Wicked Shimmy

[Anonymous]

Hey guys,

With the Fall semester over I had time to work on my mustang again and I am trying to track down this nast vibration in my car. I am almost convinced it is the Torque Converter at this point, but I don't know if there might be something else I am missing. If the car is in park or Neutral and the engine is running, as the RPM's increase the car vibrates so bad the windows shake and the noise in the car is unbearable. I put it in drive and go around the block and it is not that bad. I had the transmission rebuilt a year ago right after I bought it because it was bad, but then went back to college and didn't get to work on the car much and was unable to track down the problem. I changed the Harmonic Balancer during summer break, rebuilt the carb, changed points and replaced most of the ignition system and re-timed the car. I have never dealt with this kind of a vibration. Is it possible it is in the transmission and or Torque Converter. I can't say whether or not the problem existed before the transmission was rebuilt with 100% confidence but I have always leaned to not existing, that may be my own desire to not have it be another problem.

Jon

 

[mustang6]

Flexplates on the small sixes are very prone to cracking/breaking and when they do you get exactly the sysmptoms you are describing. Less expensive part than a torque converter, but unfortuantely the amount of labor required to change it is about the same.

 

[Anonymous]

If I unbolt the converter and slide it back from the plate, can I start the engine and run it? That would at least isolate it, or is there a better way to check the flexplate?

Jon

 

[Anonymous]

If the ring gear is on the TC how can the 200 be started with the TC slid back?

Jon

 

[mustang6]

Many times the cracking occurs around the TC mounting bolts so you would be able to see that through the starter opening or inspection opening. You may have to put some front/back motion/pressure with a large screwdriver against the convertor to reveal the cracks if they are not hammered in yet. Even if the cracking is around the crankshaft bolts where you can't see it assembled you might be able to produce some unanticipated freeplay/metal on metal sounds by prying.

 

[Anonymous]

Wouldn't this be something a reputable transmission shop should have checked before putting it back together? Would a rebuilt transmission cause this to happen where the problem wouldn't have happened as fast if the transmission hadn't been pulled, rebuilt, and reinstalled? I know the input shaft had to be replaced because it had excessive wear/play in it, and the converter was replaced because I didn't want to take the thing apart later to replace it. Looks like I might have to anyway. Since I already have plans on cleaning up/repainting the motor and engine bay I am guessing the best thing to do would be to pull them as a unit and then separate them on the floor where I am not playing Jo-Jo the Balancing man to hold things up.

Jon

 

[mustang6]

I can't imagine any reputable shop putting one together that even looked like it was starting to go, but it's possible that all the new torquing of bolts put it over the edge. All I know for sure is that when I worked in a Ford junkyard years ago, about 10-20% of the 200 sixes we took apart had broken/cracked flexplates. Most often they broke around the "ears" where they bolted to the torque converter, and only one crack could make for strange vibrations and noises on a running engine.

 

[Anonymous]

I finally got the time to check the flexplate and sure enough two cracks are in it right where it bolts to the converter. I got the new plate and will get at putting it in. While I am doing it, would it be useful to the site for me to take detailed pics and repost them to become a sticky on this? It all seems simple to me, but maybe someone else would gain some knowledge. Let me know and I will document the work.

Jon

 

[addo]

It never hurts to take good digital photos. Half the time you end up looking at them again for some unrelated detail that just happens to be in the same picture - like a weeping freeze plug...