PSA: Harmonic Balancer (1 Viewer)

[mwebfj60]

Changing Oil...check that the crank nut is still there
Changing Belts...check for harmonic balancer wobble and check crank nut

I noticed recently my crank nut was MIA, noticed even more recently that my HB was wobbly. I happened to get lucky and catch it in time.

Hard to believe the crank nut could come loose and I'm not sure how long it was among the missing. A quick reach inside the HB at oil changes is now SOP for me.

Here's the slip key

 

[Output Shaft]

Holy crap! Yeah.... Definitely I'm gunna crawl under the front of the car and twist that nut by hand (fingers) just to make sure it's not loose... occasionally now too. I had mine off a couple years ago to change the cover gasket, and I guess there's no guarantee its gunna stay put even though it was torqued to spec. Wow.

 

[roadstr6]

Check not only the HB nut but the rivets on the pulley as well. Overtightened belts lead to their demise. The rivets sheared clean on mine and the pulley broke free from the HB. PO had the belts tight as banjo strings.

 

[CaptClose]

Wasn't there a thread on here a while back where a guy found a nut on the ground and couldn't figure out what it went to, so he just tossed it. Then he discovered a few years later that it was his HB nut? Or am I nuts?

Either way, I'll check mine after I have a quick nap.

 

[Spike Strip]

The elastomer sandwich that these HBs are, the rubber middle shrinks, cracks, dries out over 30+ years and the torque on the nut and rivets lessens. I've seen and read about a disturbingly large amounts of these HBs failing now with the things looking just like the pix above.

I bought a solid one from Oz, a few years ago and someday I'll replace my old one ...

 

[NeverGiveUpYota]

Wasn't there a thread on here a while back where a guy found a nut on the ground and couldn't figure out what it went to, so he just tossed it. Then he discovered a few years later that it was his HB nut? Or am I nuts?

Either way, I'll check mine after I have a quick nap.

Yup. That was @JamesR in GA. His was off 3 YEARS before it went wobbly. He and I spoke a bunch when I repaired my keyway.

 

[micruz60]

Gaawh!!
Good catch. There is a fella in PNW that does HB rebuilds, buried in a thread somewhere here.

 

[roadstr6]

I fixed my busted HB/pulley for about $5. I couldn't justify $400 for a damn pulley. My fix would be considered a hack job by many folks but FWIW, here's how I addressed the issue: First, I used a punch and knocked out what was left of the rivets. Next, I tapped the holes in the HB for grade 8 bolts and bolted the pulled back onto the HB. I used bolts that were long enough to get a nut on the back side of the pulley. I had to be extremely careful not to use bolts that were too long for fear that they would make contact with my timing cover once everything was bolted up. Once I determined that clearance was not an issue, I tack welded the bolts and nuts to the pulley and HB. Finally, I welded the pulley to the HB with three equally spaced 1.5" beads around the circumference of the pulley. I placed the finished product in my drill press and ran it on the highest speed to check for any vibrations or wobbles. It ran true. I reinstalled it and I've been running it for several months with no issues whatsoever. It runs true on the crank...truer than the other pullies do, actually.

In my way of thinking, the pulley is solidly bolted through the now threaded holes in the HB. If all the nuts came off the back, chances are the pulley would still be held firm against the HB by just the bolts. Counterpoint: If a nut falls off, it could mangle the timing cover. Counter-counterpoint: The bolt heads and nuts are tack welded into place. Barring some sort of major catastrophic event, they aren't going anywhere.

Welding the pulley to the HB was a difficult and potentially risky decision. I am aware that welding metal over rubber is not a great idea. That's why I only ran three small beads as opposed to running one continuous bead around the whole pulley. It didn't seem to affect the rubber at all. I never even had any burnt rubber smell. Nothing smoked, smoldered, bubbled or caught fire. I just wanted the extra security of knowing that if all else failed, the HB and pulley would remain as one.

I was worried about balance being an issue with the bolts and welds and all. It doesn't seem to be causing any problems. The pulley had obviously been wobbling and working itself loose for a long time. It had to have been out of balance while that was going on. My engine didn't explode. My crank didn't break in half. Nothing happened. The balance of a 2F rotating assembly is not great anyway. The crank is stout. Hell, the whole bottom end is built like a tractor. I honestly don't think I'll have any issues with my el cheapo HB/pulley fix. If I do, I'll let y'all know.

 

[Output Shaft]

DamperDoctor

Harmonic Balancer Rebuilding/ Repair
at Dale Manufacturing

(for others stumbling onto this thread)

 

[micruz60]

^^ there it is. I was remembering Dave, Don, Dick, ah yes, Dale!

 

[CaptClose]

Crawled under my cruiser and got a hand on the HB Nut. Feels secure to me. I'll keep a closer eye on it from now on.

 

[Spook50]

Something else for me to keep an eye on.

 

[mwebfj60]

DamperDoctor

Harmonic Balancer Rebuilding/ Repair
at Dale Manufacturing

(for others stumbling onto this thread)

That's a pretty good price considering what a new replacement costs.