1968 C-4 Converter

[franklinair]

I want to disconnect the torque converter from the engine flexplate:
When I remove the four nuts on the torque converter studs, should the torque converter slide back enough from the flexplate (about 3/4") so I can reposition the flexplate (Rotate 180 degrees)?

The reason I'm doing this is I've got an engine vibration @1100 RPM. The engine has good vacuum (15" @ idle), I tried a new harmonic balancer- no change. The vibration is ONLY at that specific RPM. Lower or higher RPM, the engine is smooth as silk. A friend suggested repositioning the converter position to see if that helps. Any other ideas??:undecided

Neil

 

[miller511]

Neil,

I was able to back the converter off the flex plate (without loosening the bell housing). Not much room, but it is do-able.

Wondering if the vibration is possibly related to the transmission or rear end. Is the vibration there at 1100 rpm when in park?

Also, are your motor mounts in good shape?


-Jeff

 

[franklinair]

Motor mounts are new.
1100 RPM vibration is consistent whether in Park, Neutral, or driving.
Original C-4 that was in car prior to engine replacement.
I re-used the flex plate that was on original engine. (Also a 302)
Disconnected P/S pump, Water pump & Alt to eliminate them.
Installed new Damper. No help.
My last resort is to reposition the Flexplate & converter in case there is a balance mismatch, but that seems (to me) to be a remote possibility. We'll see.

Neil

 

[robert campbell]

Neil,
You cannot back the torque convertor off enough to re-position it without backing off the bell house bolts as said earlier. You can even put in long bolts to do it, but will need to take drive line off, remove tranny cooler lines, starter, and the shifter rod.

Doubt it will help. Sounds like the wrong flex plate on that engine.

Rob

 

[franklinair]

Today I removed the 4 converter nuts attaching it to the flexplate. Could not move the converter backwards at all. But as I recall, when putting things together, prior to mating the transmission to the engine, the torque converter was recessed and I moved it forward to get the studs thru the flexplate holes.
I think I'll just have to undo the tranny & peripherals, and replace the flexplate.
But I don't understand why- using the same parts going together as when I took it apart. The mystery continues, and I hate doing a job twice!!

Neil