Matyas

Hello everyone, I believe I am the first person to swap C8 seats into a C5 (or into anything as far as I could find online). I absolutely LOVE these seats; they have great bolstering and they're comfortable. I'm going to write up the installation process for those that try to do the installation after me. It is very easy to install them. A quick disclaimer: I had a shop do the wiring. I wanted to preserve the resale value since C8 competition seats are so scarce in the aftermarket and had the shop make connectors so the seats are 100% plug and play.

First, Remove the C5 seats. I'll go over this quickly since there are so many threads on it. Each seat has four bolts. The two bolts on the front of each seat have plastic covers on them that need to be removed. I recommend tilting the steering wheel all the way up and leaving the battery connected so you can move the seats for easy access to the bolts. Once all four bolts are undone, all you have to do is unplug the electrical connectors and you are ready to remove the seats. At this point disconnect the battery so once you start wiring you don't forget.





Next, is test fitting the new seats. You can do this step or skip it if you want. I had to do this before having the shop wire the seats since no one has done this before. In the photo above you see the driver side floor with the four bolts to secure the seat. On the C8 seats, the width of the bolts is the same as the C5, for the length (meaning the front of the seat to the back) the C8 seat bolts were 1/2 an inch shorter. Even with this discrepancy, I did not have to do anything special to get them to fit. You can put the C8 seat in the car and line up the holes on the rails, but they should fit with no modification. The seats fit well. Not only do they fit, I still have the original C5 seatbelts in the car. To achieve this a small portion of the plastic on the side was cut. The seat still looks great and these plastic panels cost $35 to replace if I ever want to resell these seats, so they are cheaper than swapping in C6 seatbelts. Here is what the seat looks like after modification.





You can see on the right side of the glossy black plastic it has been cut out for clearance. That is not stock! It will not look bad in the car and I'll post photos of the seatbelt clearance farther down. I have 97% mobility of the seats, The 3% lost is from the super-tight airbag fit, not the seatbelt. The motor will take the seat all the way back and it will make the slightest adjustment forward to release the tension on the motor from the seat being wedged into the side of the car. No other modifications had to be made. The glossy black trim on the seats can also be removed completely if you do not want to damage it. I cut it because I like the trim there.

Now that we know the seats will fit, TEST YOUR SEATBELTS. With the seats resting in place in the car, get in and buckle up. Tug on them and make sure they hold. I bought these seats from a wrecked C8 and while the airbags didn't go off the driver-side seat belt buckle had seized up to protect the previous driver during their accident and would no longer hold the buckle in. I found this out after I fully installed the seats and had to remove the driver side to swap it out, don't be like me.

OPTIONAL, if the C8 seatbelts won't click in, or you just feel more comfortable having the C5 seatbelts going to the C5 buckle, it is an easy swap. With the seat removed from the car, there will be a T50 bolt holding the seat belt buckle to the C8 seat. I had to use a ratchet with a T50 attachment to get this off. Once it is off, you will have to remove a star washer from the bolt to get it off the C8 buckle. In the picture below you can see the washer. Don't be afraid to pry and break it off. This washer is not a safety feature, it was there to hold the pieces together and make manufacturing easier. Do not cut off the electric cable holding the seat belt to the seat, more on this after the photo.





On the driver's side, the seat belt was wired to sense if the seatbelt is buckled. I left the seat belt in the car attached by the wire just laying next to the seat. The seats are snug and will prevent this from rattling around. I then took the passenger seat's seatbelt from my C5 and used the T50 bolt to secure it to the C8 seat. MAKE SURE IT IS VERY TIGHT. This is a safety feature and the one thing you cannot short yourself on under any circumstances. Go buy a ratchet with a T50 attachment and torque this thing down. Do not just use a screwdriver. This bolt is the only one holding you in place during an accident.

The last step before you install the seats is the wiring. Like I said in the intro, I had a shop do this for me. I have a C5 Z06, so they had to find a power source from somewhere to get the passenger seat to operate. I had the shop wire the seats to a connector so they are truly plug and play and should I ever resell the seats I didn't mess anything up and it looks very neat and clean. Everything works on the seats. I do not have the telescoping steering wheel on my car so I can not say if that will work or not. I also no longer have the seat memory function which is okay with me. I apologize for the lacking information as far as wiring goes, but I'll post photos below of the connector coming from the car and the seat. It does not look terribly complicated. First will be the photo of the connector coming from the car, then the photo of the connector coming from the seat. These are both driver's side photos.






Finally, time to install your seats! placing the headrest in first and then twisting the seat was the easiest way for me to get them to fit into the car. Once they were in I placed the holes on the rails over the bolts sticking up from the floor of the car. Before bolting the seats down I plugged in the two electrical connectors. This is the point where you will either plug the seats in if you make a connector or prop the front of the seat up so you have clearance to solder the connections together if you choose to take that path. It is not a tight fit under the seat with the seats in the car. With the seat tilted back, you will have plenty of room to work. Here is the seat tilted back in the car with the connector plugged in. Notice that if you do a seat belt swap you can see the original C8 buckle laying toward the center of the car still wired to the car; that is where I left it and it does not rattle at all. It does not tell me my seatbelt is unbuckled either.




Now all that's left is to take the original nuts that were holding down the C5 seat and bolt down your new C8 seats and you're finished!!!

Here are some photos of the final results!!







Here are some photos to show you how the clearance is of the seats. Two points to notice: (1) The black trim piece that was cut can be modified to your liking, the more you cut the more clearance the C5 seatbelts have; (2) The airbags are a tight fit and you lose a tiny bit of mobility as far as how far back you can move the seats, I am 6' 1" tall and I am very comfortable, I do not even need the seat as far back as it goes without this loss in mobility. The airbags are the real reason the seats lose a little mobility, but make sure that you have modified the seats or installed C6 seatbelts so the seats do not pinch the seatbelts and make them very difficult to use. The way these seats are cut, the seatbelts work perfectly with every seat position.









That's it! Best of luck finding these seats and putting them in. If you have the opportunity I highly recommend them.

The seats are comfortable, even after a two-hour drive (I'll be going further soon, but have not yet with these seats in). The bolstering is incredible. I can drive the car much harder and they just hug me in place. I don't move at all and honestly, they are a performance modification I did not know I needed. I'm 6' 1" and I weigh 195lbs with a waist size of 33" and a chest size of 42". I am comfortable, but I think I may be getting close to the limits of what these seats can comfortably support.

The C8 completion seats look incredible in the car!! I will be doing some interior modifications, like an MGW short-throw shifter, a double din head unit, and eventually, I'll replace the cracked leather arm wrest. The interior of my car is going to look amazing and I cannot wait. The seats themselves look so good. The colors match nicely and the design just makes the interior look so much better than the tired old C5 seats. I can't wait to see other cars with these as well!!!


Bonus: I turned the old C5 seats into a couch. I screwed them onto the pallet the C8 seats shipped on. Easy storage and cheap furniture as a broke law student.

WalterSobchak

There is plenty of room. I wear a 54R coat I'm 6'3 235lbs(pro card BB) also 33" waist fit great in my C8 seats (GT2 same bolsters on the side) and at Spring mountain fit great in the Competition seats. They hold you in the way they should. For some of the hefty fellas they might not want to do these.

Absolutely a great job on the build and thread. Keep updating that interior and posting more pics. Love seeing every one make their C5 better.

Matyas

Thanks! It was certainly a project. The hardest part was figuring out how to modify the seats without having any info from people before me. Overall it is not very difficult, and I absolutely love the seats!

jdmvette

Very well done! Do you have the wiring schematic for how to power them to the c8 plug?

Matyas

Sorry, unfortunately, I do not. Hopefully, these schematics are available and someone can easily figure it out. Looking at the connector it doesn't look complicated at all.

WalterSobchak

This is so good it should be a sticky. The first C5 with C8 seats!

jdmvette

Z06ster

Totally amazing. They look great. Thank you for sharing. You are now giving the guys with the C7 seats a run for the money

Matyas

I was going to do the C7 seats but a unique opportunity popped up. It was really cool doing a custom project that has never been done before.

Matyas

I've seen a lot of awesome guides on here so I just wanted to do my best to give back to the forum with a good write up!

lewislgZ06

I'm late to the party here, but great job and thanks for pioneering this endeavor! You just fell into that deal on the C8 Comp seats. What a bargain!
I was mostly concerned with the height of the seat, but if you are 6'1" and it isn't an issue for you, that's awesome.
Too bad those side airbags can't be removed, that would make the swap/functionality even that much better.

I love my Apsis modified C5 seats, but the added cushioning and bolstering has me sitting a little higher than I like, and I'm only 5'10". Over time they have broken in some and I'm probably just more used to them, but anyone taller than me would likely rub the ceiling.
You came out way, way ahead of me on cost, congratulations!
Great project and write up. Thanks for sharing.

Matyas

Thank you! As for the airbags. I'm pretty sure they can be removed, but I believe there is a hole on the side of the seat if they are.

these seats actually dont sit any higher than the stock C5 seats. I'd say maybe half an inch from the extra cushioning, but no real noticeable difference.

MWWarlord

Fantastic write up! Congrats on being the first to do this. They look great in your car. You definitely need to replace or cover that cracked center console cover. There are tons of good options out there for that. Thanks for such a great write up. Now all the rest of need to do this is the seats themselves. They'll be available one day. You really got lucky!

Tim90NOS

Great write up. Clear and concise. Followed this from your previous post and it's great to see a plan come together!

Matyas

thank you! I just finished the rest of the interior other than the cracked center console. I'll be doing that next. It's fantastic inside.

Matyas

I have finished re doing the interior! I posted a thread here

Here are some pics

Tusc

Maybe the shop can write out the wiring diagram after they did the work?

Good swap and upgrade. Glad to see they are a direct fit, too.

How do the side impact airbags work without a side impact sensor? If vestigial, can they be removed easily or would they leave a scar on the seat where they are mounted?

jdmvette

^ pretty sure you can pull the 'bag assembly out and pop the plastic back on without any visual indication that they were removed.

At least this is the way that the c7 seat airbags go, so these should be the same.

Matyas

the shop did not provide me with a wiring diagram. I can ask but I'm assuming the answer will be no.

The side airbags don't work in the C5. They could be removed somehow but would leave a large hole in the side of the seat.

Tusc

Could also pull back the wire wrap and trace each wire to the source.