DI posted a bunch of pictures of different dampers in THIS thread. I would be very interested in some resolution to this issue. I must admit I have just installed whatever damper I had on hand without regard to the intended purpose of the damper. Plus, I just bought one of those NOS dampers off of eBay and put it on my brother's van, and now I am scared that it isn't the right one.

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Casually looking for a Clifford hyperpak intake for cheap.

I don't think I'd sweat it Reed, it's not like you are running a HP engine where that extra 8 oz, can mean a few bits of HP, or keeping the crank from vibrating under the abuse... On a "stock" application I've seen it go back and forth, the forged crank dampers are lighter (but the cranks are heavier) and conversely the cast cranks are lighter (depending on year, very light), and thus have heavier dampers in a variety of flavors... more than likely due to what's hooked to the other end (that 11" flywheel is pretty heavy compared to the standard flywheel).

-D.Idiot

OK, thanks for the reassurance. I'm still interested, though.

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Casually looking for a Clifford hyperpak intake for cheap.

I am sure there are some reasons behind the different dampers.....just like there are differences in exhaust manifolds.

My conclusions when I faced my assembled damper pile was that I wanted a neutral balance damper....in good condition .....that was sized the same as the flywheel/crank combo I used.

I ended up using a nice condition cast crank/auto trans balancer on my forged /11" clutch crank with 9 1/4" clutch flywheel.

It was the same size as a 65 3 speed manual damper.

I dont think you can get it wrong without a ton of ale.....and a shed full of Chevs.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Most of what I have seen with v-8s is that the Hipo dampers are larger, for higher rpm damping and in particular damping the vibration from high rpm downshifts with a manual trans. The floating high rpm is when the worst torsional vibration is seen. Marine engines really take a beating from this too.

With the oem dampers, it seems it is more a matter of capacity that tuning for certain rpm range. With an aftermarket race damper they are trying to get more power, giving up protection to get it, and I have heard of cranks breaking that probably would have been ok with a conventional damper.

I would not run a smaller damper than the factory used on a cast crank, but would not worry about using the larger cast crank damper on a forged crank. Having said that, I would avoid it anyway since it is heavier. If I was having forged cranks crack, I would try the larger cast crank damper. Has that even happened to anyone?

I would expect to see some front and rear main beariings with contact oe heat marks from the crank if this was getting close to being a problem.

The real question is how much overkill is there with the large damper on the cast crank, can you get away with the smaller damper??? I would try to save rotating weight somewhere else if I was not sure.

But wait, if the differences between dampers is the weight of the damper, why is it okay to attach one or even two extra pulleys to the damper? Logic would dictate that if the mass of the damper was the critical issue, then dampers for vehicles without A/C and/or power steering would be different from those with A/C or p/s or both A/C and P/S, since the pulleys for the accessories would add weight to the damper.

So, in addition to the above mentioned variations, shouldn't there have been different dampers for the options ordered? Seems to me that even if the factory produced different dampers for different crank and transmission combinations, any calibration was rendered pointless as soon as any accessory pulley was added. Especially when you consider the seven pulley dampers used in stationary power generators or forklifts. Methinks that beyond the placement of the timing mark, differences between the dampers might very well be moot.

Then again, I could very easily be wrong.

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Casually looking for a Clifford hyperpak intake for cheap.

Pulleys I've seen are bolted to to the center hub, not to the outer balance ring (outside the rubber ring), thus pulleys do not affect damper performance.

The mass of the outer ring and the stiffness of the rubber should be designed so that they absorb energy (resonate) at some harmonics of the crankshaft vibrations. The rubber will to some extent convert this absorption into heat, and some of the energy of crankshaft vibration will shift to the ring's vibrations (wigglings), which assumedly will not be harmed by the vibes.

I know a couple of "big boys" who have ordered custom dampers from ATI, and you need to tell them the weight of the crank and the engine type or crank type. These are guys spinning 6500+ RPM and seeing crank damage. I have never had the need to do this myself, and I would bet anything under about 4500 RPM (stock redline) doesn't much care.

Lou

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Home of Slant6-powered fun machines since 1988

Mike has a Fisher damper that he has used on every Slant motor he has run for the last 10 years at least, cast or forged crank.

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Official Cookie and Mater Tormentor.

ohhhhh. So the dampening is provided by the material OUTSIDE the rubber ring. Okay, that makes sense then.

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Casually looking for a Clifford hyperpak intake for cheap.

I think the Fisher and ATI dampers are more sophisticated and can absorb a wider range of vibration frequencies.

Lou

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Home of Slant6-powered fun machines since 1988

Hmmmmm :shrug:

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