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-   -   NB sub-frame in NA (https://www.miataturbo.net/suspension-brakes-drivetrain-49/nb-sub-frame-na-76992/)

The Driver 08-27-2018 09:56 AM


Originally Posted by Savington (Post 1498565)
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!

Savington 08-27-2018 12:46 PM

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)

The Driver 08-27-2018 01:00 PM


Originally Posted by Savington (Post 1498638)
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-rod ends, 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!

Savington 08-27-2018 01:09 PM

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. :)

afm 08-27-2018 02:11 PM

Make sure you get NB-style inner tie rod end retention washers. It’s nice to avoid reusing them.

The Driver 08-27-2018 05:28 PM


Originally Posted by Savington (Post 1498641)
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!

Originally Posted by afm (Post 1498657)
Make sure you get NB-style inner tie rod end retention washers. It’s nice to avoid reusing them.

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

Leafy 08-28-2018 07:42 PM

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.

bbundy 08-29-2018 12:28 PM

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.

Savington 08-29-2018 04:14 PM


Originally Posted by bbundy (Post 1499033)
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.

bbundy 08-29-2018 05:47 PM


Originally Posted by Savington (Post 1499064)
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.



k24madness 08-31-2018 12:09 PM

I added LE tie rods to the NB subframe last year after reading Bob’s findings. Thanks Bob!

If class rules allow adding a NB subframe is well worth the effort. I paid $300 for a complete assembly. Pretty easy install too.

The Driver 08-31-2018 01:23 PM


Originally Posted by k24madness (Post 1499399)
I added LE tie rods to the NB subframe last year after reading Bob’s findings. Thanks Bob!

If class rules allow adding a NB subframe is well worth the effort. I paid $300 for a complete assembly. Pretty easy install too.

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!

The Driver 09-03-2018 10:59 PM

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!

Savington 09-03-2018 11:10 PM

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.

The Driver 09-03-2018 11:37 PM


Originally Posted by Savington (Post 1499901)
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!

The Driver 09-03-2018 11:54 PM

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:

Savington 09-04-2018 12:04 AM

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.

The Driver 09-04-2018 12:09 AM


Originally Posted by Savington (Post 1499910)
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!

Savington 09-04-2018 12:19 AM

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 Driver 09-04-2018 12:33 AM


Originally Posted by Savington (Post 1499913)
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!


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