DIY-ATNTFIU: Swapping R35 GT-R Seats For Fun And Profit (Maybe)

I was hoping this latest post would be an update on Project Astrid but unfortunately the man is still keeping me from my new dream girl so instead I'm reprinting a guide I wrote for the GT-RLife forum on how to install aftermarket seats in an R35 GT-R. I posted this way back in February 2013 before I had any thoughts of starting this blog and it seems to have proven useful to many people in that time. More recently a fellow owner emailed me that he appreciated the guide but he couldn't see the photos because Photobucket has been a real pain in the arse lately for me regarding bandwidth issues - so I decided to repost the guide here so I can host the pictures and re-link them. So with that, let's delve into my earliest attempt to write a guide to Do It Yourself - And Try Not To F*ck It Up!


Since I just swapped the seats in my GT-R for new aftermarket ones and had to find the relevant info in different places I thought I'd try and make a DIY to hopefully collect the most important points in one place.

In my case I decided to swap in Cobra Misano Anniversary reclining seats with the Cobra-supplied brackets from Wedge Engineering. Other seats and brackets will of course differ in the nuances but the basic process should be similar. If you're interested in my brief review of the seats and brackets here's a link to that thread:

For the process, you'll need a few important bits:
  • Aftermarket seats and compatible brackets (Duh!)
  • Socket wrench
  • Small flat tip screwdriver
  • Some Loctite or similar
  • A flashlight or preferably a headlamp to keep your hands free
  • Appropriate resistors or a pair of Works Bell U-turn Harnesses to bypass the side airbags (for more info on the resistor approach refer to Phlegmon's thread here: http://www.gtrlife.c...fromsearch__1 )
  • A used POS or Piece Of Sh*t, err, actually, a Passenger Occupancy Sensor. This is the most difficult item to source. It's basically the sensor that tells your car whether there's an adult sitting on your front seat or a nice fluffy bunny so that it doesn't mistakenly deploy the airbag in a crash and crush said fluffy bunny (It's unrestrained a$$ can fly through the windshield instead). You cannot buy this POS new (unless you're Carlos Ghosn – in which case why are you reading this sh*t?) since it's buried under layers of cloth, stuffing, and the bodies of your vanquished foes in a 2009 or later Nissan or Infiniti front passenger seat. You could tear the one out of your stock GT-R seat but why would you want to do that? Instead, find a salvage yard, plead with the nice man, and score yourself a cool Altima seat (or something – not all Nissan models may have it – read phlegmon's thread) and then spend a couple of rage-filled hours turning that bastard into useless shards all for one measly sensor that weighs next-to-nothing! Yup, it's a fun process.
  • Lots of semi-synthetic elbow grease
  • A helpful friend, lackey, or minion
  • Ice cream!
Note that the last two are optional but can't hurt.

Before we start the process, just some important cover-my-ass stuff: Note that this is meant as a useful guide and I make no guarantees that everything will go fine with your own install. Removal of the factory seats constitutes removal of certain safety equipment (i.e. the side airbags) and because you WILL be futzing with the factory wiring I make no guarantees about the function of your car's electrics. Do this at your own personal risk (and not mine please, I risk my ass enough lol).

Now that that stupid stuff is said, on to the main event:

Okay, so the first part of the process is removing the stock seats. The technique is the same for both sides only differing in the number of plugs you have to undo underneath.

Start by removing your floormats and moving the seat you're working on back all the way to get easy access to the front bolts. Once you have it all the way back pry off the plastic covers on either side covering the bolts. The service manual says to use a pawl to pry them up from the bottom but it's easier just to remove them by hand by pulling them up and away from the metal leg. After removing the covers use a socket wrench to undo the front bolts all the way.

After removing the front bolts, follow a similar process with the rear bolts only this time move the seat all the way forward to access them. The passenger side inboard rear bolt is unique in that it has only a small plastic circular cap. Just pry that off with your screwdriver.

Once you have all four bolts removed, move the seat back to about a middle position – this will make removal easier and make it less likely you'll whack something with the metal seat supports and cause damage. After that, wind both side windows down. Why? Because you'll be disconnecting the battery and without power the windows won't do their cool incremental up-and-downy thing so if you accidentally close the doors you can damage something.

And so having mentioned that, disconnect the battery and go bugger off for about 10-15 minutes and have some ice cream (or beer or ramune or something) to ensure the car is fully powered down so you don't get knocked out by an exploding airbag when you start fiddling with the electrics lol.

After having ice cream, return to the car and begin the tedious process of disconnecting the plugs underneath the seats. For this I suggest having a headlamp (or strong flashlight), a small flat tip screwdriver, and a lot of patience. Better yet, do what I did and have a helpful friend with patience and some experience do it for you and have some more ice cream while you wait.

Here you can see what the underside of the passenger seat looks like once you can lift it up - the mess of wires at the top right is what you'll be cursing at for some time:

You'll have three plugs to undo on the driver side and four on the passenger side. In the process you'll also need to undo the clips holding the harness onto the seat frame so that you don't embarrass yourself and rip out all that nice wiring when you lift the seats out. Each plug is unique to what it attaches so don't worry about misconnecting something. You'll have a yellow one for the side airbags, a small white one for the seatbelt receptacle sensor, a big white one for the seat heaters, and on the passenger side another small white one for the POS. This is what they'll look like:

After undoing said clips and plugs, it's time to get sweaty (this is where the semi-syn elbow grease comes in handy) and lift those heavy buggers out of the car. This is NOT EASY lol. Not when the seats weigh quite a bit and you have to be careful on the way out not to hit anything - but it can be done! Even a scrawny weakling like me was able to yank those bastards out and haul 'em off to the living room for the final steps. It's a good idea to cover your side sills with a blanket or something at this point to avoid scratches there if you accidentally hit them with the seat supports. Your floors should look like this:

Once in the living room, your seats are out but there's one more thing to do with them before you get all excited and whack the new ones into the car. If you plan on keeping the factory seatbelts you'll have to remove the receptacles from the side of the OEM seats. Do this by asking your helpful friend to pry open the side plastic trim carefully, undo the wiring for the seatbelt sensor plug from underneath the seat, and unscrew the bolt for the receptacle while you recuperate and have MORE ice cream. The brackets for the aftermarket seats should have a tab on the side for the seatbelt receptacles so you can have your friend transfer them onto the new brackets and then have mercy and give him some ice cream.

Here you can see the seatbelt receptacle transferred to the new passenger seat and the wire laid on top in preparation for placing the assembly into the car:

Great, so you've got your original seats out! Now it's time to get that sickening thought about how the OEM seats are really quite nice and OH MY GOD WTF WAS I THINKING REMOVING THEM ANDREMOVINGTHESIDEAIRBAGSSOICANDIEINAHORRIBLECARCRASH!

Take a deep breath and think of kittens (and all the weight you'll save – and the cool carbon fiber on your seats – and more kittens).

It's time to work on some electrics. You'll need to do two important things right now – bypass the side airbags so the car doesn't annoy you looking for the missing units and you also need to fool the passenger airbag sensor.

The side airbag connectors are the yellow plugs. They're simple enough to bypass and can be done one of two ways – use a homemade resistor or use a Works Bell U-turn Harness. Either method works and is basically the same. For a more detailed explanation refer to Phlegmon's thread.

In my case I used a pair of U-turn harnesses and plugged one end into each hole on the airbag plug then wrapped electrical tape around the plug and harness to keep them together.

For the front passenger airbag, you just take your second-hand sensor and plug it into the matching plug. If you have seats with a detachable bottom cushion you can stick the sensor underneath the cushion if you want but in my case my seats had fixed cushions so I just put mine on the floor. Some people advocate zip-tying the sensor into a nice burrito and serving it with Cholula to keep it tidy and hopefully render the passenger airbag always on but internet lore has it that flipping the sensor upside down also causes the airbag to stay on so I saved some hot sauce and did that. Seems to have worked fine for me but YMMV.

Note that the pic below actually doesn't show the final position where I put the POS - this was just an early shot when I first connected it. In my case I moved my POS back so that the front edge was under the passenger floormat while the rest was under the passenger seat. The portion under the floormat keeps it from moving while having the rest of it under the seat protects the sensor, wiring, and the IC module from errant feet. Having it a little forward instead of all the way under the seat also protects it from the unlikely event a rear passenger could shove his feet under the bracket and kick it. Other options include tucking it into the jack storage area or rolling it up and zip tying it like I mentioned before then tucking it into the bracket or off to one side. You just basically find what works best for you 

In order to hide the POS - since having it upside down puts the very visible white portion up - I ended up cutting a piece of black carpeting from a roll I had lying around and taped the sensor to the underside. I made it just big enough to cover the POS and now you can't tell it's there unless you specifically know about it.

After that important step, grab your aftermarket brackets and test fit them in the car. This is a good idea since frankly a lot of aftermarket brackets tend to suck and mine were no exception. At least in my case the brackets were level and the holes (mostly) lined up with the stock mounting points. That does not always happen. Better know now than after you lug the seats into the car.

Once you determine the brackets fit you can start mounting the seats one at a time. Attach your brackets to the new seats (or the seats to the brackets if you must put it that way) and then lug them into the car. In my case, the brackets used the stock bolts so I put some Loctite on them and screwed them back in. Since a lot of brackets don't fit quite exactly, it's a good idea to put all four bolts in loosely before tightening them down finally so you can wiggle the bracket a little if you have to.

Just a quick word of warning - don't be "that guy" who hamfists the seat bracket bolts and ends up overtightening them. I confess I didn't double check the torque specs myself but I'm a careful guy (most of the time). They're in the ESM though so check if you tend to be overenthusiastic with the elbow grease. Just don't take after one Toyota tech I know of who used an impact wrench while installing a Prius seat and overtorqued the bolts. Yeah, trying to fix stripped bolts in your floorpan is not pretty. Few things are more embarassing than not having seats in your car all because you've botched the bolts.

With a shoutout to GTRRN who provided the number since I was too lazy to look it up again lol, the proper torgue for the seat bolts is 36 ft-lbs per the ESM.

Attach your seatbelt sensors to their matching plugs and then clean up the wiring with some zip ties so that it's not ugly and so that it doesn't flap around and rattle against your brackets causing your date to think your car is a pathetic rattletrap POS bucket of bolts.

Once you have all those plugs in you'll still have one floating around unmolested on each side if you don't have seat heaters in your aftermarket seats such as in most cases. Wipe the memory of those plugs from your mind now. They do not exist in your world anymore.

Once both seats are in take a step back to admire your handiwork and utter a little prayer that everything goes well in the final part. (At this point you may also start fiddling with the seats only to find some little issues such as in my case where the brackets put the seats too high. Hacking some bits off the slider mounts fixed that issue for me but it was an annoying extra step. Thanks a lot, Wedge Engineering! No ice cream for you guys.)

The final part is turning the car back on and making sure it's all happy minus the side airbags and with a used occupancy sensor feeding it (mis)information. For that you need to reconnect the battery and then use the diagnostic mode trick.

I take no credit for the diagnostic mode trick – I got it from phlegmon's thread. Simply put, with your foot off the brake (so the engine doesn't start) you press the starter twice to turn the car's electrics on. Once you do your airbag light on the instrument cluster will turn on (it's a little dude with a circle shoved in his front) and go off after a few seconds. Once it turns off you need to press the starter button again to turn off the car and then count off five seconds then repeat the cycle again two times. In theory, after the third time the airbag light should flash on and off slowly and you'll be in diagnostic mode. At this point you can turn the car off again. Supposedly this may take a few tries but mine was done the first time so again YMMV.

After this, sit in your car, luxuriate in your new seats, put your foot on the brake, and hit the starter button. Hear your mighty engine roar, and hope to all the gods you know that a rainbow of warning lights don't come on your dash and a poofy airbag cushion doesn't try to introduce itself to your face.

If no lights come on and no airbag deploys, perform the most important step and drive that b*ch with a stupid grin on your face!

If lights do come on and you're greeted by an airbag, I don't know you and this thread never existed ;)

For comedic effect, much of the risk of this procedure has been greatly exaggerated, but don't come crying to me if an airbag does try to go Manny Pacquiao on your a$$ or if your teeth rot from all that ice cream (Didn't your mother ever tell you to lay off the sweets?) lol.

Many thanks to Phlegmon for his very helpful thread, Sube Sports for my seats, Sonora Nissan for help with the seat height problem, Forged Performance for the Works Bell harnesses, my unnamed friend who slaved away in exchange for a burger, and the syllables Ni and San, and the number 23.