Work originally completed in February 2010: 1) INTRODUCTION 2) BACKGROUND 3) THE BMW 2 STAGE AIRBAG SYSTEM 4) IDENTIFYING THE CORRECT WIRE CONNECTIONS 5) PREPARING THE RAID WHEEL 6) REMOVING THE ORIGINAL STEERING WHEEL FROM THE CAR 7) REMOVING THE SLIP RING 8) ADAPTING THE SLIP RINGS WIRING CONNECTIONS 9) FIT THE SLIP RING TO THE NEW STEERING WHEEL 10) MOUNT THE NEW STEERING WHEEL ON THE CAR 11) THE MOMENT OF TRUTH, THE TEST! 12) JOB DONE 1) INTRODUCTION . Before I start let me just say that this is one of the best modifications I have ever done to any car. It totally transforms both the feel of the car and your relationship with it on the road. I would not have gone to the trouble of writing such a comprehensive article if I did not feel it was worthwhile. Before After I have put many hours of research into this, partly because there was such a lack of information out there but I must express thanks to Mike Fishwick who wrote a guide that set me on this track and to c_w for pointing me in the right direction when I had got my logic wrong . 2) BACKGROUND . One thing that I did not really like about both of the Z3ms that Ive owned has been the ///M steering wheel. In all Z3s the steering wheel is non adjustable and the large diameter causes it to touch my thigh and actually hinder steering when cornering at any pace. Also I find the thin diameter does not help maintain a relaxed grip. So I wanted to source an alternative wheel with a smaller circumference and thicker diameter. Of course it also had to look good. I thought that there would be plenty of options given that later BMWs have provided more wheels of the style I like and there are plenty of aftermarket manufacturers. However, my initial research quickly established that the Z3 does not use a common steering wheel hub with other BMWs, even of the same era. Later wheels have successfully been fitted (eg Z4m wheel) but not without re-engineering of the new wheel hub to retain the Z3's antiquated "Slip Ring" system of getting electronics to the wheel itself. (there is a link to installing a Z4m wheel later in this thread). Looking at the aftermarket also identified that although there are plenty of suitable wheels that will fit (eg Momo,etc ), none of them retained an airbag system. This was a big no for me, as much as I may like the look / feel of a new wheel I have no intention of getting up close and personal with it! I then came across references that identified just the type of wheel I was looking for in my Z3. The wheel in question was a Raid Sports Airbag wheel. Raid make various sizes but upon recommendation I settled on a 340mm wheel. Although this does not seem such a big step change compared to the original 370mm circumference believe me it is when you have got hold of it. The smaller 320mm would definitely have been too small for my needs. So I started to do my research into this option. The first stumbling block was that Raid are a German company with very poor UK agents with regards to BMWs (and Z3s in particular). They are very popular on the Porsche scene and are seen as the upgrade to do on a 911 etc . So I had to resort to emailing Raid and their main agents in Germany (Chrome Design). Despite their best efforts this was a slow and frustrating process as I dont speak German and their English was not that good (but better then my German!). The main issue I was trying to resolve was that Mike had fitted the Raid Steering wheel to a pre 04/99 Z3. From 04/99 BMW changed the Z3 to implement their new dual stage airbag system. Previously Z3s were fitted with a single stage system. As the Raid Steering wheel is generic ie its a basic wheel that uses hub adaptors to allow it to fit many different cars I wanted to make sure that it would fit a 2 stage Airbag system Z3. I eventually got confirmation from Chrome Design that it would and they confirmed that I should get a Daytona wheel and standard Z3 Hub which would have a wiring adaptor. Note the Daytona comes in various versions eg paddle shift gear changers etc but it is the basic no frills ie just horn buttons that is needed. Raid options on their website HERE So armed with the correct equipment I needed I hit the next problem the price. These things are not cheap (and often loaded by UK agents with a Porsche premium) and with a declining sterling to euro exchange rate made sourcing direct from Germany almost as expensive. So I decided to bide my time and try to source a second hand one through my old friend eBay. During the next 12 months several Daytona wheels came up for sale but most had the Porsche bells and whistles I did not need and reserve prices in excess of a new wheel I needed. The one I bidded on actually ended up selling for more than you could buy a new one for (I was up against Porsche buyers!). But then a few weeks ago I managed to source one for roughly 2/3rds the price of a new one (advertised as a Porsche wheel on eBay). The bonus being on receipt it was not only as new as described but it was mint and had only been manufactured 7 months earlier (I later found out that Raid changed their connections a couple of years ago so this would save potential problems in getting the latest wiring adaptors). I then had to source a Z3 hub adaptor and wiring harness to allow connection. There was virtually zero chance of getting one second hand so I ordered the recommended kit from Chrome Design. The cost only being c£50 so I was happy with this in the knowledge I would get a plug and play kit. But when the hub kit arrived I was in for a surprise. It did not seem like the correct one as it had no BMW connection block and not enough wires. With help from people on ZRoadster and Z3Coupe I quickly established that I had been supplied the correct Hub (which is the same for all Z3s as this did not change in 04/99) but the wiring harness for a single stage system. Email exchanges with both Raid and Chrome Design established that they only do a single stage kit but you can buy a 2 stage adaptor separately from Raid. During the time I had been waiting to get answers I had researched the Z3 2 stage airbag system. I figured I had better know how the system works so I could have 100% confidence that if needed the airbag would deploy. This extra researched proved invaluable in that it gave me confidence that I could fit a Raid airbag to a 2 stage system and that it was actually quite an easy process. It was just a matter of connecting the right wires and making certain parts of the system redundant ie I did not need this extra 2 stage wiring harness as I could make my own. What was surprising was that given BMW have been using the 2 stage airbag system for nearly 10 years, Raid do not seem to be geared up to accommodate BMW buyers. This is not helped by the fact that all of their documentation is in German with no English translation. Having no established BMW agents in the UK also hindered the process. So I thought it would be useful to document the entire process of installation for the benefit of others who may look to do this modification. This would certainly apply to any Z3 made after 04/99 with a 2 stage system and so far as Im aware any BMW with the same system as the logic would be the same (wire colours may vary etc ). It is also worth noting that the process for older (ie pre 04/99) is simpler as there are less wires to figure out and as youll see later means that you only have one airbag circuit to deal with, otherwise fitting is exactly the same. This process is all about fitting a single stage airbag to a dual stage BMW system. So far as Im aware the Raid wheels are the only aftermarket wheels available to fit BMWs and retain an airbag system and they are single stage, ie there are no 2 stage non BMW alternatives that I know of. It is also not possible (at least Ive never seen evidence of) to fit a dual stage airbag from a later BMW to a pre 04/99 single stage Z3. Not only because of the hub connector (which can be re-engineered) but because of the electronic control units built into the car which cannot fire the 2 stage system as required to deploy correctly (I will explain how the system works later). I think its important to understand how the 2 stage airbag system works as it certinaly gave me confidence that what I was doing would work correctly if/when needed. 3) THE BMW 2 STAGE AIRBAG SYSTEM . Airbags are referred to by BMW as Supplemental Restraint Systems [SRS]. BMWs are often fitted with several such devices (drivers, passengers, side airbags etc .) referred to as Multiple Restraint Systems [MRS]. Four version of MRS were used on Z3s during their production run (nb from American Bentley Manual so may be differences between USA and Europe): ZAE (from 1996 to 02/97) which had - Centralized airbag control module with built in capability for crash detection (electronic acceleration sensor) - Driver Airbag - Passenger Airbag - Airbag Warning Light ZAE II (from 03/97 to 08/97 added - Pyrotechnic Seat Belt Tensioners MRSI and MRSII (from 09/97 to 08/98 and from 09/98 to 03/99) added - Control module coded to vehicle using DISplus, GT1, MoDIC or equivalent - Self diagnostic capability - Control Module internal mechanical safety switch (must close in conjunction with acceleration sensor before airbag activation) - Passenger Seat Occupancy Sensor [SBE] - Hall Sensor seat belt microswitches MRSIII (from 04/99 to 2002) added - Side impact (door mounted Airbags) - Side Impact Crash Sensors - Two Stage (smart) airbags - Battery safety terminal [SBK] - Fuel Pump safety cut off So these instructions relate to the MRSIII system. It is important to know what is meant by smart system. Pre MRSIII airbags were single stage ie in the event of a trigger condition being met the airbag was deployed. With dual stage airbags there is still only one airbag but 2 separate detonators. One detonator is triggered in low impact conditions and the second in high impact conditions. The important thing is the smart technology as its not just a matter of triggering one device OR the other. In a low speed collision detonator one is triggered (ie stage I). In a high speed collision the cars electronic brain determines various parameters about the collision and decides when to fire the second detonator ie it can fire immediately or be delayed. This has the effect of determining how quickly and for how long the airbag is deployed. The important thing this establishes is that there are 2 separate circuits ie one controlling Stage I detonation and one controlling Stage II detonation but Stage I is ALWAYS triggered ie on a low OR high speed collision. This is important as a single stage airbag only has one airbag circuit or Stage to trigger. Therefore it should always be connected to the stage I circuit of a 2 stage system so it will be triggered during any crash as per a single stage system. But what about the Stage II circuit on the car? We cant just forget about this as part of the diagnostic process is for every circuit to be tested. If any fault is detected the airbag warning light is triggered and the system is made inoperable until it is reset (by a specialist tool or BMW dealer).Of course if nothing is changed it will just trigger again. So the car has to be fooled into thinking that the second circuit is connected to an airbag. This is achieved by simply completing the circuit with a 3ohm resistor in the place of the airbag. This explains why it is slightly easier to connect up to a single stage system as there is only one circuit and you do not have to fool the second stage on the car. It also explains why you cannot fit a dual stage airbag to a single stage car as it would never deploy as intended in a high speed collision (there would be no way to determine the correct deployment timing etc as the required electronics do not exist in the car). So having established the Theory it was time to put it in practice . 4) IDENTIFYING THE CORRECT WIRE CONNECTIONS I referred to the following schematic to identify the correct wiring in the car. Note that the colour codes are in German so have been translated. There are 6 wires going to the steering wheel. 4 are shown on this diagram the other 2 being the horn +ve and ve. Airbag Stage I +ve = Yellow/Black Airbag Stage I ve = Yellow/Brown Airbag Stage II +ve = Grey/Black Airbag Stage II ve = Grey/Brown The Raid Daytona also comes with 6 wires but these are: Horn Button Left +ve/-ve Horn Button Right +ve/-ve Airbag +ve/-ve So its just a matter of figuring out the correct wiring to connect up: Car Yellow/Black to Raid airbag +ve Car Yellow/Brown to Raid airbag ve Car Grey/Black to Car Grey/Brown via 3 ohm resistor Car horn +ve to both Raid horn +ves Car horn ve to both Raid horn ves Now that the wiring is figured out down to the job itself 5) PREPARING THE RAID WHEEL . The first job is to prepare the wiring harnesses needed to connect up to the car. It would of course have been easier to get the pre made connector from Raid but its pretty simple to make yourself using the single stage adaptor already supplied with the hub and simply buying a 3ohm resistor. (In my case the wheel came with a Porsche adaptor which already had a 3 ohm resistor bridge to convert the Porsche 2 stage system to fit the wheel so I just cut that off and used it) Here is the back of the Raid Steering Wheel with the single stage airbag adaptor wire in place The airbag needs to be removed which is a matter of undoing 2 hex bolts from the rear The airbag can then simply be pulled off from the front. Note that in order to connect the 2 horns to one set of wires using spade connectors a handy connecting block is provided. However this used both small and large spade connectors (for +ve and ve) and I only hard large connectors to hand so I simply utilized the spare Porsche wires and put large spade connectors on the other end. This was really unnecessary as you could wire into the block directly from the car with the correct spade connectors. I simply made up the connections I would need to connect the wheel to the car. I used red to identify what would be +ve connections and blue for ve. Note the stage II circuit bridging loop pinched from the Porsche connectors with resistor visible through the shrink wrap. I just put a spade connector on each end. Next I fitted the Z3 specific metal hub adaptor to the rear of the wheel. This can only be fitted with the airbag removed as 4 screws are accessed through the airbag hole. The screws come pre applied with thread lock compound. (I was ultra cautious with all connections as this is a safety related area and so as youll see later all crimped spade connectors were soldered and connections shrink wrapped / screws thread locked to stop vibration over the years from causing any bad connections triggering the airbag light and disabling the system). The Z3 hub fitted in place The airbag connector just simply clips into place The Horn wires connect to the provided connection block <img src="http://i624.photobucket.com/albums/tt322/jonttt/_S54%20Journal/S54%20Raid%20Steering%20Wheel%20Install/IMG_0176.jpg" border="0" /> 6) REMOVING THE ORIGINAL STEERING WHEEL FROM THE CAR . DISCONNNECT THE BATTERY! Note that the airbag system has a 10 second backup charge and so you should not touch anything for over 10 seconds after disconnecting the battery. In practice by the time you get to taking off the steering column cover you have left it for a few minutes anyway. ENGAGE THE STEERING LOCK with the wheels lined up straight. This will help you connect the new wheel up in the correct position later. Some before pics for reference later First we need to remove the underside steering column cover as this hides a connection block you need to disconnect. It is held on by one Philips screw underneath. The cover then just pulls away. Be gentle, there are some plastic clips on its edge and you dont want to break them. Note the small plastic screw connector, dont lose this so make sure it has not fallen on the floor! You can then see the connection block for the steering wheel underneath which just unclips (for the first time you see the 6 wires for the 2 airbag stages and horn) The next job is to remove the original steering wheel. You have to remove the airbag to access the bolt that retains the wheel in place. To remove the airbag you have to undue two 27mm Torx bolts from the rear of the wheel (as per the Raid wheel but instead of hex bolts this uses Torx bolts ie star shaped). Nb you have to do this blind as you cant see the bolt heads and it is fiddly to get lined up so a few pics will help visualize what your doing. You can then gently pull off the airbag from the front of the wheel. Be careful as the wires are connected behind it. Unclip the wire connecting block. The dotted line shows were you are going to cut later to connect to the new wheel. The airbag can then be put to one side ready to remove the steering wheel. You need a 16mm socket and a breaker bar as you will need plenty of leverage to remove the centre bolt holding the steering wheel in place. Once the bolt is removed you are ready to remove the steering wheel. At this point it is worth covering how the wiring can connect to the steering wheel and not get trapped as the wheel is rotated. This is because there is a slip ring screwed to the back of the steering wheel. This converts the lower wiring harness you disconnected below the steering column to a thin ribbon which is wound like a spring around the wheel. As the wheel rotates one way it is unwound and as it rotates the other way it is wound. The ribbon is then converted back to wires on the steering wheel side. This slip ring needs to be transferred to the new wheel. As you pull the steering wheel from its securing mount the connected slip ring will come away with it with the lower steering column wire connector block. There is a securing pin that is released and the slip ring locks in place (ie so the ribbon coil is 50% wound). You can see the white securing pin and its associated hole here. As the pin is released from the hole in the securing ring the ring becomes locked in place. You now have the original wheel and wiring harness removed from the car. 7) REMOVING THE SLIP RING. The next job is to remove the slip ring from the original. The slip ring is connected to the wheel by 3 screws. Note that when you remove the slip ring it is no longer locked in place. It is important that when you fix the new wheel to the car that the slip ring is in the half wound position. You can try to ensure this by using tape to secure the outer and inner parts in place so they do not rotate. In practice I tried this but they became loose when handling the ring later. This presented no problem as you can count the number of turns from fully wound to fully unwound (6) and just ensure that you are at the mid rotation (3) when you mount the new wheel later. The retaining screws have a T10 torx head And removed with my (unsuccessful) attempt to tape the slip ring in place to stop it rotating freely. The slip ring can then carefully be separated from the back of the steering wheel, threading the wiring through the hole. You can now clearly see the wire connector for the bottom of the steering column and the other side which connects to the steering wheel. It is the steering wheel side we shall be adding new spade connectors to. You can just see the spring ribbon inside the slip ring that winds / unwinds with the rotation of the steering wheel. Now replace the Airbag in the original steering wheel and secure it in place with the two screws at the rear, you wont need it again. This is an ideal chance to compare the 2 wheels side by side The car looks a bit wired with no steering wheel 8) ADAPTING THE SLIP RINGS WIRING CONNECTIONS . Time to get on adapting the slip ring to take spade connectors. I simply cut in the middle (make sure you cut the steering wheel side of the slip ring!!!). I was keen to make sure that it would be an easy process to refit the original steering wheel if I ever felt so inclined so I fitted spade connectors (male v female) to both sides. I stripped the ends of the wires ready for crimping to the spade connectors and then for added robustness against vibrations I soldered (and later shrink wrapped the actual connections). So I was left with an easy reconnection back to the original wheel if ever needed 9) FIT THE SLIP RING TO THE NEW STEERING WHEEL . Thread the wires through the hole from the rear and line up the connection holes (they only line up one way). Be careful tightening the 3 retaining screws as you are putting into fine plastic thread which can be easily stripped. Note I secured the screws in place with some clear laquer from my touch up kit (to stop them undoing with vibrations). You now have all wires ready for connection to the airbag and horn at the front of the wheel. Connect up all of the spade connectors and shrink wrap them with a hairdryer to secure in place. (Do not connect up the airbag at this stage as you need to mount the wheel to the car first). Tidy the wires up to stop them fouling the mounting point. Note the horn connection block has its own storage area. 10) MOUNT THE NEW STEERING WHEEL ON THE CAR You can now mount the wheel to the car. Make sure the slip ring is in the half wound position (3 turns) and line up the locking pin with its notch. Make sure the wheel is dead centre and slowly push down on the mounting point. Secure in place with the mounting bolt. Now you can connect the Airbag connector And gently push the airbag into place on the wheel. Secure the airbag to the wheel with the two hex bolts behind (nb you may need to rotate the wheel which is now secure to get decent access) CONNECT THE LOWER STEERING COLUMN CONNECTOR BLOCK back up (if you forget you will trigger the airbag warning light meaning a dealer visit!) A side view showing how neatly the wheel mounts the steering column Replace the lower steering cover (gently clip into place and then secure with the screw, via screw clip) 11) THE MOMENT OF TRUTH, THE TEST!.......................... Reconnect the battery (no explosions yet, thats good) Put the keys in the ignition and turn to the second auxiliary position (no need to start the car). To be honest I did this from outside the car with my back facing it !!! All quiet, your OK The car should go through its diagnostic process, the airbag light should come on and then go off after a few seconds. If the airbag goes off you have a problem, if the airbag light stays on you have a problem. You will have to find the problem (should only be a wrong wiring connection) before you get the airbag light reset. In all seriousness the airbag should never deploy in this process as the car will detect a fault first. You should now check both horn buttons work correctly. 12) JOB DONE . As I said at the start this is a fantastic mod. Whether you have a single stage or dual stage system you can fit this wheel fairly easily once you know how to wire up the connections. The car is transformed both in terms of the feel of the wheel (you main interaction with the car) and in terms of drive. The best way to describe is the car feels more like a go cart. Turn in feels much more precise and you really feel as though you have more control over cornering. The only down side is the price. These are not cheap but they are top quality (why do you think they are popular with Porsche owners). If you get the chance to get one, do it, you will not regret it.