Official Transmission Swap Information (Update 21/05/2010)

[Ryan]

Guys, PM me with all of your ABSOUTELY FOR SURE knowledge, and I'll try to make it into something pretty, readable, and helpful!

Mazda Transmissions in the 90's.

Mazda made two series of transmissions that we use in our MX's. MX-3, MX-6, 626, Miatas, Escort GT, Capri's, 323's, protege's, Tracer LTS, and anything else that uses a Mazda B or K and some F series motors. All use either and F or G series transmission (I'll include the years when I know for sure)

They coded them like this

G25M-R

G2 - G type, 2.
5 - 5 speed, plus reverse.
M - Manual. You move the stick.
R - Remote. You move the stick from inside the cabin.

Switching between the generations of each transmission also happened somewhere between 92 and 94. It doesn't really make a difference, though. All I've noticed is that they synchronized the reverse gears in the 2nd gens.


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OVERVIEW
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Please know what engine you have, and what engine possibilities there are before you read this, or you'll just confuse yourself.

Also, this is juts for 5 speed boxes. The auto boxes aren't worth my time, because they suck. If yours is dead, fix/replace it and install a good cooler, and it should last longer next time.

All the 4 banger B series Mazda engines EXCEPT the DOHC BP came with an F series gearbox. The axles are thinner, they don't feature a halfshaft, and the bellhousings are only made for the 4 cylinders, which all interchange. Yup. Any B series 4 banger from the 1.3L in Europe, the the 1.8L B8 have the same transmission bell housing, that is, THEY ALL INTERCHANGE.

As far as I can tell, all the Mazda F series 4 bangers came with a G box. 4 cyl MX-6/626/Probe as well as 8th gen protege use 2.0 FS motors...

The BP came mated to a G series transmission with a 4 cylinder bell housing. This uses the same internals as the v6 G series gearboxes, but the bell housings are obviously different between 4 cyl and V6. In theory, the internals should interchange no problem. Same shaft diameters. Axles were thicker, and all G series transmissions use a halfshaft for the passenger side axle. I don't know if you can interchange V6 axles and 4 banger G series axles, but I would not be surprised if you can, if the track width is the same between the vehicles, is the question.

However, note that the MX-3 is a unique chassis and has a different track width than all the other cars, so our axles are unique to us. However, axles have a little bit of play, so finding sister axles that don't bind isn't impossible. I have read that Escort and Protege axles do not bind in MX-3's.

All V6's came with a G series gearbox, and they all interchange.

Now, there are a few potential problems to run into, swapping transmissions around.

-The 4 cyl boxes, F and G, use both digital and cable driven speedometers. As far as I can tell, 92/93 boxes were cable, and 94+ were digital. There are two different types of gears, one with a longer neck, and one with a shorter neck, and I believe the long one is the F series, and the short is the G, and you can get the G box in cable or digital.

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4 cylinder
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B6-ME & B6-DE / F(2)5M-R

Gear Ratios (Input:Output)
1st 3.416:1
2nd 1.842:1
3rd 1.290:1
4th 0.918:1
5th 0.731:1
Final Drive 4.105:1


B8 (1.8 SOHC) / F(2)5M-R

Gear Ratios (Input:Output)
1st 3.416:1
2nd 1.842:1
3rd 1.290:1
4th 0.918:1
5th 0.731:1
Final Drive 3.619:1

Note that these engines came in the hatch (B6) and the 4 door sedan(B8) Mazda 323. The only difference is the FD ratio. The sedan trans offers lower cruising speeds and longer gears.


BP (1.8 DOHC) / G(2)5M-R

Gear Ratios (Input:Output)
1st 3.307:1
2nd 1.833:1
3rd 1.310:1
4th 1.030:1
5th 0.795:1
Final Drive 4.105:1

This engine only came in the 'performance' Protege (GT or LX, depending where you live), Escort GT,Tracer LTS, and all the other BP cars. It is a G series trans, and the only G case I know of that fits on B engines. It offers closer, shorter gears for acceleration.



The Kia Sephia transmission

Gear Ratios (Input:Output)
1st 3.307:1
2nd 1.833:1
3rd 1.310:1
4th 1.030:1
5th 0.795:1
Final Drive 4.105:1

Uses 28 spline axles (K series are 28 as well), beefier diff, and the Quaiffe and MSP LSD fits with a little modification.


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6 cylinder
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MX-3 (K8) & Probe GT (KLDE) / G(5)M-R

Gear Ratios (Input:Output)
1st 3.307:1
2nd 1.833:1
3rd 1.310:1
4th 1.030:1
5th 0.795:1
Final Drive 4.388:1

Short acceleration gears. There is some controversy over some of the later model PGT's getting a 4.105 FD. Ford is retarded and can't tell me the ratios, so I guess you'll have to keep pulling them apart and counting teeth. For now, if I were you, I'd assume they all have the 4.388 FD. Its much more likely that previous owners swapped in the MX-6 trans for the longer gears, than Ford put them in there OEM without someone finding that out for sure.


MX-6 (KL-DE) & 626 (KL-DE) / G(5)M-R

Gear Ratios (Input:Output)
1st 3.307:1
2nd 1.833:1
3rd 1.310:1
4th 1.030:1
5th 0.795:1
Final Drive 4.105:1

Same as the MX-3 GS (K8) transmission, just longer gears from the FD ratio.


MX-6 (FS) & 626 (FS) / G(2)5M-R

Gear Ratios (Input:Output)
1st 3.307:1
2nd 1.833:1
3rd 1.233:1
4th 0.914:1
5th 0.717:1
Final Drive 4.105:1

Different 3, 4, 5 from the KL box. Further spaced gears. This is a 4 cyl box, remember.
Also, http://homepage.ntlworld.com/mx6-uk/mai ... #transspec" onclick="window.open(this.href);return false; says that the FS came with a 3.850 FD. Nothing in the Mazda manuals ever showed this... I'd assume its incorrect.



Collected from people:

The one you're looking for is either the 626 or Mx-6 tranny's. They have a longer final drive ratio (4.11:1 rather than 4.38:1) as well as a longer 5th gear.

Hello, just to finish the thread, I can confirm that 1.6 DOHC automatic transmission fits the 1.5 dohc engine found in az-3. The car is fully operational, easy swap. The only thing different is the speed sensor but you can use the old one on the 1.6 as well. I hope someone finds this helpful

Subject: Official Transmission Swap Information

Ryan,

Just an FYI, when I swapped in the MTX, I had to get a new drivers side axle (most already knew this). However, the passenger side axle from the ATX seems to be too short for the MTX. I tested this by installing the axle into the hub and screwed the nut on hand tight. Then, I tried putting the intermediate shaft side into the tranny and the mounting holes for the shaft bracket wouldn't line up by about 3/4 of an inch or so. I could only get one bolt in to the block but then the shaft was then pulled out of the tranny by about 3/4 of an inch. I had to go to work afterwards but I plan to investigate this further. If I take the CV axle out of the hub and can get everything else to line up, I can check to see how far off it is from the hub itself.

Basically, it's looking like one would have to buy the DS and PS cv axles for a MTX if they were converting from the ATX. I also measured the intermediate shaft from the PGT and the MX3 and they are the same.

Hope this info helps your FAQ!

I will follow up with you to let you know how I make out with the PS axle.

Brian

HI, Ryan. I've been doing research to find the tallest gearsets possible, and found some info that you can add;
The secondary shafts are different lengths between the G-series generations.
A 97+ 2.0 SOHC lx/se ford escort has this gearset:

3.31 1st
1.83 2nd
1.23 3rd
.91 4th
.717 5th
3.85 final

It is a second gen G-series

well the actual length of the speedo gears are different. the F series gear is about 1/2 inch to an inch longer. Other then that they are the same, but it's that difference that makes them unuseable

the tooth count/pitch and all that is right, but when I temp. used the gear in the transmission, it was fine in the transmission, my speedo read (though a bit off), and it was fine in there. But the actual gear is still a bit longer and i had to make a blocking plate to raise the gear up a bit so that it hit fine on the drive in the transmission. pretty much the only differences are in length, the f series being a longer gear

The escort axles are doing great. no pulling or binding.

Things on my MX3 from the escort:
Engine
Tranny
Driveshafts
ECU
Wiring harness

5th gear swap guide, thanks to nerd racing!
F Series 5th Gear Swap


K8 transmission speedometer gear info:

outer face of trans to end of gear (teeth edge) = 50mm

Diameter of hole in transmission = 28mm

outer diameter of gear 25.5mm

# of teeth = 21

2 wire pigtail.

Alright, I just discovered that the wiring in the ATX engine harness is not identical to the MTX harness.

#1, there is no neutral switch connector. You must ground one side of the switch, and run the other to the same wire that the clutch switch is, that is a brown/yellow wire that should feed into pin 1R, the same wire that runs to the clutch switch

In the ATX harness, pin 1R(22 pin plug, bot row, 3rd from left) is currently filled with a pink wire that ran to the TCM and up into the dash, through the black plug called X05. If you have a manual dash harness, these pins won't match up (pink wire goes into nothing in the dash, and brown/yellow from clutch feeds into nothing in ECM)

Just make it so the one leg of your clutch switch (not starter interlock) and one leg of your neutral switch both make it into 1R. ground the other legs.

B6T transmission VS KL Probe/MX-3 transmission

http://www.mx-3.com/phpBB3/viewtopic.php?f=30&t=78191

[npspears]

Very cool write up, thanks for taking the time to do this Ryan. If you look on the online manuals, the transmission for the 95 4 cylinder is the F25M-R. I'm pretty sure the 94 also came with this tranny but I'm not positive because when I was cleaning the tranny the numbers came off. I'd say I'm about 90% sure the 94 is an F25M-R.

[Daninski]

I'll check my 96 Junkyard Dawg.

[Ryan]

Thanks guys, I need as many replies and as much input as possible!! Sunday morning, this thing is getting some work

[Ryan]

Okay, so going is really slow... apologies... I hate working through summer... Why can't I just fool around like all my friends? Why must I work 50 hours/week and not be home all week? Sigh.

The manuals section on this site is awesome. Takes forever to load on my dinosaur, but it will be my main reference...

[Ryan]

Updated, can someone please be kind and answer some of the questions?

[Ryan]

bumping this. Anyone with info? are SOHC and DOHC trannies interchangeable? aka is a 92 tranny compatable in a 94 car? or vice versa?

someone please make a blurb on the K series trannies? I have no clue, I'm a four banger guy...

[mx3boyze]

Not sure of any ratios or anything but the MX-3 GS (K8) Tranny and the Ford Probe GT (KLDE) Tranny are the same.

[Savin]

bumping this.

Uhh....isn't it kind of hard to bump a sticky? lol I mean its already at the top of the section

Literal meanings aside, I know what you meant. Bumping it up in the 'new posts' area
Just so you know, if I knew anything about the k-series stuff, I'd tell you. But that invovles thinking on my part. I'll do a bit of searching for ya though.

[Ryan]

thanks to mx3boyz for his contribution, the interchangeability of the trannies between OBDI MX-3 GS and Probe GT.

[nerd racing]

So now lets see a write up on a G-series swap into an RS with a BP.

[Ryan]

Someone may be able to do that eventually using this info but not yet!

Read for the huge quote in the middle, I believe its a breakthrough for this community!

If I take quotes from probetalk, is there a legal or polite way of doing it or something? should I make an accnt just so I can ask to quote them on here?

[Rachelle]

so what tranny would i need for a klze 5 speed???

[Ryan]

The stock MX3 one works just fine.

[wytbishop]

I've never read this thread Ryan, it's great. I do have issue with one thing you wrote.

"If I say OBDI or OBDII I am refering to the On Board Diagnostic System, which is related to the year of the car, and the sub-generation of the vehicles. An OBDI Mx-3 RS is a SOHC 4 cyl with a F5M-R, and an OBDII MX-3 RS is a DOHC 4 cyl with the F25M-R. This crossover happened somewhere between 93 and 94.
OBDI means 93 or earlier
OBDII means 94 or later"

I don't think this is accurate. The change to OBD2 was made mandatory for the 96' model year. Mazda began producing OBD2 cars in mid 1995. I had an ODB2 95' RS and have had the argument many times that 95' was an OBD1 year and predominantly it was I think. I believe all 94's are OBD1 and only some 95's.

I can't confirm that, but I know many many people have told me that my 95' RS could not have been OBD2...but it was.