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6.2 / np465 question

Discussion in 'The Garage' started by rustywagoneersdotcom, Sep 1, 2006.

  1. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    Good Afternoon, Folks.

    New here, first post, first thread, etc.
    The 700 in my diesel Sub laid down again, and I am fed up. Pulled apart an 84 light 3/4ton (9.5 14b - 4.10's)
    Swapped axles, 2 inch lift, 36's and swapped in the 465 / 208 combo. (light duty, family hauler camping type rig, not psycho rock crawler).

    Anyone else find after doing similar that the diesel shakes the cr@p out of the 465 (lots of gear noise at idle, quiet on the road)
    If so, what did you do about it? Change idle speed? Dual-Mass Flywheel? Nothing?

    any info appreciated.
    I would have thrown this in the diesel section but I have 4 kids and NO money...

    peace
    Dave
     
  2. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    beuller?
    beuller?
    beuller?

    anyone?
    anyone?
    anyone?
     
  3. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i did not notice any gear chatter - did almost the exact same swap into my blazer - 6.2/465/205/14bff/d44. sorry. is your flywheel new? did you have a flexplate which was balanced to your engine previously? how's your harmonic balancer? i don't know why that would happen at idle - perhaps if it's coming off of idle you have u-joint problems? can you further define this:

    maybe that will help.
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Noisy at idle could just be a bad throw-out bearing...

    Rene
     
  5. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    new T/O brg (full clutch set) completely silent with clutch pedal depressed.

    gas 350 flywheel, balanced to match the flexplate which came off the 6.2 / 700 combo. changed ring gear to 6.2 ring gear (after finding out the hard way that 6.2's use a 10-pitch /139 tooth ring gear versus the gasser 12-14 pitch / 168 tooth...

    when i say 'shakes the crap out of the 465' i mean, it is like the countergear is bouncing back and forth as the truck idles in neutral. imagine the input gear rotating faster each time a cylinder fires (positive pulse) and slowing at the next compression stroke (negative pulse)

    there is no vibration, no shaking that you can feel as the engine runs, it is just a LOT more noise out of this 465 now than when it was in the gas pickup which was disassembled.

    thanks for the input so far, any more also appreciated.
    peace
    Dave
     
  6. diesel4me

    diesel4me 1 ton status Premium Member

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    hmmmm...

    I was under the assumption no other flywheel ,gas or diesel,would bolt up to a 6.2???....thats what I've read anyway!..I thought only a 6.2 or perhaps a 6.5 one would fit...I have no clue whether the diesels are internally or externally balanced..I know the 400 sb and 454 are externally balanced,and will shake like a hula dancer with the wrong flywheel (or harmonic balancer) on them!..

    I don't know about your vibration problem,but I do have a friend with an 87 C30 ramp truck I drive sometimes--it has a SM465/6.2,and I don't notice it vibrating that much--more than a gas motor would,but not enough to be annoying or make you think there is something wrong with it.. perhaps your bellhousing is misaligned a bit,causing run out in the mainshaft?..:crazy:
     
  7. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    the 6.2's are definitely externally balanced...
     
  8. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    And definitely use their own specific flywheel...

    Rene
     
  9. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    no shaking at all, perfectly smooth.. flywheel has same bolt pattern as SBC and BBC at crank flange, gas and 6.2 use same diameter pilot bushing, etc etc etc. this flywheel was balanced to this engine, and the ring gear was changed to the 6.2

    it is 100 percent externally balanced.

    the problem is that the 465 is noisy at idle, in neutral. if the trans had been noisy in the gas truck i would say it was the trans, but then again, i wouldn;t have stuffed it in this one...

    say you have the label specified 800 rpm (or whatever rpm) idle... the engine, measured by the minute, is indeed making 800 revolutions... but the instantaneous velocity will spike 'up' at each firing impulse. this trans acts just like the countergear is being tossed forward at each impulse and as everything rotates the countergear is using up the backlash in the teeth, 'rattling' from drive side to coast side of the input gear teeth...

    anyway... it appears that no one using this combo has experienced this condition so far...

    thanks for the input, folks.

    peace
    Dave
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    My SM 465 had roughly 300,000 miles behind a 350 before I swapped in a 6.2 and bolted it up, and it acted no different and was not noisier in any way. That SM 465 after spending 3 years behind my 6.2 is now in Colby's truck behind yet another 6.2 and I'm sure Colby will chime in on whether or not it is noisy behind his. I don't think it is.

    The 'velocity spikes' you mention are much stronger with a diesel, however even at 600 rpm I'd say those spikes are so close together that they shouldn't be noticeable. 600 rpm = 10 revs per second = 40 spikes per second (4 cylinders fire per revolution)

    Rene
     
  11. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    once again, thanks for the input... i was afraid no one else would have had theirs act like this... i guess i will change it to 85-140 and make sure i have a spare in stock, just in case this thing is indeed grinding itself apart...

    peace
    Dave
     
  12. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    At this point I'd be suspecting a bearing, if the old oil is silvery looking there probably isn't much point in using a thicker oil...

    Are you running 90W now?

    Rene
     
  13. u2slow

    u2slow 1/2 ton status

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    The input bearing is a common item to replace on a SM465. That said, I have never 'needed' to change one. I run 85W140 oil in mine with the 6.2L. I've never found a 465 to be exactly what I would call quiet though.

    The correct 6.2L flywheel weighs at least 50% more than a 350 flywheel. I wonder if there enough weight there to properly dampen the velocity spikes.
     
  14. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Well the SM465 is a rock crusher trans so that means it has straight cut gears so you always here at the very least a definative whirr from it. It is easiest to hear it at idle, at least for me.

    The engine I have in my truck now is 305 from an auto Firebird and all that was done was swap the flywheel from the junk 350 to the 305. But I would be sceptical that you can use a gas fly wheel with a diesel. I think the fly wheel is your problem.
     
  15. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Only first and reverse are straight cut, the rest are helical...

    Rene
     
  16. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Wait, I thought they were all straight cut? :dunno:
     
  17. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Not the greatest view, but you can see it here.

    [​IMG]

    Rene
     
  18. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Better view...

    [​IMG]


    And, it looks like it's just reverse that is straight cut...

    Rene
     
  19. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

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    Wow that is informative. :D

    Thanks ;)
     
  20. rustywagoneersdotcom

    rustywagoneersdotcom Registered Member

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    thanks folks. I could definitely see a heavier 'wheel being a lot of help.

    i will have to try to find a REAL 6.2 flywheel, instead of my homemade one..

    85-140 is a fair amount quieter... the stuff that i topped off with 90 wt may have been slightly thinner, judging by the rate at which it came out of the gearbox. BUT no shiny, flaky, silver, etc, so i think all is (relatively) well.

    peace
    Dave
     

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