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Should my flex plate flex when I bolt up torque converter

Discussion in 'The Hokey Ass Message Board' started by mmtoyman, Jul 8, 2012.

  1. mmtoyman
    Joined: Jul 9, 2006
    Posts: 49

    mmtoyman
    Member

    I'm putting a TH350 behind a 283 and there is about a 3/16 gap between the flex plate and torque converter, that when I bolt up the two you can see the flex plate flex. Its the same flex plate and converter, the motor/ crank is the only variable.The converter spun freely before trying to bolt then back up. Any help or suggestions or do I have to pull the motor out??
     
  2. ibarodder
    Joined: Oct 25, 2004
    Posts: 222

    ibarodder
    Member

    A gap of 1/16-1/8 inch is normal, when the flexplate to convertor bolts are tightened, the flexplate will bow backwards slightly and hold the convertor against the crank.
     
  3. landseaandair
    Joined: Feb 23, 2009
    Posts: 4,385

    landseaandair
    Member
    from phoenix

    Did you make sure the crank didn't have a pilot bushing in it? All the ones I've done fit tight.
     
  4. slddnmatt
    Joined: Mar 30, 2006
    Posts: 3,671

    slddnmatt
    Member

    make sure if the torque converter has a drain plug, or two for that matter that they are lined up with the wholes in the flexplate...
     
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  5. while there will be some gap withe the convertor fully seated in the front pump, you should be able to pull the torque convertor forward right up to the flexplate without any bolts. if the flexplate is bending to get them tight to each other that is not right. there must be something wrong like landseaair suggested OR maybe there is a burr keeping the snout of the torque convertor from slipping into the end of the crankshaft. i always trail fit the snout of the torque convertor into the crank
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 44,337

    squirrel
    Member

    Also make sure you put the flex plate on the correct way, not backwards.
     
  7. mmtoyman
    Joined: Jul 9, 2006
    Posts: 49

    mmtoyman
    Member

    I thought it should have slid right up also, but I DID NOT check the crank for a pilot bushing, slipped my mind. So now I'm going to try to get a hold of the guy I got the motor from, to see what trans he was running. Hope its this simple, but that means the motor and trans gotta come back out. Shit!!!
     
  8. ^ ^ ^ Here's your answer! ^ ^ ^

    That flexplate should NOT flex or be pulled into place.

    If you start that thing up like that you'd better keep your feet away from your tunnel or you will be a much shorter man.
     
  9. tfeverfred
    Joined: Nov 11, 2006
    Posts: 15,796

    tfeverfred
    Member

    Never seen that before.:confused:
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 44,337

    squirrel
    Member

    that's something you'll see on older Fords.
     
  11. Sumfuncomet
    Joined: Dec 31, 2011
    Posts: 579

    Sumfuncomet
    Member

    Excellent advice above, I have seen the drain plug in some converters hit the flex plate unless they were indexed to clear, the other bit of advice about bench fitting all the parts together ..before..trying to bolt it all together in the car is excellent advice, also be sure to pour trans fluid into the converter snout before installing it, you do not want converter spinning dry waiting for the transmission pump to fill it. Lentech Transmissions and TCI have some good advice on line.......go slow, think twice, get good advice...good luck
     
  12. The convertor should rest easily against the flex plate without having to be pulled tight with bolts, sounds like the flex plate may be bolted on backwards. Those old Ford convertors with the drain plugs and studs were a major pain in the butt.

    Good luck
     
  13. mmtoyman
    Joined: Jul 9, 2006
    Posts: 49

    mmtoyman
    Member

    Update: The motor/trans is back out and apart, to discover that the 283 crank has only a 5/16 " recess in the rear of the crank, while the 350 crank has a 5/8 " recess, along with the snout of the converter being 5/8 " long, thereby preventing the flexplate and converter from mating up by 5/16". Has anybody run into this before, I talked to 3 SBC people before I ever started this project, and noone knew anything about any mating issues. So do they make a TH350 converter for the earlier motors that has a shorter snout, do I explore the possibility of a custom made converter($$$$), or am I back to square 1 looking for another used motor for this project.
     
  14. If you've still got clearance so that the converter isn't bottoming on the trans pump you could run spacers between the flexplate and the converter - just be sure you've got enough clearance.
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 44,337

    squirrel
    Member

    sounds drastic, but you coud pull the crank out of the engine and have the pilot hole machined deeper by a shop with a good sized lathe.
     
  16. nutajunka
    Joined: Jan 24, 2007
    Posts: 1,466

    nutajunka
    Member
    from North Indy

    I would double check everything that the other members meationed, because I have pulled alot of powerglides off 283's and replaced with turbo 350 and 400's with know problem.
     
  17. lippy
    Joined: Sep 27, 2006
    Posts: 4,226

    lippy
    Member
    from Ks

    Or get the correct converter. I wonder if you could machine the end of the converter. Lippy
     

  18. Exactly. The automatic crankshafts were bored for the torque convertor snout, but the manual transmission ones weren't. I ran into this once in the late 70's on an earlier SBC swap. They since changed.
     
  19. 383 240z
    Joined: Oct 28, 2007
    Posts: 429

    383 240z
    Member

    If he set the converter ALL the way in, the proper procedure is to pull the converter to the flexplate, then bolt it up. Keith
     
  20. tb33anda3rd
    Joined: Oct 8, 2010
    Posts: 15,289

    tb33anda3rd
    ALLIANCE MEMBER
    1. Connecticut HAMB'ers

    nothing wrong with using spacers as long as the converter does not hit the tranny. 3/16 will clear. i can not remember the vehicle, or the swop i was doing but i had to do just that and did not have a problem.
     
  21. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,094

    d2_willys
    Member
    from Kansas

    What year 283? If 57-61 then you could have a stick, Powerglide, or Turboglide crank. If you didn't already know, each one used a different pilot bearing!

    Mount the engine on an engine stand, and remove the crank and have the crank machined for the converter hub, as Squirrel suggested.
     
  22. thorpe31
    Joined: May 4, 2011
    Posts: 166

    thorpe31
    Member
    from nor-cal

    The crank was cut for a Turboglide, Powerglide or manuel transmission. There is the manuel stick pilot bushing (1.094 od x .592 id x .750) and then 2 others to convert a Powerglide (1.065 od x .592 id x .750) or Turboglide ((1.709 & 1.00) od x .592 id x .650) to a manuel transmission.
     
  23. mmtoyman
    Joined: Jul 9, 2006
    Posts: 49

    mmtoyman
    Member


    Swapping a Powerglide for a TH350 would not cause this issue, however,
    I believe the the root of my problem is that the 283 was an original stick shift motor from a 66 el camino and the crank was not fully machined for the converter to fit. It is not an issue of reversed flex plate, drain plugs in converter-it has none, pilot bearing in the way, or just being stupid. I am checking into a custom converter being made with a PG front section,and TH350 rear section. I have the PG front converter half, to trial fit tonite after I get home from work.
     
  24. tommyd
    Joined: Dec 10, 2010
    Posts: 11,322

    tommyd
    Member
    from South Indy

    If it's only the length of the converter snout thats the problem then I would machine the converter snout or hit it with a grinder to shorten it. If it's not a high horsepower deal what could it hurt?
     
  25. You should be able to fell the bush if there is one by moving the converter back. Its easier to drop the box and remove it and if it doesnt have a bush sand any sureface rust etc from the crank and converter spigot and hand fit. Its just as easy to do it right as to do quick temp job and you will sleep better knowing that. Best of luck. JW
     
  26. Commish
    Joined: Jan 9, 2010
    Posts: 379

    Commish
    Member
    from NW Ok

    I never run it to that in any of the swaps I have done over the yrs., but if it was mine I would go with the thinnest spacers I could get by with and run it.
     
  27. Dyce
    Joined: Sep 12, 2006
    Posts: 1,835

    Dyce
    Member

    I would either grind the convertor to fit the crank or use washers and space it out. I've seen enough flex plates crack to tell you not to pull it up with the bolts. You can't hurt the convertor by grinding the snout down that far. If you have a lathe with enough swing chuck it up and cut it that way.
     
  28. d2_willys
    Joined: Sep 8, 2007
    Posts: 4,094

    d2_willys
    Member
    from Kansas

    Hmmm, you say you have a stick crank. How is the PG converter hub going to fit in the stick crank, unless the PG hub is shorter than th350?

    If you go with custom converter, then you are restricted to custom converter. Why not just remove crank, have it machined for deeper bore and reinstall? That way no restrictions to using readily available converters.

    And the best part: The engine gets new front and rear seals.
     
  29. Jimv
    Joined: Dec 5, 2001
    Posts: 2,927

    Jimv
    Member

    Why not just drill the crank out to size!!Its not rocket science & just go up in steps( drill size).Its so close to center that its not going to make a rats ass about balance or anything.
    Get a calipers and just keep checking.
    Like always everything appears to be a project.Its usually not
    JimV
     
  30. Oh my !!! I was an engine builder on V8s with 400 plus SBCs in the eighties, just do what you got to do as its yours and have to live with the fix you choose. Best of luck. JW
     

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