NB sub-frame in NA
 

is this worth the trouble? I have the front of my car completely apart at the moment and was thinking it was a now or never kind of time. I have access to all the parts for pretty cheap.

all I really need is the sub-frame and rack, correct?

thanks...

More caster, less play in the steering rack bushings. Bolts right in. Just the subframe and the rack is all you really need.

thanks. for some reason I thought I read the steering geometry was better on the NB set-up, helped with bumpsteer maybe???

my car is a anomaly. the last time I lined it up, I had 5* of caster and around -3.5* of camber. I can make the numbers with the factory sub-frame.

Isn't the tie rod attachment points on the front NB uprights higher (7mm or so) to help with bump steer? Isn't that why you don't need R-package outer tie rod ends on a NB? That's why I was planning on swapping in everything on my car, subframe, depowered rack, upper control arms, uprights, lower control arms.

IIRC, the upper and lower control arms are interchangeable (but the upper balljoint and upright are NOT) but the NB bits have better reinforcement?

The difference in geometry is all in the front subframe rack and suspension mounting points. roll center hight is also different, slightly lower.

:dunno:

I believe those are poorly written and wrong.

The rack moved up a bit and the lower A-arm pivot points on the subframe moved down. The changes are is described in a Mazda published book on the NB. looks like they just slid the welded on tube the big bolt goes through for the upper A-arm back a bit to get more caster.

FWIW Im running an NB front sub frame with LE tie rod ends now.

But are you also running NB uprights? If what I've read is correct, the LE tie rod ends with NA uprights and control arms and NB subframe and rack will work fine. It's the LE tie rod ends with NB uprights and control arms that aren't needed, as both attempt to correct the toe curve.

Keith @ FM and Lance Schall both cited the same NB FSM.

I'd really like to know one way or the other, because if I don't have to go to all of the hassle of swapping uprights, I won't.

I was wrong. the book does say the tie rod attachment point was changed on the upright. doesn't say by how much. ill have to dig up my collection of parts and see that.

I have NA uprights with LE tie rod ends and an NB sub frame and rack on my car.

Awesome. I wanted to use NB uprights so I didn't have to special order expensive R-package tie rod ends and could use OTS parts.

Now I just need a single upper control arm and a set of NB shocks and springs to do my swap.

NB plus LE tie rod ends?

It would be nice if it's a fail (adds bumpsteer), so I don't have to worry about it.
I have not measured my bumpsteer (lazy, as always), but if anyone have tried it would be nice to know how stupid it was.

That's a really good question, actually.

I'm looking at doing a complete front suspension update/refresh this year on my NB after I get another DD sorted out. As I was going to replace the tie rod ends anyway, I figured I would just do the LE ones "because they are better" but if that's not the case on an NB, I'd like to hear it.

Pretty sure the LE ends don't shift as much as the NB upright does if the 7.1mm figure is correct. There is a sweet spot in there somwhere seems like mazda would have figured it out the first time or at least by the second time.

Hazarding a guess, I'd say the LE tie rod ends were a band-aid on the factory lowered (1" lower?) R-package car, and they fixed it when they upgraded the production to the NB. Maybe, knowing that they had to create a band-aid part, they found that the 7.1mm adjustment produced a better toe curve for both stock and lowered cars, and they chose to make it standard? I can't believe they'd R&D new parts just to cater to the performance crowd who lowers their cars, so it must be better at stock height too.

From what I can tell, the 90-93, 94-95, and 96-97 NA were all different heights, with the 96-97 being the highest. Some people have referenced 12.9" front as being Mazda's short end of the ride height specification range on both the 94-95 and the NB (per M.net).

Edit: Been thinking about this more, and the other changes made with the NB suspension must have contributed to this decision. I wonder what the toe curve looks like between an NA with LE tie rods, and an NB?

If you buy the entire NB subframe assembly the swap is a breeze. Prior to the swap I was unable to get more than 2.5degrees of camber on right front. After 3+ is possible. Bump steer was never an issue for me but I figured why not take advantage of all of the upgrades and do the entire assembly. I got a real clean one for $300 complete.

I suspect the NB is pretty neutral with bumpsteer at stock height but most of us run quite a bit lower on the track so the LE ends with the NB rack and uprights might be the best combination until the drop spindles are widely available. Or I'm cornfused... :hustler:

The spline on the NB rack is bigger than the NA miata rack, making the u-joint that connects the column to the rack not fit. Do I need to use an NB ujoint, or make something custom for it to work?

Nope. Na u joint fits the NB rack. Unless na manual and power are different.i know the manual na fits the power NB rack.

My NA had a factory NA power steering. So, if I understand what you posted, is that the NA manual steering rack U-joint will work on the NB power steering rack. I believe I just confirmed that the NA power steering U-joint will not work on the NB power steering rack. Darn it.

NB lower U-joint will fit the NA shaft. That's what I have done on all the NB>NA swaps I've done.

And I get that now, and thanks for your response. I just found out the hardway that the NA U-joint would not work. It wasn't listed in any of the threads I saved for this swap. Nor did the NA tie rods worked either, though luckily Rock Out has the MOOG ones priced CHEAP!. Now at least, people will have a thread to go to, listing those A-most parts for a swap!

NA tie rod ends work just fine. The FUCA balljoint is longer to accommodate the deeper NB taper pocket, and the NB steering arm point on the spindle is lifted, but you can bolt the NA tie rod end to it. In fact, that's the preferred setup for lowered cars. I can't recall where I read this, but IIRC Bob Bundy did the math and said that an NB subframe/rack/spindle setup with 93LE/94R tie rod ends produced nearly zero bumpsteer all the way to full bump travel.

To swap an NB subframe into an NA, you need these parts and only these parts (and why you need them):

• NB subframe (this alters the FLCA pickup points and improves camber gain)
• NB steering rack, inner tie-rods, and mounting hardware (this is more reliable than the NA rack)
• NB lower steering column universal joint (required to attach NA shaft to NB rack)
• NB front upper control arms (or NA arms with NB balljoints) and NB-specific upper balljoint nuts (required to use NB spindles)
• NB front spindles (this reduces bumpsteer)
• NA 93LE tie rod ends (this further reduces bumpsteer, to effectively zero)

I do have the 93 LE tie rod ends. But I have no clue what is an "inner tie rod end", but I'll assume is just the tie rod. And if so, you just confirmed what I stated earlier regarding the MOOG NB tie rods I bought. They have their own part number, different from the NA tie rods.

I just got screwed last night on the U-joint to the steering shaft. For that part number: NC10-32-850 hooks it all up. I mean you posted it on your list, but I found out last night, as it wasn't listed anywhere else. Not here, not on M.Net or even the Grassroots Forum. It is in 2 out 3 now!

Oop, yes. I misread. Yes, the NB inner tie rods are different and correspond to the rack. I thought you said you needed NB outer tie rod ends, which is not the case. :)

All good ace!
The MOOG tie rods came with them. I got a new found respect to Rock Auto!

Now that I think of it my NB rack came with the U joint and I used that one on the NA shaft because I couldnt get the NA u-joint off the rack.

You will want NB knuckles as well. Bump steer is crazy with NA knuckles on an NB sub frame. Yes the knuckles are different. I think the best setup is all NB front end with LE tie rod ends for an aggressively lowered car.

I distinctly remember reading a post by you saying that you had measured the bumpsteer with that combo (NB subframe/spindles + NA LE tie rods) and it was ~1/16" from static ride height to full bump.

yea NB subframe knuckles with LE tie rod ends was the best. NB with NA knuckles was not so good and LE tie rods made that mismatch combo worse. If you run at stock OE ride height probably just stay all stock NB almost nobody in these forms runs stock ride height however.

Hehe, I paid $10. Right price, right place at the right time. I spent more on the U-Joint ($40) and the steering rack bracket ($2 used, NLA by Mazda, I bought 2 of them!), than I did on the rack and subframe itself!

And the NA steering column intermediate shaft won't work on the NB U-joint... If one tries to buy part NC10-32-090D new, is NLA. You then have to buy NC10-32-100D and new that one is oer $350, but used is less than $40 for both, thank GOD!

I believe that's false. I read that on M.net before I did Rover's swap, so I ordered the NB intermediate shaft too. It's identical to the NA one. I then skipped it when I ordered the swap parts for my current customer S1/ST4 build, and it worked just fine. NA column, NA intermediate shaft, NB lower universal, NB rack.

Really? The intermediate shaft is too long to bolt with the NB steering U-joint! I mean, could you describe how you made it work? I'm supposed to order the NB intermediate shaft tomorrow!

https://www.miataturbo.net/suspensio...me-swap-62426/

Darn it, right here is spelled out that the NB steering IMS is needed. Gosh darn it. :slap:

Post #19 from Doward says the u-joint is required, but not the shaft. The shaft is the long metal thing with the male splines, the u-joint is the bendy thing with female splines.

I get that boss! But it looks like one of us is misreading post#19. I read it as "The little shaft with the boot, is that what y'all are calling the "intermediate" shaft? If so, it is an NB piece and splined perfectly with my NA column", right?

I may just be tired, which I am, and in no way I'm trying to argue, just confused, that's all!

Yes, but it has nothing to do with an incorrect length as you alluded to. The length is correct, the spline diameter is just larger on the NB rack. You need the NB u-joint for the diameter, not the length.

The problem I'm having is that the NB U-joint is bigger than the NA, which makes the shaft too long to fit. Looks like I'm doing something wrong, but exactly what?
Should I unbolt the rack, plug the u-joint to the shaft, and bolt the rack back?
Sorry for all the stupid q's, but I'm at a loss here!

Well this is all good info. Recently swapped to an NB subframe/rack on my NA with non-LE rod ends. Looks like I won't be changing to LE and will be keeping an eye out for NB knuckles.

As for the rack, I did use the NB u-joint with the NA shaft. If it's too long, slide it back into the column, it's a safety feature with ~6" of play...

FWIW I also mated the entire NB power steering setup onto my NA, only changing the reservoir. I did opt to run an aftermarket cooler with soft lines to the reservoir/rack however.

^Thanks Curly, I'll try that tomorrow. BTW, next time I'm in Oregon (is where a month ago I bought the car that's getting this subframe), I'll buy you a cold one!

How are you guys buying these sub frames? When I bought mine it was complete with control arms, rack and knuckles. I just bolted it to the body, engine and steering shaft. I then added the LE tie rods later.

It's painfully pedantic, but the NA and NB arms interchange and the NA arms have the double-shear endlink mounts. Not a big deal on most cars, but when you've got a 1-1/4" bar with a 3/16" wall thickness in the car, the swaybar system needs all the help it can get.

The ideal setup is an NB subframe, NB rack, NB FUCAs, NB spindles, and NA lower arms, Bauer ELBJs, and 93LE tie rod ends.

While the NA is double shear the material is a lot thinner than the NB single. I added the Racing Beat tab to the NB to make it double shear. It seemed like the best idea with that monster front bar. Otherwise I agree with and copied your formula. :-)

IIRC supposedly there was also more reinforcement in the NB arms under the tabs too.

NB1 FUCAS :party:

Parted out a car, so I only took what I needed Long story: My car is getting less and less track orientated (have a fully caged car for that) and I wanted comfort, aka PS. I don't have/want ABS, so I sold the ABS NB hubs. Since you need to keep NA subframes with NA racks and NB subframes with NB racks, I took the opportunity to upgrade to the "better" suspension geometry. Installed all my NA hubs and arms with NB subframe, rack, tie rods, and I think some barely used MSM outer tie rods, and voila, power steering.

Good to know, I'll try to source some NB knuckles. I was parting out with a friend, and we had a buyer for all the ABS knuckles/hardware.

+1. The spindles are half the benefit and like 5% of the work. Makes no sense to run an NB subframe and NA spindles.

Confirmed, and done!


Quick Q? Right now I have the NB power steering reservoir, and it fits rather wonky. Would the NA reservoir (I have one) would fit unto the NB rack hoses?

I used the NA reservoir. I think the smaller line that comes out of the back of it, I the NA hose didn't see to fit quite right, so I just used some bulk hose. The larger hose I don't recall if I used the NA or NB, but it was an OE hose.

Thanks dude!

Sorry to thread jack, but we're parting out another 2003. Just so i'm clear, I want to grab the front knuckles and upper arms? How horrible would it be if I kept my non '93LE outer tie rods? Also it's 90% a street car, so do I strictly need the ELBJ? Don't get me wrong, I'm club orange and am happy to grab Emilio's new front end service kit, but I also don't know if I necessarily need near 4* on the street.

Does anyone know how to visually (or otherwise) differentiate between NA and NB front upper arms?

I have a set that I plan to use to facilitate a bushing swap, but when I obtained them I didn't realize there was a difference in the upper arms, and I don't know for sure whether they came off an NA or NB...

Thank you! That was the nugget I needed for a useful search result.

Found this:
https://cimg2.ibsrv.net/gimg/www.mia...b1fb3ed36d.jpg

Which I think answers my question... just have a little more research to do to confirm NB1 v. NA, and I think the answer is still in the underside bracing.

EDIT: OK, I believe the FUCAs I have are NA... It appears the underside bracing was extended from NA to NB1, and again from NB1 to NB2. If anyone has any different info, please speak up.

https://farm5.staticflickr.com/4833/...1e17dfe6_c.jpg

It doesn't matter since you don't have the ball joint anyway. The big problem is the NB upper ball joint taper is different, so you have to match the knuckle and ball joint (which most people.never change out if the arm).