Prodigy's How-to Rebuild Your Transmission (G15M-R)


G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
Tools needed:
-new razor blade
-1-2 cans of brake cleaner
-safety goggles
-3/16 steel punch
-Red Locktite
-Ultra Gray RTV
-10mm, 12mm, 14mm, 32mm sockets
-inch lbs. torque wrench
-foot lbs. torque wrench
  • Remove ALL RTV with a razor
    -Clean bellhousing and outer transfer case housing with brake cleaner (use safety goggles!)
    -Allow time to let housings dry

  • Replace differential

  • Replace steel ball, spring, knuckle edged piece (with the roll pin hole side up)

  • Align shift forks
  • Combine shift forks with gear sets (out of transmission)

  • Set the gear set assembly into position
    Note : Do NOT break the plastic oil funnel!
    -Wiggle the differential to allow the gears to slide into place.
    -Insert steel punch into roll pin hole

  • Insert reverse gear, then reverse gear shaft
    -Make sure that the arm is inside the grooved edge.

  • Insert reverse arm rod (dimpled side facing out)
    -Check shift fork alignment
    -Apply threadlock to bolts
    -Torque bolt to ___ ft. lbs.
    -Check reverse arm rod alignment

  • Remove steel punch and insert roll pin into the knuckle edged piece
  • Check shift fork alignment

  • Replace magnet

  • Make sure that the reverse gear shaft hole is facing outward

  • Replace oil channel on outer transfer case housing (10mm bolt - ___ ft. lbs.)
  • Apply RTV on the inside edge of all of the bolts (3/8 continuous bead)

  • Check shift fork alignment!
  • Replace outer transfer case housing
    -Apply threadlock to bolts
    -Finger tighten (15) 14mm bolts and let RTV cure (1 hour minimum)
    -Torque the (15) 14mm bolts to __ ft. lbs.

  • Replace:
    -Reverse gear shaft lock bolt
    -Ball + spring (reverse gear tensioner)
    -Shift fork shaft lock bolt
    -Reverse gear sensor (if removed)

  • Slide main shaft collar onto the main shaft
    -Replace fifth gear selector + fifth gear onto main and secondary shafts
    -Insert roll pin into the fifth gear selector
    -Apply threadlock to locking nuts
    -Torque locking nuts to 90-140 ft. lbs.
    -Using a punch, hammer the ring to lock the nuts onto the main and secondary shafts
    -Take extreme care to NOT break the black plastic oil channel!

  • Apply RTV to case
    -Replace fifth gear cover
    -Finger tighten (9) 10mm bolts
    -Torque to __ ft. lbs. after an hour
  • Press in new oil seals for the axles


G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
Note : This how-to is incomplete.
I'll resize the pics and get the torque specs when I have time.


G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
Glad it could help... I still haven't had enough time to get around to getting the torque specs.


Da Short Bus Drivr
'02 P5 Vivid Yellow
Glad it could help... I still haven't had enough time to get around to getting the torque specs.
your fired........(2thumbs)

dude....don't worry about the torque specs....people can get the manual and find that.....those pics alone are worth gold when doing it....let alone the non manual descriptions


El Duderino
2008 Mazda MX-5 5MT PRHT
Question: How much time and money would this cost if you only have say, the tools (like actual tools not the locktite and crap)? Because I am sure that my transmission is going bad. I'll send ya a PM for some advice since the thread I started about it didn't gain any traction.


4ever needin' work
Midnight P5 '02
This is really good! I have been looking at what I can do to beef up my tranny and now I have the pics to understand what goes on inside when I do the job!

Great thread prodigy!


G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
send me a msg with your email address - I have the Mazdaspeed rebuild pdf w/ torque specs


mazdaspeed protege
its the big gear looking thing to the right on the transmition with all the circular pieces on it.


520whp - 509wtq at 27 PSI
2003.5 Mazdaspeed Protege
I was wondering if any of you guys have the Rebuild PDF with all info, torque specs and how to reshim the transmission. Thanks..


520whp - 509wtq at 27 PSI
2003.5 Mazdaspeed Protege
I have a good friend of mine here in SPAIN that owns a Shop and he have the Mitchel on Demand5 Software where theres everything about the Mazdaspeed Protege Transmission. But my problem is theres so many sections that i dont know which to print.

So far this sections are the ones i have selected and i have printed out of couse choosing Previously the vehicle in this case the 2003 Mazdaspeed Protege.

1. OVERHAUL - F25M-R & G25M-R

But im still missing info most likely..

Im kind of lost what exactly i need to reinstall and adjust the transmission, i need to give the shop this info in order for them to replace my broken TBK 3rd gear for PAR 3rd gear replacement and i believe readjust and reshim or what ever its called to put everything back together to work propertly and not granade it self.

I know there were a PDF file floating around in this forum with the proper info but i just cant find s*** honestly any help with be highly appreciated.


G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
I put together a website to sell the parts needed for a 01-03.5 G15MR 2.0L Protege transmission.
I work for Mazmart so we should have the best prices available worldwide.
I can't provide part numbers to the public but I can insure the correct part if you send your VIN # with the order (there's countless revisions and VIN-splits depending when your car was manufactured).

Note : I'm still working 7 days a week so I barely have time to provide info.
The synchronizer part #'s have superseded to 2012 Mazda 3/6 parts. Those are the most up-to-date synchros that will work on this transmission.

The rebuild PDF can be found here :
It's copyrighted so it's for educational purposes only and is intended for personal use only.

You will need new bearings/races for the main shaft, secondary shaft, and differential + new synchros + updated 3rd gear shift fork (for 01-02 models) + new main and secondary lock nuts for a proper rebuild.
I highly recommend buying a new black plastic oil channel just in case you break the original one. Chances are you'll break it.
I should have a rebuild "kit" and all the other parts on the website after work on Monday hopefully.
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520whp - 509wtq at 27 PSI
2003.5 Mazdaspeed Protege
IM a little confused, I need Bearing and Race for Primary and Seconday, Lock nuts. I found the Lock Buts, but im a little confused to which are the primary and secondary bearings with races.. sorry for my ignorance. but which are those parts im looking for... also how do i make the order from here in SPAIN ???? i need these parts ASAP, i dont mind using UPS or Fedex i just need them badly. The Shop that is rebuilding my transmission already designed and built the Reinforcement according to them better than what PAR did to prevent case flexing and to preventing primary and secondary shafts to separate causing gears failure. But since both of my bearings have a hairline crack on them they cannot put everything together without replacing them...

* 17-629 (No.1) Lock Nut (Main shaft)
* 17-629 (No.2) Lock Nut (Secondary)

Now are these the bearings i need ???

* 17-290 Taper Bearing (w/ Race) $27.74 Will i need 2 of these or ??????????


* 17-180 (No. 2) Taper Bearing (No.1) $15.42
* 17-180 (No. 2) Bearing Race (No.1) $6.23

* 17-180 (No. 1) Taper Bearing (No. 1) $15.51 now here where is the bearing race # 2 ????

Im so confuse in here i just dont seem to find out exactly what are the bearings i need from this list...

Since you are the expert here Prodigy just list me what i need. A Professional shop is doing the rebuild i just wanna make sure to provide them everything need it since in this damn country you cant find anything. Will i need shims ?? even tho they have already installed my PAR gear and did the reinforment piece to prevent case flexing, the funnel is intanct should i replace as well the LSD bearing ??? will i need new seals like where the drive shafts go ??? sorry for these dumb questions im just new to this tranny world..
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G15M-R guru
'02 protege LX, (3, yes 3) '99 protege ES', '90 Miata, '89 240sx
Mazdaspeed2oo35, MSG sent.

Here's what is recommended for a rebuild.

price each | Qty needed
3.85 (1) Main shaft oil seal
5.84 (2) Axle oil seals (11.68 for both)
16.68 (1) Locking Nut (main shaft)
15.72 (1) Locking Nut (secondary)
34.58 (2) LSD bearings (69.16 for both)
21.65 (1) Lower Main shaft bearing
27.74 (1) Lower Secondary shaft bearing
15.51 (2) Upper shaft bearings (31.02 for both)

Oil pass channel (not needed but is VERY likely to break) +26.83
All (5) Synchros (May not be needed but it's a good time to replace) +180.00

(2) main/secondary shaft shims
(1) LSD shim

The shims may or may not be needed. (It depends on clearances when built).


So much to do...
2007 Mazda 3 GT Hatchback
Great write up! I'm looking at doing a G35M-R rebuild and every little bit of info helps :D