balancing act

[daves68]

OK, here's the problem. I have a 1975 440 w/cast crank going into my 68 Charger.  The crank, rods,new pistons, flex plate and torque converter are at the shop and are ready for balancing. The shop called today and said they were having trouble balancing the whole assembly because something seemed to be wrong with the torque converter. So, I'll get a new one. Here's the catch - which one? The more I look, the more confused I get. This is an externally balanced motor and has the correct damper with the eccentric weight. I assume the new converter must have weights but I find 3 weight choices and don't know which to get. Also, at this point is it possible to make the whole thing an internally balanced engine or is that too costly and difficult? And, to add to the confusion, which stall speed? The car will be primarily cruising and road trips, maybe an occasional rice rocket/fart can combo at the stop light, but no serious racing.  Appreciate some help here so I can get this thing back together.
Thanks, Dave

[John_Kunkel]

The best way to go is to get a B&M flexplate that allows the used of any neutral balanced converter on your externally balanced motor.
The B&M part number you need is 10237.

BTW, it's near impossible to spin balance a converter on a regular balancing machine because the converter internal parts flop around unless mounted on the transmission. It takes special equipment to spin balance a converter.

[daves68]

Thanks John,
If I buy those 2 items, do I then leave them out of the balancing procedure at the shop and just have the crank,rods,etc balance completed, then bolt them on later? Sure would make it easier.

[John_Kunkel]

When using the B&M flexplate it needs to be bolted to the crank during spin balancing to provide the external weight.

[daves68]

John,
OK, Guess it's time to shop.
Thanks.
Dave

[is_it_EVER_done?]

Actually, you could have them balance everything with your stock flexplate instead of buying an offset weighted flexplate (which would STILL have to be balanced with your other components).

After balancing, any neutral balanced converter can be used, but as others have pointed out, it is impossible to balance a torque converter on an engine balancing machine unless it is equipped with a stator centering device (which I have never even seen nor heard of on an engine balancer). This leads me to wonder about the qualifications of the machinist, or even if your converter has any real problem?

[HeavyFuel]

The best way to go is to get a B&M flexplate that allows the used of any neutral balanced converter on your externally balanced motor.
The B&M part number you need is 10237.

BTW, it's near impossible to spin balance a converter on a regular balancing machine because the converter internal parts flop around unless mounted on the transmission. It takes special equipment to spin balance a converter.

This thread is kinda old, so I will  feel free to highjack it.

John, it sounds like you are a tranny guy, so I've got a couple questions.

My engine is already rebuilt to factory specs, and now the tranny is getting it.  The shop doing it, says to bring in the old converter with the tranny and they will order up a new converter.  Do I need to do this, or can I order one up myself?  Why would they need it?

Since my engine is already done, the only thing I can balance now is the converter to the flexplate, is that right?

Also, I looked up the flexplate that you listed, and it says that is is for cast cranks.  I think my HP 440 has a forged crank, and would this flexplate still apply?

One more thing.  Should I let the shop pick out my tranny rebuild kit, or should I order one up from Hughes or somebody like that to make sure I don't get a bunch of cheap junk?

[John_Kunkel]

This thread is kinda old, so I will  feel free to highjack it.

John, it sounds like you are a tranny guy, so I've got a couple questions.

My engine is already rebuilt to factory specs, and now the tranny is getting it.  The shop doing it, says to bring in the old converter with the tranny and they will order up a new converter.  Do I need to do this, or can I order one up myself?  Why would they need it?

Most shops won't warranty their work unless a new/rebuilt converter is used. You'll have to ask them about their policy concerning customer supplied converters but I wouldn't think they'd have a problem with it.

Since my engine is already done, the only thing I can balance now is the converter to the flexplate, is that right?

Also, I looked up the flexplate that you listed, and it says that is is for cast cranks.  I think my HP 440 has a forged crank, and would this flexplate still apply?

If the motor has a forged crank it doesn't need any external balance unless it has the heavy rods/pistons like the '70-'71 HP.

One more thing.  Should I let the shop pick out my tranny rebuild kit, or should I order one up from Hughes or somebody like that to make sure I don't get a bunch of cheap junk?

Again, you'll have to talk to them about that. You should have every right to ask them what parts they'll be using; if they're not into performance work and can't supply good quality stuff I'd take my business elsewhere.

[HeavyFuel]

Ok, I thought I had a forged crank, which I thought was stock for a 440 mag out of a 68 R/t. 

But, my converter has those weights on it, which means it is a cast crank and externally balanced, right? 

So now I pick up a good neutral converter and balanced flexplate from like B&M, correct?  Is the balancing standard on all of the converters, or do I need to know some stuff from it to order up the right flexplate?

My brain hurts.

[John_Kunkel]

The thin sheet metal weights on the outer periphery of the converter shell aren't for externally balancing the crank, they're for balancing that particular converter.

Crank balance weights are welded to the front cover of the converter and face the engine, if there are no weights there the converter is neutral balanced.