Harmonic balancer help. Please?

[Topsykidd23]

I have a 1974 260z with a 2.6L and the harmonic balancer has 2 pulleys and the inner pulley has separated. I was wonder if anyone would know what different years of balancer/pulley would fit the 74 motor. Im just now starting to search for parts.

Thank you.

[Diseazd]

All cranks 70-83 are the same dimensions and you should be able to inter-change dampers. The timing marks are in different locations depending on what motor they came from.

[Topsykidd23]

Thank you Diseazd that helps alot. Now all I have to do is look for parts. Hopefully the timing marks are on the pulley that didnt separate.

[jmortensen]

The ZX pulley is larger and heavier. I don't know what the others look like, but I would suggest you try to find an early one, just for the weight savings. Original dampers are getting pretty old at this point, but I don't think there are too many inexpensive aftermarket options. If you have trouble finding one, I'd bet my brother-in-law has a couple. You can email him at mat m at m2differentials dot com.

[Diseazd]

You can still buy a 79 (early 280) damper new from Nissan......it is about the same weight as the early Z's. Seems to me they were about $150.00. The single groove performance dampers from MSA are cheaper, but they fit so damned tight that if you're not lined up just right, they can drive out the woodruff key. I would go with the 79 280 damper (the timing mark can be filed into the damper). All IMO. Guy

Edited July 14, 2011 by Diseazd

[Jeff G 78]

I'm in exactly the same boat on my 260 race car. Is there any way to tell if a damper is good by looking at it? I have several spare engines that I can steal parts from, but I don't want to waste my time only to have another 35 year old damper fail mid-race. Does the ZX damper have extra pulleys for power steering, or is it still a two row? I'd rather not spend $150 on a damper for a $500 race car, but I also don't want to break a crank when an old damper fails.

[Diseazd]

Jeff....I would assume you could compare the TDC mark on a damper to a good one to see if the damper has failed. Don't know how else you could test it.

[Darrel]

Rebuild the old one.

http://www.dalemfg.com/harmonicbalancer_018.htm

[Jeff G 78]

Thanks Darrel, I was trying to remember the name of that company. I assumed they would be more expensive than that. If I don't have any good used ones, I'll go that route.

That's what I was thinking too Guy, but I wonder if there's a way I can check not only if it has already slipped, but if it's near failure and about to slip. My October race is 25 hours, 25 minutes and 25 seconds long, so I'd rather not be nearing damper failure at the start of the race. :paranoid:

[beermanpete]

I have seen 2 types of dampers for the Z engine.

The earlier type has 2 belt grooves. Both are the same diameter and width. Both are part of the damper ring. There is a group of timing marks that line-up with a bolt-on pointer on the passenger side of the engine.

The later type also has 2 belt grooves but 1 is larger in diameter and wider than the other. Also, the larger groove (closer to engine) is part of the damper ring. The smaller groove is part of the hub. There is a single timing mark that lines-up with a series of lines cast into the timing cover on the driver's side of the engine.

Some cars have a third pulley groove that is bolted on with 2 small screws. This seems to be for the air-injection pump used in the emissions system.

As Diseazd said, the cranks are all the same and all dampers are interchangeable in that regard. The differences seem to be in the pulley sizes and the timing marks.

[240260280z]

The single groove performance dampers from MSA are cheaper, but they fit so damned tight that if you're not lined up just right, they can drive out the woodruff key. Guy

Gee that is a bummer. I am about to reassemble a motor in 2 weeks and that part has been waiting patiently in a box for 3 years.

[Diseazd]

Jeff.......I have 2 brand new comp single groove dampers. They were so tight I was afraid to "drive" them on. I had my machine shop hone them out to make an easier fit. I'll be happy to mail you one free of charge (half the prize money for winning your race) if you pm me your address. It'll have to be mailed when I get back from ZCON though. Let me know if you want one. Guy