Violent shakes / vibrations

My 89 chero 4.0 auto vibrates around 2000 rpm, it feels like it gets worse when the torque converter locks up. Took off front ds no effect, checked rear ds rear ujoint under caps are good although there is some play at the yoke into the transfer case. Also vibrabes badly 55-80 mph. The motor was appartently replaced with a later HO motor - as the leftover intake man is the newer syle, is the flex plate different? Front end doesn't shake -I replaced the tie rods/draglink/steering stabilizer with a used very good junk yard unit $20 , old one was pretty bad.

Ant ideas?

badgator said:

Ant ideas?

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You said around 2000 rpm, does that mean it does it sitting still?

Only when driving

I had something very similar happen it turned out to be the transmission bolts to the engine were getting loose. I would check those, your mounts and flexplate.

pete

Going to Daytona u pull it to day for spare parts today, only junkyard I ever heard of that has sales, rear end $19.95! Changing rear u joints before, will check flexplate bolts, tranny mounts, But how do I disable the lockup converter?

badgator said:

...how do I disable the lockup converter?

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I wouldn't do it. Trans will run too hot.

Only had 2 bolts between motor and trans! Guess that can cause problems. Have to get bolts a try later.

Installed switch between trans ecu and #3 solenoid, no problems, no tranny should overheat with lockup disabled.