At my wits end with these damn torque converters

[ULTM8Z]

Well the transmission is out.... new record for me... ~2.5 hours.

Nothing obviously wrong anywhere that I can see...

The crank pilot seems mostly clean. Maybe a light steel wool abrading to get rid of some minor surface grime, but other than that seems fine. Dowel pins and holes look good.

Flexplate doesn't show any obvious cracks or damage.

I also checked the end play on the crank. Got a dial indicator on the back of the crankshaft. Took a small crowbar and carefully pried it forward on the crank pulley. Zeroed out the dial indicator, and using a flex plate bolt on the back of the crank, I pried it backward. Did that about 5 times and the best I could get out of it was about .004 to .005. Rotated it a couple of times too to make sure it wasn't binding or anything. But that seems within spec from I'm reading online.

The reality is this engine is smooth as an electric motor when the converter was disconnected from it, so I'm not really considering the engine to be suspect anymore.

Any rate, I'll take it into my transmission guys this week and see what he says I guess.

 

[CorkyE]

Hopefully they find the issue, let us know if so. Good luck

 

[biker]

Good. Was wondering how you were doing. Hopefully the trans guy finds some big glaring smoking gun. Gotta be the TC if it isnt the engine.

 

[ULTM8Z]

Well I took the tranny in today. Asked him to go through it with a fine tooth comb looking for anything that could generate the vibration in this 3000-3500 rpm range (funny how all three converters I've had exhibited the vibration in this same rpm range).

 

[ULTM8Z]

Well, my transmission guy got back to me. Everything in the transmission looks good evidently. Nothing he could see that would be causing the out of balance condition, and no collateral damage from the converter failure.

Good and bad news I guess... happy there's nothing broken/wrong, but I'm still left without a definite root cause.

But what's cool is he's also not going to charge me for the inspection. Honest guy... he could have made something up to squeeze a few bucks out of me, but he didn't. So kudos to him on that.

So at this point all I can do I guess is just get a new converter and flexplate and put it all back together and see what happens I guess....

 

[Lowend]

This disturbs me... something is wrong.
Thinking down the line:
This happens in N/P, so it's not the driveshaft. Maybe the speedo gear/cable? Although I can't imagine that making much noise, it would just break the nylon gear.
I dunno, I'm grasping at straws here

 

[ULTM8Z]

Its not just the noise. There was a definitely loss of power being delivered to the rear wheels.

I just don't know what else to check at this point.

 

[Lowend]

Hmm Fluid cavitation inside the torque converter....
https://digitalcommons.mtu.edu/cgi/viewcontent.cgi?article=1419&context=etds

 

[biker]

Its not just the noise. There was a definitely loss of power being delivered to the rear wheels.

I just don't know what else to check at this point.

I really think it is the torque convertor itself. It failed internally somehow, but of course I think you are more concerned about something engine/transmission related causing the TC to poop.
If you can get the TC to someone who builds them, maybe they can do a post mortem of sorts on it to determine what failed and the possible cause.

 

[muscl car]

Could the problem be coming from the Gear Vendors unit ???? , also did your transmission guy cut the torque open to inspect it ????