How many people have asked this question, can Chevy SS seats fit a G8, or "can this fit?", or "can that fit?"
*Disclaimer* If you are actually crazy enough to attempt this as I was, you should appreciate GM's sense of humor. They changed so many little things between the two cars such as how things mount as if almost to make converting a VE into a VF a seemingly impossible task. These cars as shells are virtually identical, same platform, just different on the outside.
I also take no responsibility for damage you may cause to your property, this is purely for informative purposes.
Currently my car is a 2009 G8 GT on the outside, but on the inside it is 2017 VF commodore, commonly referred to as a Chevy SS
Please note: I am going into what fits, I had to make minor modifications here and there, some cutting, some drilling and some welding. I will simply give a rough idea of what is involved as I did not document it very well until I neared completion. If you need pointers I am happy to help, but also note, if you are going to attempt this, get yourself a donor car. (Mine donor was a rear end hit from an auction that had no hope of seeing the road again so I did not feel bad cutting it up)
Well here are the answers to the above questions:
What can actually fit... Starting from back to front as this is where the battery sits
Well the harness is a direct bolt in as long as you transfer over all the modules and harnesses (roof, trunk, console, dash, engine bay, and engine), it even mounts in the same places as the G8 harness did. Tail light wiring, and license plate lamps, back up camera will be different as you can imagine since the G8 has camera and license plate in the boot lid and not the rear bumper as the SS does and the G8 doesn't have the Chevy-esq lights in the boot lid, so there is a bit of cutting and splicing here, but not too bad (diagrams can be posted later if there is interest in this)
Essentially everything will fit in the same spots until you get to the dash. On the G8, we have a bulkhead connector on the passenger and driver side footwells. on the SS, the BCM is located in the passenger footwell and the main bulkhead connector is on the drivers side. No biggie since every component is being transferred. So in a nutshell, the electrical system will have to be transferred completely if you want this to work.
The doors are a direct bolt in, but you need to get cute with the grommets where the harness travels from the door to the body.
The seats are tricky. The mounting rails (welded to the body) between the two cars are slightly different and the front rail is spaced differently in both cars. You will need to drill out the spot welds and move the rails back some. I dont have a specific measurement, I used a seat to get a precise location by using the rear rail as a reference. I did end up grabbing the rails from the donor car for the front only, in retrospect I wish I had done so for the rears as it would have made the process easier.
The dash is tricky too but will mount as well, and there is one mounting point that both cars share which I used to locate all the other mounting points. This will require cutting off the VE mounts for the dash that are on the A-pillar and some fabwork will be required to make a set of mounts to fit the new dash in. I got a little creative and reformed/welded/made the VE mounts work for the VF dash frame mount.
The Console will need the mounting plates from the VF car as the VE is different. But ironically you will notice on the VF that the cutout for the G8 parking brake cable is still there with a rubber plug. This is just one of those things that shows how similar both cars are. You will see plenty more of these little similarities as you go. The shifter will mount the same.
The hardest part was the firewall.
The SS has a solid firewall reinforced by a plastic bracket that has the brake pedal, gas pedal and associated components and in turn is mounted/supported by the dash frame. The G8 has a removable piece of firewall that all these components mount to. I took the G8 plate, and mounted the SS plastic bracket to it and reinstalled it. The hard part was getting everything precise because if it is off, then you wont know it until everything is assembled. I used the brake booster mount and the steering shaft hole as a reference for this.
The SS windshield will mount on a G8, as will the back glass.
The front and rear subframes are a direct bolt in, my G8 has electric steering and electric parking brakes now (this was by far the easiest). The G8 and SS alternator are the same. (I had to reuse my G8 alternator)
The fuel tank and evap/charcoal canister mount the same, I replaced mine with an SS tank as the connectors and evap system was different and wanted everything to be uniform.
The front and rear electrical boxes mount up to the body as long as you have the corresponding brackets.
The exhaust will also mount the same, slight modifications are needed to the muffler hanger if you plan to use the bi-modal exhaust from the SS which is what I did.
You need to get a little creative with the hood release. All the side trim plastics need to come from the VF. The seatbelts and roof airbags can stay so long as you splice in the proper connectors and I personally replaced the impact sensors on the front clip and the sides.
I went a step further and transferred the HID projectors from the SS to the G8 headlights. (this required ungluing both headlight sets).
The SS fans, condensor, radiator, etc bolted right up.
The battery jump start point also transferred.
I also transferred the fuel lines and brakes lines which I would recommend if you strip the car down that far. The series 1 VE has different fittings for the brake system than the series 2 cars got (closest we have to a series 2 is US Spec WM 2011-2013 Caprice PPV) and also the VF 2014-2017 SS and WN Caprice I believe share the VE series 2 brake lines.
Also, I transfered the battery cables too since the VF cables are much thicker. The VF has more grounds in the harness, so you need to add some along the body for these additional grounds. (The whole body is grounded so this isnt too bad)
The wiper/wiper motors are the same, the cowling is different, as is the hood and fender mount. The front clip/crash bar, looks very similar, but the donor one was tweaked so I did not bother studying it too close.
Any questions.. feel free
Also if anyone is interested in getting rid of their onstar module properly and safely, the procedure is simple for any GM car from 2008 through at least 2018. Disconnect the antenna connectors from the module, find the two white plugs that contain the CAN wires, on Global A cars they are white and blue, early camaros are tan and tan-with stripe, G8 is brown and brown/black-tracer. Simply cut them off the white connectors and splice them together. (For example on Global A - white goes with white, blue goes with blue.) I have found that a lot of Comm errors are caused by the Onstar module (specifically on the new K2xx trucks) and this takes it out of the CAN loop while retaining the function of the factory microphone and ditching the invasion of privacy that comes with this ONSTAR gimmick. I can post a diagram of this if anyone is interested too.