Ok here's the situation- I have a vibration coming from what seems to be where the tranny meets the driveshaft. It started small and over the past couple days it has gotten way more violent. It starts when I hit 30mph and continues all the way up as I accelerate getting worse as my speed increases. It will continue this vibration if I push in the clutch and coast, but it stops when I let off the gas completely with the car in gear and coast. I was looking at the mazdatrix troubleshooting guide and it sounds like it might be the u-joints. Does this sound right? I also hear a single click whenever I take off. I think this might be my tranny mount. All of these sounds seem like they are coming from right under the shifter. Any ideas? I live in San Francisco so jacking up the car and checking things out is not as easy as it sounds. I just want to know if I'm on the right track

 

Yep.

 

Yep, rear u-joint is gone. You're looking at about $250 if you replace the driveshaft yourself, and maybe $4-500 if you have a shop do it.

 

I posted u-joints last night..... why it didn't show up, I dunno. I have two spare n/a driveshafts. Pay shipping +$10 and it's yours.

 

So i went with the mazdatrix aluminum driveshaft. Alot of people on here said it wouldn't be noticeable. They were dead wrong. My car accelerates faster and pulls harder now. It was kinda pricey but who cares. I also went with the stock cross member and mazdaspeed mounts for the tranny. No more weird noise or vibrations. Now my brakes are being sketchy. I think its a clogged vacuum on the brake booster. It never ends. Buy your G-ma a jitterbug phone for xmas. She'll love it

 

I have the same problem and it turned out that my rear u- joint is gone as well as the front diff mount. If you have an S4 then I am sure you know that mazda made u joint that were not replaceable, so therefore a new driveshaft is needed.

 

Ya I found out they weren't removable a long time ago. Trust me once you get all that **** dialed in you'll be a happy camper. My car drives like it's a kid again!

 

Word son....drive shaft replacement ftw....I got the same violent shake last nite in the rain, it sucked. Think I need to visit Mazdatrix too. Tranny mount and driveshaft for me probably.