There are a couple of things that have been keeping me back from posting much:
1. Firstly this is all pretty untested, I have about 300miles on the set up and everything is ok at the moment. If you follow this you do so at your own risk and I take no responsibility for any failures or losses from others attempts.
2. Yes I know the car looks pretty untidy, its solid and mechanically perfect, the reds flat as its just some base coat atm and new wings/bonnet/tech 1 kit/bumpers/valances/drivers door etc are coming as round two.
3. Yes other methods are available there are seas of text on those already available via a search.
4. Yes 17" wheels, they weigh 1kg more than the 205/50/15 bbs I had on before and drive BETTER (yes better) that the 15s did thanks to reasonable weight, proper offset and semi decent tyres.
Now onto the meat.
I have been toying with a 5 stud set up for a while, the motivation has been mostly the poor brakes and subjective wheel choice for the e30, the catalyst has been the daily needing some major running gear repairs.
With that in mind all of this has been done for a total of about £1200 (no labour cost obviously) which includes everything listed below.
Parts needed:
Front:
E36/46 bearing x2
M24x1.5 pitch nyloc nuts x2
Plate steel for brackets 320x50x10mm min
Plate steel for bracket spacer 320x18x18mm min
M12x1.5 10.9 or 12.9 grade bolts 40mm long x9
M12x1.5 nyloc nuts x4
15mm wheel spacers (good quality with little run out) x2
E46 328 brake discs x2
E30 brake pads SET
Aluminium stock sizes TBC (I think 50x75dia minimum)
Aluminium tube Size TBC (80mm dia x5mm wall iirc)
EN8 bar stock 100mmx50mm dia min
EN1 bar stock 100mmx40mm dia min
Copper brake line/goodridge hoses/new fittings optional
17x7.5”a BBS RC41 with 215/40/17 x2 (or any other 4x120 ET40 wheels but 16”a min for 300mm discs, 15”a wheels will take a 280mm disc)
Rear:
E30 trailing arms x2
E30 325 wheel bearings x2 (76mm versions)
Z3 donor arms complete x2 (as you need the hubs and brakes/h brake)
RTA bushes x4
Beam bushes x2
Liquid 75a poly kit optional but recommended
New H brake cables
E30 drive shafts
E30 rear beam
E30 rear brake pads SET
Z3 rear discs x2
Hand brake pads SET optional
New diff bush (optional)
Again Goodridge and new pipes optional
17x8.5”a BBS RC42 with 215/40/17 x2 (or any other 4x120 ET40 wheels)
Starting with the rear:
This is a pretty simple case of taking the E30 trailing arms and fitting the Z3 hubs and brakes.
6 pot or late model 4pot hubs with the greater offset and 76mm bearing are needed for two reasons.
1. Not all z3s have the large bearings apparently some have a 73mm bearing (bmwfans with the vin number to check)
2. Not all Z3s have the same offset to the rear hubs apparently, I can only say 6 cylinder and late 1.9 with any certainty.
It might be possible to find some hubs with the 76mm bearing and a lower offset on other versions of the Z3 which might help get some wider wheels under the rear arches as the ET40 8.5”a wheels with 215 are at the limit of the rear arches. I had to roll a little to clear comfortably.
The discs are 270mm but the callipers are identical to touring callipers with a bigger bracket.
The Callipers bolt directly to the E30 arms.
Hand brake is a direct fit and works with E30 cables.
Optional things to do are add a plate to the top of the beam as the diff bolts can come loose and crack this area of the beam, lots of power seems to as well.
Split the beam as seen below and add M8 pinch bolts to make changing the bushes a doddle.
Another optional but recommended thing is to fill the diff and beam bush voids with 75a polyurethane. 75a is very similar in stiffness to rubber and makes them behave like solid rubber bushes.
No plasticy squeeking rear steer killing polys on this executive turd to knock your fillings out.
Based on the way this thing feels and the minimal increase in vibration/noise I won’t be fitting poly beam bushes to anything ever again, even track stuff.
The front is a bit more of a challenge:
Everyone knows E36/46 bearings won’t just bolt on to E30 legs and E36 legs maul the steering geometry. There may be a better way to do this with E46 legs but this has yet to be properly worked out/tested, though I have access to a shell to mock it up on if anyone wants to donate some legs.
There are 3 things to get right at the front:
1. Axle size
2. Hub locking nut
3. Offset
1. To get the axle size correct we need to sleeve the bearing to 31mm from the 37mm of the inner diameter of the E36/46 bearing.
The inner sleeve is simply EN1 20mm long and something link 31.05ID and 37.05OD giving a sliding fit on the axle and press fit in the bearing inner.
The outer sleeve is a flanged sleeve about 25-30mm long to just overlap the gap between the two bearing cups and leave a 1-2mm gap between the sleeves when tightened.
The flange is there to prevent the E36/46 bearing slipping over the hub nut.
It’s about 49/50mm OD on the flange, ID and OD of the sleeve are as the inner.
2. The hub locking nut is so easy I can't understand why it has not been done before.
Simply take a standard M24x1.5 nyloc nut, burn the nylon out and machine the outer so about 6mm of the nut slips inside the outer sleeve.
This makes a nut with a metal rim that can be knocked over to lock the hub, the correct amount of thread engagement and a nut hex the same size as a stock nut.
The only thing with it is you might need to split the rim with a hacksaw blade before hitting it with a punch as it’s thicker and harder to knock over.
This can be torqued as a normal E30 nut, the E36 and E30 have the same hub torque, 36mm socket.
3. The Offset is a little more contentious.
There is 2 ways to solve this, discs with less of a deep hat height as E46 discs touch the track rod if put on direct. This would then need no/less calliper spacer bracket and a wheel spacer outboard of the disc as normal.
With the disc against the hub the offset would be about ET25, quite close to stock M3/E34/E38 so maybe one of those might provide a correct 300mm disc.
In my case I had the E46 300mm discs so went with the TVR method. Two things to note, this has been done by TVR and other kit car builders before and is perfectly safe, it has even been done and used in motorsport/rally situations, it’s tried and tested even if it not best practice. Secondly it is the clamping force of the bolts creating friction that holds the wheels on NOTHING ELSE, not the bolts, not the centre bore.
To get the disc out correctly I took the Hub spacers and turned them into disc spacers, To do this I opened up the inner bore to (79mm I think) to clear the disc ring and bore them to (72mm I think) for the centre bore.
If this is perfectly concentric to each other and the outer is not really a big issue, it is much more critical to use good solid spacers with no runout/thickness variation.
When on the hub they leave very little for the wheel to mount on and nothing to centre the disc.
This is solved by making a disc ring with (72mm ID and 79mm OD about 6-7mm thick) and tapping it on over the remaining centre spigot on the hub.
This centres the disc lovely. I had less than 0.1mm run out with a wheel centre fitted on the functional diameter of the 300mm discs. (Up to 0.4mm is the max allowable if you want to avoid brake judder).
Wheel Centring is the next thing, for this I machined billet 6068-T6 end caps with an OD that presses into the inner bore of the Hub and an OD that suits the wheels (72mm I think) centre bore.
Concentricity is key, to get this right I used one lathe set up, machined the step and out without taking the bar out of the chuck, bored the recess as the third operation and then chopped the bar off and turned it around to face off the outer face.
Tested to 85 MPH and no wheel wobble.
Remember to add a 10mm thread in the centre so you can wind a head bolt or similar in to extract the centre cap once fitted or there’s no getting them out of the hub.
To aid wheel/disc fitting, cut the head off one of the M12x1.5 bolts and use it as an alignment stud.
With all of this fitted you will have E30 struts with E36/46 hubs and offset.
I have cad drawings and measurements for most of the above which I will dig out and add.
Brake brackets are pretty simple. For the 300mm E46 disc you need a flat 10mm thick steel bracket to move the calliper out 20mm, the hole/bolt spacing is 90mm.
With the offset I used you need to add a 15mm spacer between the bracket and calliper to centre it on the disc.
This assembles nicely with M12x1.5 40mm long bolts.
Do the bolts on the hub first and the calliper second and the hub needs nuts that are not accessible when the calliper is fitted. Torque to (90lb/ft I think).
Picture dump, will move them to the right sections later.
I will also try to get some photos of the car at the end of the week when I can get out in the daylight.
Initial trial + CAD drawing to work things out. (this was solid, see later pictures)
Onto some pics of the actual bits going together:
I shall say no more 
