[csbythesea]

I have a 1977 W400 (old dually airport fire truck).
Have new driveline, rebuilt brakes, diff, wheels balanced, tranny and transfer case serviced (checked out fine).

Still can't get rid of pulsing vibration eminating from motor/tranny/transfer case area at 3K rpms.

New to dodges....harmonic balancer shot?, heard something about differnet weights for different years of 727 (internal or external?)....any ideas or any one have the same problem?

Thanks, -Shawn

 

[mopar redneck]

First whats the motor? Yes it could be the harmonic balancer. I've had some people swap a 360 into something that had a 318 in it and use the same balancer. .... doesn't work. Could be a possibility.

 

[csbythesea]

It's a 440 that originally came with the truck.
I had the heads rebuilt, new cam, intake, carb, headers and distributor. Didn't touch the bottom end...but pulsing vibration at 3K was there when I bought it, just can't get rid of it.

Should I check harmonic balancer or weights (internal vs. external) on tranny first....which is easier/cheaper to replace?

-Shawn

 

[Rock Ape]

Is the vibration there if you just rev it up to 3k without the vehicle moving???I had a 396 chevy I bought that the guy put forged pistons in and didnt rebalance the crank and it had a screwed up vibration,but I could get it to do it without moving the vehicle....

I was able to decide it wasnt the trans by taking the bolts outta the converter pushing it away from the flex plate slightly and starting the car....still had a vibration......Rebuilt it with a balanced bottom end and it was fine....verify you balancer(if you can)first.

 

[Elwenil]

440s could have a cast or forged crank. It's possible that the harmonic balancer or flywheel/torque converter or both are for the opposite that the current engine is.

 

[BumpyDodge]

Check for missing balance weights on the converter and/or flexplate.

 

[Flyinwillies]

Definetly check the torque converter... If it has a thin harmonic balancer on the front it is externally balanced and there should be wieghts on the torque converter. thick balancer internally balnced no weights. I ran into the same issue on a BB dodge I bought had a new 440 (78) but had an unbalanced T/C. good Luck.

 

[Elwenil]

The thickness of the balancer is not always a good indicator. Read over this page at 440Source for more info on the various balancers:
http://www.440source.com/dampers.htm