Road Runner Nest

Hey guys,

My 400 has a fairly noticeable harmonic engine vibration. It's worse on the highway and makes driving it there really uncomfortable. Is it possible it has the wrong balancer? I seem to recall seeing liquid filled balancers available at one time, anyone know about these? I had another one of these cars years ago with a 440 and that one vibrated too. Anyone else run into this?

Thx for any help.

Greg

Are you sure it's from the engine? Does it make the noise when the car is not moving? In 71, Chrysler issued a TSB about transmission tunnel noise. Also, could be rear end/gear noise....my 0.02

Yeah, it's engine. If I rev it up in park I still get the vibration. Monkeys have worked on the car throughout it's history, and I'm still in the process of backtracking through a lot of what they've done. I have no idea yet if it's even got the right balancer.

Could be a possible Torque Converter issue too.

If you have a cast crank converter on a steel crank, or the other way around. Or just a bad internally damaged converter.

If you have a cast crank there should be 2 large weights on the converter. The steel crank version varies a bit. Usually no weight, or a really small one.

Something I was unaware of until I got my Runner. I had always thought that all 400's were cast crank, but there was a 400HP version in 72 that used steel. So... it pays to check closely.

Yes, that thought had crossed my mind too. I have a rear main seal starting to leak, so maybe I'll use the opportunity to examine the converter as well. Anything's possible on this car, after all the last owner put a huge amp in the trunk but neglected to fuse the power feed wire, which melted itself to the underside of the old carpet and fried quite a few wires under the dash. He also filled the A-pillar rust holes under the vinyl with plumbing foam. This car deserved better (and got it, thankfully).

72 74 400 4bbl 4speed are steel crank

72 -74 400 atuo are cast crank

Are we sure only 4 speeds got the steel crank?

The friend who sold me my Runner has a yellow factory auto with 400 and the air grabber and it was a steel crank car as well. Anyone else know of steel crank auto cars?

Mine is one now.

Shown above is damper #3614374, used on 400's with external balance cast cranks, /or automatic trans application 400 4bbl or 2 bbl(applications with 400 engines manual transmission applications used forged cranks.) I

3614371 72-75 std forged