Driveline shake...
 

So I relized that my trans crossmember was bad(had bad trans movement) ordered a new one and replaced it(88 bux from a local mazda dealer) put it on ran it around the block no problems let the car idle and warm up took it out again and sure as shit the trans movement is back Havn't had a chance to check the mount but its brand new has less than 6 miles on it. the movement is so bad it sends a shake all the way back to the diff and it stutters when letting out on the clutch from a stop. any ideas if something else is bad besides the trans cross member?

have you looked at the diff/actual transmission mounts?

Driveshaft u-joints?

^ yes make sure your driveshaft ujoints are not sloppy

If not replaced worse problems follow... Trust me

u joints

do ujoints change from 88 to 90? because I have a 80 trans but don't know what year the driveshaft is. also where can I get them without buying a new driveshaft.

IIRC all the 2nd Gen driveshafts have u-joints welded to the driveshaft. I believe some people have replaced the u-joint despite that fact....though I wouldn't mess with it. A driveshaft failing and falling out at the transmission at highway speeds could ruin your day/life.

That being said, I have a spare N/A driveshaft I'll sell you for cheap.

I believe that all NA shafts interchange, as do turbo-to-turbo (but I could be wrong).
At any rate, Mazda didn't make the u-joints replaceable for some reason.
People have claimed to have found a workaround for this but if you can just replace the shaft with a good used one, that's what I'd do.

Could be the U-Joints

I *think you're right on this.

There are quite a few parts on our cars that are getting pretty scarce... And it is only going to get worse. It would be nice to see an alternative, other than a brand new $$$$ aluminum $$$$ shaft or whatever. :-/

Hate to bring up a dead thread, but I was wondering if this issue was ever resolved? I'm having the EXACT same problem as if i were describing it myself. I was just wondering if it ended up being the u-joints before I source out a new driveshaft.

i would guess one of or a combination of all:

chattering clutch due to hot spots on the flywheel
broken front diff mount
seizing u-joint


my car has always chattered from a stop, i blame it on the lightweight chromoly steel flywheel and non name brand OE replacement clutch(it grips fine so i live with it)

if you have a solid puck clutch installed, suck it up 'cause it isn't going away.

By the description and that the OP had a new mount, it's U joints. I read that Mazdatrix offers an aftermarket replacement that the U joints are replaceable.

Sounds like the OP also has a clutch with heat glazing.

And I read that the NA driveshafts are different between manual and automatic transmissions.

yeah I replaced my clutch to no avail. My flywheel didn't look like it had hot spots, but it could be the fact that they just weren't visible. I believe I'll just go ahead and get the driveshaft and replace the clutch and throwout bearing while I'm underneath there and resurface the flywheel. I had it on the lift and the motor mounts didn't look bad at all, but when I step on the gas I shake for like 4 seconds before it subsides and smoothly accelerates. So I know it's something loose PLUS possibly the flywheel but my guess was the looseness in the drivetrain was amplifying the shudder. Hopefully replacing this takes care of my issues. Thanks for the help and again sorry for bringing up a dead thread but the explanation was spot on.

a clutch issue would only be present while the clutch is slipping, so if it's shaking with the pedal completely out then it is likely not the clutch.

^Agreed.

Also, considering the engine torques clockwise (as you're facing the front of the car) the passenger side motor mount gets the primary stress. Give that a good look.

My front unjoint was broke out of the driveshaft on one side so yes it fixed my problem but I also have a lightweight 8 lb flywheel and a stage 2 clutch but if your getting vibration when you move it's most likely a unjoint but while your under there check your rear trans crossmember mount

Cool, I was right.