Hi guys,
I have a fairly stock 360 (4006830-360-6) engine and a 904 (PK3681843) transmission in my 74 Dart Sport. I have owned the car for 6 or 7 years now and it has always had a rhythmic vibration between 45 and 65 mph.
A year or so ago I had the stock flex plate break on me. I replaced it and it broke again just the other day. I am fairly sure it the correct torque converter (externally balanced), but I will verify this again.
I put the following parts on in the past few years: New harmonic balancer, new driveshaft, new u-joints, new motor and transmission mounts, and changed from an 8 1/4" to an 8 3/4" rear end. It had the same vibration with the previous rear end.
I have also have several rim/tire configurations over the years. I just had new tires installed and finally got a decent alignment (non computer), and it was driving the best it ever had besides the vibration until the flex plate cracked.
If I have the correct torque converter, and if both dowel pins are present for bellhousing to engine alignment, what would cause the flexplates to fail other than engine to transmission alignment? I thinking that the bellhousing may need to be checked and aligned with offset dowels. What else should I take a look at?
Like I said, I need to verify somehow that its the proper torque converter, because if my research is right than this transmission was originally behind a 318.
