Any thoughts? One of my friends said it could be exhaust related. I still lean towards the driveshaft.

Under light throttle it vibrates horribly. Under medium throttle it's not as bad. When you let off the gas and keep it in gear it's fine. So I know it's not the wheel bearings and I assume it's not the motor mounts.

My thoughts are that the driveshaft Ujoints might be bad.

Here's another strange part: Let's say I'm driving around and it starts to vibrate. If I clutch in and put the shifter in neutral, the shaking stops. If I just push the shifter out of gear, no clutch, something's still shaking like hell under there. Then I can move the shifter half an inch or so towards a gear slot, something clicks, and the shaking stops.

 

Check U-joints. Also check the diff bolts that secure the driveshaft to the diff for tightness.

 

First I would try swapping out drive shafts as that can be done very easy and quick and make sure to tighten them bolts but not too tight.
If problem is still there I say it is in the tailshaft of the tranny.

Good luck

 

Im with doc, a lot of the times its the u joints are bad or driveshaft

 

trans mound mab3?

 

Transmission mounts really like to rot due to oil exposure. when I swapped my mount was in 2 pieces. but I expected that.

 

Tentatively I'm thinking it's going to be both the trans mounts and the driveshaft.

 

It is. I've had the same horrible shaking ever since I put the new transmission in. I secured it with makeshift transmission mounts and it's just as you describe if not worse.
I know it's the drive shaft to because as you described, even when the car is in neutral at highway speed it still vibrates.

It doesn't bother me much since it's more like a good massages type vibration, and since it's been going on for months now I don't think anything could really break. But I suggest swapping out the u-joints at a machine shop (there's a write up with the part # on the replaceable ones for our cars) and getting a NEW transmission mount from Mazda or one of OEM quality.

 

I have the EXACT same problem in my SE. All evidence points to the driveshaft, but I won't know for sure until I get another one and swap it out.

Yeah, that doesn't help much...

 

$150FC: Just a little bump here since I finally fixed my problem. I finally put a new (to me) driveshaft on the car, fixed the exhaust (the vibrations were rattling the exhaust nuts loose) and took it for a drive. It feels nice and smooth again.

I did notice when I had originally checked the old shaft there was just barely a little wiggle at the ujoint, with the new one it is gone. It is rock solid, almost like it was welded together.

Wasn't sure if you had already fixed yours or not, but thought I would chime in just in case.

 

Well, I bought a driveshaft and it's for a small flange diff, but I know for certain that the old driveshaft is to blame (I felt the front u-joint and it's hideous.) I'm trying to get my money back from the eBayer who sent me the wrong one, so I can get a good one.