Rebuilding 12A Trans
- Thread starter benracin
- Start date
It's almost $500 in parts if you do it right - and you don't have to ship a core. The 1st gen one seems like a steal.
Order all the parts from Mazda, then buy the tools you need to actually do it with some semblance of efficiency, then tell me what you spent.
Its a value for me.
AB
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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com
Order all the parts from Mazda, then buy the tools you need to actually do it with some semblance of efficiency, then tell me what you spent.
Its a value for me.
AB
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Andy Bettencourt
06 ITS RX-7
FlatOut Motorsports
New England Region
www.flatout-motorsports.com
As long as the gears are OK you're looking at about $200 for a couple synchros (assuming that's the only problem), all the bearings and new snap rings, nuts, etc. from Mazdacomp. That is hardly ever the case.
And as for the dealers doing a rebuild, here is my story and I'll post pics tomorrow to back it up. I've torn down six non-rib transmissions. Five were from 2nd gen cars and one was from an early Ford Courier pickup. All of them exibit a very bad misalingment of the gear set. Literally half of the main transfer gear does not mesh. I noticed this on the first trans to fail on my car. I tore it down and immediately said the guy that built this was an idiot. Turns out that's the way they come from the factory. The best part is that the correct shims are not available from Mazda to correctly align the gears. The gears aren't the only problem. The two bearings that support the rear of the output shaft and the rear of the counter shaft do not sit fully in the case. One of the bearings rides nearly half way out of the case the other half way in the case. The allows the shafts to flex and aggrevate the poor alignment problem. Sending the trans to a dealer or generic rebuilder who will use the shims that are available from the factory is not the answer. Custom shims, alot of time, and an experienced Mazda rebuilder is the answer, IMO.
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Chris Ludwig
08 ITS RX7 CenDiv
And as for the dealers doing a rebuild, here is my story and I'll post pics tomorrow to back it up. I've torn down six non-rib transmissions. Five were from 2nd gen cars and one was from an early Ford Courier pickup. All of them exibit a very bad misalingment of the gear set. Literally half of the main transfer gear does not mesh. I noticed this on the first trans to fail on my car. I tore it down and immediately said the guy that built this was an idiot. Turns out that's the way they come from the factory. The best part is that the correct shims are not available from Mazda to correctly align the gears. The gears aren't the only problem. The two bearings that support the rear of the output shaft and the rear of the counter shaft do not sit fully in the case. One of the bearings rides nearly half way out of the case the other half way in the case. The allows the shafts to flex and aggrevate the poor alignment problem. Sending the trans to a dealer or generic rebuilder who will use the shims that are available from the factory is not the answer. Custom shims, alot of time, and an experienced Mazda rebuilder is the answer, IMO.
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Chris Ludwig
08 ITS RX7 CenDiv
ooof, well, reluctantly I'm convinced that you're right.. I'll make a final decision after I tear this tranny down and see what I really need, but you're right, if the parts cost 200, plus new gears (3-4th were grinding so I"m sure those need replacement) plus a GTUs 5th gear, and $$ for tools. Then to only to have it wear out in just over a season because of poor alignment, I'm sold.
It's only money right? <whimper>
PaulC
It's only money right? <whimper>
PaulC
SPiN Racing
New member
Footnote on the ISC Racing Trannies from Mike..
Have to say.. he knows his stuff. I watched him rebuild one one day while doing some work with him.. and it was really nice to see.. He prolly could have done it blindfold he knew what he was doing soo well.
Ever see a gunsmith take apart a automatic and re-assemble it? That is how he did it.. He did a excellent job... from what I could see.
I myself will be buying one from him soon as this one gets to the point I need to change it.
Have to say.. he knows his stuff. I watched him rebuild one one day while doing some work with him.. and it was really nice to see.. He prolly could have done it blindfold he knew what he was doing soo well.
Ever see a gunsmith take apart a automatic and re-assemble it? That is how he did it.. He did a excellent job... from what I could see.
I myself will be buying one from him soon as this one gets to the point I need to change it.
Here's my take on Rear wheel drive, manual transmissions...
Wear generally takes place in the easier to wear parts first, like the brass syncro rings. Generally, physical gear replacement isn't neccesary due to a bad syncro unless the syncronizing teeth on that gear are worn or missing. Also, most trans', I say most becaue I haven't seen all of them, do not require shimming of bearings to allow proper bearing pre-load or gear alignment. Manual tranny's do not have hardly any shaft endplay and do not require a certain amount and gears are pretty much set where they can go on the shafts due to the position of lock rings and splines.
What I would do for a trans rebuild....
Tear it down, replace all the brass parts and bearings no matter what. Inspect each gear individually for wear and replace as neccesary taking mileage into account. If it is a racing application, I would replace gears with hardened ones only if there becomes a problem with wearing out gears pre-maturely.
Again, this is just my take, I only have 5 years experience as a Ford mechanic, and am no longer doing that, but I do feel very confident in my abilities, the only question is, do You feel confident in my abilities?
Wear generally takes place in the easier to wear parts first, like the brass syncro rings. Generally, physical gear replacement isn't neccesary due to a bad syncro unless the syncronizing teeth on that gear are worn or missing. Also, most trans', I say most becaue I haven't seen all of them, do not require shimming of bearings to allow proper bearing pre-load or gear alignment. Manual tranny's do not have hardly any shaft endplay and do not require a certain amount and gears are pretty much set where they can go on the shafts due to the position of lock rings and splines.
What I would do for a trans rebuild....
Tear it down, replace all the brass parts and bearings no matter what. Inspect each gear individually for wear and replace as neccesary taking mileage into account. If it is a racing application, I would replace gears with hardened ones only if there becomes a problem with wearing out gears pre-maturely.
Again, this is just my take, I only have 5 years experience as a Ford mechanic, and am no longer doing that, but I do feel very confident in my abilities, the only question is, do You feel confident in my abilities?
Hmm Beer!!Originally posted by ddewhurst:
***the only question is, do You feel confident in my abilities?***
John my man, that would depend on how many tall COOL ones you had consumed. Do the two of you have THE TRANS rebuilt ?
Have Fun
David
No, the trans ain't done yet. We're prolly just gonna run the crappy one for awhile longer.
[This message has been edited by noresull (edited May 13, 2004).]
Ben & John, not trying to throw a scare at ya & not knowing what issue you guys have with the trans & depending on what the trans is doing you might not want to wait untill it craps out. As mine was on it's way south (over 2 or 3 races) the first issue was not shifting smoothly from 3rd to 4th, (the following all happened at Road America) next it'got to be a bitch to get into 4th, then at above 5,000 RPM it would kick it back out of 4th & finally it got to the point that I couldn't hold it in 4th at Road America.
Ben, did ya buy the 1 5/8 inch socket & was that the correct fit on the trans nut ?
Have Fun
David
Ben, did ya buy the 1 5/8 inch socket & was that the correct fit on the trans nut ?
Have Fun
David
My trans used to grind going from 3rd to 4th just a little. Things may be getting a little worn in there, but I think a lot of it was due to me rushing the shift back when I didn't know the gear box well. You'll have to correct me if I'm wrong, but it seems like these transmissions like to be shifted at a slower pace. Since I started shifting a little slower, and also since I put in new trans fluid the grind has pretty much gone away. So as far as I can tell, it's still good to go. I just wanted to make this other trans work since the prev. owner told me it was "better". Plus it would be swell to have a back up.
Since I started messing with it though I've had lots of other distractions like re-doing the rear end of the cars suspension stuff. I've got a lot to do if I'm going to make the 5th. Right now I'd have to say I'm dreaming if I think I can make it, but you never know. I won't be able to afford new tires by then but that way if you beat me I have something I can blame it on.
Since I started messing with it though I've had lots of other distractions like re-doing the rear end of the cars suspension stuff. I've got a lot to do if I'm going to make the 5th. Right now I'd have to say I'm dreaming if I think I can make it, but you never know. I won't be able to afford new tires by then but that way if you beat me I have something I can blame it on.
lateapex911
Super Moderator
You know.....funny you should mention the speed of shifts and the ginding getting better...
Speed DOES make a difference.
And I know this is nuts, but I swear i have had Mazda transmisssions that were bad when I bought them seem to get better with a few months TLS (tender, loving shifting)...but how can a car heal itself???
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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
Speed DOES make a difference.
And I know this is nuts, but I swear i have had Mazda transmisssions that were bad when I bought them seem to get better with a few months TLS (tender, loving shifting)...but how can a car heal itself???
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Jake Gulick
CarriageHouse Motorsports
ITA 57 RX-7
New England Region
[email protected]
***I won't be able to afford new tires by then but that way if you beat me I have something I can blame it on.***
Ben, my reason for racing a Spec-7 was ECONOMICS. As the deal is converted to ITA/7 the same tires will be used. We will NOT talk about how many heat cycles are on the tires. Most people talk about heat cycles, some people talk about races & I talk about years.
I got the car down to 1788 pounds but but that could be because there are pieces all over the garage floor.
***...but how can a car heal itself???***
Jake, I'm religious but I ain't touching that with a ten foot pole.
Maybe Ben should say a few words over my car. Shucks if his words made my car faster than his I would be willing to cough up some tire money to him.
Have Fun
David
ps: I'm going to the Farm for the National this weekend & that should get the hart pumping.
Ben, my reason for racing a Spec-7 was ECONOMICS. As the deal is converted to ITA/7 the same tires will be used. We will NOT talk about how many heat cycles are on the tires. Most people talk about heat cycles, some people talk about races & I talk about years.
***...but how can a car heal itself???***
Jake, I'm religious but I ain't touching that with a ten foot pole.
Have Fun
David
ps: I'm going to the Farm for the National this weekend & that should get the hart pumping.
