For the past year and a half, my car has been making clunking noises when going over low speed bumps. I checked my suspension and steering components as best as I could and could not determine anything loose or worn that might be causing the problem. I also had the car checked out by a couple of different garages and neither could find anything wrong so I took the advice of one of the shops when he told me to just wait until it gets worse. Well the clunking never really got worse but then a few weeks ago I started hearing a very pronounced vibration sound inside the cabin, The sound was like internal engine noises being heard through a stethoscope. I presumed it was a broken transmission mount causing metal to metal contact of the the engine/transmission with the car's frame/under-body. I had already changed the engine mounts about a year and half ago (coincidentally the clunking noise started shortly after). I bought an aftermarket trans mount of e-bay and proceeded to change out the old one. When I took the old one off it was not broken and actually looked to be in pretty good shape for a 20 year old mount. The only thing I noticed was that the rubber seemed quite soft compared to the new one. I put in the new one anyway. As I was finished tightening up the bolts I notice that the cross bar between the angled rods of the front (trapezoidal shaped) brace was almost touching the bottom of the transmission bell housing. I am not sure if at some point the bar got pushed upwards very slightly but I decided to remove the front brace and I paced a washer between the brace and the frame at each attaching bolt. This lowered the brace ever so slightly. Upon completion I no longer have any clunking noises or vibration. I am guessing that my soft transmission mount was causing the bell housing to hit the cross brace at low speed bumps and that was the noise I used to hear. Also lately the cross brace may have gotten pushed up slightly so that it was making continuous contact with the bell housing causing the vibrating noises to emanate through the cabin.

Long story short, new trans mount and adjusted cross brace makes for a nice Lexus like ride again.

 

Sounds about right lol. Little changes in the engineering cause big trouble. That brace can be bent back flat fairly easily, too.