Is it possible to install an external balanced flexplate to an internal balanced crankshaft? My engine is a 460 and the builder said that it is a 1971 and the flexplate is from a 1977 (I think.) Is there a change in bolt hole pattern that prevents interchanging these components? I have a vibration that I cannot seem to isolate. Got a new harmonic damper, and that helped some, but still has a nasty vibration at all RPMs. Vibrates with tranny still in neutral or park, as well as drive. My harmonic damper does not have the additional external balance piece. Thank you.

 

the bolt patterns are the same between the 2. if you do have external bolted to a internal motor it'll cause vibration like you've got. you'll want to bolt a external plate and external damper to a external balanced motor and the same for internal.

if my memory is well a 1971 460 is internally balanced. then late 70's and up where externally balanced. so i'd double check to see which you have and if wrong parts added. if it's so thats where your vibration is coming from. since yours does it at all speeds, gears and neutral/park thats where your problem is.

 

I had the same problem on a 460 a few years ago. Turns out the place I bought the flexplate from sent me the wrong one (external balanced) It's easy to spot an external balanced flexplat, it has a weight welded to it (about 3/4"x1 1/4" in size) Internal balanced flexplates should have no weights on it anywhere. 460's went to external balance in 1979.

 

Thank you. Can I spot this weight from under the vehicle, by removing the access cover from the front bottom of the transmission?

 

how exactley does a flexplate....that doesn't move.....cause a vibration? DO you guys mean flywheel? There is a difference and you could really be confusing some people.

 

Flexplate is used with automatic trans in place of flywheel. What are you calling a flexplate?

 

maybe he could be thinking of a dodge? they use what they call a flexplate that sets between the flywheel and converter on there auto's

 

Yes, the weight can be spotted from under the vehicle with the inspection plate removed.





A flexplate is a flexplate, they are all the same and they all spin with the engine. This is what is usedto couple the crankshaft to the torque converter on most (if not all) vehicles equiped with an automatic transmission.Dodge flexplates are different, as they don't have the starter ring gear attached to them but they still couple the crankshaft and the converter.

 

Sounds a lot like a flywheel to me. What do you call the thin gauge metal piece that fits between the motor and the tranny?

 

Ford manuals call it the engine rear plate.