RX-7 T-II trans brackets
 

I spent a lot of time searching and reading, and decided I am going to purse installing a RX-7 T-II transmission in my car, as I am going to turn any Miata trans to cheese. I found the adapter plate, and read several articles about installation. What I am curious of, does anyone make a trans mounting bracket/brace, or does anyone have the dimensions of a bracket/brace they have built? I have/am attempting to contact anyone that posted about doing an install, but am having little success.

I already know I can buy lots of cheap 5 and 6 speeds, but if I am going to have to replace one constantly, I feel like I need to go a different direction. KMiata BMW trans option is too expensive, although they do carry the PPF diff eliminator.

My expected build is over 400 on E85, so I really don't expect the factory gearboxes to hold on very long.

Thanks in advance!

If you have mechanical sympathy some people have drove years on 450hp and a 6 speed

I don't. That's the problem. I am being honest with myself. If I am going down the route I am going, why stop and have the most incredibly weak link in the chain still in the car. I already have an RX-7 non turbo LSD unit to go in the diff, seems that the RX-7 trans is the way to go too. I suppose I can do what I saw in the posts for this, and machine something myself, but I would have to get someone else to do the machining, and then weld them in, and I'm not exactly sure how to go about that, which is why if I could find someone that kept their specs for the brackets they made, or someone offered them...

Sigh.

How much do you plan to spend on the RX7 swap and what are these brackets you keep referring too with no pictures or link.

No "kit" exists. If you can't fab, this is not the option for you. The TII trans is also not going to be great for someone without mechanical empathy, it's much weaker than the bmw trans, with crap synchros, is old, shifts like crap, and the ratios aren't awesome.

If you can't fab AND think the Kmiata bmw trans is too much money, a 400whp BP is not for you.

TII tranny into Miata!! -- is probably the most comprehensive post I have found.

BTW -- I can fab, I just moved into a new place, and I don't have the facility to fab at this moment, but thank you you informative reply -- I figured it would take 2 or so posts to get that kind of response here (which is shame). What I was looking for is to see if someone might have gone down this path, and perhaps kept the specs for creating the trans mount.

As far as costs:
-- Adapter $450
-- Trans, rebuilt $750 or low miles
-- Driveshaft $500
-- Sell my new FM stage II clutch and buy a different clutch ($?? 250?)

I figured the cost of the Kmiata BMW trans:
-- $2300 for adapter
-- $1000 for the trans
-- $400 clutch

Again this is a nebulous number, I have it in a spreadsheet, I will go drill it further down.

^He's right.

But my friend of a friend who drifts a 240 knows a guy with a miata who said it would work

Sorry, i didn't mean to assume, i just took your prior posts at face value. :)

That parts list doesn't include a clutch or mounting solution. And even barring those two items, paints the "it just works and uses a muuuuuuuch cheaper AND better transmission" Kmiata kit as a great value.

IMO of course. If you're hellbent on using that trans, then carry on and document!

Sorry, I joined here in 09, and have always written posts, and then deleted them because of some reception to them.. I understand people need to search and read, I think I probably spend 6+ hours doing that on this subject (just searching and reading).

conceal ^^ You may actually be right, and I am trying to cheap out on something I probably shouldn't. Based on your comment, I am going to revisit the BMW solution as well. I have to be brutally honest, with myself -- I have never in my life been able to be "non abusive" in my treatment of cars. Considering the other parts I have, and re-reading my logic (hey I'm not always the smarted tech guy in the room) -- I think I just realized I am probably trying to (as said), "go cheap" maybe. From what I have read, and I read everything I could, the RX-7 solution was supposed to be more than enough to handle this kind of powertrain.

I, checked every source I could find:

https://www.beavismotorsport.com/gui...for-miata-mx5/ (more diff than trans)

^^^ post above, and searched hard on the topic.

Everywhere I found, it sounded like a really positive/possible combination, especially if I was going to put in a RX-7 diff. I would have to buy the PPF removal kit from Kmiata anyway. I am assuming you have way more experience in this subject matter than I do (I'm more of a muscle car guy -- and yeah, I have had a few Miatas) and I would hate getting a bad gear ratio, because that is one of the positives everyone (that I could search and find) talked about..

Sigh -- re-researching again. I know that the: carpassionchannel had a series of putting in the Kmiata BMW solution.. Honestly, If I want to side step the clutch, I don't want to immediately get a thunk sound.

The other expensive option, would be to put in Quaife gearset.

My BMW KMiata swap shifts like a bolt-action rifle, and so does Tony Montana's. Those are the only two I have experienced.

Quaife is not a solution. FM dropped them because they ended up not being that much stronger and definitely not worth the cost. There are a few people on here that have broken them over the years.

BMW trans swap is really the answer and it is expensive. If there was a cheaper easier option we would all already be doing it.

My friend has a Z4 with the 6 speed. Only manual that I have driven that feels as good as the Miata 5 speeds. Clutch is a little wonky feeling cause it has the assist spring on the peddle though.

Ok -- this kinda of input is what I was looking for... Most people here have more experience at this than me at this kind of choices. I thought I had gone down a reasonable solution, and, based on response -- it was not the right solution, great (I'm guessing negative Cats? == bad).

Anyway, I am going to hijack my own thread, since I have already put it out there... With the BMW option, you can select from the ZF, or Getrag (which is suppose to have a wider gear ratio -- which as a Miata owner would love) options. Comments on which is more appropriate, or that you have liked?

Second -- is going the RX-7 LSD complete swap the right way to go, in your experience? I can buy a gusseted/braced 1.8 diff housing and use that, then I found out the RX-7 diff unit was a swap in with the Miata bushings. This seems like a good route (then I was ^^ wrong before) for the money. Comments?

Approximate prices (labor aside):

Trans --

BMW:
BMW Kmiata swap kit: $2600 (included driveshaft << plus, plus hydraulics << plus)
BMW trans: $550 - 700 (based on ZF or Getrag -- ebay)
BMW ACT clutch: $700
PPF delete: $300
Misc: $150

Total: $4450 ish

RX-7:
Adapter plate: $450
Fab trans mount: ?? $400 (guess here - labor mostly)
Driveshaft (custom): $500
Trans: $700 (ebay)
PPF delete: $300
Clutch: $500
Misc: $150

Total: $3000 ish

Costs for diff --

1.8 diff LSD (own):
Gusseted diff casing: $165
Misc: $150

RX-7 LSD:
Complete diff: $500
Bushings: $50
Misc: $150

Not sure about prices in your area but i fount ZF trans close to me for 300.

If it was me i would do the BMW ZF trans with either a getreg diff setup from them or a miata diff with a os giken. Just my :2cents:

I'm sure your right -- I didn't get much of a hit in my area, so I used EBay prices as a starting point.

(Actually see one locally for $400)

I'm using a stock 530i clutch.

Check car-part.com for transmissions too. We've never paid more than $300 for a ZF 5-speed or Getrag 260, and have never paid more then $500 for a ZF 6-speed. And those prices have always included delivery to our shop.

Yup, our kit isn't super cheap, but a transmission swap like this has a lot of components that tend to add up fast, especially when done right. Most of our customers just want a big box of all necessary parts that are made to work together. However, you can also order the adapter and flywheel separately and then come up with the rest yourself as you would with any other one-off solution.

Learn how to avoid beating on your car: $FREE

Oem trans isn't something he can trust long term with his power goals no matter how nice a guy he is.