If the drive shaft is out of balance or the angles of the u-joints is incorrect due to weak springs or more commonly altering the carefully-designed ride height, your dentures will vibrate out!
The most common cause of a failed torque converter is a failure of the clutch to lock up, or it may shudder. (Be aware too that the wrong transmission fluid will cause a shudder). With the engine warmed up, accelerate gradually up to highway speed and keep an eye on the tach. You'll feel the shifts to second, third, and overdrive, plus you should feel the lockup occur. That will be in third or overdrive and you'll see about a 200 rpm drop. Once that has occurred, press the accelerator pedal a half inch to accelerate perhaps another ten miles per hour. The tach should not increase suddenly. It will creep up slowly along with vehicle speed.
Next, hold the gas pedal perfectly steady and briefly tap the brake pedal with your left foot. You will see the engine speed go up 200 rpm, then drop back down a few seconds later when the torque converter relocks. It unlocked in preparation for coming to a stop. It will also unlock as you approach wide-open-throttle or if you just accelerate quickly. If you feel a shudder for one or two seconds each time it locks up, start with a fluid and filter change.
If you feel that shudder and / or you notice that 200 rpm increase while you're cruising at a steady highway speed, suspect the throttle position sensor. The lockup feature was first developed by Chrysler and used on some '76 or '77 models and they were hydraulically-controlled. Yours is electrically-controlled. The throttle position sensor is one of the things the computer looks at to determine when lockup is appropriate. Normally a dropout in signal voltage will set a fault code and turn on the Check Engine light, but if the dropout is too short, there may be no code set but you will have intermittent unlocking. That seems to be much more common with diesel engines.
Saturday, February 23rd, 2013 AT 1:57 AM