This us a follow-up to my previous post about an '89 Dodge B250 with a rumble/vibration problem that begins at 40 mph and grows steadily worse with speed. The strangr thing is, it depends totally on engine load. When I lift off the gas at highway speed, the rumble/vibe instantly disappears. Get back on the gas, and it immediately reappears.
The reason for this new posting is that I just found the owners manual and read it. The manual says “some models” have a lockup torque converter with an electronic clutch that kicks in at 40 mph under light load…which is the exact conditn where I started hearing/feeling the vibe rumble. And if I interpret the manual correctly, it means the lockup disengages when the load is released…exactly what happens when I lift off the gas and the rumble/vibe disappears.
So the question is, could it possibly be a problem with the lockup torque converter? I’m hoping a tranny expert like transman will tell me no, because obviously I’d rather have it be some bad U- joints. But it seems beyond coincidental that the symptoms appear exactly when the lockup ( if it’s in there) should be kicking in.
By the way, it’s an A500 trans, if that helps.