cracked flywheels, ideas!!

Discussion in 'Transmission' started by coupechamp, Apr 2, 2010.

  1. coupechamp Forum Member

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    hi all, had this happen to the flywheel last season, it's a Eurospec item. Problem is it was replaced with another, but from a different source. Just rebuilt the gearbox so thought while it's off take a look and see how things are. Well the replacememnt is now going the same way, it has a crack rotating around the bolt holes just like in the pictures.....the worrying thing is that this one has only done ONE race, some running in the garage and a power test last week since going in!!! Any ideas as to possible causes. I know theres a crankshaft damper out there, but this car is only 210hp!! anyway as always ideas welcome :thumbup:
    [​IMG]
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    [8(]
     
  2. danster Forum Addict

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    I thought this was all discussed in your previous thread as to the cause. If not look at the crank damper harmonics thread as to why this happens.:thumbup:

    Edit: the bolts have been slack on this one and you said previously that it was tightened up onto an already damaged crankshaft face.
     
    Last edited: Apr 2, 2010
  3. A.N. Other Banned after significant club disruption Dec 5th 2

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    There is a covering spreader plate missing I think - trying to find the part number.

    What does the flywheel weigh, and what were the bolts torqued up to?

    Were brand new bolts used the second time?
     
  4. coupechamp Forum Member

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    been looking for the post, not found, but saw the harmonics one! The current flywheel (same as old one) weighs 6.5kg's, it had new bolts and a plate, and was torqued to (if i remember right) 60Nm plus the extra turn. When the other one went it also lost the damper from the other end, and a solid one was found to replace it. Didn't like the look of the standard one for racing, as i thought it could go again, but hey, now look..[:^(]
     
  5. A.N. Other Banned after significant club disruption Dec 5th 2

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  6. coupechamp Forum Member

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    oh yes, brings back memories..[xx(]
     
  7. A.N. Other Banned after significant club disruption Dec 5th 2

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    The weight seems fine - nothing too lardy.

    What was Europec's verdict on the first flywheel?

    Ignore the second with the solid damper for a moment.
     
  8. coupechamp Forum Member

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    according to Jabba, who spoke with them they said it was nothing to do with them!! i then got one from TSR but when it arrived i then saw it was the same make, Now i'm not blaming anyone, as there clearly seems to be something going on, but it's annoying how it only did 1 race.... Need to look at a few things, like the damper, i know Bill does one, but also now need to source a good flywheel. :)
     
  9. A.N. Other Banned after significant club disruption Dec 5th 2

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    Usual buck passing, endemic in tuning.

    What make is on these flywheels?

    Some pics of the bolts you're using would be useful.
     
  10. coupechamp Forum Member

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    there stamped up EUROSPEC, standard bolts, could get pics up tomorrow, just popping out for a while :thumbup:
     
  11. Dave

    Dave *Very Smart* Pedantic Old Fart Paid Member

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    Look at how the washer face of the bolt has dug into the fasce of the flywheel, this will not happen due to torquing up.. Look at the crack, it is around the outer edge of the washer face.
    So, the centre of the flywheel is tight to the crankshaft, and the flywheel is breathing axially. i.e. backwards and forwards along the longitudinal axis of the crank.

    For some reason you are getting longitudinal vibrations. A crank pulley vibration damper is tuned to specific out of balance forces at 90deg to the axis of the crank. Is your crank floating backwards and forwards along the mains? Too much clearance?
     
  12. danster Forum Addict

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    IIRC from your previous thread, the first flywheel gave problems as the flywheel bolts came slack and as a quick fix this was rectified by re tightening the bolts then this did not last and resulted in the flywheel failure.
    If this was the case the damaged crankshaft / flywheel face was never really an ideal situation to assume it was anything to do with the actual flywheel.

    The engine has now allegedly had a new crank and a second new flywheel fitted so effectively a fresh start with the 2 undamaged surfaces between the 2 items.
    It has now done the same thing as the previous one.[:s]

    Can you be 100% that the crank was replaced?
    This is expensive as presumably the second crank is now damaged at the face the flywheel mates too.

    Doweling flywheel to crank, Rosten performance diamond impregnated shim, proper ARP bolts with shoulder. These are all options but the surfaces of the 2 components must be good to start with. I lap my flywheel to the crank with valve grinding paste to ensure a perfect mating surface. It is not just the bolts that hold and clamp the flywheel to the crank but the surface area of the 2 clamped components.

    Alternatively duff torque wrench!
     
    Last edited: Apr 2, 2010
  13. danster Forum Addict

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    If the bolts had been tight there would not be any wear under their heads, no?
    If they come slack then the flywheel wobbles and clutch release is pushing occasionally this may cause the forces you state though.
     
  14. A.N. Other Banned after significant club disruption Dec 5th 2

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    Where I've seen loose flywheels, there tend to be thread marks on the hole sides.

    Oval holes also.

    What can you guys see from the pics?
     
  15. Dave

    Dave *Very Smart* Pedantic Old Fart Paid Member

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    Quite right. So, if you did not have two flat faces mating, then the system would breath.
    If the two components are only touching on the inner diameter, then, what we see would happen. But, I still think it's axial vibrations, as the bores of the holes are not elongated.
     
  16. coupechamp Forum Member

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    see what your all saying. Definately new crank, infact complete engine was in a box waiting to go together. Jabba assembled it, the 1st engine is sitting at the back of my garage. As for movement length ways in the crank...!! Eurospec have just replied to my inquiry and want to know what sort of damper is on it...
     
  17. A.N. Other Banned after significant club disruption Dec 5th 2

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    They need to be given first and second occasion pulley dampers.
     
  18. coupechamp Forum Member

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    remember the pictures are of the 1st flywheel which was actually in two pieces...but together, the new one has a crack maybe three quarters way around bolt holes, and all bolt holes are still round, and theres no sign of the washer digging in effect, guess i caught this one a little earlier.:clap:
     
  19. Dave

    Dave *Very Smart* Pedantic Old Fart Paid Member

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    Vibration dampers are "tuned" to specific engines!
     
  20. A.N. Other Banned after significant club disruption Dec 5th 2

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    So the pic at the top of the thread is the first, which had a vibration damper?

    Best put some pics up of the second + both dampers :thumbup:
     

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