, like gerrybg said? We'll find out when someone attempts to do this.

Nice pic thanks Sterling. So from the measurements in the pic it pretty much proves that the extra 10mm is in the arms and they have welded the bearing tube 10mm further out and the hubs are the same across all the years. Thanks heaps for that.

So I can swap my SE V6 rear 5 stud hubs into my 87-89 Z31 arms and then I just need to use the 5mm spacer behind the Z32 rotor and it should be all a bolt up.

In the US do they put salt on the roads in winter as it looks like things rust up there real bad.

The Z32 rotors are a little taller, so he'll need to space it outwards a bit more to get the rotor centered with the Z32 rear calipers. He already has the Z31 87-89 arms. If he were to use the S12 arms, I'm guessing he'd have to space out the Z32 rotors 15mm to use it.

Gerry, are you going to have an e-brake? Are you going to use the F31 backing plates or Z32 modified?

The Z32, R33 etc etc, (all use the same rear brakes) rotors are 63mm 'tall', the Z31 87-89 are 57.2mm. So almost 6mm difference. My spacers are 5mm, so that should be close enough.

I could have got hold of a backing plate off a HR31 JDM import skyline turbo, from what I'm told they have the same rear end as an F31 in the US. After a bit of research I found that HR31/F31 guys have had to space Z32 calipers out 6mm to run Z32 rotors and calipers ,(also the Z32 rotors just cover enough of the brake shoes for them to work). Using their own HR31 rotors the Z32 calipers fit fine with no spacing issues if you follow. This tells me that the HR31 rotors must be close on 6mm taller again than the Z32 ones. So I figure that the F31/HR31 drum hbrake shoes etc are 'taller' than the Z32 stuff, and would probably hit the back of the hub.

(Actually one of the Aus members on here did a rear conversion using Y31 Cima rear bits, which are the same as F31 also. The hub/axles on those are longer and this is what gives them the backspacing behind the hub face for the rotor and park brake stuff, I've seen pics of it and knew from those.)

So I'm going to use Z32 backing plate, drum brakes rotors and calipers. Also I've found out that the 2 rear handbrake cables on F31 and HR31 attach together the same as s12 and Z31 ones in the middle, but on the ends are like Z32 to operate the drum brake. So I've got hold of a pair off a HR31.

So hopefully with all the right combination of parts should all bolt up.

I'm a scrounge hound and have got all this stuff for very little as far as $ goes, otherwise I wouldn't have bothered. When it all gets here we'll see how it goes.

The HR31 backing plates only lined up for two holes when turned about 30 degrees. The bolts are also metric 10mm rather than 8mm for the s12 and Z31.

I have drilled the 2 holes that line up to 9mm and then retapped them to 10mm which was pretty easy. I've then given the trailing arms to a machinist with a bench drill and he is going to drill 2 holes in each to match the other 2 holes in the backing plates.Then it will all be a bolt up with all the parts I have, (I got my Z32 rear calipers with all the lines, hoses and good pads the other day).

I got my HR31 hbrake cables and they are a perfect fit for the s12. The front ends that join towards the front are exactly the same as the s12.(This I believe is the same for M30 cables).

So for people in the US what you could do if you wanted to go to this trouble, (which I wouldn't have bothered if I hadn't got all the parts for next to nothing like I did), You would just use M30 backing plates and hbrake cables and trim off the edges to accomodate the bigger Z32 rotors.

Finished my Z32 2 pot rear brake conversion, wasn't to hard, getting the bits together was the hardest part.

I used:

87-89 Z31 trailing arms.(Could be done with normal s12 trailing arms with bigger spacers but starts to get complicated and messy)

Brake backing plates and hbrake shoes and bits from HR31 JDM Skyline or Y31 JDM Cima, (same as the M30 in the US).

handbrake cables from a HR31 JDM Skyline, (US would use M30)

5mm slip on spacers

HR31 or Cima flexible brake lines (US M30)

Z32 rear calipers

Z32 rotors

Z31 5 stud hubs, (not necessary you can stay 4 stud if you wish)

Steps:

1. Widen the diameter of central hole in the backing plate to clear the Z31/s12 bearing tube which is a few mm to wide, (I just used an angle grinder and die grinder)

2. 2 diagonal holes in the backing plate will line up with 2 on the Z31/s12 arms. Redrill these holes using a 9mm drill bit, then retap them to 10mm x 1,25mm thread

3. Bolt the plate on then mark the 2 other holes that don't line up and redrill holes in the trailing arms using 9mm drill bit and tap to 10 x 1.25mm, (I got an engineer with a pedestal drill to do this for me cost $30 for both trailing arms, I have since bought a pedestal drill so next time (not that there will be a next time!!) I can do it myself

4. Cut the  outside portion of the backing plate off with a thin cutting blade in the angle grinder, (its to narrow for the Z32 rotors and you only need the centre bit the brake shoe mechanisms mount to.)

5. That's about it really, then everything bolts up.

I'll get pics when I get time.

I haven't bolted these arms up to my car yet, I'm waiting on my rear srping mounts from megan so i can bolt everything on together and be done all at the same time.

Oh almost forgot to mention with this brake setup the track is 15mm wider per side so you may need a guard roll with your tyres pushed out this much, depending on combination of wheel width, tyre size and rim offset.

Here's links to the pics as promised. I haven't swapped the stub axle in yet. Last photo shows where I've redrilled one of the new holes required.

http://img229c.imageshack.us/img229/7537/reabrake6xm3.jpg
http://img229.imageshack.us/img229/8603/reabrake4sg1.jpg
http://img229.imageshack.us/img229/4736/reabrake1wf3.jpg
http://img229.imageshack.us/img229/5025/reabrake2co1.jpg
http://img229.imageshack.us/img229/3158/reabrake3jc9.jpg
http://img229.imageshack.us/img229/4475/reabrake5xu7.jpg

E-brake performance question here.
Stock S12 setup really sucks.
Would upgrading to late Z31 vented be enough to get lock on demand or would it be advised to step up to this drum setup?  I've heard these types of e-brakes usually work very very well.

My vented rears with hawks HPS are pretty great, although I don't yank my e-brake left and right. The stock e-brake honestly is fine with some decent pads. The vented brakes only cool better than the solid disks. They use the exact same brake pad and the surface area is still the same. It's only moved out like an inch or so for more leverage.

Good work Gerry!

also noticed you have the rear threaded coil over section, were you able to purchase it seperately to the set?

Yeah I did, I found a NZ distributor of Megan products, (there are none in Australia that i could find). They were just arranging a container of stuff to be shipped from the US, and I asked them if they could just buy the adjustable spring seats from megan for me and they were able to arrange it.
Because they were already getting a container I didn't have to pay freight from the US, just postage from NZ, which was only $25 or something.

I have some s13 koni yellow rear shocks here, and a few sets of coilover springs to run with them.

Sweet, was it TNT Performance? They seem to be the only NZ distributor.

I picked up a set of S15 Tein Flex coilovers so will try out the rears and see if they can be adjusted low enough, the tube is really long!

Yep was TNT, (the South Island branch)

al3x
Sweet, was it TNT Performance? They seem to be the only NZ distributor.

I picked up a set of S15 Tein Flex coilovers so will try out the rears and see if they can be adjusted low enough, the tube is really long!

bin lookin at this converion...would it be possible to do with s12 arms/hubs and z32/r33gts backing plates..cuz the r31/m30 gonna be impossible to find where i live

i really need ah e-brake wid sum bite n the hub/rotor set up would be perfect with project mu shoes n pads

Z32 rear swap is completed? you have other pictures of swap?

is a complex assembly

Can I just take the whole trailing arm from the m30

Not farmiliar with the M30 as we didn't get them here. If the shock mounts in the same place as an s12/Z31 it would be okay, but I suspect it doesn't, it is more like skyline R31 R30 etc which mounts the shock on  'stub' sticking out from the trailing arm.

can someone reupload the pics?

(Could be done with normal s12 trailing arms with bigger spacers but starts to get complicated and messy)

Hey, I finished my HNR32/BNR32/Z32 2 pot rear brake conversion (without hand brake) on Nissan Silvia S12 '84 FJ20E (European market) 290mm rear brake discs. Maybe it will be interesting for someone.
Previous owner installed aluminum brakes from HNR32 (Nissan Skyline R32 4WD RB20DET, brake discs 280x30mm front, 297x18mm rear), the same as on Z32, and rear brakes the same as on GT-R 32 (BNR32). I have S13 suspension on front, so that's clear. At rear brakes was installed on original S12 brake disc 290x10mm (i think all was bolt-on), but that disc is too thick.

So I bought brake discs from Toyota RAV4, original code 43512-42010. Gave them to turner - reduce external diameter from 302mm to 290mm, and increase internal diameter from 62mm to 68.09mm. Drilled 3 holes on each disc for 4 lugs hubs.

Original Disc | Z32 disc | RAV 4 disc






Also I bought original brake pads from Subaru Impreza WRX (same construction of calipers) - code 26696-FA000. I prefer them because it's break pads + all mounts + all plates in one pack!

So here we are:







All fits perfect :) Also I cut a bit baffle-plate.

old thread i know but question. i heard that only z31 turbo trailing arms were 10mm wider. but is it true that all z31 arms are wider?
and if i was to use my stock s12 arm, how big of a spacer would i need to machine to have full z32 rear 2 pot brakes with functional ebrake.

pakii-afa on 11:24:48 PM / 07-Dec-13
old thread i know but question. i heard that only z31 turbo trailing arms were 10mm wider. but is it true that all z31 arms are wider?
and if i was to use my stock s12 arm, how big of a spacer would i need to machine to have full z32 rear 2 pot brakes with functional ebrake.