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Rebuilding 12A Trans
Has anyone tried rebuilding one of these transmissions? I have a transmission I want to use that broke a 3rd gear synchro I think. As far as I can tell and going by the book, I've got to take everything off starting from the drive shaft side taking apart the entire thing in order to get to it. Right now I'm stuck with a large lock nut on the main shaft that you need a 1 1/2 foot deep socket to get out. I looked on mazdamotorsports.com and couldn't find it. If anyone has delt with these things, how did you get that thing off? Unless there's a way to get at the sychros from the other side, but as far as I can tell you'd have to take out both shafts at the same time, and that's not happening unless this lock nut comes off.
The lock nut I believe is holding in 5th gear and is in the 5th gear casing of the transmission. Has my do it yourself strategy hit a road block?
Thanks
Ben
#33 IT7
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You'll need that socket and real long gear puller. Seems there was a thread on this not too long ago. Buy a socket that fits, cut the ceter out of it so that it slides over the shaft. Weld a length of tube to it and fab a 1/2" square hole to mount it to your favorite impact. For the gear puller just use some thick flat stock to make the jaws.
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Chris Ludwig
08 ITS RX7 CenDiv
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Ben:
Just double clutch. You won't need the synchro then!! 
Plus, it'll make it that much easier for me to get around you!!
Seriously, though, if there's anything I can do to help, give me a call. I have access to things others dream about at work...
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Bill
Planet 6 Racing
bill (at) planet6racing (dot) com
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Well in the book it says that you are suppose to put new nuts on when you put it back together, so you could use a chisel to get it off (hack way) I did close to what Chris did. I made the tool ten years ago and have used it many times.
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Economics question to those that have dealt with the 1st gen transmission. If a person has an extra transmission ($150) presumed good available is the economics in repairing the trans or replacing the trans ?
Question two: When the 4th (IIRC 4th & not 3rd in my case) gear synchro goes I found the synchro teeth worn ragged, the syncro cracked in two pieces (still in place) & the actual gear worn ragged.
What is the order of failure ?
The synchro wear ?
The synchro crack ?
The gear wear ?
Thanks
David
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Can a hacksaw cut through a socket? Pretty tough material.
And Mister Bill, when I had a stick shift to drive everyday I practiced both kinds of shifting heel toe style like a good practicing race car driver should. Have you got that heel toe stuff down yet? Otherwise I'll just pass you when you lock up the breaks letting out the clutch.
BOOYA!!!
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P-shaw! That's the beauty of front wheel drive! It's just like hitting the brakes really hard!
Actually, I've worked most of the winter on heel-toe. Problem is, it's been mostly with winter-style shoes on. I need to go practice with my driving shoes now that it is warming up...
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Bill
Planet 6 Racing
bill (at) planet6racing (dot) com
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Any idea what size this socket is? I measure the nut as being about 1 5/8 inch across although I'm guessing it's metric.
Thanks.
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Ben, 1mm = .03937"inch therefore 1.625 /.03937 = 41mm Remember the 1 5/8 (across flats) inch is your number.
Have Fun
David
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Man, I hope that's right. I'd hate to buy a socket, chop it and have it not fit. Anyone else know what size this puppy is?
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***Man, I hope that's right.***
Thanks Ben
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Just use an 1 5/8". Sometimes Sears doesn't stock the big metrics so it may be easier to find and has worked just fine for me. I normally hate using english "equivalents" because of my line of work and seeing that they really aren't the same. But for anything over 1" in size the english sockets seem to work just fine.
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Chris Ludwig
08 ITS RX7 CenDiv
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Sorry David. I was doubting my measuring skills more than your incredible knowledge. 
-- 1 hour later --
For the fun of it I tried a chisel on that nut out of pure frustration. Now I have a dented chisel. Nothing a beer won't cure!
-- 5 minutes later --
um... the beer didn't work either. I feel better though! Maybe it takes two!
Ben.
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Those of you who have done rebuilds
What tools did you end up having to buy from Mazda, and what tools did you end up making/fabricating or simply finding something off the shelf?
PaulC
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And what is your parts list for a minimal rebuild?
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Marty Doane
ITS RX7 #13
CenDiv WMR
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I guess mine is just a little different since I'm taking a junk transmission and putting some of the parts into a new one. So far the tools I've bought are a drift set for hammering out those little pins, a pair of snap ring pliers and one other set of pliers that I can't remember the actual name for. They're used for taking out those washer looking rings. Those are darn handy. Also a dead blow hammer.
Tools that I need to make are that giant socket we've been talking about. I think that's it for tools!
Oh, you need a bearing puller, and a LONG one at that. I bought a normal bearing puller then got some metal stock from menards and created longer arms for the puller so now it's like 2 feet long. Works pretty crazy, but it does work.
I haven't started putting it together yet, but I know one thing that will need replacing, and that's this nut that I'm dealing with. It has a tab that gets hammered down into a slot so it doesn't spin. It's garbage once taken off.
Other than that maybe some snap rings, anything else you break in frustration, and the beer bottles that got emptied.
How's that! As far as what needs replacing in a "real" rebuild I would like to hear as well.
Ben.
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I solved my tranny rebuild the easy way. I went to one of the local Mazda dealers, whose decals I run on the car, small decals, and had them rebuild it. About $800.00 CDN.
It was just easier, and I know it's right.
Probably more expensive than doing it myself, but the thought of doing the tranny is just too hellish to contemplate.
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G. Brooke Carter
Wheat Buckley Racing
# 10 Challenge Car
2003 Class Champion
Calgary, Alberta
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I would do that except I'm already on my first rebuilt tranny, and it's dying after 2 seasons, and I've already lost one race because I couldn't get it into gear. So I want a fresh rebuild, and a spare rebuilt ready to go. I know what you mean though, I had no qualms about digging into the car, basically building the whole car myself, but when it comes to rebuilding engines or trans, I've always farmed it out.
PaulC
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When you buy the parts, then add up the labor, we have found that the overall value of a tranny outright from Mike is a great value. $500 for a 1st gen. with no core and all his experience.
http://www.iscracing.net/clutch.htm
AB
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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com
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Oh, the socket is 0000-09-0215
If you search their catalog, search on special tools, with no other criteria, and it's the very last tool in the list.
PaulC
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