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Marrad ST3 Racing Seat Install with Stock Seat Belts
There was no official thread on installing these specific seats so I decided to help out Mark over at Marrad. This is a relatively new seat on the market designed specifically for small coupes such as Miatas (NC only will not fit NA or NB), S2000s and Corvettes. I'm sure they would fit in a myriad of vehicles, these are just the confirmed applications I know of. One of the main selling points of these seats are the holes designed to allow the OEM seat belts to function inside the seat rather than travel over the top of the side bolsters. I personally chose these seats because of the overall design - they appear to almost look like an OEM option over the usually brash, overly stimulating aftermarket seat designs.
In this thread, I go over the install of the seats, using the stock seat belts from a 2006 Z06.
***Standard disclaimer - I assume no responsibility for any damage. Please be careful - the consequences of an improper install could be extremely dangerous. Remember these are the safety devices that save your life in the occurrence of an accident - DON'T CHEAP OUT OR USE SHORTCUTS***
Tools Needed:
- Precision flathead
- 6mm Allen Wrench
- 1/2" Wrench
- 14mm Open End Wrench
- 15mm Wrench
- 13/16" Box End Wrench
- Heavy Duty Scissors to cut zip ties
- 15mm Socket
- Electrical tape/Zip Ties to clean things up
- 2 Grade 8 or higher 1/2" bolts that act as the Seat Belt Anchor
1. Take Seats out of Car:
Move the seats rearward, and pop off the two clips holding the trim pieces that cover the bolts. Pull the trim pieces forward before you pull up. Unbolt the the two 15mm bolts holding the seats to the floor.
Move seats completely forward, position them as low as they can go, and recline the seat forward. This is the easiest position to pull the seat out of the car in. Disconnect the Battery and unbolt the the two 15mm bolts in the back of the seat.
Remove the 15mm nut holding the seat belts to the stock seat belt anchors.
The passenger seat has an extra connector that you need to plug first.
Now rock the seats off the studs in the floor and disconnect the two wiring harnesses underneath the seat that control the airbag and seat belt sensors as well as the motors on the drivers side seat.
At this point you are ready to remove your seats. I found it easiest to aim the top of the seat towards the opposite side of the car and pull the base of the seat out of the car first. But I've seen it done the opposite way as well.
2. Removing Seat Belt Receiver off of Stock Seat:
This is the step I couldn't find any information online for - I did not want to remove the the whole harness which requires you to take the cover off the bottom of the seat and I did not want to cut into any wires if I didn't have too.
Remove the 13/16" nut - BE CAREFUL - the amount of the nut that is exposed is very thin and the stud has thread locker on it. Use a 13/16" box end wrench and take your time.
There should be two wires coming off the Seat Belt receiver - one goes a small connector that is clipped to the bottom of the seat in between the bolster and the stock rails. Its relatively hard to get to, but with a precision flathead, I was able to pop out the male side of the connector. This same procedure applies to the passenger seat.
The other wire is the main yellow seat belt connector that you will plug back into the harness that goes underneath the seat when you re-install. There is not enough room on the driver seat to simply pull it through the seat rails like on the passenger side, but luckily you can take apart the connector quite easily...
Remove the "U" pin that connects the positive and negative pole. With the "U" pin removed, you can now stick a precision flathead into the connector to pry the two small plastic retaining clips holding the two wires into the connector.
With the wires now completely out of the head of the connector, you can pull the wires clear through the rail of the seat and install everything back together. You now have everything you need off of the stock seats without cutting anything except a few zip ties!
3. Assembling the Marrad ST3 Seats for installation:
This is everything that the seats came with:
Use the 6mm Allen bolt supplied in the kit to bolt the stock seat belt receiver to the custom adapter that is sandwiched in between the brackets and the sliders.
The only thing that I had to purchase separately for the install was a bolt that acts as the seat belt anchor stud on the door side of the seat. Place the bolt sticking outboards in the other custom adapter plate that is also sandwiched in between the brackets and the rails.
You are now ready to install the seats on the brackets with the supplied 6mm Allen bolts at your desired height and angle. It should look like something like this all put together...I ended up taping the two seat belt wires and hiding them away with zip ties for a clean look later.
4. Installing Seats back into Car
Now simply put the whole assembly back into the car and do the whole procedure in reverse:
- Reconnect the seat belt wiring harness
- Bolt down the 4 bolts holding the seat to the floor
- Tighten the bolt to the 15mm nut which now acts as the Seat Belt Anchor to the Custom Adapter on the door side.
- Reconnect the battery
Take your time and make sure all bolts are securely fastened. I kept the bolts holding the brackets to the rails a little lose during the install and tightened everything down at the end.
The fit was extremely tight for me against the tunnel because I have heat insulation material installed on the floor wrapping over the tunnel underneath the carpet. If you have insulation material on the tunnel you might not have full range of use from the sliders.
Overall I am really happy with these seats. I always thought the biggest downfall from these interiors were the stock seats. They look and feel like old sofas which might be okay for some, but for those willing to sacrifice some ingress/egress room for super supportive, great looking racing seats, these are an awesome option. No longer waste all that energy at the track bracing yourself in the car and use it to concentrate more on your line!!
As far as size and feel, I am 5'11" 180lbs with a 32" waist and these seats fit me just right - not too tight, not too loose. My shoulder positioning in relation to the harness pass through was at a great height for the use of a harness later down the road. The Marrad seat brackets are very low profile - even on the highest setting I could fit in the car with my helmet on no problem. The seats themselves are very comfortable and once everything was bolted down there is no flex in the at all.
For any other questions or concerns you can contact Mark at Marrad (Info@marradind.com or 860-848-0036). He is vocal here on the forum, extremely helpful and always responded fast. Thanks again Mark!!!
Last edited by bmalczewski; 11-03-2017 at 10:57 AM.
That's an awesome mod. If the previous owner of my car had not already went with another brand of aftermarket seats I would be adding this option for sure.
I made a link to a package with the ST3 seat and mounting hardware used (ultra low brackets, dual locking sliders, side mounts and seat belt adapters) for $999 below. That will save $128 per seat over purchasing the seat and hardware package separately. The seats with diamond stitched inserts can be requested with the up-charge waived until supplies run out.
Before I create another thread, I wanted to bump this one...
I bought the ST3 seat earlier this year, and at this point I've managed to get a couple thousand track miles on it -- or in it. I couldn't be happier! I'm 6'4", with a longer than average torso for my height, and this seat makes everything work, and work well. My waist is around 38" (probably a little more), and this seat fits incredibly well -- I don't even think an extra helping at Thanksgiving would be an issue.
I simply can't say enough good things about it!
Last edited by DinkyDonut; 11-17-2017 at 03:18 PM.
ok...thats all good stuff....but what about both cables coming off the seat belt pretensioner (receiver)...the one with the yellow harness connector i get....what about the other pretensioner (receiver) cable with two wires inside...both are black...?....also what about the seat belt retractor...do you hook that up as well...? nothing is said about that....the retractor plug out is on the right side of the passenger seat and the left side of the drivers seat...the drivers side retractor "does not" have a plug out.
If anyone is looking for a complete set, I have a pair that have been sitting in my house for a while that I would really like to get rid of. Used them a handful of times before I ended up selling the car for a c7. These seats are amazing and customer service is awesome too. The link is below and I am open to offers.
I made a link to a package with the ST3 seat and mounting hardware used (ultra low brackets, dual locking sliders, side mounts and seat belt adapters) for $999 below. That will save $128 per seat over purchasing the seat and hardware package separately. The seats with diamond stitched inserts can be requested with the up-charge waived until supplies run out.
can I pick up this deal with the diamond stitch to save on shipping?
Yes. I have a few seats left with the diamond stitching. You should see a box labeled "additional information" during checkout. Request the diamond stitching and I will include that at no additional charge while supplies last.
I have about 6 pre-upholstered ST3 seats remaining. We will be making a new mold soon that will have even larger lap belt holes to allow the C5 seat belt retractors to fit through them. After that the ST3 seats will be made to order but more expensive.
We are working on a new mold for our ST3 seat. It is the shell on the left in the photos below (the shell on the right will be for the Miata).The lap belt holes will allow the C5 belt retractor to fit thru, making it easier to use C5 or C6 seat belts.
We are working on a new mold for our ST3 seat. It is the shell on the left in the photos below (the shell on the right will be for the Miata).The lap belt holes will allow the C5 belt retractor to fit thru, making it easier to use C5 or C6 seat belts.
I'd like to buy one of these when they're available, along with your aluminum rails for my C5Z. I can give fitment feedback too, if you need it.
Please send an email to info@marradind.com requesting to be updated on the ST3 seat. I try to keep a folder of interest rather than re-read each post.
Some C6 customers did not want the enlarged lap belt hole needed for the C5 retractor. We had the new ST3 mold modified so it has markings for both size holes. I hope to have a cover on it soon to photograph and begin taking orders for the C5 or C6 version again.
10-26-2017, 10:44 AM
Marrad ST3 Racing Seat Install with Stock Seat Belts
