Harmonic Balancer suggestions needed

[Larry Callahan]

MotiV8r currently has an ATI 917780 harmonic balancer and it has come unglued.

http://www.summitracing.com/parts/ati-917780





Has anyone ever had a problem with one on a Gen 1 SBC?

Did I just get unlucky or are there issues with them?

[k7king]

I have one on my SBC and have never had an issue. I would contact ATI.

[71RS/SS396]

What do you mean it came unglued?
Do you mean the bolts came loose that hold the dampener to the crank hub? The bolts may not have been loctited
ATI is one of the best out there, you can buy replacement parts for them through ATI.

[Motorcitydak]

That is shocking, I would contact them and go from there. I got the feeling they are king of the hill for balancer's

[TheJDMan]

No experience with ATI, I have run Fluidamper for years. That said I would also call ATI as they are SFI certified and should not come apart like yours.

[Fuelie Nova]

I have run several of them with no problems. I am curious what unglued means also. They rebuild them pretty cheap and fast turn around. I have always bought blems off their eBay store for $199. Normally they have a small spot in the paint but have a new warranty.
Tom

[Larry Callahan]

Hmm. I will remove it and see if I can figure out what happened and let you all know.

[TheJDMan]

I gotta ask, 1st Gen SBC? When did you install a 1st Gen SBC? I thought Motiv8r was running an LS motor.

[Larry Callahan]

Gen 1 SBC. Dart Little M block with a Compstar crank.

It never had an LS in it but if I had to build it now it would.

[David Pozzi]

We had a truck with a knock up front. I found the balancer would move when I tugged on it. I assumed the balancer was cracked, it turned out the crank snapped through the first throw & front main. It was a stock cast crank, nothing performance.

[Larry Callahan]

We had a truck with a knock up front. I found the balancer would move when I tugged on it. I assumed the balancer was cracked, it turned out the crank snapped through the first throw & front main. It was a stock cast crank, nothing performance.

Don't scare me like that. LOL!

[CarlC]

That's funny David. My Bro-in-Law had the same thing happen on one of the family el Caminos. That guy was all thumbs and elbows working in cars.

[TheJDMan]

We had a truck with a knock up front. I found the balancer would move when I tugged on it. I assumed the balancer was cracked, it turned out the crank snapped through the first throw & front main. It was a stock cast crank, nothing performance.

I was told by Scat tech support that they do not recommend running an active harmonic balancer such as ATI or Fluidamper with their cranks because they have seen some broken cranks which have been attributed to those type dampers.

[Fuelie Nova]

What do they recommend?
Tom

[TheJDMan]

Scat recommends a conventional damper with a non-movable elastomer cushion between the hub and inertia ring like this one.

http://www.summitracing.com/parts/pf...make/chevrolet

[BBPanel]

Scat recommends a conventional damper with a non-movable elastomer cushion between the hub and inertia ring like this one.
http://www.summitracing.com/parts/pf...make/chevrolet

Any update on the damper failure?

And to followup with Scat recommendation - this is from one of their publications:
"Fluid, balls, springs, inertia rings with rubber O-Rings, etc. Can you balance a wheel on your race car if the tires are flat???? How
can your rotating assembly be balanced if to quote one manufacturer, “These units (Dampers) should not be on the crank
for balancing as the inertia weight may not be centered until the engine starts.” NEWS FLASH!!!! Centrifugal force will always take
the inertia weight off center no matter what RPM. Your assembly is never balanced. TELL TALE SIGN!!!! Metal transferred on nose
outside diameter and damper internal diameter . . . A fatigue crack starts. SNAP!!!! The crank breaks"

I thought the primary reason for a damper is to dampen rotating harmonics - now I suppose some of those harmonics is coming from an out of balance situation - but if the "conventional" damper is not perfectly balanced isn't it going to do the same thing? Seems like the ATI/Fluidampr is trying to dynamically offset those harmonics since they probably are different for every rotating assembly. Curious what ATI or Fluidampr would have to say about this.

[TheJDMan]

I'm kinda curious to find out more about this balancer subject. I have a nice Fluidamper and a conventional style Professional Products damper and I would really like to know which one I should use on my new under construction 383. For now I am inclined to go along with Scat's recommendation.

Larry,
Have you found out anything more on Motiv8r?

[Larry Callahan]

I haven't had the time to uncover the car and get to this yet. Maybe in a couple of weeks. I'm really hoping it's not the crank.

[71RS/SS396]

I'm kinda curious to find out more about this balancer subject. I have a nice Fluidamper and a conventional style Professional Products damper and I would really like to know which one I should use on my new under construction 383. For now I am inclined to go along with Scat's recommendation.

Larry,
Have you found out anything more on Motiv8r?

Steve, I wouldn't use the Fluidamper, they were originally conceived for low rpm diesel engines and imo are not good for gas engines. I've seen more than 1 broken crank from them, the fluid can turn to a solid mass inside which will result in a broken crank.

[Jim Nilsen]

I am currently running a Fluidamper 6 1/4" with my 383 gen 1 sbc and have had no problems. I was told that to run the lightweight aluminum flywheel I had it was recommended. Now it is hooked up to a flexplate and a button style dual disc 7 1/4" clutch and it is doing well there too. I would have gone with a larger damper but it wouldn't fit.
Make sure you check both the engine parts manufactures and the trans/clutch manufactures both and see what they say too.

Good luck and I will be thinking the best for you.