I have seen in a number of places that RX8 seats can be fitted to an Excel. My seats are in really bad shape so I thought I would try fitting a pair - to help others following this route I thought this guide may also be useful.
The passenger side RX8 seat is manually operated, but the drivers side is electrically moved. That means there are a few differences between them. The passenger seat tilts forward to allow access for rear seat passengers, however the drivers side does not.
Both seats have heater elements in them (that I have not used), and both also have seat belt warning wires. The seats also have air bags in them. This means there are connector plugs on both seats, although with different pin configurations. The yellow connector is for the air bag - don’t connect anything to this. I just tucked it up under the seat base out of the way.
Step 1 - remove existing seats
Existing seats are held in with 4 M8 bolts. Sliding the seat forwards or backwards allows access to the bolts at the front or back of the seat rails. I wedged the bolt with a spanner, and undid the nuts under the car. Lying beside the car I was just able to reach the bolt head as well as the nuts, but it would be easier with another pair of hands.
Once the bolts are undone the seats just lift out. They are fairly light.
I found a stack of 3 thick washers under each seat to lift it off the floor slightly.
Step 2 - cut brackets off RX8 seats
The RX8 seats have extra brackets welded to the seat rails. All of these need to be removed. I drilled through the rivets and spot welds holding on the main brackets, and used a cut off disk in an angle grinder to remove the 2 posts from each seat. Once removed the passenger side seat rail is flat, but the drivers seat has a bolt protruding which I think holds part of the slider mechanism.
Passenger Seat - with and without brackets
Drivers Seat - with and without brackets
The seat belt sockets also need to be removed. This is just one bolt and disconnecting the wiring plug. Unfortunately these sockets don’t work with the Excel belts as it would be easier if they could be kept - the sockets in the car want to use the same space as part of the seat.
Step 3 - drill new holes in the RX8 seat rails
Carefully measure the spacing of the holes in the floor as you will need to drill holes in the RX8 seat runners.
I found the passenger side holes were 43cm apart across the width of the seat and 33cm lengthways. However the drivers side was 43.3cm apart - which did make a difference.
The passenger side RX8 seat is pretty easy as the existing holes are the right width apart. I opened up the second hole from the front to 9mm (to give some wiggle room), then measured 33cm back and drilled another pair of 9mm holes.
The drivers side is a bit more complex. Due to the electric mechanism the runners are wider than on the passenger side. I found that there was not enough space between the front mounting hole in the car and the gearbox tunnel to re-use the holes in the centre line of the runner. As a result I drilled new holes in the seat runners offset towards the centre of the car. This allowed the seat rail to fit in the gap next to the tunnel - however the front bolt now prevents the seat sliding all the way forwards, although it moves far enough for me. If you have less insulation on your centre tunnel you may not have to offset the holes.
Step 4 - fit the passenger side seat
The Passenger side seat should drop in fairly easily. I weaved the seat through the door and placed it in position. The RX8 seats are taller than the Excel seats, and also the seat base seems slightly higher - it certainly does not sag like my old seats. I decided not to use the spacers from the Excel seats and so to drop the RX8 seat as low as it would go.
Slide the seat forwards and push the rear bolts through the runners and floor. I loosely attached the nuts to stop the bolts moving too much. Even doing this takes some swearing as the seat wont slide forward far enough to reveal the holes in the runners without hitting the tunnel and moving out of position. I raised the front edge slightly, put the bolts through, then slid the seat back until it sat into the correct position. At this point the rear bolts are under the seat but I managed to wedge a spanner against them.
Then slide the seat backwards, drop the front bolts through and tighten them fully. These bolts are easily accessible. I then went back and tightened the rear bolts.
Step 5 - wiring in the drivers seat
The drivers tilt and slide mechanism is electrical, so to move the seat forwards and backwards to access the bolt holes you need to get some power to it. I just used a couple of jump leads from a battery while fitting, but have made up a small loom for normal power.
The RX8 seat has 2 connectors on it. The yellow one is for the air bag, so just tuck this out of the way.
The other is a multi-plug that covers the movement motors, the lumber support, seat heaters and seat belt warning wiring. You only need 4 of the connectors - 2 for the movement motors, and 2 for the lumber support.
I found a wiring diagram on the web, but the wiring is pretty simple. At one end of the connector block are 2 thicker wires. These give power to the movement motors. The Purple wire is -ve, and the Grey is +ve. At the other end of the connector block are the wires for the lumbar support. White/Yellow is -ve and Yellow/Red is +ve. If you get them connected the wrong way around all that happens is that the switches move the seat in the opposite direction.
I connected in to the car's +ve power supply post with an in-line 30Amp fuse (as on the wiring diagram), and to a convenient earth connector in the loom, and ran the wires under the carpet beside the sill.
Step 6 - Fit the drivers seat
Fitting the drivers seat is the same as the passenger seat. Slide it forwards to drop the rear bolts through the rails, slide it back until the seat fits beside the tunnel and then wiggle the rear bolts down through the holes in the floor. Then slide the seat all the way back and fit the front bolts.
I retained the spacers under the seat runners, but after trying the seat for size I would probably remove one or two of them to drop the seat down a little.
