727 Trans or Torque Converter Sound

[khryslerkid]

I'll start off saying, I hate these kind of threads and here I am starting one. It's very hard to describe what's going on without being there in person but I'll do the best that I can.

Driving my '62 Polara, 440ci. with the original pushbutton transmission (rebuilt), I'm noticing a harmonic type of sound that's more pronounced in the transmission's location. It's not coming from the rear of the car but in the hump area in the floor.

It puts me in mind to the harmonics that you would get from a fan or a worn bearing or maybe a worn gear. It has a steady cadence like a whirl, whirl, whirl. It is about the same level as the header, dual exhaust note and you really have to pay attention in order to pick up on it.

This takes place at 1800 to 2000 rpm, running between 45 to 50 mph on a level, cruzing road. As this is taking place, I can put it in neutral and it immediately stops. Place it back in drive and it's back.

I have heard that torque converters can do this but there's no other signs of shifting problems or delays placing it in gear, noises ect. The trans was a high milage unit and was rebuilt by a very reputable shop. The only real problem that was found during the rebuild was a worn tailshaft bushing that was replaced.

Let the past experiences with this condition commence!

 

[rlem1977]

Maybe front pump starting to go?

 

[493 Mike]

Is the transmission touching the body anywhere? Lots of transmissions will make some planetary noise but not in 3rd.
Mike

 

[66Satellite47]

Just a WAG, planetary gear train in the trans, maybe. Good luck.

 

[khryslerkid]

Is the transmission touching the body anywhere? Lots of transmissions will make some planetary noise but not in 3rd.
Mike

It has the normal first gear whine (ever so slightly) but that's gone the moment it shifts to second.

The trans isn't touching anywhere. I am using a Schumacher torque strap but it has rubber isolators on it. Some engine vibration is transferred through it but not like solid mounts.

 

[727]

When you put the car in neutral do you maintain engine RPMs?
Had a hormonic that drove me nuts. Turned out to be an autozone alternator with a smaller pulley than the original used with a mechanical voltage regulator. I changed the drive train twice while on the hunt.

 

[khryslerkid]

When you put the car in neutral do you maintain engine RPMs?
Had a hormonic that drove me nuts. Turned out to be an autozone alternator with a smaller pulley than the original used with a mechanical voltage regulator. I changed the drive train twice while on the hunt.

When I place it in neutral the engine rpms increase, then I'd lift just a bit. I can hold it at that rpm anytime in neutral and I'm not having the symptoms.

 

[snakeoil24]

Check the thrust bearing in the motor. Drop the oil pan and look to see if the thrust area is damaged.

 

[khryslerkid]

Check the thrust bearing in the motor. Drop the oil pan and look to see if the thrust area is damaged.

That thought crossed my mind. Thought I'd try and see if there's any excessive end play in the crank.

 

[oldbee]

Original 2-pump trans? Throwing out ideas.

 

[khryslerkid]

Original 2-pump trans? Throwing out ideas.

Yep

 

[oldbee]

NO expert on those things,but I’ll go with frt pump. Sure fluid level is Ok?(I’m sure u already checked)

 

[khryslerkid]

NO expert on those things,but I’ll go with frt pump. Sure fluid level is Ok?(I’m sure u already checked)

You suppose to put fluid in it?

 

[beanhead]

Wish I could help. My 727 has a little whine between 45-50 too..goes away as soon as I lift, or accelerate just a little, and it doesn't always seem to do it...I'm just hoping it hangs in there until I can rebuild it..best of luck to ya

 

[khryslerkid]

Check the thrust bearing in the motor. Drop the oil pan and look to see if the thrust area is damaged.

I setup a dial indicator and the cranks endplay is .004

 

[snakeoil24]

Ok that is good but still look at the thrust face of the bearing.

 

[khryslerkid]

 

[snakeoil24]

Sounds great

 

[khryslerkid]

Replaced the wheel, sound still there.
Swapped the driveshaft for another shaft, sound still there.

 

[oldbee]

Check driveshaft angle,(?) sometimes these videos don’t help us at all; i kept thinking u-joint till I saw this is another d-shaft.Kinda sounds like binding(?).