Say i was willing to swap to a TII rear end if need be, what's the lowest (numerically) rear end i can easily get in an NA Miata?
Trying to weigh options between using a 6spd or a TII trans for a future project.
Need lower number rear end because the motor doesn't rev and 6spd gearing is ridiculous. Trying to avoid topping out 2nd gear at 45-50mph.
I looked into this a while back. All I really have is good luck. I think the best "easy" ratio I found was 3.9.
singleslammer wrote: I looked into this a while back. All I really have is good luck. I think the best "easy" ratio I found was 3.9.
Yeah, that's what i'm worried about. I'm ok with waiting for a 3.63 to pop up, but wondering if the TII rear end opens up any easily-found possibilities.
The issue here is that using the 6spd is way easier in this instance.
I think a full TII trans/rear end setup would probably work fine, but that requires more work on the transmission end.
My MSM has the 6spd/4.10 setup and it sucks unbelievably badly. If i attached it to the motor i'm looking at, i'd top out 2nd gear at like... 42mph.
Looks like the lowest without switching to the TII diff would be 3.6 in the 01 Australian 6-spd. I'm not sure where to find the interchanges for the TII diff.
IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff?
also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.
psteav wrote: IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff? also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.
Oh, that sounds easy to find. 
But that would work nicely with the 6spd i think...
Now the other question is... would the 4.10 out of a TII be any stronger than a Miata 4.10? And what about using a Miata 3.90 with a TII trans?
In reply to psteav:
Yeah I had recalled our conversation about that but he said easy. A diesel courier is a rare bird.
The way this thread is going, sounds like an 8.8 swap would be the answer.
Ranger50 wrote: The way this thread is going, sounds like an 8.8 swap would be the answer.
I don't really know much about this... i can do this while keeping the double wishbones? I assume a custom driveshaft would be necessary?
I want to know what engine you are thinking about. 
7.5 and 8.8's were available in IRS confiurations in Mark8's, MN12 T-birds and Cougars, then finally in the Mustang Cobras.
z31maniac wrote: I want to know what engine you are thinking about.
F2T.
Had a couple deals fall into my lap over the weekend that makes this possible for almost no cash outlay.
The next issue is a driveline that will handle well over 400wtq without complaint.
Ranger50 wrote: 7.5 and 8.8's were available in IRS confiurations in Mark8's, MN12 T-birds and Cougars, then finally in the Mustang Cobras.
So i'd be swapping the entire rear setup, which would also necessitate a hub swap, yes? Trying to keep this simple and as bolt-in as possible so i don't lose interest. Willing to take a chance on shattering a diff or trans in the process so long as i can get the car up and moving quickly once i start working on it.
Unless you get some custom axles made for the 8.8 diff and Miata hubs.
EvanB wrote: Unless you get some custom axles made for the 8.8 diff and Miata hubs.
That's where i was going next... i assume that i live in the area where i could probably get this done the cheapest.
92CelicaHalfTrac wrote:psteav wrote: IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff? also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.Oh, that sounds easy to find.
TII diff is quite a bit stronger than a Miata 4.10. IIRC, it's an 8" ring gear versus a 7", and will hold up to whatever an F2T will throw at it.
Someone used to make custom hubs that would work with stock Miata axles, and then about all you had to do was sort the PPF mounting (which won't be there on the TII pumpkin). Doesn't solve the lack of gear ratio options, though.
psteav wrote:92CelicaHalfTrac wrote:TII diff is quite a bit stronger than a Miata 4.10. IIRC, it's an 8" ring gear versus a 7", and will hold up to whatever an F2T will throw at it. Someone used to make custom hubs that would work with stock Miata axles, and then about all you had to do was sort the PPF mounting (which won't be there on the TII pumpkin). Doesn't solve the lack of gear ratio options, though.psteav wrote: IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff? also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.Oh, that sounds easy to find.
Well... if i use the TII diff and trans, it seems like that would SOMEWHAT get me in the ballpark of what i'm looking for. On a 24.5" tire, it would get me to 55mph in 2nd bouncing the rev limiter. Bonus points for the trans being stronger as well. It's close enough that if i wanted to push a little harder i could just raise the rev limiter.
I know there's a bunch of write ups on how to get the TII diff on a Miata, so i'm not REAL worried about that.
http://www.bossfrog.biz/Miata_V8_Swap.html
You can get axles to use with the ford 7.5" out of an IRS Tbird for $650 here. Keith might be able to hook you up too since Flying Miata makes a kit for this too.
Edit: Here is another:
http://www.driveshaftshop.com/mazda-1989-2005-miata-with-ford-8-8-rear-conversion-400hp-direct-bolt-in-axles
psteav wrote: IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff? also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.
I've been looking at this for awhile now, even using car-part.com that courier R&P is almost pure unobtainium. 8.8 out of the T-bird is what I'm leaning towards for a "cheap" rear gear change. Though there is a freshly rebuilt Cobra aluminum rear that has been popping up on CL for the last 6 months. Thinking 3.35 with a true trac for my F2T/six speed that I'm slowly accumulating parts for. Trying to keep it in challenge budget but I'm afraid the 6 speed/t-bird rear is going to push it out of that range.
In fact we discussed this in the parking lot at the challenge while you were charging your phone.
So, I see it mentioned above, where does one find the 3.63 unicorn gear?
Nevermind. Occasionally, I should click on the links in a thread.
Spinout007 wrote:psteav wrote: IIRC, the only easy options for the TII are 4.10 and 3.90. 3.90 is only FD RX7s with an automatic. Don't quote me on that, but I was looking for the same reasons you are. Maybe look into the 8.8 T-bird diff? also, http://solomiata.com/RingandPinion.html has the info for the regular 7" R and P. Now all you need is to find a diesel Ford Courier.I've been looking at this for awhile now, even using car-part.com that courier R&P is almost pure unobtainium. 8.8 out of the T-bird is what I'm leaning towards for a "cheap" rear gear change. Though there is a freshly rebuilt Cobra aluminum rear that has been popping up on CL for the last 6 months. Thinking 3.35 with a true trac for my F2T/six speed that I'm slowly accumulating parts for. Trying to keep it in challenge budget but I'm afraid the 6 speed/t-bird rear is going to push it out of that range.
Oh you're doing this, too?
What's your solution for clutch/flywheel/starter? F2T everything with a bent clutch fork?
Ranger50 wrote: So, I see it mentioned above, where does one find the 3.63 unicorn gear?
1st gen 626 or Aussie-spec NB Miata "SE." (Mazdaspeed Miata.)
In reply to 92CelicaHalfTrac:
Damn ninja edit didn't work, yeah we talked a bit about it at the challenge. Haven't gotten it all worked out yet. But yeah, F2T everything with a bent or "modified" clutch fork is prob going to be the answer.
Looking at roundy round multi-plate clutches and seeing about a lightweight flywheel to help it rev a bit. I understand the F2T isn't much of a high rpm screamer, but being able to acess the top end quicker isn't going to hurt my feelings. And it has enough low end grunt to not need a heavy flywheel in a car like the miata. The wife wants a pretty much stock miata, and I want something that will do what I want when I want. So working on finishing up the rebuild on our old car for her first. Then the F2T car will begin in earnest.
92CelicaHalfTrac wrote:Ranger50 wrote: So, I see it mentioned above, where does one find the 3.63 unicorn gear?1st gen 626 or Aussie-spec NB Miata "SE." (Mazdaspeed Miata.)
There are a couple of miata race shops that are selling them new, but they cost right at 500 or so. Try and snag one off of miata-turbo as they come up there every couple of weeks or so.
Spinout007 wrote: In reply to 92CelicaHalfTrac: Damn ninja edit didn't work, yeah we talked a bit about it at the challenge. Haven't gotten it all worked out yet. But yeah, F2T everything with a bent or "modified" clutch fork is prob going to be the answer. Looking at roundy round multi-plate clutches and seeing about a lightweight flywheel to help it rev a bit. I understand the F2T isn't much of a high rpm screamer, but being able to acess the top end quicker isn't going to hurt my feelings. And it has enough low end grunt to not need a heavy flywheel in a car like the miata. The wife wants a pretty much stock miata, and I want something that will do what I want when I want. So working on finishing up the rebuild on our old car for her first. Then the F2T car will begin in earnest.
Ohhhh... i remember talking about this with you now...
You'll probably get to the assembly stage before i will, so i'll definitely be watching with interest. 
I think the multi-plate clutch might be overkill... My car seems to rev slow compared to others that i've driven. (Response-wise, that is. It revs just fine under full boost.) Dan's MX3 was downright responsive, felt a LOT like a BP to me.
There's a few other things you can do to open up the top end a bit without getting drastic with a pain-in-the-ass clutch. Would DEFINITELY do a lightweight flywheel, though.
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