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Question on running a lock-up converter without lock-up

Discussion in 'The Garage' started by Robert79K5, Jul 21, 2005.

  1. Robert79K5

    Robert79K5 1/2 ton status

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    okay so I have a nice 82 c10 with a fresh 700r4. It was my diesel doner truck but after getting the diesel out of it I decided to fix the thing up and toss a gas engine in there.

    I have been driving it around town only because I havn't ordered the kit from bowtie overdrives yet to make the lockup converter work with the gas engine.

    I commute 47 miles to work each way and I was thinking about driving it tomorrow.
    Will running it without the ability for the torque converter to lock up overheat the transmission fluid and/or hurt my transmission? It's just a half ton 2wd with small street tires so I don't think It will be under any kind of real load going up and down the rolling hills we have around here.

    FWIW I put a big cooler on it alredy.
     
  2. BigCountryx

    BigCountryx 1/2 ton status

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    A 3hr trip with a utility trailer toasted my 700r4 because my TC was not locking up. $1600 later, I wouldn't chance it.
     
  3. Blazr77400

    Blazr77400 1/2 ton status

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    You should be okay, I havent had my lockup working since I have had the trans in(since 2000). The temps could climb, but as long as you dont have a High Stall torque converter you should be ok.
     
  4. big jimmy 91

    big jimmy 91 1/2 ton status

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    My lock up started to screw up and my trans guy said I have 2 choices...

    Replace the lock up convertor ($$$$)

    Un-plug it and keep driving it with no problems other than loosing a little fuel milage

    This is what I did with mine , unplugged the lock harness and the chattering type vibe went away , but my rpm. went up about 200 or so on the hwy.
    (it was caused by the lock having a problem un-locking while in motion)
     
  5. 6.2Blazer

    6.2Blazer 1/2 ton status

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    I've always "heard" that running it this way would cause issues, and my dad had a late-90's S-Blazer that toasted a 700r4/4L60E at relatively low mileage (fluid was completely black) in which they found the torqu converter not locking up. After replacing the trans under warranty and fixing the torque converter issue he probably put another 100k on that vehicle with no issues.

    The only thing I don't know is how the converter not locking up causes that much more heat vs. a regular ol' non-lockup converter.........I assume something in the general design of it, but just not sure.
     
  6. Emmettology 101

    Emmettology 101 3/4 ton status

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    I've always heard dont run OD without the TC locking up or you'll burn up the clutches...
     
  7. 85mudblazin

    85mudblazin 1/2 ton status

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    Your gonna burn it up. That is all :(
     
  8. gmcjimmy90

    gmcjimmy90 Registered Member

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    as long as your gear ratio isnt lower than 3.73 no problem that is what a tranny shop told me. i ran mine like that for years until i finally put it on a toggle switch (just besure to turn it off before you stop.why not use the factory vacuum switch from the early 80's 350 lock-up
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Do a google search on 700R4's. I did awhile back while looking for line pressure specs, and noticed that one site mentioned specifically that the early 700's (up to '84 or so) will be toast if run without the converter lockup working.

    After whatever year it was, there were modifications made to the transmission that stopped that from being a problem.

    This is of course just info off the 'net, so take that with a grain of salt if you do find it. May have even been TCI's website.
     
  10. diesel4me

    diesel4me 1 ton status Premium Member

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    lock up dilemas.....

    My 81 G10 van has a TH350 with a lock up converter--when Ifirst bought it,I noticed it would not "lock up" at all-after I drove it 80 miles to my brothers house,I could smell ATF,and the torque converter was so hot it melted the plastic dust cover! :eek1: ...I THOUGHT I smelled plastic burning on the way there! :doah: ..

    My brother used to be a GM tech during that era--after some quick diagnosis,we determined the stop light switch had somehow gone out of adjustment,preventing the TCC from engaging!..(and my brake lights to stay on all night! :doah: )..after we fixed that,it was fine for the 40,000 miles I put on it afterwards--but I have always feared the tranny would croak on a long trip after that.

    .I did drive it to NY several times,and to Nashville TN!--no problems at all!...I'd reccomend a LARGE cooler,and for you to at least hook up a manual switch to let it lock up--700R4's are more fragile than the TH350's--they dont like not being in perfect condition and are fussy about the TV cable adjustment--even if its off slightly the tranny wont last long.. :crazy:
     
  11. R72K5

    R72K5 Banned

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    i never run lockup in my 80s th350 with C and they are just fine, same with the 350c in my 81 pickup, no problemo whatsoever at all, its not plugged in or anything, switch gone,
    (i dont even care or worry about it, i dont need lockup with 2.73 gears lol it already freakin idles on highway speeds, i need deeper axle gears liek 3.73 REALLY bad, i get no RPM at all ever but the truc will book pretyt damned fast for having crap 2.73 in it though., i guess the old 350 is stornger than i think, hum,.., maybe ill break a U joint, lol.)


    the 81 th350c has no overheating issue and has fluid that is perfect red clean

    so i dunnno about this,,.


    but... in 700r4's, hmm ...who knows..

    seems like its all opinions/gamble really..

    but if its nice and fresh and sinc eits 700r4 then personallyt id leav eit parked and drive soemthin else tomrrow, really.,

    good luck
     
  12. Robert79K5

    Robert79K5 1/2 ton status

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    Thats exactly whats going to happen. Im not a gambling man so Ill just putter to work in the ole s10 tomorrow untill I get around to ordering the kit that I need to do this right.

    Thanks for all of the opinions and first hand stories guys. :waytogo:
     

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