Can anything in a 700R4 go bad that would cause it to vibrate the entire car only at certain rpm ranges? I'm trying to isolate a vibration that has developed between 2,000 and 2,800 rpm's. It is not driveline related, as the vibration occurs with the car sitting still in Park. Also, can the torque converter cause this?

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Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
Former Paxton (6-psig): 12.57 @ 111 mph.
Former Paxton (6-psig) & former 50-hp nitrous: 12.04 @ 114 mph.
Current ATI D1SC (Initially 10-psig): Projecting high 11's.
Future ATI D1SC (15-psig): Gotta catch them pesky 26-psig boosted TTA's!!

http://willie.camaro-firebird.org/

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

Willie, have you checked your various mounts? One might be broken. When the engine runs between 2,000 & 2,800 rpm the torque is just right to cause the vibration. Slower speed and the motor moves back to center, faster speed it twists to the point of stopping. Just my humble .02. Good luck

 

Try unhooking the torque convertor from the flexplate and rotating the TC to change where it is bolted to the flexplate.

I had a TCI Saturday Night Special that would vibrate between 2200 and 2500 rpm (it was slightly unbalanced). I changed the mounting holes like above and the vibration went away.

Sparks a flyin'

 

Willie,

Check your harmonic balancer as well. Sometimes the elastomer seal dries out and the balancer stops doing its job.

 

Thanks for all the info guys....

I found the problem. I couldn't believe it. It was a wobbling water pump pulley!!! I can't believe this would cause that noticeable a vibration. Tighten four 10mm bolts with lock tight and bye, bye vibration... Amazing.

Willie