Fitting Smaller Raid Airbag Steering Wheel to 2 stage system
             
by 
Jonttt » Mon 08 Feb, 2010 20:54 
                            Fitting a Smaller Raid Sports Airbag Steering Wheel to a BMW Dual Stage Airbag System. 
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 β€SLIP RINGβ€ 
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 β€feelβ€ 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 Z3mΆs that IΆve owned has been the ///M steering wheel. 
In all Z3Άs 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 β€thickerβ€ diameter. Of course it also had to look  good. 
I thought that there would be plenty of options given that later  BMWΆs 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 BMWΆs, 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 β€up  close and personalβ€ with it! 
I then came across a great post by Mike Fishwick on the Zroadster.net knowledgebase HERE in which he explained how he had identified just the type of wheel I was looking for in his 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  β€stumbling blockβ€ was that Raid are a German company with very β€poorβ€ UK  agents with regards to BMWΆs (and Z3Άs in particular). They are very  popular on the Porsche scene and are seen as β€theβ€ 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 donΆt 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 β€dual stageβ€ airbag system. Previously Z3Άs were  fitted with a single stage system. As the Raid Steering wheel is  β€genericβ€ ie itΆs a basic wheel that uses β€hub adaptorsβ€ 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 β€Daytonaβ€ wheel and standard Z3 Hub  which would have a wiring adaptor. Note the Daytona comes in various  versions eg β€paddle shiftβ€ gear changers etc… but it is the basic β€no  frillsβ€ 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 β€Porscheβ€ 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 β€Daytonaβ€ 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 β€as newβ€ as  described but it was β€mintβ€ 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 β€plug and  playβ€ 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  Z3Άs 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 β€single stageβ€ 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  β€redundantβ€ 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 β€gearedβ€ 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 IΆm 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 β€figure outβ€ and as youΆll 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 IΆm aware the Raid wheels are the only  aftermarket wheels available to fit BMWΆs 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 IΆve 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 itΆs 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 SYSTEMβ€¦β€¦β€¦β€¦β€¦β€¦β  €¦β€¦β€¦.. 
Airbags are referred to by BMW as β€Supplemental Restraint Systemsβ€  [SRS]. BMWΆs 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 Z3Άs 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 (β€smartβ€) 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 β€smartβ€ system. 
Pre MRSIII airbags were single stage ie in the event of a β€triggerβ€ condition being met the airbag was deployed.  
With dual stage airbags there is still only one airbag but 2  separate β€detonatorsβ€. One detonator is β€triggeredβ€ in low impact  conditions and the second in high impact conditions. 
 The important thing is the β€smartβ€ technology as its not just a  matter of β€triggering β€ one device OR the other. In a low speed  collision detonator one is β€triggeredβ€ (ie stage I). In a high speed  collision the cars electronic β€brainβ€ determines various parameters  about the collision and decides when to fire the second detonator ie it  can fire immediately or be β€delayedβ€. 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  β€circuitsβ€ ie one controlling β€Stage Iβ€ detonation and one controlling  β€Stage IIβ€ 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 canΆt just forget  about this as part of the β€diagnosticβ€ process is for every circuit to  be β€testedβ€. 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 β€fooledβ€ 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 β€foolβ€  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 β€Theoryβ€ it was time to put it in practice……. 
4) IDENTIFYING THE CORRECT WIRE CONNECTIONSβ€¦β€¦β€¦β€¦β€¦β  ¦β€¦β€¦β€¦β€¦ 
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 +veΆs  
Car horn –ve to both Raid horn –veΆs 
Now that the wiring is figured out down to the job itself 
5) PREPARING THE RAID WHEELβ€¦β€¦β€¦β€¦β€¦β€¦β  ¦β€¦β€¦β€¦β€¦β€¦ 
The first job is to β€prepareβ€ 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 β€single stageβ€ 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 β€made upβ€ 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 β€bridgingβ€ 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 youΆll see later all β€crimpedβ€ 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 
 
 
6) REMOVING THE ORIGINAL STEERING WHEEL FROM THE CAR……………….. 
DISCONNNECT THE BATTERY! Note that the airbag system has a 10 second  β€backupβ€ 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 donΆt want to break them. 
 
Note the small plastic screw connector, donΆt 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 β€blindβ€ as you canΆt 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 β€breakerβ€ 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 β€trappedβ€ as the wheel is rotated.  
This is because there is a β€slip ringβ€ screwed to the back of the  steering wheel. This β€convertsβ€ the lower wiring harness you  disconnected below the steering column to a thin β€ribbonβ€ which is wound  like a spring around the wheel. As the wheel rotates one way it is  β€unwoundβ€ and as it rotates the other way it is β€woundβ€. 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  β€slip ringβ€ will come away with it with the lower steering column wire  connector block. 
There is a securing pin that is released and the β€slip ringβ€ locks in place (ie so the ribbon coil is 50% wound). 
You can see the white securing pin and its associated β€holeβ€ 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 β€SLIP RINGβ€ 
The next job is to remove the β€slip ringβ€ 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  β€lockedβ€ in place. It is  important that when you fix the new wheel to the car that the slip ring  is in the β€half woundβ€ 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 β€slip ringβ€ 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 β€ribbonβ€ 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 wonΆt 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 CONNECTIONSβ€¦β€¦β€¦β€¦β€¦β  ¦β€¦β€¦β€¦. 
Time to get on β€adaptingβ€ 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 β€crimpingβ€ 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 WHEELβ€¦β€¦β€¦β€¦β€¦β€¦β  ¦β€¦β€¦β€¦β€¦.. 
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 β€strippedβ€. 
Note I β€securedβ€ 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). 
 
β€Tidyβ€ the wires up to stop them β€foulingβ€ the mounting point. Note the horn connection block has its own storage area. 
 
10) MOUNT THE NEW STEERING WHEEL ON THE CAR………………† ¦β€¦ 
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, thatΆs 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 DONEβ€¦β€¦β€¦β€¦β€¦β€¦β  ¦. 
 
 
 
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 β€feelβ€ 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 β€go cartβ€. 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.