1973 RoadRunner 440 Harmonic Balancer Issue
 

Hello All:

I have a bit of an issue I am hoping you can help me with. I have a 1973 Road Runner with a 440. I recently had an issue where the cooling fan made contact with the radiator which destroyed my radiator. I replaced the radiator as well as the fan clutch and water pump.

Now here is where the real issue comes in to play...

I noticed that the harmonic balancer was a bit wobbly. Not terrible, but I was able to notice that it was a bit off kilter so I began to investigate. I found that the center bolt in the middle of the harmonic balancer pulley was "hand loose". I was able to spin it by hand. I grabbed my trusty impact and was able to slightly tighten, but then noticed that the bolt would tighten and then strip out and then become loose again.

At this point, I haven't pulled the balancer b/c I am not sure what I am about to get myself into. This is my first mopar and I am not completely familiar with the interworkings of the mopar engines.

How do I begin to troubleshoot this issue? Is it as simple as the threads in the crank shaft are stripped? Is there anything else to check? A harmonic bal key or anything else?

Thanks !!

4440RR1973

Glad you caught the loose balancer, the bolt might be the wrong one,assuming it's a cast crank,the bolt should be 2 1/4" long. There should be a key on the crank. The balancer should be a snug fit on the crank. I would get a new bolt first and try that.

good luck,john

Thanks John, I will start by checking out the bolt. I am really hoping that somebody just through the wrong bolt in place.

Do you have any additional info about the correct bolt? Corse or fine thread?

Bolt is 3/4-16 ,I forgot to ask if it was a stock damper or aftermarket?

john

I believe it's a stock damper. Thanks!

whats the correct size bolt for the balancer- anyone know?

crank bolt
 

The link shows the crank bolt 2 1/4 long 3/4/-16 US thread. You may get licky and find the bolt only is damaged. I have repaired issues like this by using the next size bigger metric bolt. tou will need to drill and tap the crank. I think the next size will be M20x1.5
http://www.jimsautoparts.com/mopar_p...rankshafts.htm

I would like to say thank you to this thread. Did a DA thing last night and stripped the first two threads on a 440 crank, which I would have never thought I would do. Went looking on google to find thread and pitch which refereed me back here.... Who knew, so thanks. Just to broaden this issue for someone else down the road. You can find a tap for Mopar cranks at Summit, the part number is: AAF-ALL11068 and the link is: http://www.summitracing.com/search/P...?Ns=Rank%7cAsc

Hopefully this will help someone when feel like I did and hit ohhh $&!t button like I did.

AGAIN - Thanks