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Well after a great deal of measuring, steel fabrication and rail modification I am happy to say it can be done, and I must add that the NC seats are far more comfortable than NB8A Seats!
Here is a a photo of the Drivers seat which has been completed and the passenger seat is not far behind. The most difficult part is modifying the NB seat rails which requires cutting off the seat belt bracket which on the NB8A is attached to the seat rail, NC seats have the seat belt stalk attached to the seat base.
When all is completed I will put together a "how to" with photos and measurements for anyone who wants to proceed with this modification.
I have used a pair of NC 2006 special edition red leather seats which I purchased from Chris at MX5racing. - Next modification are the NB8B Door Trims I also purchased from MX5racing, will be converting the trim insert to red to match seats.

Very nice!

Would love to see the DIY write up.

"it can be done" covers a lot of ground and the comfort is probably going to be better though you will need an extended road trip to make a judgement. Seat height also seems a matter of interest as the NB does seem tight for some. Presumably a costing will also be of interest to those feeling the need for more comfort. An interesting exercise.

Yup would love to know how it effects the seat travel? Do you have more leg room? More head room?

Great stuff. Looking forward to the "How To.." instructions.

very nice.

The seat base and back on the NC seats are far "thinner" than the NB8A seats, the steel brackets I had made up are made from 5mm x 32mm steel so the actual mounting is 5mm higher, yet the seating position is slightly lower than the standard seat. The only problem is that the mounting holes on an NC Seat base are 260mm apart compared with the NB at 300mm (front to back measurement) and thus seat travel is reduced, this is easily overcome via a slight change in my design. I have set the seat travel to suit my height yet my friend who drives my car who is 5"8 tall can still adjust the seat to suit herself, you can change mounting points to have the seat range suited to taller drivers (more to the rear) or to suit shorter drivers (more to the front).


Steel bent to order at Mascot Steel $63
High Tensile Bolts 16 sets M10 and M8 $30 Bunnings.
A new angle grinder (for cutting seat belt bracket welds) $39 Bunnings.
Blood Sweat and Tears (from broken nails) Priceless.

I suppose flat mild steel has adequate strength- not sure what is the standard normally used. The bolts used by Mazda probably have a marking on them of the grade- given that Bunning's is not really an engineering supplier they should be marked to be sure they are correct. My guess is that seat mounting is actually quite critical though one of the racing guys might be more definitive. Since the NC seat is thinner then they must be using a different grade of filling to provide an improved comfort.

nice work! Now how about those Recaro seats in the new NC?

The seats and seat runners are manufactured with high tensile steel, the advantage being high sheer strength (tear resistance) with greatly reduced weight - the metal used is very thin. The steel I have used is from Mascot Steel Supplies and possibly a little overkill in terms of the sheer strength required at 5mm, but I would rather overdo it than risk the alternative, the Bolts and Nuts from Bunnings are High Tensile as per the Mazda OEM bolts and are more than suitable for the job, but even I was suprised that Bunnings actually stocked them.
The NB8A seat base is absolute overkill - the padding is very thick 2-3 times more than the NC and then it is enclosed in a metal case, almost bullet proof. The NC just has padding with exposed support springs, I would guess that the foam used is more dense then the NB.

nice work!

MXHEVN wrote:nice work!

interesting colour combination though.

Like you can talk

good MX5Chic it is excellent that you you have looked to engineer it properly- those not so aware as you might take shortcuts. The difference in the seat structure is really quite interesting. I well imagine that the OE seat engineers would have lots of stories to tell about design manufacture and construction.

aww c'mon i'm sure they have some more exciting stories to share.

The problem using high tensile bolts, is that they don't "bite in" compared to the lower grade 8.8.

So just be weary is the bolts do start to come loose, or use loctite.