thrust bearing failure

Discussion in 'PSI Superchargers Tech Questions' started by hydrotherapy, Mar 26, 2021.

  1. hydrotherapy

    hydrotherapy Member

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    Brad block ,lencodrive thrust bearing wearing on back side ,sent crank to marine crankshaft had repaired, checked flywheel run out ,dial indicated bellhousing to converter hub ,checked that the hub was .100 inside the bellhousing, drilled a .060 hole through thrust side of bearing in main bearing oil galley .After about 5 runs check bearing and it is worn about .008 ,also the crank is stranded and I have .008 end play with new bearing .I've tried both v and m bearings.
     
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  2. blitzkrieg

    blitzkrieg Member

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    Its the torque converter
     
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  3. TOL

    TOL Active Member

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    What type converter and flexplate?......
     
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  4. hydrotherapy

    hydrotherapy Member

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    Neil Chance billet nsx ,it has a billet steel no ring gear .LSC flywheel
     
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    Last edited: Mar 28, 2021
  5. TOL

    TOL Active Member

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    Do you measure your converter charge pressure?
     
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  6. Graham Brown

    Graham Brown New Member

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    Converter charge PSI x converter drive tube's square inches area = pounds force on the engine's thrust bearing ....... "unless" you are suffering severe converter ballooning without enough pump housing clearance and then the engine's thrust bearing force is huge. That problem will also show evidence of scuffing between the converter drive tube and the trans pump housing.
    BTW: The old SS cars with 3000+ lbs pressure plates had similar thrust bearing problems.
     
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  7. hydrotherapy

    hydrotherapy Member

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    I do measure the presure out of the cooler lines ,and it runs about 60psi on launch then in high gear it's about 40psi
     
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  8. Graham Brown

    Graham Brown New Member

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    It's preferable to measure the pressure on the inwards flow port because if there's any internal flow restrictions in the converter then the outwards cooler pressure could be lower.
    I've seen some converters with very shallow channels on the stator thrust washers and the restricted flow resulted in higher converter temperatures etc.
    Remember that pressure is a measurement of resistance to flow.
     
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  9. hydrotherapy

    hydrotherapy Member

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    So if I modify the valve body so I can use a transmission cooler when in the pits that should be the presure side that chargers the converter ,and I can put a presure sensor on the fitting on the outside of the case correct.
     
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  10. Graham Brown

    Graham Brown New Member

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    I'm not familiar with the Lencodrive hydraulic layout but it sounds good in theory.
    I'm assuming that you taking hot fluid from the pan and then pumping it through the external cooler system and then returning it via the new converter charging port ..... providing the returning fluid can only flow in one direction through the converter and not bleed back through the valvebody into the pan. This method would flush out hot fluid from the converter back into the pan and then go through the external cooling system again.
     
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  11. rb0804

    rb0804 Active Member

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    Yes. There’s a spring check in the converter feed circuit so if you wanted to push fluid through the converter via an external chiller you have to put a fitting in the valve body and route it outside the case. This could double as converter line pressure. When you log pressure on the out going side of the converter, it tends to drop off as the converter begins to couple and move away from torque multiplication. Be careful with the magnesium case as it’s tricky to drill and tap. In my opinion the Lenco drive valve body sucks, the way it regulates converter pressure is less than ideal. If I was to personally run one I’d make my own valve body. That being said lots of folks run pretty good with those things with minimal mods.
     
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  12. Graham Brown

    Graham Brown New Member

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    Whilst the converter is multiplying torque the stator is stationary and the fluid flow through the stator channels is not too messed up.
    As the converter reaches coupling speed the stator starts overriding so the channels are now spinning which could reduce flow through them and also reduce the exit pressure.
    Inwards pressure should stay ~ constant as its controlled by the valvebody but the flow volume could be reduced.
     
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  13. rb0804

    rb0804 Active Member

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    I can buy that, I just know that on the data log as the converter approaches couple at the top of the gear change the pressure is pretty low, when you shift and it goes back into multiply mode for a bit the pressure on the outlet side of the converter increases again and then begins to decrease again as slip decreases.
     
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  14. Graham Brown

    Graham Brown New Member

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    It's only a presumption, could be any number of reasons.
    Where does the returning cooler circuit fluid go in a Lencodrive, in most OEM's it's used for lubrication and the exit pressure is a consequence of converters inwards volume being greater than bearing leakages etc.
     
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  15. Moparious Maximus

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    I went through a similar issue with mine. Ended up being crank flex and to little thrust clearance. Is it also hard on #2 and #4 main?
     
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