1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

The Miata 6 Speed Transmission into an FB Thread...

Old 12-03-06, 09:05 PM
  #26  
Administrator
Thread Starter
iTrader: (8)
 
mar3's Avatar
 
Join Date: Nov 1999
Location: So. Arlington, TX!!!
Posts: 12,838
Likes: 0
Liked 18 Times in 13 Posts
Originally posted by blazer1313

so as I gathered....in order to fit a miata 6 speed into a FB, you'll need to bring your FB transmission, the 6 speed straight to a tranny shop. There they can swap out the casings and input shafts.

It sounds WAY to complicated to avoid the tranny shop..trying to frankenstein a miata 6 speed, 5 speed, and your FB tranny if not just the rx8 tranny...
The solution is dependent on the input shaft spline and diameter of the Aisin AZ6 transmission, which is either the same or different than the FB clutch, depending on what part of the thread you read here, it seems. I didn't pursue this because the cost was escalating each time I figured out the next step and I had access to an $80 '84 transmission courtesy of 79+80+84rx7...but here's how it would've gone down if I was willing to spend 3X what I paid for the car in the first place...
  • Buy used Aisin AZ6 transmission for $950, shipped to your shop of choice...$1050 if you want a residential delivery.
  • Custom mounting plate fabrication, 1" plate....unknown price, guesstimating something in the neighborhood of $500.
  • Driveshaft shortened and balanced, $145.
  • Custom center console since the shifter position is going to be about 1 - 2" further back...price dependent on materials of choice.
Other than that, it's quite possible.

Since I have a spare transmission for Furious, I now know I'll never actually be trying this swap....
mar3 is offline  
Old 12-03-06, 09:33 PM
  #27  
Death to Infinite Scroll
 
peejay's Avatar
 
Join Date: May 2001
Location: Cleveland, Ohio, USA
Posts: 11,652
Liked 37 Times in 34 Posts
But still, $2k is a hell of a lot cheaper than a decent gearset for the 5-speed, if you consider the 6-speed to be a race 5-speed with a useless extralow gear.

I don't know of anybody who still makes gearsets for the smoothcase, but you can get decent-ratioed gears for the Turbo unit for about $5-7k.
peejay is offline  
Old 12-05-06, 12:45 PM
  #28  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,390
Likes: 0
Liked 107 Times in 97 Posts
Originally Posted by mar3
The solution is dependent on the input shaft spline and diameter of the Aisin AZ6 transmission, which is either the same or different than the FB clutch, depending on what part of the thread you read here, it seems. I didn't pursue this because the cost was escalating each time I figured out the next step and I had access to an $80 '84 transmission courtesy of 79+80+84rx7...but here's how it would've gone down if I was willing to spend 3X what I paid for the car in the first place...
  • Buy used Aisin AZ6 transmission for $950, shipped to your shop of choice...$1050 if you want a residential delivery.
  • Custom mounting plate fabrication, 1" plate....unknown price, guesstimating something in the neighborhood of $500.
  • Driveshaft shortened and balanced, $145.
  • Custom center console since the shifter position is going to be about 1 - 2" further back...price dependent on materials of choice.
Other than that, it's quite possible.

Since I have a spare transmission for Furious, I now know I'll never actually be trying this swap....
not sure if i posted it here or not, but mazda has 3 flavours of this transmission, and then another 6 speed box thats totally different.

the 06 miata has a 6 speed, based off of the P type transmission from the ford trucks, and since theres no rotary bellhousing, this ones a no go

y601: this is the 00-06 miata non turbo 6 speed
y602: this is the mazdaspeed miata trans, its got some hardened parts in it, but basically its not much different
y610: this is the rx8 trans.

the miata's use an NA clutch, the rx8 uses a turbo 2 clutch. the miata uses the NA output shaft, the rx8 uses a turbo style. the rx8 has a rotary bellhousing, which looks like will go onto a miata transsmission. the miata has a spot for a speed sensor/speedo drive, the rx8 does not.

the rx8 has the shifter location where the fd does, or 2" further forward than the 81-92 rx7 transmissions. i dont know about the miata.

if you have a miata, the 6speed except for 1 bolt with the 5 speeds.

the rx8 transmission uses a slightly different starter than a t2, one of the mounting bolts is/are different. also the rx8 uses a weirdo slave cylinder.

so if you're putting an rx8 trans into an fb heres your list of problems/fab items
1. you need a turbo clutch and flywheel
2. turbo style driveshaft
3. shifter moves!
4. you need to fab a trans mount, as the miata and rx8 use power plant frames
5. you no longer have a speedo drive...

miata trans into fb
1. you need the rx8 bellhousing, it looks like it works, but it might not
2. you need a turbo diameter clutch with non turbo clutch splines, i think RB has it
3. shifter might still move, i dunno
4. still need to fab up trans mount
j9fd3s is offline  
Old 12-05-06, 03:34 PM
  #29  
Administrator
Thread Starter
iTrader: (8)
 
mar3's Avatar
 
Join Date: Nov 1999
Location: So. Arlington, TX!!!
Posts: 12,838
Likes: 0
Liked 18 Times in 13 Posts
Forgot the trans mount fabrication, so add about $75 to the above total. With the plate, it won't matter what the bell housing pattern is, FB, RX7,8, etc...only the actual width of the housing. Since the Aisin AZ6 transmission was meant to bolt into the 10AE Miatas, the width shouldn't be that much different than the normal Miata transmission or floorpan mods would have had to be part of just the 10AE cars and not the whole car line, an unlikely mass production scenario.

The actual extra length of the Aisin AZ6 transmission input shaft is what makes the plate scenario feasible, it's just a matter of determining who's right on that dimension (shaft diameter and spline count...) and the same dimensions of the hole in the FB NA clutches...

Last edited by mar3; 12-05-06 at 03:45 PM.
mar3 is offline  
Old 12-05-06, 04:29 PM
  #30  
love the braaaap
 
85rotarypower's Avatar
 
Join Date: Jul 2003
Location: Bognor, Ontario
Posts: 3,771
Likes: 0
Liked 3 Times in 3 Posts
I really don't see the point of having a 6 speed in an FB. It will make the top end even lower than it already is as the Miata 6 speed has a higher top gear than ANY 5 speed mazda produced. 0.84 something compared to 0.81 as the highest on any 5 speed. You'd need a 3.7 gear in the rear end to compensate for the higher 6th gear ratio. Unless your engine is mostly stock or makes real crappy torque, its a pointless change IMO. A turbo engine would tear apart any mazda 6 speed anyway, and the gears would be too short for a turbo., making it only feasable on a NA engine.
85rotarypower is offline  
Old 12-05-06, 07:03 PM
  #31  
Administrator
Thread Starter
iTrader: (8)
 
mar3's Avatar
 
Join Date: Nov 1999
Location: So. Arlington, TX!!!
Posts: 12,838
Likes: 0
Liked 18 Times in 13 Posts
Then you don't see the point in having fun or having a sense of adventure...

Thanks for the input!!

mar3 is offline  
Old 12-05-06, 08:13 PM
  #32  
Death to Infinite Scroll
 
peejay's Avatar
 
Join Date: May 2001
Location: Cleveland, Ohio, USA
Posts: 11,652
Liked 37 Times in 34 Posts
Originally Posted by 85rotarypower
I really don't see the point of having a 6 speed in an FB. It will make the top end even lower than it already is as the Miata 6 speed has a higher top gear than ANY 5 speed mazda produced. 0.84 something compared to 0.81 as the highest on any 5 speed. You'd need a 3.7 gear in the rear end to compensate for the higher 6th gear ratio.
You have it backwards. It means 5th gear will be more useable instead of having to shift to 4th all of the time.

The .825 sucks with 3.91 gears. The .711 or whatever the FC is 5th gear sucks even with 4.78 gears, not just because it is way tall, but it's also a huuuuge drop from 4th, so on the highway you're either at redline, or at only 4k.

I found the video, but the nVidia card on this computer is being a bitch. When I try to grab the video from the camcorder, I get the sound but a blank green screen instead of video. It's from my car with the 4.78 gears and the FC transmission... speedo is pointing something like 100-110mph, tach is barely showing 4000. One'a these days I'll put a 1st-gen transmisson back in this car, I mean it.
peejay is offline  
Old 05-07-08, 02:59 PM
  #33  
Always entertaining
iTrader: (2)
 
swbtm's Avatar
 
Join Date: Mar 2008
Location: North Jersey
Posts: 663
Likes: 0
Liked 7 Times in 7 Posts
sorry to raise this from the dead... there are only a couple other threads about miata transmissions that i can find. I'm curious about swapping a 5 speed miata tranny' into my 83 gsl, the ones from the NA models, they are really cheap now. I'm getting a 12a aggresive sp built now, would these tranny's be able to hold up to our higher revving engines?

Also, a couple years after the fact... how have the swaps and altering the gearing worked out for everyone??

Thanks
swbtm is offline  
Old 04-23-10, 04:12 PM
  #34  
Banned. I got OWNED!!!
iTrader: (2)
 
Join Date: Oct 2004
Location: London, Ontario
Posts: 6,122
Likes: 0
Liked 0 Times in 0 Posts
so a couple of years later .... anyone get a 6 speed in yet
dj55b is offline  
Old 04-23-10, 08:02 PM
  #35  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,390
Likes: 0
Liked 107 Times in 97 Posts
Originally Posted by swbtm View Post
sorry to raise this from the dead... there are only a couple other threads about miata transmissions that i can find. I'm curious about swapping a 5 speed miata tranny' into my 83 gsl, the ones from the NA models, they are really cheap now. I'm getting a 12a aggresive sp built now, would these tranny's be able to hold up to our higher revving engines?

Also, a couple years after the fact... how have the swaps and altering the gearing worked out for everyone??

Thanks
http://www.mazdatrix.com/faq/miatainputshaft.htm

people put the miata GUTS in to the rx7 case all the time. the miata trans is probably stronger than the FB, gearing is better too
j9fd3s is offline  
Old 04-23-10, 08:12 PM
  #36  
Armchair engineer
iTrader: (2)
 
j9fd3s's Avatar
 
Join Date: Mar 2001
Location: http://www.k2rd.com
Posts: 24,390
Likes: 0
Liked 107 Times in 97 Posts
Originally Posted by dj55b View Post
so a couple of years later .... anyone get a 6 speed in yet
cue the crickets....

i think my rx8 trans is actually going into an rx3. the shifter lines up with the rx3 (or SA).

in an FB the shifter will be in the radio, unfortunately.
j9fd3s is offline  
Old 04-24-10, 01:18 AM
  #37  
Function > Form
5 Year Member
iTrader: (1)
 
Unevolved's Avatar
 
Join Date: Jun 2009
Location: College Station, TX
Posts: 330
Likes: 0
Liked 0 Times in 0 Posts
For what it's worth, some of my Spec Miata buddies are of the thought that the 6-speed transmissions aren't worth the hassle. Apparently they don't hold up well in a road racing environment. (Disclaimer: I know they're not spec-legal)
Unevolved is offline  
Old 04-24-10, 01:35 AM
  #38  
Banned. I got OWNED!!!
iTrader: (2)
 
Join Date: Oct 2004
Location: London, Ontario
Posts: 6,122
Likes: 0
Liked 0 Times in 0 Posts
Originally Posted by j9fd3s View Post
cue the crickets....

i think my rx8 trans is actually going into an rx3. the shifter lines up with the rx3 (or SA).

in an FB the shifter will be in the radio, unfortunately.
lol ... that could swing both ways though. I have seen many threads that people figure things out and then just completely forget about this site or their thread update.
dj55b is offline  
Old 04-18-15, 11:07 PM
  #39  
Can Post Only in New Member Section
 
Join Date: Apr 2015
Location: Boise I'd
Posts: 1
Likes: 0
Liked 0 Times in 0 Posts
Bellhousing

Originally Posted by Siraniko View Post
I have no experience with the 6 speed but the 5speed's or early miata's bell housing has different bolt pattern; therefore it wont fit. However, we did a transplant on a 1st gen tranny housing and shortened the input shaft. Btw, this tranny was in my bro's RX-2.
What is the little gap by the starter I have a 79 Mazda rx7 and I didn't notice it tell putting it all together. and it seems to lead straight into the transmission I was wondering if this is how it's supposed to be or if there is something that is supposed to be there to close the gap.
Zion is offline  
Old 04-19-15, 10:17 AM
  #40  
Lapping = Fapping
iTrader: (12)
 
Jeff20B's Avatar
 
Join Date: Aug 2001
Location: Near Seattle
Posts: 15,577
Liked 35 Times in 33 Posts
Yeah, a little rubber piece. They're usually long gone.
Jeff20B is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Mazda84GSLSE
Introduce yourself
13
04-27-18 07:35 PM
Enzo1944
New Member RX-7 Technical
2
09-06-15 08:57 AM


Thread Tools
Search this Thread
Quick Reply: The Miata 6 Speed Transmission into an FB Thread...


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: