torq converter vibration

[biginch=bigfun]

I need a little help here. I've been trying to rid my car of a vibration that comes throught the floor. after a lot of work starting in the rear; wheels/ tires, axle bearings, drive shaft, freshly rebuilt trans, having the drive shaft rechecked for balance. I think I might have it pin pointed to the torq converter...

When I first put this combo together the entire engine was a 1978 440 and that is what stock converter I bought for the car. Then I had total cam failure which sent metal through everything. Rather than have the crank turned down & polished a friend gave me a good 1975 cast crank.

After diagnosing what i believe to be a balancing issue in the crank/converter area I went online to search out other stock converts. I found they offer a seperate convert for 73-76 that have two small weights out toward the ring gear and another for 77-79 that has the big "butterfly weight mounted inward near the flex plate mounts. The butterfly style is what I currently have. I'd like to know if I am on the right track because I have never messed with the cast crank 440s before & i dont want to drop the tranny & buy a different convert. on a hunch!

Ideas & insight wanted!!!

thanks in advance,
Louis

 

[khryslerkid]

The majority of cast cranks are externally balanced. Requiring a balanced front crank pulley, balanced flywheel and balanced torque converter. I would think you have to match up your components to the correct crank that you are using. A chart with corresponding part numbers could be a start...

 

[biginch=bigfun]

Thanks Khryslerkid. Cool avatar too.

I had an overly simple understanding that all steel cranks are internally blanced & all cast cranks used the same external balance. But I'm starting to think there are different balancers & torq converters depending on the years.

 

[khryslerkid]

I'm thinking maybe the same thing. I was hoping that someone with more experience in these combinations would chime in.

Are you saying that your torque converter has the weights on it?

And are you using the front balancer from your old crank?

 

[biginch=bigfun]

Yes, a weight balancer from the 1978 on a 1976 crank. The converter is the stock reman. I originally bought for the 78. It has one large butterfly weight minted closer to the center of the converter instead of two small weights out toward the ring gear.

 

[sleepar]

Once you find the correct components for a rotating assembly harmonic ballancer to converter pistons rods etc. Have the entire assembly ballanced at a shop. They Bob weight and spin it up and then you're ballanced do it for 8500 rpm even though you may never see that rpm. Buying parts and putting them together with out this is taking a huge chance on several companies and go the extra mile.

Have all the pistons adjusted to weigh the same as the lightest one to .001 grams
That's the $50 version of 2¢ worth

 

[biginch=bigfun]

Thanks sleepar. But there is no way I'm gonna spend the time & money to tear down & balance a stock cast crank engine. I think I'd rather use this as an excuse to buy a stroker kit!

Thanks again to the two of you that replied!

 

[biginch=bigfun]

Hey just wanted to share what I've learned recently. 1978 & 1979 cast crank 440s DO have their own harmonic balancer. It is called a bullet nose Because of its tappered edge lead toward the counter weight. These cranks also use a different converter that uses a single large weight instead of the normal "two small weights".

So now I have to find the other style of cast crank balancer & buy another torq converter. In theory all should be well after that! lol

Hopefully this situation will be of use to someone else who wants to use a cast crank 440.

 

[transman]

Here's a bit of a run down for you.
1977 up 400&440 engines used an 11" diameter converter that had a single 120 gram weight on the back (ring gear side) that was triangular in shape.

1973 to 1976 400&440 used both an 11" & 12" converter with two small retangular weights on the back.

In 1972 Chrysler used the 12" converter only.

All of the above are for 400 & 440 engines with a cast/forged crankshaft.

Engines with a steel crankshaft used converters with no weights, other than converter balancing weights that are welded to the side of the converter, not the back half.

All of the above information is for factory STOCK applications only.

Hope this helps.

transman

 

[khryslerkid]

Hey just wanted to share what I've learned recently. 1978 & 1979 cast crank 440s DO have their own harmonic balancer. It is called a bullet nose Because of its tappered edge lead toward the counter weight. These cranks also use a different converter that uses a single large weight instead of the normal "two small weights".

So now I have to find the other style of cast crank balancer & buy another torq converter. In theory all should be well after that! lol

Hopefully this situation will be of use to someone else who wants to use a cast crank 440.

Now you're on the right track!