Disclaimer: If you attempt any of this, it is at your own risk. Let me reiterate the service manual and factory say explicitly not to modify the SRS system or any portion thereof.
Now for you adventurous types, read on!
I. Purpose:
a. To greatly enhance the NSX’s interior.
II. Background | Research:
b. One of the first things I learned was that even if you figured out the rest of the fitment issues, the main issue with compatibility was the difference between the single and dual stage airbags, which corresponds to different inflation rates for slow/high speed crashes. I read these two things in my research and decided it was too risky to try and wire up a dual stage airbag and that I didn’t want to mess with it.
i. To enhance the protection of the driver and front seat passenger during a variety of frontal impact collisions, the RSX utilizes varying airbag deployment power. The system, which uses a dual-stage inflator, automatically adjusts the deployment of the driver and front passenger's SRS airbags based on the severity of the crash. During a slower speed collision, the dual-stage inflator system is triggered in sequence, resulting in slower overall airbag deployment with less initial force. During a high-speed collision, both inflators operate simultaneously for full immediate inflation, to correspond with the greater impact force.
http://www.hondanews.com/searc...acura
ii. The EP/RSX airbag WILL NOT function properly (whether you have both or single connectors hooked up), it's a dual stage bag and won't deploy correctly with just one set of wires hooked up. With only two wires hooked up, it still won't work, as your SRS light will be on, indicating that your SRS system is not functioning and won't deploy at all, even if it did, it wouldn't know how to deploy the twin detonators. BOTH detonators have to go off to fill the bag, the only thing that differs in light to hard crashes is the timing of their deployment. If you use an EP/RSX dual stage airbag, you risk more injury that if you left it disconnected. Even if your light is off, as this is only a matter of resistance. The design of the airbag deployment is different. BE SAFE.
c. The dual stage airbags had two detonators (2 pairs of wires) and the single stage airbags have one detonator (1 pair of wires) which made it easy to tell them apart, except I found that when I was trying to buy one people would get confused by terminology and no one ever takes a picture of the back of the airbag, resulting in a lot of dead ends.
d. The NSX obviously has the older single stage airbag so I compiled a list of the airbags and their compatibility (dual vs single stage):
i. USDM RSX (DC5): Dual Stage
ii. JDM RSX (ITR –DC5R): Single Stage
iii. USDM Civic Si (EP3): Dual Stage
iv. USDM S2000 (AP1): Single Stage
v. USDM S2000 (AP2): Dual Stage
e. These are all physically interchangeable! Not 100% sure yet otherwise as I haven't completed or verified successful installations using the different permutations.
f. I bought the Momo DC5R wheel with the red H badge knowing that it had the single stage airbag. If I had to do it over again, I’d just get the AP1 airbag since it’s more readily available and less expensive but I didn’t think I could switch the covers at the time so oh well. I currently have been using the updated Acura “A” Emblem in my modding so the DC5 wheel was my choice for overall consistency. Although, if/when I get some red seats and matching carpet, I want to use the DC5R wheel to match. To each his own, we all have our own opinions on what looks appropriate.
g. Another difference between the DC5 and the DC5R wheel is the quality and color of the leather did not mesh well with the black (not onyx) NSX interior IMO. The DC5R wheel is charcoal with a grainy texture so it may work ok with onyx leather on the newer cars but the DC5 wheel is perfectly black with a smooth texture. The AP1 wheel has perforated leather and also goes well with the older black NSX interior. I actually ended up with that one too but decided to go with the smooth leather for my personal preference.
h. The good news is that you can mix and match these in pretty much any combination you like by switching the detonator portion of the airbags. For example, I needed the single-stage airbag/detonator from the AP1/DC5R but I wanted the airbag cover to have an Acura badge and not a Honda badge. It is not possible to switch just the airbag covers because they are tamper-proof (and the airbag could unravel) so the alternative was to swap the detonator portions out from the backside. It is tough, but possible! You can see how I did this in the pictures below.
i. Prime member Erick (EVO575GTC) who is also a vendor for aftermarket steering wheels and hubs was I think the first to recognize that the depth of the NSX and S2000/RSX wheels were different and that the depth could be made up with the addition of a short hub. Special thanks to him for his insight on this project. The short hub also solves the other problem of differing splines because you are not directly mating them to each other, you are mating the NSX-specific hub to the steering column and then the wheel assembly bolts up to the hub. Another problem that came up here was the depth of the new wheels spline. The two options to solve that problem are to cut this piece off or use an additional spacer to clear it. I believe another Prime member Gary from the UK (Hagasan) has developed a hub that solves this problem (option 2) and is specifically designed for this mod, which may be a better way to do the swap for some of you. I feel pretty confident that mine is fitted securely, though the donor wheel requires permanent modification.
III. Materials | Supplies
a. Breaker Bar with 19mm socket
b. Torque Wrench with 19mm socket
c. Allen Key Set or Hex Keys for the airbag’s bracket
d. Long Pair of Pliers
e. Power Drill & Bits
f. Power Reciprocating Saw
g. Screwdrivers set (Philips/Flathead)
h. (4) Male/Female Wiring Connectors (8 total) or Jumper Wires
i. Longer Bolts and Washers for the Short Hub
j. New Torx or Hex head bolts for the airbag assembly
k. SOS Rapid Short Hub or other compatible hub
l. New steering wheel and compatible (suggestion: AP1) airbag
m. RSX steering wheel or other dual-stage airbag if desired
n. Eye and Ear protection
o. Steering Wheel Puller Kit (maybe)
Sorry for the hasty materials list, I didn't take exact notes on this portion but I may still have the packages so I can add the information later.
IV. Preparation
a. Modify the Airbag:
i. Swap Single Stage Airbag Detonator onto desired airbag (if you want to use the RSX airbag cover for example): First remove the metal brackets in the way so you can get to the detonator. Using the long pliers, remove the 4 tamper-proof nuts from the rear of the airbag and do the same for the airbag you want to swap the detonator onto. Swap the detonators and reinstall the nuts. Don’t forget to put that bracket back on too.
ii. Remove all the tubing from both airbags so you can get a clear view of which wires are which. Cut the connector off the NSX airbag and the airbag you want to swap it onto. Crimp butt connectors onto the ends of the wires and take care to put the appropriate male/female connectors on each.
iii. Match the positive wire to the positive wire and negative to negative. On the NSX, the red wire is the positive and the white is the negative. On the other airbag (AP1, DC5R) both wires are yellow so you have to pay attention to the orientation of the wheel. With the airbag oriented correctly up/down and the detonator wiring base “pointed” to the right, the bottom wire is the positive. Mark it down with the sharpie so you always remember! Mate them up using the butt connectors so you will be able to interchange them in the future. Make sure to get a secure connection here.
b. Modify the wheel:
i. Using the power drill, drill two holes into the metal structure of the steering wheel base to align the wheel properly with the aftermarket hub. They are only slightly off. Alternatively, you could purchase a hub adapter piece to mate these up. It would add some length to the assembly but would probably make things easier and perhaps safer, though I am not sure if it's 100% plug&play.
ii. Using the power saw, cut off the metal spline from the back of the wheel. It would be wise to bubble wrap or otherwise protect the leather on the wheel and use some vice grips here. You have to do this to get the wheel to fit in the mounting hub, or you can use a metal spacer to give it some room to fit. Cutting it off retains more OEM like spacing between the wheel and the turn indicators and wiper controls, but your preference. I used the SOS rapid hub, other hubs may be different.
V. Installation
a. Follow the service manual procedure for removal of the airbag assembly and steering wheel.
i. Park the car and make sure the wheels are straight (drive forward a bit before putting it in park to make sure).
ii. Disconnect the battery completely and let it sit for 5-10 minutes to ensure any residual charge is released. Tip: Make sure your windows are down if you want some extra room to move around the car.
iii. Remove the airbag assembly:
a. Unscrew and remove the covers from each side of the steering wheel.
b. Remove the T6 torx bolts from the left side, and be very careful not to damage the heads or you’ll have to cut them off.
c. Remove the red jumper connector.
d. Disconnect the yellow airbag harness.
e. Put the red jumper connector on the end of the yellow airbag harness.
f. Remove the bolts from the right side behind the cruise control.
g. Once the airbag is free, pull it towards you (but not completely out) and disconnect the other wires going to it so that you can remove it completely.
h. Store the airbag face up so that if it deploys somehow, it will not become a projectile.
iv. Remove the steering wheel:
a. Make sure the wheel is still straight.
b. Using the 19mm socket, remove the center nut holding the NSX wheel on.
c. Carefully work the wheel off being careful not to damage anything or use a steering wheel puller kit if necessary.
v. Install the new hub and pull all the wiring through it. Mine was a very snug fit.
vi. Tighten the steering wheel nut and torque to service manual specs.
vii. Install the new wheel:
1. Align the wheel, notice that the location to feed the wires through on the new wheel should be directly opposite from where the NSX and hub has it located.
2. Insert the longer bolts and washers you bought and tighten the wheel down securely. The washers should be snug around the bolt but have enough area to cover any gap between the bolts and the holes you drilled in the wheel. Make sure you tighten it down absolutely securely so that everything acts as one piece, you don’t want to put shear loads on those bolts or have any play in there at all. You could even double up on those washers for extra piece of mind.
3. Test drive the car for a short duration to make sure the wheels are aligned properly before hooking up the airbag. Loosen/tighten the bolts to adjust as necessary for proper alignment.
viii. Install the new airbag using the NSX connector you swapped onto the back of it. You can hook up the cruise and horn now as well. It was getting dark when this time finally came so I still have to go back and jump those wires. Other members have already done both of those successfully so I’m not too worried about it other than to have all the information in one place.
ix. Gather the wires and place the airbag in the steering wheel housing. Now reconnect the battery to test that everything works properly. I would advise you to not sit in the driver's seat, sit in the passenger's seat and turn the key from there. I even had someone put the clutch in with a broom while I started the car from the passenger's seat, just in case.
x. Install the replacement bolts to hold the airbag in place and put the plastic covers on to finish it up.
Before:
After:
More Photos: http://www.nsxprime.com/forums/showthread.php?t=136513
Review:
a. A solid aluminum hub increases rigidity and thus road feedback, steering input response now feels more direct too.
b. The steering wheel diameter is slightly smaller, providing a lower moment of inertia for quicker steering response.
c. The steering wheel is now lighter, also providing a lower MOI and reduced effort that may especially benefit those of you that have the manual steering rack.
d. Thicker wheel and grips feel nicer.
e. The horn is now the entire center portion saving you from hunting for small buttons in emergencies. This location is also now the industry standard for horns so switching from other vehicles will be more intuitive.
f. You can replace your worn out or scratched up wheel.
g. The new steering wheel looks much better than original 90s era one with A-C-U-R-A spelled out across it's mondo airbag.
Now for you adventurous types, read on!
I. Purpose:
a. To greatly enhance the NSX’s interior.
II. Background | Research:
a. I was able to find most of what I needed to know through online research on forums --Honda-tech was the most help. I started out by researching the affected systems and their components: SRS computer, cable reel, sensors, detonators, inflators, and the steering wheels, steering columns, and mounting hub spline. Each of these was a different opportunity or avenue that someone had pursued to make their swap work or one that had prevented them from doing so. Some people had really gone to great lengths to make their swaps work –even switching out their whole SRS system and computer, or steering column, etc. I wasn’t willing to go that far so I wanted to just focus on just the SRS system and keep it simple. In summary, a sensor detects a collision and sends an electrical signal to the computer and the computer sends another electrical signal to the airbag detonator to ignite and therefore chemically inflate the airbag. This mod focuses on just the last thing to happen before the bag inflates because it is a simple binary (on/off) operation run through only two wires (+/-), which is easy to manipulate.b. One of the first things I learned was that even if you figured out the rest of the fitment issues, the main issue with compatibility was the difference between the single and dual stage airbags, which corresponds to different inflation rates for slow/high speed crashes. I read these two things in my research and decided it was too risky to try and wire up a dual stage airbag and that I didn’t want to mess with it.
i. To enhance the protection of the driver and front seat passenger during a variety of frontal impact collisions, the RSX utilizes varying airbag deployment power. The system, which uses a dual-stage inflator, automatically adjusts the deployment of the driver and front passenger's SRS airbags based on the severity of the crash. During a slower speed collision, the dual-stage inflator system is triggered in sequence, resulting in slower overall airbag deployment with less initial force. During a high-speed collision, both inflators operate simultaneously for full immediate inflation, to correspond with the greater impact force.
http://www.hondanews.com/searc...acura
ii. The EP/RSX airbag WILL NOT function properly (whether you have both or single connectors hooked up), it's a dual stage bag and won't deploy correctly with just one set of wires hooked up. With only two wires hooked up, it still won't work, as your SRS light will be on, indicating that your SRS system is not functioning and won't deploy at all, even if it did, it wouldn't know how to deploy the twin detonators. BOTH detonators have to go off to fill the bag, the only thing that differs in light to hard crashes is the timing of their deployment. If you use an EP/RSX dual stage airbag, you risk more injury that if you left it disconnected. Even if your light is off, as this is only a matter of resistance. The design of the airbag deployment is different. BE SAFE.
c. The dual stage airbags had two detonators (2 pairs of wires) and the single stage airbags have one detonator (1 pair of wires) which made it easy to tell them apart, except I found that when I was trying to buy one people would get confused by terminology and no one ever takes a picture of the back of the airbag, resulting in a lot of dead ends.
d. The NSX obviously has the older single stage airbag so I compiled a list of the airbags and their compatibility (dual vs single stage):
i. USDM RSX (DC5): Dual Stage
ii. JDM RSX (ITR –DC5R): Single Stage
iii. USDM Civic Si (EP3): Dual Stage
iv. USDM S2000 (AP1): Single Stage
v. USDM S2000 (AP2): Dual Stage
e. These are all physically interchangeable! Not 100% sure yet otherwise as I haven't completed or verified successful installations using the different permutations.
f. I bought the Momo DC5R wheel with the red H badge knowing that it had the single stage airbag. If I had to do it over again, I’d just get the AP1 airbag since it’s more readily available and less expensive but I didn’t think I could switch the covers at the time so oh well. I currently have been using the updated Acura “A” Emblem in my modding so the DC5 wheel was my choice for overall consistency. Although, if/when I get some red seats and matching carpet, I want to use the DC5R wheel to match. To each his own, we all have our own opinions on what looks appropriate.
g. Another difference between the DC5 and the DC5R wheel is the quality and color of the leather did not mesh well with the black (not onyx) NSX interior IMO. The DC5R wheel is charcoal with a grainy texture so it may work ok with onyx leather on the newer cars but the DC5 wheel is perfectly black with a smooth texture. The AP1 wheel has perforated leather and also goes well with the older black NSX interior. I actually ended up with that one too but decided to go with the smooth leather for my personal preference.
h. The good news is that you can mix and match these in pretty much any combination you like by switching the detonator portion of the airbags. For example, I needed the single-stage airbag/detonator from the AP1/DC5R but I wanted the airbag cover to have an Acura badge and not a Honda badge. It is not possible to switch just the airbag covers because they are tamper-proof (and the airbag could unravel) so the alternative was to swap the detonator portions out from the backside. It is tough, but possible! You can see how I did this in the pictures below.
i. Prime member Erick (EVO575GTC) who is also a vendor for aftermarket steering wheels and hubs was I think the first to recognize that the depth of the NSX and S2000/RSX wheels were different and that the depth could be made up with the addition of a short hub. Special thanks to him for his insight on this project. The short hub also solves the other problem of differing splines because you are not directly mating them to each other, you are mating the NSX-specific hub to the steering column and then the wheel assembly bolts up to the hub. Another problem that came up here was the depth of the new wheels spline. The two options to solve that problem are to cut this piece off or use an additional spacer to clear it. I believe another Prime member Gary from the UK (Hagasan) has developed a hub that solves this problem (option 2) and is specifically designed for this mod, which may be a better way to do the swap for some of you. I feel pretty confident that mine is fitted securely, though the donor wheel requires permanent modification.
III. Materials | Supplies
a. Breaker Bar with 19mm socket
b. Torque Wrench with 19mm socket
c. Allen Key Set or Hex Keys for the airbag’s bracket
d. Long Pair of Pliers
e. Power Drill & Bits
f. Power Reciprocating Saw
g. Screwdrivers set (Philips/Flathead)
h. (4) Male/Female Wiring Connectors (8 total) or Jumper Wires
i. Longer Bolts and Washers for the Short Hub
j. New Torx or Hex head bolts for the airbag assembly
k. SOS Rapid Short Hub or other compatible hub
l. New steering wheel and compatible (suggestion: AP1) airbag
m. RSX steering wheel or other dual-stage airbag if desired
n. Eye and Ear protection
o. Steering Wheel Puller Kit (maybe)
Sorry for the hasty materials list, I didn't take exact notes on this portion but I may still have the packages so I can add the information later.
IV. Preparation
a. Modify the Airbag:
i. Swap Single Stage Airbag Detonator onto desired airbag (if you want to use the RSX airbag cover for example): First remove the metal brackets in the way so you can get to the detonator. Using the long pliers, remove the 4 tamper-proof nuts from the rear of the airbag and do the same for the airbag you want to swap the detonator onto. Swap the detonators and reinstall the nuts. Don’t forget to put that bracket back on too.
ii. Remove all the tubing from both airbags so you can get a clear view of which wires are which. Cut the connector off the NSX airbag and the airbag you want to swap it onto. Crimp butt connectors onto the ends of the wires and take care to put the appropriate male/female connectors on each.
iii. Match the positive wire to the positive wire and negative to negative. On the NSX, the red wire is the positive and the white is the negative. On the other airbag (AP1, DC5R) both wires are yellow so you have to pay attention to the orientation of the wheel. With the airbag oriented correctly up/down and the detonator wiring base “pointed” to the right, the bottom wire is the positive. Mark it down with the sharpie so you always remember! Mate them up using the butt connectors so you will be able to interchange them in the future. Make sure to get a secure connection here.
b. Modify the wheel:
i. Using the power drill, drill two holes into the metal structure of the steering wheel base to align the wheel properly with the aftermarket hub. They are only slightly off. Alternatively, you could purchase a hub adapter piece to mate these up. It would add some length to the assembly but would probably make things easier and perhaps safer, though I am not sure if it's 100% plug&play.
ii. Using the power saw, cut off the metal spline from the back of the wheel. It would be wise to bubble wrap or otherwise protect the leather on the wheel and use some vice grips here. You have to do this to get the wheel to fit in the mounting hub, or you can use a metal spacer to give it some room to fit. Cutting it off retains more OEM like spacing between the wheel and the turn indicators and wiper controls, but your preference. I used the SOS rapid hub, other hubs may be different.
V. Installation
a. Follow the service manual procedure for removal of the airbag assembly and steering wheel.
i. Park the car and make sure the wheels are straight (drive forward a bit before putting it in park to make sure).
ii. Disconnect the battery completely and let it sit for 5-10 minutes to ensure any residual charge is released. Tip: Make sure your windows are down if you want some extra room to move around the car.
iii. Remove the airbag assembly:
a. Unscrew and remove the covers from each side of the steering wheel.
b. Remove the T6 torx bolts from the left side, and be very careful not to damage the heads or you’ll have to cut them off.
c. Remove the red jumper connector.
d. Disconnect the yellow airbag harness.
e. Put the red jumper connector on the end of the yellow airbag harness.
f. Remove the bolts from the right side behind the cruise control.
g. Once the airbag is free, pull it towards you (but not completely out) and disconnect the other wires going to it so that you can remove it completely.
h. Store the airbag face up so that if it deploys somehow, it will not become a projectile.
iv. Remove the steering wheel:
a. Make sure the wheel is still straight.
b. Using the 19mm socket, remove the center nut holding the NSX wheel on.
c. Carefully work the wheel off being careful not to damage anything or use a steering wheel puller kit if necessary.
v. Install the new hub and pull all the wiring through it. Mine was a very snug fit.
vi. Tighten the steering wheel nut and torque to service manual specs.
vii. Install the new wheel:
1. Align the wheel, notice that the location to feed the wires through on the new wheel should be directly opposite from where the NSX and hub has it located.
2. Insert the longer bolts and washers you bought and tighten the wheel down securely. The washers should be snug around the bolt but have enough area to cover any gap between the bolts and the holes you drilled in the wheel. Make sure you tighten it down absolutely securely so that everything acts as one piece, you don’t want to put shear loads on those bolts or have any play in there at all. You could even double up on those washers for extra piece of mind.
3. Test drive the car for a short duration to make sure the wheels are aligned properly before hooking up the airbag. Loosen/tighten the bolts to adjust as necessary for proper alignment.
viii. Install the new airbag using the NSX connector you swapped onto the back of it. You can hook up the cruise and horn now as well. It was getting dark when this time finally came so I still have to go back and jump those wires. Other members have already done both of those successfully so I’m not too worried about it other than to have all the information in one place.
ix. Gather the wires and place the airbag in the steering wheel housing. Now reconnect the battery to test that everything works properly. I would advise you to not sit in the driver's seat, sit in the passenger's seat and turn the key from there. I even had someone put the clutch in with a broom while I started the car from the passenger's seat, just in case.
x. Install the replacement bolts to hold the airbag in place and put the plastic covers on to finish it up.
Before:
After:
More Photos: http://www.nsxprime.com/forums/showthread.php?t=136513
Review:
a. A solid aluminum hub increases rigidity and thus road feedback, steering input response now feels more direct too.
b. The steering wheel diameter is slightly smaller, providing a lower moment of inertia for quicker steering response.
c. The steering wheel is now lighter, also providing a lower MOI and reduced effort that may especially benefit those of you that have the manual steering rack.
d. Thicker wheel and grips feel nicer.
e. The horn is now the entire center portion saving you from hunting for small buttons in emergencies. This location is also now the industry standard for horns so switching from other vehicles will be more intuitive.
f. You can replace your worn out or scratched up wheel.
g. The new steering wheel looks much better than original 90s era one with A-C-U-R-A spelled out across it's mondo airbag.
Last edited:
