Heard something today about using fluid dampners. I called Scat and talked to a guy named Bob, he said "do not use fluid dampners" they can cause the crankshafts to crack.

Then I talked to an engine builder in So. Cal and he said the same thing and that it wasnt just with Scat cranks.

They both suggested using performance rubber balancers instead of a fluid dampner.

Is this true?

 

That's new to me, but where there's smoke... I have heard of dampers that were undersized and shaved the crank when they were installed. I have no clue if the undersized dampers were unique to a certain brand, or which brand, if so. Don't take my never having heard of it, as a denial. I'll be watching.

RACE ON!!!

 

I really don't want to hear this. I have one that was on my Vortec crate motor and now about to put on my internally balanced 400. They cost too damn much to be tearing stuff up. I will say that there are certain brands that I will never buy, that alot of other people swear by.

 

Never had a problem with mine, used to beat on the mtor pretty hard. That was on a reground GM steel crank.

 

I've heard that rumor & I've also heard it refuted. My trans guy won't use anything from B&M, my motor guy won't use "The Rattler" for a dampner...sometimes I think it just comes down to personal preference & maybe the occassional bad experience whether or not it related to the part in question.

 

I used my Fluidampr on my cast crank in my 355, and it's now on my billet crank in my 388. I never heard of that happening, but doesn't mean it hasn't. Wonder if there was a different root cause

 

There was an issue about HB radius not being big enough to clear crank radius and therefore causing stress problem at crank snout. This caused crank to fail. Could be similar issue.

 

Hummmmm, I've got a nice little fluid damper hanging on the end of an expensive project I just finished. I'm hoping Smoked Tires is on track with his thoughts.......

 

Just put my dampner on last night

 

i'm getting ready to buy

 

Please elaborate Caboboy. The Fluidampr wasn't cheap when I bought it a few years ago and it's competively priced to the Rattler's and ATI's. I would never have put it on my new engine if I thought it was an inferior product and would cause costly parts to start breaking

 

I heard from an experienced cylinder and race engine builder, who's opinion I respect, that the fluidampr has broken crank snouts from being "too good" at cancelling out the harmonic vibrations. I had both an ATI and a fluidampr and chose to run the ATI after talking too him. He also told me (don't know if it is true) that is was based originally on a lower rpm application and was adapted to it's current use. The older fluidamprs are a lot heavier than the ATI's too.

Probably not as big a worry for guys running the big block crank snouts, but do your own research and come to your own conclusions.

 

I too hope it was something else because I'm using one also

 

I emailed Fluidampr over the weekend after reading through this thread. I wouldn't expect any company to come out and say that they have an inferior product, so take this for what it's worth.

-----Original Message-----

Hello,

I bought one of your 6.25" internally balance sbc balancers for a 355 I was running on the street. I have since built a custom 388sbc that I now have the balancer on.

I have been told that I should remove the Fluidampr from my engine because there have been cases where it caused the end of crankshafts to snap off. Is there any truth to this? I have mine on a custom Sonny Bryant billet crankshaft so you can see my concern being that this was a very expensive crank. My car is street driven with occasional trips to the strip and autocross each year. It is not uncommon for my engine to see 7,000 + rpms at times.

Your insight is imperative to my continued use of the Fluidampr.
Thanks.
Sincerely,
Mike


Mike, dampers do not snap off the end of crank shafts. Because our competitor has nothing good to say about his product, he can only knock the competition.

Sunny Bryant probably makes the best crank on the market so we understand your concerns.

Fred Roland
Fluidampr / Vibratech TVD
------------------------------------------------------------

Here is my 2cents on crank shafts snouts breaking off... If I'm spinning my engine at say 5,000+rpms and one of my rods break, wedging itself into the side of my cylinder. My harmonic balancer's weight is essentially like a flywheel at this point and the enertia is going to try and keep spinning, end result.... the weight of the flywheel snaps the crank snout off. I would expect this would be the case regardless of the balancer manufacturer. So to say it was the fault of the harmonic balancer, I'm not so sure.

BTW, did you hear how bad those CenterForce pressure plates are

 

i'm still ??????

 

I heard the same BS from a california race motor builder about "FluidDampers"

I pointed him to website that had done testing on all the major SFI rated Dampers. The ATI was the best dampening for over 7500 rpm motors. But it was just splitting hairs of measurable changes that only could be seen in electronic testing.

I've had "FluidDampers" on all of my motors for the past 14 years including 9000 rpm dragster motor. I've never had a crank or rods fail.

Just use the proper tools to install and remove them. Never. Never pound on the damper to get it on or off. Fluid dampers are an extreemely tight fit. I honed the interior with a brake piston hone and boil the damper in water for about ten minutes before spraying the crank snout down with WD-40 and sliding it on.

 

It would be nice to know what the root cause of any crank breakages has been. Is it from lower rpm torsional vibrations with corresponding larger displacements? Is it caused by bending loads on the crank snouts? Which balancer type and weight causes the smallest loads on the crank over the range of rpm's?

There doesn't seem to be any real data available from manufacturers to help make an informed decision - just marketing...

 

i like info

 

Yeah, what the Scat guy said concerned me a bit. But at the same time, with all the people using them without problems, Im wondering how much of what Scat and the engine builder in CA said has to do with personal bias.