M4 Shimming Issue

Discussion in 'Gun Building, Modifications & Repairs' started by rispoli, Aug 3, 2020.

  1. rispoli

    rispoli Member

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    Quick up to speed ive got shs 12:1 gears w a 28tpa motor. I got this “matrix m4 grip” off evike and i shimmed the whole gb real nice but i noticed it looked very odd with about 1mm of shims under all the gears. for example here is the size of shims under the gears

    BEVEL
    Top-.1
    Bottom-1.3

    SPUR
    Top-.1
    Bottom-1.0

    SECTOR
    Top-.6
    Bottom-1.0

    Seems very odd but sounds nice wen i spin the gears with motor. I go to close up the gb and the air nozzle will depress and stick in the gb binding between the shell and sector gear. Im assuming its bc gears are shimmed so high up but idk what to do if i try to drop em down then bevel gear will be very tight against pinion. im thinkin my grip doesnt let the motor sit evenly. any ideas? maybe i should buy another grip? what m4 grips do u folks like ive heard good things of ZCI basic grip
     
  2. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    How did you do your shimming test?
     
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  3. rispoli

    rispoli Member

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    individually by hand and alltogether by hand then motor + gears and contacts lettin the gears spin.

    im pretty sure its the shitty grip i have u can see the motor angled up (right side of shell)
     
  4. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    Please expand on by hand and all together. What was the final process on checking the shimming by hand and all together?
     
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  5. rispoli

    rispoli Member

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    Bakersfield
    i spin the gears by hand to see if they move freely. i spun the gears individually to remove side to side play and individually spin freely. then i install gears eith trigger contacts and motor w motor grip and spin the gears with the motor in and my lipo
     
  6. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    Okay...sounds like you don't "button" up the box when you test the gears.

    I find it rare that a gear needs more than .5mm in shims per side. Seeing 1+mm on one side is indicating you are not doing it right.

    Shim by the bevel and then Button up the box and spin the gears as set. Get 2 rotations...your good.
     
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  7. rispoli

    rispoli Member

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    thing is i do though i screw the box together on each gear when shimming then altogether to see how well they spin or for any play up and down. im thinkin the issue is the alignment the grip holds my motor, the pinion is angled up or to the right half of the shell causin me to have to shim the gears very high up
     
  8. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    That was the comment that I was hunting for:

    "...I do screw it all together..."

    Then you may indeed have a wonky grip.

    Matrix is an Evike House Brand...their parts are "not" top tier stuff.
     
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  9. rispoli

    rispoli Member

    429
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    Bakersfield
    Bumpin this so i can get some more help. ZCI grip came in alignment is better shell closes just fine tappet plate can move freely. Every single part in this shell is brand new. Now it doesnt want to shoot in semi maybe 1/10 shots itll shoot semi. Ive sanded the guides on the piston down slightly and ive sanded the guides on the shell about 3/4 of its original size. I couldnt get to the guides by the spring guide too much but its still sanded down about 7/8 its original size. Everything is shimmed well and here is the shims on each gear

    BEVEL
    Top-.4
    Bottom-1.1

    Spur
    Top-.4
    Bottom-.8

    Sector
    Top-.7
    Bottom-.9

    Does this seem shimmed too high where cutoff level is barely engaging the cutoff cam on the sector gear. Or the shuttle engages the contacts too early where the cutoff cant hit the shuttle? Please some help or thoughts is appreciated. Thanks
     
  10. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    I have never seen or performed shimming where I use over .4mm on one side.

    Your bottom shimming might very well be the issue.

    What bearing/bushing are you using. Care to post a picture of one half of the shell with them in?
     
  11. Beetlebz

    Beetlebz Well-Known Member

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    If the shimming was that far off how did he get the shell closed? Adding what, an extra 1mm+ in some cases to each gear id think would bind up those gears tight if the bushings were flush. Are we sure they're the right gears?
     
  12. Guges Mk3

    Guges Mk3 Well-Known Member Supporting Member Lifetime Supporter

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    That is why I want to see how the bearings/bushings are seated.

    Most are raised slightly, some are flush and on rare occasions...shallow...but that could be a shim issue in itself.

    You can close an over shimmed mechbox...the gears just won't turn...but his are "Turning".

    Nothing can be taken at face value without pictures.
     
  13. ma_airsoft

    ma_airsoft Well-Known Member Supporting Member

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    what method are you running on shimming? should be lifting the bevel gear to the pinion, not lowering it onto the pinion.