1992 Mustang LX 5.0 Vibration

Hi all,

I'm new to the forum, and having an engine vibration problem that seems that the mechanics I've seen so far can't figure out.  The car is completely stock other than a brand new Ford racing 3:73 rear end assembly.  The vibration was here since I bought the car 6 months ago.

So far I have replaced:

all four springs and shocks
Harmonic balancer
all four brakes
tune up/plugs/wires/distributor cap
trans fluid change
new tires/alignment
Ford racing 3:73 rear end(whole thing new from Ford)
New universal joints
Snap On engine fuel system flush
New starter
New fan and fan clutch
New trans mount and cross member




There is a vibration coming through the floor, whirring through around every second or so, and a bit less, when idling in Park, and gets worse when car is in motion. At highway speeds, and shifting the trans down from overdrive to 3rd, it the vibration actually comes through the dash at higher(3-4000) RPM's.

The motor has 140 k on it, but runs good otherwise.  I had the harmonic balancer replaced, and I'm still having the vibration.  I'm assuming this problem is in the engine or trans, since it still slightly vibrates when in Park and neutral (AOD trans)

If anyone can give me some tips on what to look for, it would be greatly appreciated.  Possibly the trans input shaft or torque converter?  Flywheel problem?

I'm getting to the end of my rope and ready to bring the car to Ford to have a look at it.  The vibration gets worse at 1200-2000 rpm, and does not sound or feel healthy.  

Thanks!  

I would say it is in the drive line. Sounds like a bent input shaft. The torque converter should just be replaced. It has just too many miles on it and is on its way out. If I remember correctly the converter is a lock up type, without proper maintenance they can go bad just as you described. While you have the tranny out, put a dial indicator on the crankshaft. Bar the motor over and see if the cranshaft is bent. Any more than two thousands is too much in my opinion. Call Ford for this spec. or check a chiltons repair book.