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guess what - 200 MILES AND ANOTHER BROKEN FLEX PLATE!!!

Discussion in 'The Garage' started by scrappyk5, Jun 12, 2003.

  1. scrappyk5

    scrappyk5 1/2 ton status

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    i pulled my tranny( 700r4 ) , back in febuary cause it was leaking. ( this tranny has been in for about a year ),. soo
    i replace all the gaskets and the torque converter . good to go for about 4 months . then i get a bad vibration about
    two weeks ago , and find out my flexplate is broke. so i pull the tranny and put in a flexplate . now two weeks later and only about 200 hundred miles , and i am underneath the truck checking on a squeeking and i take off the inspection cover and look up and W.T.F !!, the flexplate is cracked . am i doing something wrong ? is something bent ? when i bolt up the tranny housing to the
    engine block , there is a gap of about an 1/8 " between the flexplate and the torque converter which is
    good , and i tighten the three bolts in sequence when i bolt up the converter.. sooo i ask W.T.F ?
     
  2. Don

    Don 1/2 ton status

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    Are You using O.E.M. Flexplate's?
    Is the engine/flexplate balanced?

    T.C.I., Summit, Jeg's, B and M, all make heavier, thicker flexplate's to help cure this problem. /forums/images/graemlins/eek.gif
     
  3. chevyracing

    chevyracing 1/2 ton status

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    Could be a bad thrust journal in the engine causing the crank to move fore and aft. When the crank travels rearward it is putting stress on the flex plate as the torque converter seats. I would check the endplay on the crankshaft.

    Another thing I have seen, and this is not taking a blow at anyone, but the flexplate was mounted backwards. It will bolt up and the torque converter will usually bolt up to it okay as well, but it will not allow the torque converter to seat all the way, causing the torque converter to "float" on the shaft putting strees on the flexplate as it does so.

    John
     
  4. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    I don't understand this?
    [ QUOTE ]
    when i bolt up the tranny housing to the
    engine block , there is a gap of about an 1/8 " which is
    good

    [/ QUOTE ]
    There should not be a gap between the tranny and the block.
    Is the crack starting from the inside or the outside?
     
  5. doctor4x4

    doctor4x4 1/2 ton status

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    Great call Storm Trooper i caught that statment my self i dont think he has the torque converter on the 3rd step in the pump housing
    as ur bang on the tranny bell housing and engine should be very tightly against each outher and hes dame lucky if he didnt crack the tranny housing also
    well that's it from here
     
  6. Don

    Don 1/2 ton status

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    I think He's referring to the distance between the converter, and the flexplate, when the trans. and engine are already bolted together.
     
  7. scrappyk5

    scrappyk5 1/2 ton status

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    yes , i am sorry i wrote that wrong. after the tranny and
    block mate up , theres a gap between the torque converter
    and the fleaxplate of about an 1/8 to a 1/4 inch.
    is it normal that when i tighten the three bolts , its
    kinda like hard , another words the torque converter doesnt
    just come sliding forward to the fleplate with ease.
    everything spins normal after all is bolted up.
    the flexplate is bolted on the crank the only way it can be,
    so its not backwards.
    man i am stumped /forums/images/graemlins/1zhelp.gif
     
  8. Blaze

    Blaze 1/2 ton status

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    Damn, Mike. You are just having bad luck with your trucks. Sorry to hear about it, bro. /forums/images/graemlins/frown.gif
     
  9. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    I've never had that problem. The TC should mate with the plate easy. Make sure you double check that something isn't holding it out away from the plate causing undo stress on it. Where are the cracks starting????
     
  10. Fubeca

    Fubeca 1/2 ton status

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    [ QUOTE ]
    theres a gap between the torque converter
    and the fleaxplate of about an 1/8 to a 1/4 inch.
    is it normal that when i tighten the three bolts , its
    kinda like hard , another words the torque converter doesnt
    just come sliding forward to the fleplate with ease.

    [/ QUOTE ]

    Sounds like this is your problem. On all the trannys I've done, the torque converter slides right out to touch the flexplate. It sounds to me like the flexplate is being bent as you tighten the bolts. /forums/images/graemlins/ooo.gif
     
  11. slimlynn1

    slimlynn1 1/2 ton status

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    [ QUOTE ]
    yes , i am sorry i wrote that wrong. after the tranny and
    block mate up , theres a gap between the torque converter
    and the fleaxplate of about an 1/8 to a 1/4 inch.
    is it normal that when i tighten the three bolts , its
    kinda like hard , another words the torque converter doesnt
    just come sliding forward to the fleplate with ease.
    everything spins normal after all is bolted up.
    the flexplate is bolted on the crank the only way it can be,
    so its not backwards.


    [/ QUOTE ]
    It sound like the hub of the new torque converter is hitting the crank. Where did you get the new torque converter. Is it a remanufactured one or is it a new one. Make sure that it will bolt on without hitting the crank or you will have this problem again.
     
  12. Calclips

    Calclips 1/2 ton status

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    That sucks man... I had a blown tranny in my truck and I "fixed" it... but it didn't work. I know how frustrating it is to keep having to pull trannys... took me 3 trys to finally get one in there that works.
     
  13. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

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    It was not mentioned anywhere before, but are there also problems with the starter too? Does it lock up at times? I had a cracked flexplate On my Nova and kept haveing problems with the starter locking up. Actually it was the starter gear was getting thrown over the ring gear and getting stuck so it could to retract. After a couple of starters we started looking at the rest of the parts. Small blocks can sometime need shims to get the right clearance to between the ring gear on the flexplate and the starter. Without the proper clearance damage can be done to the flexplate. The shims are available at any major parts store in the Help! section and they install easy enough without taking the whole starter out, just loosen the inner bolt and take out the outer bolt and slide the shim(s) in.

    We found that my flexplate was cracked and it was the cause of my repeat starter failures. Also if you are not useing a mini starter and are useing the original style starter motor, you may want to look for a brace that was used by the factory back in the 70's. The brace bolts to the block and then to the rear of the starter (opposite end from the nose cone). With a heavy factory starter, all of the weight is on the nose and could use the extra support the rear bracket provides.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    The torque converter MUST be able to slide forward until the lugs are touching the flexplate. Check to make sure that the center of the torque converter isn't preventing the lugs from touching. If the lugs don't touch the flexplate, then you need to change your torque converter again. /forums/images/graemlins/frown.gif You either have the wrong one for your application, or the one you have has ballooned. (The latter is pretty rare behind stock engines).
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    Just an in-general question, but what if the engine has been swapped out or rebuilt (or just the crank) and it was originally a manual trans motor with the pilot bearing still in place?

    Not sure if that's even a possibility, but only reason I can think of short of the converter "nose" being messed up.
     
  16. doctor4x4

    doctor4x4 1/2 ton status

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    Hey scrappy
    Glad 2 here i didnt read it wrong :-)
    Anyway but i gotta say u still might have the flex plate on backwards as it will fit either way ( from my experience) but there really is only 1 way that it should be
    or like the 1 person said your torque converter is f ' up from the start ya mabe got a bad 1 from the factory
    or and heres a new 1 are u sure the flex plate ya have on ther is the proper 1 for that motor ?? check your casting nus 2 be sure what ya got and look at 2 of em at the store when ya go 2 get ur new 1 2 be sure they ar the same
    cause flex plate and torque converter should bolt right up smooth like butter :-)
    Good luck and let us know what it was
    /forums/images/graemlins/usaflag.gif
     
  17. DUKSRULE

    DUKSRULE 1/2 ton status

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    Here are some more thoughts

    1) Did you torgue the new flex plat to the crank or just german torgue it up there? If the cracks are coming from the center that could be it.
    2) Check that the alignment dowels are sticking far enough into the tranny from the motor. If they don't go into the tranny far enough it will be able to move a little bit. Also are you using shouldered bolts to mount the tranny? If so make sure the shoulder or even the bolt itself isn't bottoming out on the block making you think the tranny is tight. I use a bolt with like a 1/4" shoulder to mount the tranny. Any movement of the tranny on the bloack will flex the flywheel and then crack it.
    3)Does the converter slid forward that 1/8 inch to mount to the flex plate? Or ar you drawing it in with the bolts? If it doesn't go all the way forward your flex plate will bow when you put the bolts into the converter. This will case the cracks around the converte bolts.

    On another note I would steer clear of the heavy duty parts to correct the problem. If you use them then it will be stressing something else. It is best to fix it the right way and be done.
     
  18. scrappyk5

    scrappyk5 1/2 ton status

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    all these are great thoughts i will take into consideration

    for starters , the engine is in a s15 ,( thats why i posted in the garage section ) . i changed out the 2.8 motor for a crate 3.4 almost two years ago. now i did buy a aftermarket cheap flexplate , but it was for a 2.8 ( i wasnt thinking ).
    so i called the dealer and it is a different part number and the 3.4 flexplate is thicker . soo , i will buy one monday from the dealer and try this again.
    now when i install everything probablt next weekend when i dont have my son and have more time, i will make sure of the following :
    1. the tranny seats against the block tite
    2. the flexplate is torqued and bolted correctly.
    3. the converter does slide forward to butt against the
    flexplate.
    4. make sure the nose of the converter does not cause the
    converter from mating flush with the flexplate.

    am i covered ?
    oh by the way , the converter cracked near the center .
    and also the thrust bearing was replaced when i did allthe seals.
    thanks everyone
     
  19. doctor4x4

    doctor4x4 1/2 ton status

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    only thing ya for got was 2 say a good prayer first :-)
     

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