Fluid Damper

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Well they do get them wrong. I have had a few occasions where the dampener will not fit the crank snout.
 
Bewy said:
Well they do get them wrong. I have had a few occasions where the dampener will not fit the crank snout.
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LOL...that’s not wrong either. They have a specific press fit they want so the bore comes undersize so it can be honed for proper press fit. Not every crank has the same diameter snout. I’d rather the bore be undersized and have to hone it than have the bore be some nominal dimension and not have enough press.

Too much press and the damper can fracture at the key slot. Too little press and the damper is less effective.


Unless you had one where the bore in the damper was too big to start with. That is no bueno. I’ve seen guys use stud and bearing mount Lok-Tite to correct that issue and you can see the fretting between the cap and the block is exponentially worse.
 
Little late to the party, but there's a bolt on option. March performance 10151 crank pulley has the correct offset for the early fluidampr/SM/CAT/etc. It doesn't require any shimming, but it's single groove only, so WP/ALT only.

I also had an issue with the pilot diameter being too short, I had to take mine apart and put it in the lathe to bore it out
 
TurboGLH said:
Little late to the party, but there's a bolt on option. March performance 10151 crank pulley has the correct offset for the early fluidampr/SM/CAT/etc. It doesn't require any shimming, but it's single groove only, so WP/ALT only.

I also had an issue with the pilot diameter being too short, I had to take mine apart and put it in the lathe to bore it out
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Have you used that pulley? Because I have several FD and not one is a 3/4 inch offset and that’s what the March pulley is.
 
yellow rose said:
Have you used that pulley? Because I have several FD and not one is a 3/4 inch offset and that’s what the March pulley is.
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Sure have, it's on my motor now. To be fair, mine is the SM knockoff, but my pulley alignment with the water pump was good.

I didn't think about the issue until I had the balancer in hand, once I had it mounted I took my measurements and got right around .750. I was going to use a 69 earlier pulley and shim the pump pulley out when I found the March pulley.

IMG_20200905_163047.jpg
 
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TurboGLH said:
Sure have, it's on my motor now. To be fair, mine is the SM knockoff, but my pulley alignment with the water pump was good.

I didn't think about the issue until I had the balancer in hand, once I had it mounted I took my measurements and got right around .750. I was going to use a 69 earlier pulley and shim the pump pulley out when I found the March pulley.

View attachment 1715698703
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Interesting. I’ll measure my stuff again when I get home but the chicom knock offs were only .610 offset and the FD’s were .585 IIRC. I think the OE damper was .980ish and the chicom measured 1.5xx something. I have it written down at home.
 
volaredon said:
I've thought about a fluid style damper but don't know enough about them to spend that much on one.in the past when I have had a bad damper I've headed to the junkyard and gotten my replacement
But as luck would have it they don't have a single forged crank slant 6 in the yard right now.
So I sent that one in and a 318 one for my son to go on his internal balance 408
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a B damper will fit a slant. But good luck finding a B/RB in a boneyard these days. It will stick out like 1.5 inches more though.
Bewy said:
One wonders how these dampener companies can get these measurements soooooo wrong. They are just simple measurements....
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I dont think they get them wrong as all their production is highly (probably 100%) CNC automated. I think its user error in understanding how tight these need to fit. Snout shape/eccentricity of 50 year old crankshafts is probably all over the board too with prior balancer hammered on or installed dirty. If you hone out a balancer to fit, you may be defeating the design of the fit classification for harmonic transmission from crank to damper. Question: how does tooling sharpness affect CNC production? Is the cut/material measured or is the tool depth measured? I'm thinking the latter but there has to be a QC step to determine if the cut is accurate?
 
I recently went through the damper offset problem when I installed a Speedmaster fluid damper on my SB. I used a 69 and earlier crank pulley that is 3/4" shorter than the later style crank pulleys. The power steering pump pulley lined up fine, the water pump needed a 1/8" shim. The longer crank bolt I sourced from a Fastinal Supply.
 
Pishta,
Not all dampeners are interference fit, like Mopar. Some like Pontiac just slide on. They are kept tight by a very tight crank bolt, torqued to 160 minimum. Some aftermarket Pontiac units are tight & will not slide on. Poor QC, so the aftermarket does get it wrong...sometimes.
 
Bewy said:
Pishta,
Not all dampeners are interference fit, like Mopar. Some like Pontiac just slide on. They are kept tight by a very tight crank bolt, torqued to 160 minimum. Some aftermarket Pontiac units are tight & will not slide on. Poor QC, so the aftermarket does get it wrong...sometimes.
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You have to check with the manufacturer. I know, for a fact that FD doesn’t make a slip on damper. Even Pontiac. They are press fit and there is a spec for it.
 
The inside diameter was to tight with my damper. The machinist had to hone it to fit.
 
Is this one of the new Fluidamprs that fit properly? I bought it from Fluidampr in January 2020.
DSC_1042.JPG
 
TurboGLH said:
Show us the other side, if the front face has a recess, then it's the newer version, if it's basically flat, it's the old one.
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Yeah, I just realized I posted the wrong side. Here you go. Recessed.
DSC_1043.JPG
 
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