brianlloyd New Reader
6/11/11 7:16 p.m.

I wrecked my 1999 NB at the track some time ago. I purchased a 1990 NA "tub" to get turned into my track car. I am in the process of transplanting as much as possible from the NB to the NA (hence the name 'Frankenmiata').

The body and engine of the NA are in good shape. (Only 50,000 mi on the engine.) With over 200,000 mi on the body, chassis, and the rest of the drive-train you can imagine that there's lots of slop. Before I wrecked I had replaced nearly everything in the NB's chassis and suspension, e.g. bushings, brakes, bearings, shocks, springs, anti-sway bars, etc. The wreck crushed the left rear quarter of the NB, e.g. bent both control arms, the upright, the wheel, and bent the chassis, but everything else seems to be in pretty good shape. I plan to use what I can use and then part out the rest.

My immediate plan is to move the tranny, diff, the entire front suspension, shafts and axles, and as much of the rear suspension as I can salvage. I can either use the NA uprights and install new bearings and seals or use the right upright from the NB and get a left NB upright from a junkyard and put in new bearings and seal.

I hope to build up a hot-rod motor out of the 1800 cc engine from the NB and then put it into the NA later.

Now for the reason for the post. I need someone knowledgeable to tell me something of what I am going to run into regarding the suitability of using various NB parts on an NA car. For instance, I have heard that the front-end geometry is different and that I may need to move the front sub-frame and steering rack in order to make use of the NB control arms, uprights, and hubs. Can someone confirm or deny this information? I know that some suspension components are compatible but I just don't know which ones.

Anyway, thanks in advance for any help any of you can render.


Tom Heath
Tom Heath Web Manager
6/11/11 7:48 p.m.

Keith will be along at some point to cite chapter and verse of Miata swappability, but what you're proposing is completely possible. I'll do my best in the meantime, since I'm stuck in a Boston hotel until morning.

NA/NB front suspension geometry is different, but it's relatively slight.

I think the answer for using NB arms/uprights/hubs is to use the NB subframe. IIRC, it's direct fit and will then allow the further subassemblies to be used. Even if yours is bent, they aren't exactly uncommon or necessarily expensive. I haven't heard of anyone moving/adjusting the NA subframe for the same purpose, but it might be possible.

brianlloyd New Reader
6/11/11 8:06 p.m.

In reply to Tom Heath:

OK, thanks. Someone had said that I would have to change the subframe. I took some quick and dirty measurements but couldn't find a difference, hence the questions.

I don't think that the subframe is bent or damaged. All the damage on the NB seems to be limited to aft of the firewall (with the exception of one tie-rod).

Is it possible to change the subframe without pulling the engine? Can unbolt the mounts, jack up the engine, and drop off the subframe?

Thanks for the quick reply. I appreciate it!


brianlloyd New Reader
6/12/11 1:02 p.m.

Seems I asked this question about a year ago. I am thinking this is one serious case of CRS. All my answers are already there. Now I know why I was thinking that maybe I needed to change the front subframe.