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700r 4 tranny question

Discussion in 'The Garage' started by scrappyk5, Sep 15, 2003.

  1. scrappyk5

    scrappyk5 1/2 ton status

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    if the torque converter lock-up doesnt work , will it
    lead to early tranny failure ? even though there is no signs of the tranny overheating ?
     
  2. outlaw612

    outlaw612 1/2 ton status

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  3. scrappyk5

    scrappyk5 1/2 ton status

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    sorry to ask , but why?
    just curious /forums/images/graemlins/confused.gif
     
  4. heavy4x4

    heavy4x4 1/2 ton status

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    It will create extra heat, thus shortening the life of the tranny.

    When my converter unlocks on the interstate, I can literally watch my tranny temp needle climb.
     
  5. 88Silverado

    88Silverado 1/2 ton status

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    For many many years trannys did not have lockup converters.
    Run a temp gauge and measure the fluid temp in the pan.
    Most trannys can safely operate into the 200-210 region.
    Above this it starts to degrade the fluid and problems can occur. You can run without lockup but you will need to be more aware of the temps and watch the fluid for signs of overheat.
     
  6. Chris_T

    Chris_T 1/2 ton status

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    You will get a lot of extra heat, and you also lose a lot of the performance of the OD. I had a wiring problem on the trail and had to drive home without the lockup. I can tell you I could barely tell the difference between 3rd and OD without the lockup. I also could see the difference on the tranny temp guage, but it was OK with my cooler. Having the convertor lock wastes a lot less energy from the engine. It's simple to wire and worth the effort.
     
  7. Emmettology 101

    Emmettology 101 3/4 ton status

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    I spoke with Rossler Transmissions about this(they built my tranny and deal with alot of the big names in drag racing) They advised against running in OD without the lockup. They said it burn up 4th... I asked if I could run it a short way with it and then go ack to 3rd and they said they would shift it like that and to make sure the convertor locked up when it shifted into OD. You can get some aftermarket kits that will lock up the convertor at certain speeds soo you can use OD or you can get a convertor made to lock up on its own so you dont need the add on stuff. Rosslers do something internal on the tranny to engage the lock up if you do away with the ECM.
     
  8. 88Silverado

    88Silverado 1/2 ton status

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    The heat in the tranny is caused by converter slippage. Normal converter stall is around 1800 RPM's.
    Yes, Lock-up removes the slippage and is more efficient but it has nothing to do with OD. Art Carr performance trans doesnt recommend lockup on his setups. I dont see how you can damage 4th or OD if the converter isnt locking up? . You can tow all day in 3rd without the converter locked up, and theres no reason you cant have it shift into OD without the lockup, the converter is slipping, not the clutches. Whats not good is the trans shifting back/fourth between OD and 3rd, this is where the clutches get worn. As long as the temps are below the 210ish area, it should be OK.
     
  9. scrappyk5

    scrappyk5 1/2 ton status

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    well i do ask out of curiosity becouse i dont think mine works. i have a tranny cooler , and i have also heard a
    million times not to tow in (OD) and i have also heard not to cruise around town with the tranny in (OD) , becouse it will lock in and out at low speeds.
     
  10. Chris_T

    Chris_T 1/2 ton status

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    Not cruising around with the tranny in OD is a load of bull. Most stop and go driving isn't going to have the tranny hunting for the right gear around 3rd/4th. Of course if you find yourself in a situation having the tranny hunt you can juist shift it into 3rd to go up that hill or pass that grandma (or whatever).

    That said, I sometimes do shift mine down to third if I'm driving backroads right around the shiftpoint, mostly cause my convertor doesn't unlock in OD unless I switch it and it bogs on hills. For short segments at highway speed I will manually unlock the convertor on a steep grade, but then lock it right back up.

    Not towing in OD is to prevent the aforementioned heat buildup caused by the trans up and down shifting. Another reason I've heard is that the transmission pump spins 30% slower in OD. Then again, my '94 says tow in 3rd, my dad's '98 says tow in OD. My 72 with the lockup convertor wired to a switched power source will pull no problem in OD as long as my speed is sufficient.
     
  11. 88Silverado

    88Silverado 1/2 ton status

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    Theres several different opinions on this.
    In OD, the pump is running 30% slower and therefore does not move the fluid fast enough to be cooled properly.

    Also some state in OD, GM bypasses the cooler. I cant verify this.

    If lugging in OD with OR without lockup, you generate more heat. One is from converter slippage the other is due to load on the system when its locked up. Just because the converter is locked up doesnt mean it wont get hot. Load will generate heat. Since the pump is running slower, the fluid cant be cooled efficiently. Therefore run in 3rd or (D) for more fluid flow and pressure and reduce the load on the system.

    Again, heat is the problem, the fluid starts to oxidize when it gets around 250-260 for extended periods of time.
    If you have a temp gague on the tranny, that will help you determine things. If not, I would suggest looking into why your not locking up and have it fixed.
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    [ QUOTE ]
    You can tow all day in 3rd without the converter locked up

    [/ QUOTE ]

    Since when? My 700R4 locked up in 2nd, 3rd, and 4th gears. All of them are capable of locking in 3rd and 4th.

    Without it, towing a trailer, I'd bet you could burn that tranny up in one long trip!
     
  13. 88Silverado

    88Silverado 1/2 ton status

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    Maybe I should have re-phrased that to "Depending on the load..."

    Bottom line is it depends on the load your pulling and the cooling efficiency of the system. It wasnt until recently the lock-up converter came to be. For years and years the norm was towing with a TH350 and non-lockup. A 700R is basically a TH350 with OD addition. Now days many computer controlled cars will lockup the converter in 2nd and 3rd. This is a good idea. Ive never really noticed if my blazer locks up in 3rd or 2nd. Will have to check that. But again, you can burn up a 700R in lockup, in 3rd, if your pulling a big enough load and cant keep the fluid cooled. Fluid failure due to overheat is the number one killer followed by incorrect setup of TV cable so theres not enough pressure to fully engage clutch packs.
     
  14. blasterD

    blasterD 1/2 ton status

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    I talked to Steve from Bowtie Overdrives the other day and he said that any time the transmission is in 4th the converter should be locked. His reason was that in overdrive there is such a load on the transmission that if you don't lock the converter it will burn the fluid. He also said that you could have normal temperatures in the pan but still be cooking the fluid in the converter because of the high load.
     
  15. 88Silverado

    88Silverado 1/2 ton status

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    This is true. I have his 200R stage-2 in my 71 Elky. He forces it to lockup as soon as it shifts into OD. Im not saying driving around in OD without things locked up is good /forums/images/graemlins/thumb.gif
     
  16. scrappyk5

    scrappyk5 1/2 ton status

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    i have heard of people hooking up there own lock-up for an earlier vehicle. i think my problem is in the ecm is why mine is not locking up. does anyone know how i can get
    mine to lock-up without it hooked up to the ecm? i mean is there some switch i can run from power to the lock-up
    solinoid on the side of the tranny?
     
  17. 88Silverado

    88Silverado 1/2 ton status

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    You basically need to apply +12V to pin-A (on a 200R, may be pin-B on 700R) on the trans plug. Might want to call a shop and confirm that.

    I would look into why the system isnt locking up.
    Check the ECM codes and see if anythings there.
    I believe you can short Pin-A to Pin-F on the ALDL plug (obd-I) and it will force the converter into lockup. You can use this for troubleshooting.

    I would also check the fuses to make sure one is not popped. I heard about a converter not locking up and when chased down the fuse for the Radio was blown. Apparently they wired multiple systems to the fuse and figured if the radio quit, someone would notice and fix it.

    Heres some troubleshooting info:
    Generic GM Driveline

    Heres a link with some additional info for you
    700R info

    Heres more info on BTOD page worth looking at.
    Lockup wiring

    IF your going to manually lock it up you must have it running thru the brake switch. You MUST have a way for the +12V to be removed when you apply the brakes for safety reasons. If not, you cant stop the truck without stalling the engine, or worse yet, if you lock em up trying to stop fast, now you have no engine, no power brakes or steering /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif

    BTOD makes a real nice kit for this and reasonably priced.

    Heres more info on lockup wiring (about half way down the page) More info

    And finally, heres everything you ever wanted to know about GM transmissions but were afraid to ask GM Transmissions

    Again, the circuit is not that difficult. I would start tracing down things to figure why the ECM is not locking it up. Could be a bad pressure switch in the trans which is easy to fix. /forums/images/graemlins/thumb.gif
     
  18. scrappyk5

    scrappyk5 1/2 ton status

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    thank you very much for the help.
    i have read through that stuff and i think what happened
    almost two years ago when i put my motor in , i didnt ever adjust the tv cable correctly. cause since then , i have
    had to rebuild my transmission twice cause of the clutchpacks burning up. as far as the ecm goes , i had someone at a tranny shop hook up some type of gaget that
    said the converter lock-up was kept reading "yes-no". which he said it meant that the ecm was not working right to keep
    the ttc solinoid working properly.
    i am having the tranny re-built again as we speak, i am getting tired of pulling it. and my pocket has gone bare /forums/images/graemlins/eek.gif.
    i guess i could buy a new ecm and see if that solves it ,
    but thats about $200.00 lost if thats not the problem.
    that why i was asking about doing my own lock-up switch
     
  19. 88Silverado

    88Silverado 1/2 ton status

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    [ QUOTE ]
    said the converter lock-up was kept reading "yes-no". which he said it meant that the ecm was not working right to keep
    the ttc solinoid working properly.

    [/ QUOTE ]

    The ECM gets its inputs from other sensors to let it know when its in 4th, speed etc. which tells it to apply voltage to the lockup system. I would suggest having another tranny shop check that. The TV is critical to the trans. Normally (if its exact factory setup) you can release the TV latch (so cable moves forward), Open the throttle plate to WOT, While holding WOT, Pull the TVCable back until full extension and lock it in place. Normally, that will work. However, the best way is to hook up a pressure gague and set the TV for about 3-5psi increase over idle pressure.
    BTOD has a pressure kit, little pricy but much much cheaper than rebuilding a trans.

    Good Luck /forums/images/graemlins/thumb.gif
     
  20. fr8train

    fr8train 1/2 ton status

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    Hey what they said /forums/images/graemlins/grin.gif Got your PM. Since I am bluebie again I cant respond to it. PM me an email address to get back in touch with you.
     

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