Z32 / M30 2 pot rear brake conversion

[brewster240]

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

[mod_mastaz]

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.

[brewster240]

m30

[mod_mastaz]

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.

[brewster240]

easy

[mod_mastaz]

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.

[rage]

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

[brewster240]

control arm

[gerrybg]

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.

[gerrybg]

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.

[seishuku]

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.

[brewster240]

#4?

[seishuku]

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.

[gerrybg]

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.

[200sxkitcar]

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.

[mod_mastaz]

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.

[brewster240]

hubs

[mod_mastaz]

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.

[gerrybg]

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.

[mod_mastaz]

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?