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Matthewga
12-12-2010, 11:01 AM
1995 Mazda Miata MX-5, 5-Speed 1.8L BP Engine.

Background: I got the car 3 months ago from my Aunt; it had been parked for ~2 years but she had it touched-up before I bought it for $800. It has 170k miles, a decent-sounding engine, new tires and belts. Apparently what it didn't have a was a good alignment, because it's been vibrating at certain speeds since I got it.

Driving home from work Friday on 75N in I heard a pretty disturbing noise. A crack/bang, something flew out from under/back of the car, and the car started shaking uncontrollably. I was doing maybe 85MPH, which I've done several times before without dramatic effects, in fact higher speeds often seemed to drown out the vibrations.

I had been suspicious of the driveshaft being warped/off-balance, since I knew the tires were new. After Friday's "boom" it was unable to drive much more than maybe 15MPH without shaking/sounding violent. It's hard to say the exact speed, because the "boom" incident made the speedometer inoperable (perhaps the speedo cable was what flew out onto the highway).

So I finally got it home late last night and put it on stands today to take a look. This is what I found at the transmission output onto the driveshaft.

Link to image: http://www.facebook.com/photo.php?pid=16047601&l=cce62827db&id=810900404http://www.facebook.com/photo.php?pid=16047601&l=cce62827db&id=810900404http://www.facebook.com/photo.php?pid=16047601&l=cce62827db&id=810900404http://www.facebook.com/photo.php?pid=16047601&l=cce62827db&id=810900404

It looks like someone took a hammer to the end of the transmission. I also spun the tires slowly and watched the driveshaft, and confirmed that it does have a subtle movement as it rotates, i.e. not necessarily warped, but it doesn't spin in one place as it should. I imagine this off-axis rotation of the driveshaft, at about 85MPH, was pretty excessive on the transmission and it went just busted open.

So what I'm looking for from folks today, I suppose, is a couple of things:


Is this a reasonable conclusion, based on the history and the image?
Am I correct in assuming that this sort of transmission issue can not be repaired, as it is the casing of the transmission?
If the above is correct, I need the names/numbers of junk yards or other good places to find a cheap transmission.

Any sort of help, advise, feedback is welcome. Thanks IA.

EDIT:
Follow up question, does anyone know if the transmissions from the 1.6L Miatas will fit the 1995?

Echonova
12-12-2010, 11:36 AM
You're better off replacing the transmission. Luckily, Miata parts are cheap if you can DIY.

www.mazmart.com
www.panicmotorsports.com

If you're not mechanically inclined www.rspeed.net/

badassf4i
12-12-2010, 02:16 PM
Do not replace the transmission with a 1.6 trans. They are crap compaired to the 1.8 hence 1.6 people trying to swap in 1.8 drivetrain parts