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Discussion Starter #1
So, last July is last anybody posted on the Miata drivetrain swap. Anybody ever make any progress? I'm starting to get into mine, picked up a complete rat that a tree fell on, then somebody chopped the roof off. This one will be my guinea pig, if it works, I'll go after my nicer one. One of the hard parts is the length from front pulley to shifter, but I can cut the shift turret off (already have) and move the shifter forward close to five inches. That will help with the additional 10", so the engine won't have to go so far forward. Still worried about the hump over the timing belt up front for height.
So, anybody else ever make theirs run?
 

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Detritus Maximus
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I know the RX7 had many configurations for the transmissions as far as shifter placement, including some interchanges with the old Cosmo, rotary pickup, and the 70's RX 100/2/3/4. I can't recall offhand if the RX7 and Miata trans are swappable.
 

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Non Civilian
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As far as I can tell you will be the first. Make sure to take lots of pics of the process. I am looking into this swap myself.
 

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I know the RX7 had many configurations for the transmissions as far as shifter placement, including some interchanges with the old Cosmo, rotary pickup, and the 70's RX 100/2/3/4. I can't recall offhand if the RX7 and Miata trans are swappable.
Doesn't look like it, I have the Miata drivetrain in the shop along with a rotary bell housing and they are very different bolt patterns.

If you were willing to go with an auto trans behind that Miata engine you might have a pretty easy swap on your hands, though. After swinging the Miata drivetrain into my own GT I decided it might just be easier to graft the nose and tail from a GT onto a Miata and build myself a convertible GT clone that way.
 

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boomerang opeler
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what are the side by side's for the miata and gt ? are the close enough to do a body swop onto the miata floor pan ? if so it can save a lot of work
when i was going to d frankenopel it worked out far easier to take the jag body off the floor and the floor out of the gt and mate them that way !!
 

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Detritus Maximus
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This is something I found on a Mazda truck site:

Modifying Mazda Transmissions


"It is well known amongst the Miata racing teams that many Mazda 5 speed transmissions can be modified using parts from other Mazda transmissions. This is because all 5 speed transmissions mazda made before 93 are made the same way, the only differences comes from slight design improvements in the newer model transmissions. Some transmissions after 93 might work as well but I have not examined any to know for sure.

Solomiata references 3 types of Mazda 5 speeds.

Type I is the really early style transmission used in the RX-2, RX- 3, and RX-4. These where known to be pretty stout transmissions that the later Type IIIs where modeled after.
The Type II also known as the Model M trannies is what is used in the B2200/B2000. The model tranny in my 91 B2200 is a M519. These trannies where only used in naturally aspired (non-supercharged) cars. These cars include RWD 626, 79-85 RX-7, 86-91 NA RX-7, B2000/2200 truck, and Miata. The main difference in these transmissions are the gearing, bell housing and tailshaft, making these the key interchange parts. The bell housing is basically an adapter to whatever block you are using. It is stated that input and output shaft lengths may very .5" between some model trannies so be cautious which tranny you select.
Type III or Model R trannies are used in the turbo vehicles. These transmissions are based off the Type I transmissions and have a better synchronizer design and beefier output shafts. Output shaft diameter was increased from 15/16" up to 1" I have not seen parts from these to know if the synchronizers are interchangable with Type II trannies. These trannies where used in the turbo RX-7's, 929, B2600, and MPV."




This may mean that you can use a Miata bellhousing and earlier trans/shifter setups.
 

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Discussion Starter #7 (Edited)
I'm not that worried about the trans, the shifter will move easily. Well, easily with a Tig welder :) The "cut the body off a Miata and graft the Opel onto the floorpan" idea is intriguing. I just *happen* to have a '99 Miata roller with a throw-away body. It's amazing just how little these GTs are, they make a Miata look big! Thinking about it, I'd probably have to narrow the miata pan.
PS. Not sure what Randy is talking about with the bellhousings. Only the automatic has a removable bellhousing. The bellhousing is integrated into the main gear case on the sticks.
 

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Detritus Maximus
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Well, as I recall the advantage is that you can mix and match the various bellhousings, transmissions, and turrets they made over the years and get the gears/shifter placement you want.

But I think I see the problem...your 99 Miata trans may be a different type. The list above does say that it works thru '93, but not about anything after that.
 

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Discussion Starter #9
What I'm saying is you can't mix bellhousings, they are part of the trans case itself. I can see tailhousings being swappable, but you can't take the bellhousing itself off a miata stick trans, five speed or six speed, 1990-2005. Trust me on this. I have at least a dozen in the shop.
Physically all years from 90-05 swap, even five and six speed, although only two of three starter bolt holes will line up due to a starter change in '99 if you swap from early body to late body and keep the original starter.
The automagics are removable bellhousing. But either way, cutting and welding the turret will get that end fixed. I need to drop out the existing drivetrain and see where things land.
 

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Discussion Starter #11
Glad you like the FMII, I wouldn't leave home without one. Well, unless it was an LSx powered Miata like Elvis. Another day wasted? cleaning the home garage while the Mopel project waits up at the shop....Happy New Year everybody!
 

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Discussion Starter #12
Oops. Just noticed your second link. Yup, that's the shot out my office window at the rat choptop GT, with our turbo Westfield in the background. Now there's some fun for you.
 

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I don't know if I mentioned this before, but good old Hot Rod Mag once showed a pretty cool way to give a junk Miata a new life. A company makes a complete body kit for it. Comes out looking like a 68 Mustang convertible, but kind of smaller. Probably a simpler project than breeding a GT with a Miata. Maybe if you Google "mustang miata" it would pop up.
 

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Discussion Starter #14
Yeah, there are quite a few body kits for the Miata. Ones I'm aware of: 65 mustang, aston martin, cobra, z3, probably more. And of course the Se7ens, but those don't use the Miata body or chassis at all. But, I don't want a Miata mustang, I want a GT! If I were to do any of the body kits, it would be the Cobra, but then I'd only do that on an LS engined Miata. Couldn't psychologically deal with a four cylinder sound track on a Cobra. See here for LS engine Miata: Flyin' Miata : Projects: The V8 Miata Project
I will try to do the same type of build diary for the "MOPEL"
I went through the sr20 build (at least one of them) but couldn't find reference anywhere to distance from front of crank pulley to shifter. Anybody have that dimension?
 

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Opeler
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Yeah, there are quite a few body kits for the Miata. Ones I'm aware of: 65 mustang, aston martin, cobra, z3, probably more. And of course the Se7ens, but those don't use the Miata body or chassis at all. But, I don't want a Miata mustang, I want a GT! If I were to do any of the body kits, it would be the Cobra, but then I'd only do that on an LS engined Miata. Couldn't psychologically deal with a four cylinder sound track on a Cobra. See here for LS engine Miata: Flyin' Miata : Projects: The V8 Miata Project
I will try to do the same type of build diary for the "MOPEL"
I went through the sr20 build (at least one of them) but couldn't find reference anywhere to distance from front of crank pulley to shifter. Anybody have that dimension?
my friend has an sr in a s13 i can try to get that measurement this weekend. just front pulley to shifter? I know the sr going to come out longer but i don't know how much longer. i have see the blocks sitting right next to each other and i know the sr is bigger block wise. i might even have a picture of a sr and miata block sitting side by side.
 

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Opeler
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just spoke with my step dad and he lost the pictures when he had a harddrive crash on his computer but he did remember the miata bare block was 1.5" shorter than the sr bare block and about 10lbs heavier(miata). i should have a measurement on saturday for the pulley to shifter length.
 

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Opeler
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i got the measurement for the sr20 pulley to shifter. its not exactly accurate as the engine was installed. but to get you within an inch or so it looks to be 57" pulley to shifter.
 

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What I'm saying is you can't mix bellhousings, they are part of the trans case itself. I can see tailhousings being swappable, but you can't take the bellhousing itself off a miata stick trans, five speed or six speed, 1990-2005. Trust me on this. I have at least a dozen in the shop.
Then obviously you have not taken one appart since I have a Miata transmission mounted to my B2200 engine. All I had to do was remove the bell housing, tail housing, and shifter feet off the miata transmission and put my pickup truck counterparts right on. This is the second one I have swapped into this truck, the first one was a 1st gen RX-7 tranny that swapped the same way. Several people on my forum and the RX7club have also done different engine and transmission mix and matches. If you guys are having problems with shifter location, the tail housing and shifter feet from the B2200 or B2000 will move the shifter forward by a few inches.

Kyrasis6
Owner of Mazdatruckin.com
 
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