Crankshaft Dampers

Discussion in 'Drivetrain, Exhaust and Electrical' started by captdistraction, Dec 13, 2016.

  1. BigTaco

    BigTaco TMO Addict

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    Do you recall who you spoke to?
     
  2. 2012-Boss

    2012-Boss TMO Addict

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    upload_2018-11-17_13-48-16.png

    It looks like a factory damper to me with the dry sump pully bolted to the front. It definitely isn't an ATI.

    https://roushyates.com/engines/ford-mustang/

    Black Boss has a Roush built 5.2 in his new car. He does not have a dry sump. Maybe he will chime in with what balancer Roush used.
     
  3. wwilde001

    wwilde001 TMO Addict

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    The Roush built 5.0 dry sump motor in my car has an ATI damper. So far so good.
     
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  4. 2012-Boss

    2012-Boss TMO Addict

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    I should have said that I really don't think there is a problem with the ATI damper. The 5.0L Roush engines I have seen all had a ATI. I suspect that improper installation and / or the damper or damper bolt coming loose would eventually cause a failure.
     
  5. captdistraction

    captdistraction I am the breaker of things

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    I’m sure I wasn’t capable of installing it correctly, which explains the failure. Doesn’t explain why I wasted everyone’s time with failure analysis.


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  6. 2012-Boss

    2012-Boss TMO Addict

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    I sincerely apologize, that was not meant as a shot at you.I really was just stating that if something like that comes loose, it can eventually result in a failure due to unseen fatigue.

    For example, I found that one of my Howe ball joints had come loose early this summer. I tightened it back up. It sheared in two in turn one at Watkins Glen over Labor Day. I personally believe that the ball joint failure was directly attributed to it loosing torque earlier in the year.
     
  7. racer47

    racer47 All I got left is fast

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    I still think that capts motor was not balanced as good as it could be, which was no fault of his. These are production built motors, even the crate motors. They get what is commonly referred to as a "Detroit Balance". Which is not a balance at all. Its just that all parts are made to a certain weight. Some combinations of parts are good, some are not as good.

    Engine balancing is harder than most guys think. My buddy from high school now owns his own engine machine shop. He's scrapped plenty of cranks because they were not able to be balanced to racing tolerances. And not just stock cranks. He's had to send back brand new aftermarket cranks.

    On top of this, I sent pics of the crank failure to the head metallurgist at my work. He said it failed due to low cycle torsional fatigue. Which agrees with the theory of a poor balance.

    Stock rubber dampers really only work well at one rpm. Fluid dampers work less well at that same rpm but also add damping over a wider rpm range. If the crank has a known torsional vibration issue at a given rpm, lets say 7000 rpm, and Ford designs the stock damper for 7000 rpm, than you will not improve on that with a fluid damper. If you change to non-stock rods and pistons and wrist pins and actually spin balance the crank for these new weights, then maybe the peak torsional is no longer at the same 7000 rpm that it was stock. In that case, its possible that the fluid damper will work better than than the stock one. But without actually testing torsional resonances, we are all just guessing.
     
    Last edited: Nov 30, 2018
  8. Mad Hatter

    Mad Hatter Gotta go Faster

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    Just got my rotating assembly back from Balancing,,,.... All good and fine... But the OEM Damper was out a little and was left at zero.... That left a doubt in my mind if the extra wieght to one side was on purpose?? Should have I balanced my damper?? Just last minute jitters before starting the build.
     
  9. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    I'd think you'd want it at zero, but I've never adjusted one. How far out was it? Maybe check another 1 or 2 dampers.
     
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  10. Mad Hatter

    Mad Hatter Gotta go Faster

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    It was out by a gram or 2, the shop said it was within parameters but they left everything at zero.

    thanks, I will go worry about something else now.
     
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  11. 2012-Boss

    2012-Boss TMO Addict

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    Is this related to your post in the road racing forum concerning drilling a few small holes in the balancer as part of engine / crankshaft balancing? In that post you said that three small holes were drilled into the balancer as part of crankshaft balancing. Are we talking about the same balancer?
     
  12. Mad Hatter

    Mad Hatter Gotta go Faster

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    Sorry, yes the crank was balanced with three small holes and the Damper as well had three holes.
     
  13. 2012-Boss

    2012-Boss TMO Addict

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    Ok. The damper is supposed to be neutral balanced out of the box, but it is an OEM piece so it will not be perfect. Like your balancer, you can expect it to be off by a gram or two.

    Your machinist removed weight from your balancer to balance your overall rotating assembly. If you ever need to replace your damper, you will want to make the new damper match its current drilled ballance as part of the overall rotating assembly. The same goes for the flywheel.

    If everything was manufactured perfectly, there would have been no need to remove weight from the balancer. But, even if your balancer had been perfect, the machinist might have needed to remove some weight to offset something elsewhere in the assembly.
     
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  14. Grant 302

    Grant 302 OPM Spent: $587,402 Moderator

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    Been wanting to get this off my chest about the ATI damper and what I think went wrong with its use on @captdistraction 's engine. I just really didn't want to get in the middle of this subject earlier.

    First, there's been a LOT of finger pointing (not by Capt) at Ford and 'Detroit Balance', etc. There's also been somewhat an irrational disbelief that ATI couldn't have *anything* to do with the failure. I'd like to point out a few simple things that help *me* to believe that there was nothing wrong going on in the crankcase side of his engine. The first thing is that there wasn't a primary failure *inside* the engine. If there were issues with balance, I would expect a failure propagating from one of the fillet areas of one of the journals. Second, the failure was all the way out at the snout. So I don't see how a balance issue goes from inside the crankcase through the OPG and past the timing chain drive...only then to destroy the snout. Just doesn't make sense to me.

    So if we just look at the front cover items, there's the OPG, timing gear, and the ATI damper. So far, I haven't seen any reason to 'blame' the OPG, or the higher amplitude of forces and jerk coming form the valvetrain side...

    Deductive reasoning leaves one thing square in the bulls-eye.

    Okay, so what, Grant?

    I don't think the failure was really torsional as presented and argued. Sure, once a crack was formed, it was propagated by normal torsional stress and cycling from valvetrain events. However...the issue, I believe, is that the ATI does not have enough mass to damp the vertical forces and vibrations in bending on the crank snout.

    Or that's what Chris' pictures lead me to believe.
     
  15. bauern

    bauern TMO Intermediate

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    Has anyone used the 2018+ Coyote viscous damper? I haven't used one myself, just asking.
     
  16. Mad Hatter

    Mad Hatter Gotta go Faster

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    Hmm... DId not know the 2018+ came with a different damper!
     
  17. captdistraction

    captdistraction I am the breaker of things

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    The weights of all the 2011-2017 dampers also vary greatly. I don’t know the exact reasoning or how to select one for a given application


    Sent from my iPhone using Tapatalk
     
  18. Mad Hatter

    Mad Hatter Gotta go Faster

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    Looks like lots of things on the engine are all over the place..... Looking at the intakes, you can see that they have pretty big variations.. Not to mention oil passages on the block etc....
     

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