Well, my 3rg gear is broken after some heavy track abuse with a 400+ rwhp car. I was thinking maybe I could try rebuilding it myself. I work from home so I have tons of free time to learn and tinker. Is there any guide on rebuilding our transmissions? Like how to disassemble it, see what needs to be replaced and what to buy etc? I did some searching but haven't been able to find anything yet. Any help would be greatly appreciated.

Also, do JDM trannies bolt right up like USDM? Yes, I know they have a shorter 5th gear, but that is actually preferred since I road race. Just wondering if they are differen't from USDM so that they have to be modified to fit/work etc.

thewird

 

www.davidgeesaman.com. I have a full transmission writeup.

The JDMs are nearly identical. Some later model years have only a single synchro on 1st and 3rd while the USDMs have a double cone synchro on 1st through 3rd. I don't know which years and models but they're out there.

The challenge here is that 3rd is deep within the tranny and you'll destroy all of the ball bearings as you remove them. So at a minimum you'll need a new 3rd and countershaft plus all the ball bearings. If you buy the bearing kit buy it from Rockland Standard Gear or another aftermarket shop to save money. (It's usually the same bearings mazda gives you but with less markup). You'll also need to cobble together some special pullers that aren't really complicated but I haven't found an affordable off-the-shelf solution for a couple of them.

All in all, a low mileage JDM transmission from a reputable parts importer is actually a good deal.

 

Oh awesome, thanks! Maybe I'll buy a JDM one locally ($190 CAD I just found!) from an importer, they have a ton of them. And hope for the best. In the meantime I can pull my busted tranny apart and see if I can have any luck rebuilding it.

BTW, where would one buy the JDM short 5th gear without buying a JDM tranny?

thewird

 

If you can get to the importer in person, I urge you to bring a flashlight and 12mm wrench (electric impact is ideal) and remove the lower plate to the main gear housing. Inspect all of the synchros, shifter teeth, and gear teeth in the main gear casing. Buy the one that looks absolutely brand new inside.

Dave

 

rhdjapan.com can get the 5th gear. freeking expensive though. i was going to rebuild mine but ended up buying a JDM tranny. slapped right in.