I just got my first seven and when I let off the gas then get back on it...it THUMPS in the rear end I can't really tell if it's coming from the diff or it's some part of the suspension and I won't really get a chance to get the car on a lift to check it out by myself so if someone who has run into this before has an idea of what this is let me know....
is it the diff?
the suspension?
or just the nature of the beast?

let me know ...
thanx

TOM

 

Broken front differential mount. $160 form www.mazdatrix.com and about 3 hours of work! Not an easy job for a first-timer, but it can be done. Do a search for the procedure, and fix it quick. That sound is the differential flexing up and hitting the rear subframe. This causes a lot of stress on the halfshafts, possibly breaking them! Good Luck!

 

I don't think its just the nature of the beast. At least not to thump hard.
I could be something simple like your spare tire isn't tight against the hatch and it thumps back into place when you accelerate. Dunno though.
If not, id guess its in the differential.

 

If it is thumping when you let off the gas, and then get back on it, it is the diff mount. Mine did this till I fixed it. Now, no more bump. It is pretty common for this to happen.

 

Would the diff. mount also account for a grinding sound when letting off of throttle at most speeds?

 

could have something to do with the throttle cable as well. not sure if that would cause a thumping...but when mine was misadjusted, the car seemed like it had a mechanical delay when re-applying the gas pedal...