2000 base model, 5 speed, no rust miata.
The rear subframe is bent, left spindle and axle are trashed, and differential is now making strange and unsettling noises.
My parts car will be here monday. Complete with torsion rear!
Anyway, my thought is to pull both cars into the shop, jack up the ass end and put on stands, unhook ppf, brake calipers, and driveshaft. Drop entire assembly from moth. Put good rear in my car, bent it parts car.
It can't possibly be this simple. What am i missing? Any tips, tricks, or suggestions? I thought about borrowing my brothers motorcycle jack for stability.
So, hive, i beseech thee: learn mr rear end swaps on the nb miata!
From what I remember of a friend swapping Miata rear end bits around on an NA, it should be about that simple.
It's pretty simple. Make sure you have the back higher than the front so you don't dump all the transmission fluid when you pull the driveshaft. You'll need to pull the exhaust too.
In reply to Dusterbd13 :
Is this the car you just painted? What happened???
In reply to Pete Gossett :
Yes. Got smacked in the left rear corner by Mrs magoo last week. Quarter is a little mangled as well.
Good call on trans as well guys.
Exhaust: is there a flange or anything specific for where i should remove?
Lastly, the big aluminium bracket that runs to the trans: looks like 4 bolts and pry off. Anything special there?
Disclaimer - I've only done this on an NA. NB bracing is different but the major mechanical bits are the same.
I pulled the exhaust at the cat inlet flange.
Pull the driveshaft, catch any trans fluid that leaks.
Unbolt the shocks from either the top or bottom, each has its own challenges.
Support the transmission-remember that the PPF is all that locates the back half of the trans, so if you don't hold it up, it'll sag. Your motor mounts (which if you haven't replaced them, probably need it) won't like that either.
Unbolt the PPF from the trans. Nothing special here, just pries off.
Unbolt subframe, lower to the ground. It's heavy with everything on it.
I replaced just the subframe, so I disassembled everything else on the car and pulled just the subframe itself. It's probably easier with the diff still in it so you have something lower for the jack.
Oh, and there's a big wire bundle that is clipped along the PPF. Remember to remove that, and unbolt the brake line that runs along the body to the back at the junction block on the passenger side. You'll probably have to pull the speed sensor too (sorry, keep remembering things as I type this)
How much time should i figure for this? Pretty much remove and replace 2. Put bent in parts car, good in daily, push out of shop.
Also, any way to not have to open the brake system? Save me having to bleed them.
Dusterbd13 said:
Also, any way to not have to open the brake system? Save me having to bleed them.
Put something of the correct length between the driver's seat and the brake pedal, so the pedal is pushed about an inch. That will put the MC pistons past the compensation ports so it wont drain all the fluid from the reservoir. swap everything over per the advice above, then just let the rear calipers gravity bleed while you're tightening up all the other stuff. Easy peasy, lemon squeezy.
In reply to cmcgregor :
Very little difference between the NA/NB it is just as you described for both.
They're being mean. There are locking sleeves in the PPF/diff joint. This will drive you a certain amount of crazy if you don't know about them.
From memory, and it's been a while - remove the two big bolts and their lower collars from the PPF. Unbolt the spacer on the bottom of the diff (one or two bolts, depends on NA/NB). Now use a pry bar to twist the PPF enough to allow you to pull the spacer straight down, then you can pop the PPF off the top of the diff and you're free. This is a fairly easy procedure, although I'm sure it's impossible according to some forum.
If you do mix NA and NB, keep in mind that the NB rear uprights have an extra 5mm of track on each side. This can adversely affect your tire clearance if things are close.
In reply to Keith Tanner :
Yeah pulling the diff end is a while different story. I thought he was swapping the subframe, diff and ppf as a unit from his parts car.
It's probably easy to separate the collars from the diff if you don't live in New England
The ppf is the aluminium frame from diff to trans, correct? If so, minne appears to be straight still. However, diff, subframe, ds axle/spindle/control arms are garbage.
The parts car is a 99 with tan leather and a torsen. Mine is a 2000 base. Should all he. Direct swap, right?
Mine is a California car, the parys car is a southern car. I dont expect to need a torch, but am prepared for that if need be.
Is it quicker/easier to pop the aluminium frame from diff or trans? Again, at this point i jusnt need the car back together before the rental goes back.
Unbolt the diff from the PPF. The two big bolts are a trick, loosen them about 1/2" and smack with a hammer to drive the nut inserts out the top of the PPF, then remove.
Brake line bolts through the rear subframe so yes, you have to open it and bleed the brakes when done.
I removed the diff before doing the subframe. All in it wasn't bad and can be done on jack stands in the driveway in an afternoon.
Yes, the PPF is the aluminum frame. I'd just disconnect it at the transmission end if it were me. Less work that way. Everything should be a direct swap from a '99 to '00.
KyAllroad said:
Unbolt the diff from the PPF. The two big bolts are a trick, loosen them about 1/2" and smack with a hammer to drive the nut inserts out the top of the PPF, then remove.
I don't like blowing the splined inserts out of the top of the PPF myself. You only get to do that so many times. I do tend to keep my cars longer than usual, though.
It's easier to pull the PPF off the trans end, but then you have to remove the wiring harness that's clipped to it with 18 year old plastic which is fiddly and doesn't always end well. I'd take it off the diff end off myself.
It's not so bad to bleed the brakes once in a while 
As noted, just leave the rear caliper bleed screws open and let them gravity bleed, you'll find you have very little to do when the time comes.
It wouldn't hurt to have a transmission plug handy for when you pull the driveshaft unless you only have the back of the car lifted. You could leave the driveshaft in place but then you'll be working around it and calling it names.
Let us know how it goes. I'm curious which way you'll end up going.
I pull the parts car in tonight to start disassembly. Im not sure which one im going with yet. We'll see what happens.
Trans end won.
Two hours from drove in to on the ground outside and getting pressure washed.
Tomorrow i pull the junk rear, put in the good rear. Hopefully i can do 2 hours total for remove and replace.
Related question: how do i knowwhat ratio i have? Parts car feels a hell of a lot stronger than the daily. Even with 2x the miles and a blown head gasket.
JoeTR6
HalfDork
9/22/17 9:26 p.m.
Dusterbd13 said:
Related question: how do i knowwhat ratio i have? Parts car feels a hell of a lot stronger than the daily. Even with 2x the miles and a blown head gasket.
Put a mark/tape on the output flanges and turn the pinion. Count how many times the pinion turns to get 1 turn on the output flanges. It's accurate enough to tell whether you have 3.9, 4.1, or 4.3. Good to hear it's going well. I couldn't get the PPF separated from my diff, and now need to replace the diff mounts.
...trying real hard not to make jokes about how your car isn't straight anymore, and how your solution is to swap out all its junk...
