NA vs NB subframes, control arms, spindles
 

I have a 90, I'm replacing my suspension over the winter to 949's BGK.
While I'm in there, I've sandblasted and painted a front and rear subframe (and control arms) from a 94 with the factory braces. They are shiny and painted and ready to go in. I just need to drill my zerks for the control arms.

I just bought a 2002 LS parts car. I understand this suspension geometry is slightly better than the NA. What exactly is improved? Worth the swap? I already have the 90 parts out, but my 94 parts are ready to bolt in... I still need to gut the 02.

Are the control arms the same?

I understand the rear has more width to it-- this is located in the hub carriers, correct?

Is my best bet to mix-and-match or go NB all the way? Marginal gains? I'd rather not waste all my work/ $$$ with blasting/ painting, but if it's a real benefit...

I believe you can mix and match control arms. The NB have a stronger sway bar mount even though its single shear as opposed to the double shear of the NA arms. I know there is talk of mix an match lower arms, cannot comment to uppers. I do know you need all the steering bits to match the subframe, except for possibly outer tie rods but not 100%.

Im doing just this to my 94 at the moment. Ironically, also out of an 02 LS parts car..

https://www.miataturbo.net/attachmen...ine=1355257679



As posted by Keith Tanner:
>>
"The front NB subframe does have some improved geometry. The lower A-arms are moved forward. The steering rack has better mounts. The front uprights have the steering arm moved up about 7mm, and the upper control arms have a slightly different taper on the ball joint and more reinforcements.

If you're going to swap the front, you ideally need to do the subframe, rack, uprights, upper control arms and maybe the tie rods - not sure about the latter. If you have those parts, it's a straight bolt-in.

The rear subframe is identical other than exhaust hangers and brace mounting points. It did let me run the stronger rear subframe brace which was good, because I planned to use the brace as a skid plate. And I did, big time. The rear uprights give an extra 5mm of track on each side, so I used 1994-97 uprights to give myself a bit more fender clearance. Again, this all bolts together although the 1.6 cars don't have the mounts on the chassis for the subframe brace and you'll find the exhaust hangers are in the wrong place for an NA exhaust."

Great info, thanks.

I suppose what he means by "the stronger rear subframe brace" he means the 94+ ladder shaped brace versus the single bar found on a 1993. All the ladder-style bars look the same to me.

Are you running the NB rear uprights on your car? Does the added track width co-inside with a wider front width? Or did they just push the rears out (maybe they're not the same track width on the NA)?

I suppose the last question is: is it worth the effort to swap it in? Could there be a measurable difference in the handling or does it just look better on paper when we crunch the numbers?

The NB rear ladder braces are thicker even than the 94-97 ones.
I will be running NB uprights at all four corners, yes. The car is still under the knife so to speak so no performance evals. 5mm wider, both front and rear. It is worth it for me because the parts car paid for itself and I basically got the entire undercarriage and vvt motor for free. The car has been engine-less for a month or two and was scheduled for some heavy rack time this winter anyways. It kind of fell in my lap, I never had NB chassis stuff on my must have mods list.

Is that 7mm on both the rack and the knuckle? If just the knuckle how does that affect bump steer/roll steer? I cant visualise the mx5 steering layout atm...

Just knuckle. Rack is mounted different than NA but theoretically at the same spot/height.

I just completed a NA to NB subframe swap. If you are a track junkie with high end suspension mods the swap makes sense. If not don't waste your time.

I have seen the single point attachments for the sway bar pull out of the lower control arms on an NB that went with heavy sway bars.

I have seen them crack as well. This seems to make sense. It incorporates another tab. This will be stronger than either NA or NB stock mounting points.

http://www.racingbeat.com/manuals/54111%20Flange.pdf