Community thoughts on fluid damper

[dvw]

The only way you'll know if it's a perfect fit is if it's measured. We are talking .000X press. Can you measure to .000X accurately at home? This would be micing the crank (.000x readout). And then measuring the dampner bore with a tool like a Sunnen rod hone machine or dial bore gauge (.000x readout). If not, you don't know if it fits correctly. Have I done it like that? Yes. Did it work? Yes. Was it correct? Who knows. Can't blame failures on the manufacture if the part installation was suspect. In my case, my Fluidamper cracked and leaked. Why? It was sized correctly. It was also used when it was purchased. So who knows why it failed. Just because you can pound it on doesn't mean the fit is correct.
Doug

 

[Wietse]

It all comes down to the tolerances given for the application.
The damper (regardless what type) for these series crank have a "light interference" fit, which requires additional light force by some means. (pressed, heat shrunk, etc.)
If the nominal size would be, say, 1.000", the shaft can tolerance can be 1.000" +.0005" which means the shaft will measure anywhere between 1.0000" and 1.0005".
The size for the damper bore, with this fit could be 0.9990" + .0005" so you have a guaranteed interference anywhere between .0005" - .0015".
With this one can be tighter than the other but that is inevitable with said tolerances but are acceptable as per manufacturer.
I am sure Chrysler has a set tolerance for this and normally aftermarket manufacturers will follow these as well.
Sometimes different material selection requires a review of tolerances due to thermal growth etc. that need to be taken in consideration.

 

[QuebecRollin]

Yeah right, 'cause y'know - if one's bad then they all must be bad !!

View attachment 1308896

You cherry-picked a piece of what I said to respond to which really is not fair.

My full comment included that this was a known issue at that moment in time and could possibly have been corrected since.
I can’t confirm the current quality of fluidampers because I have not used one since.
My issue was on an original 60k mile crank that had the OEM damper swapped to the fluidamper.
As you can see from the more recent posts in this thread, aftermarket dampers attempt to be within a tolerance range. In my situation (and others at the time) they where being produced with a bore that was larger than the max tolerance.
That to me is an engineering mistake which could and did cost end users a great deal of money and time.
I’ve built 100’s of cars in my career and although it doesn’t happen often I have run into issues with over-sites in even the best aftermarket parts.
Fitment issues are the most typical type of defect in aftermarket parts.
Unfortunately for something in the rotating assembly it’s not acceptable.

 

[Gunner1]

These were the hot ticket in Nascar for a short time. Then everyone dumped them and went back to elastomeric dampers. I believe that the ATI is right now the one I see most. If I remember right you can buy tuning kits for them if you have the ability to read orders of vibration on your dyno.