Harmonic Balancer Broken

[Zed Head]

The fracture surface looks oily.  And not seeing how you get that "pointer" groove without some wobble.  Could be that the damper rubber is gone.  Who knows.  We need to know.

[Terrapin Z]

There is oil spray on the surface too, and most notably the out of true groove. I would venture to say that had been broken for some time while it was a runner. 

Hopefully mine will get him on to the next stage. 

[DadAndLadZ]

46 minutes ago, Zed Head said:

Could be that the damper rubber is gone.  Who knows.  We need to know.

Here's a video I just now shot! 

 

Also now that I have a used one on the way (thanks to @Terrapin Z!), does anybody know who rebuilds these? The only company I have seen advertise this service is Godzilla Motorworks out of Texas and they charge $350.

Edited August 31, 2022 by DadAndLadZ

[KenFirch]

You could call Damper Dudes in Anderson, CA and see if they do Z dampers.  They did a SBF one for me a couple years ago for $78 + $15 shipping.  Or Damper Doctor in Redding, CA.

[DadAndLadZ]

2 minutes ago, KenFirch said:

You could call Damper Dudes in Anderson, CA and see if they do Z dampers.  They did a SBF one for me a couple years ago for $78 + $15 shipping.  Or Damper Doctor in Redding, CA.

Dang, thanks!

[zclocks]

21 minutes ago, DadAndLadZ said:

Dang, thanks!

I have used Damper DR in Redding Ca. They did a great job , but cost was $225 with shipping. You have to supply the damper as they mostly do American cars. 

[Captain Obvious]

Couple thoughts:

After watching the video, you can see that BOTH sides of the Woodruff key shot have cracked. You can see the rough grainy surface of the cast iron on both sides of the groove (or where the groove is supposed to be). One side is a huge chunk missing. Other side is a smaller piece missing. It would be important to find all the loose metal.

The little rubber ring and round spring are what's left of your front oil seal when it disintegrated. So when you say "The seal itself looks fine"... That would not be the case.   The little rubber ring is the sealing lip that has been sheared off, and the round spring is the garter spring that is supposed to provide the pressure on the back (wet) side of the seal.

I'm coming back to thinking it was broken upon installation and has been cracked for some time. Surprised there was still enough of a seal to keep it from spraying oil out at an impressive rate, but I guess it depends on just how much oil is flinging around behind that pulley. Maybe the oil slinger was doing exactly what it's supposed to do.

Woof.

Last thought is about having that balancer rebuilt... I'm no expert on the topic, but I don't think you're going to find a company to fix that. The companies that rebuild those things specialize in vulcanizing rubber and balancing the result. I would not expect them to make new parts, just rejoin old parts.

[Racer X]

I agree with the Captain regarding the history that leads to the removal of the damper, and about getting this damper rebuilt. The part that mates with the crankshaft is broken, and cannot be repaired. The parts are cast, then machined, and replacing the broken bits, and machining back to OEM condition would be a expensive and difficult job, if it could be done at all.

Get another damper, and install it correctly. 
 

What does the crankshaft snout look like? It needs to be smooth and shiny, without any defects or damage, and the keyway should be in good condition, no burrs or irregularities. The damper should slide on easily without any force, and also be easily removed, without the need for tools.

 

[Zed Head]

Things will get more clear when you get that used damper and test fit it.  The woodruff keys are available.  There is a recent thread on the forum from a guy who was having trouble getting the damper on without pushing the key out of its slot.  Some good details in it, I'll see if  can find it.

I wonder if those seal parts that you found aren't from a previous seal.  That's a 280ZX damper on a 260Z.  Somebody's been in there before.

Here's the part number for the woodruff key.  #10.  Search the part number and you'll get lots of hits.  Your local auto parts store might even have it.

http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-240z-260z/piston-crankshaft

[Zed Head]

Can't find it but this one is interesting - 

 

[DadAndLadZ]

@Captain Obvious and @Racer X I have sourced a used replacement from @Terrapin Z and will be sending it in for refurbishing.

I got a strong light in there and bumped the engine around with a remote starter to inspect the end of the crankshaft and don't see anything obviously chewed up, will get in there and do a thorough cleaning/inspection before proceeding any farther.

And yeah, someone has done A LOT of updating on this car in the past... The balancer is a later model, the carbs are from a 240Z, there is a five-speed transmission(!)... I wish I knew who had done all this work years ago just so I could pick their brain about what else lies in store. LOL... 

[Zed Head]

I found the thread I was thinking of.  It's actually just a portion of a longer thread.  The weirdness starts at post #24.