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Thoughts on 700r4 tranny????

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by blazen_md, Jul 15, 2002.

  1. blazen_md

    blazen_md 1/2 ton status

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    I have a 1990 k5 with a 6in suspension and 35 ssr's I have 4.10 gears with an auburn unit. I have a 350 tbi motor nothing special really done to motor just exhaust k&n filter and poweraid throttle body spacer. I am getting my 700 rebuilt is there any sugestions on what I should do as far as torque convertor shift kits etc. One added thing I do go wheelin quite a bit but it is also my everyday driver.
    I appreciate any help thanks.
     
  2. deothrwhtmt

    deothrwhtmt Registered Member

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    See what goes into the raptor and bowtie O/Ds trannys. .......it looks like a corvette servo/solenoid and better clutch packs. The bigger options are the hardend carriers and bigger pumps.
     
  3. trailblazer87

    trailblazer87 1/2 ton status

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    If you are serious about the off-roading, get a non-locking torque-converter, you will lose a touch of mileage and your motor will rev. about 200 rpm higher on the freeway but it will be much happier. If it is just light stuff then go with the regular t-converter. Definately get the corvette shift servo. and an aftermarket tranny cooler. You will also want the heavier Sun gear for O/D, this is the weak point in the 700's.
     
  4. TorkDSR

    TorkDSR 1/2 ton status

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    i swapped a 700 into my 79 k15, and i love it. i never set the stock tork converter up for lockup. whats the difference btw a locking one that doesnt lock, and one that was never supposed to lock?
    Ryan
     
  5. trailblazer87

    trailblazer87 1/2 ton status

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    The added slip seems to work better off-road, but it does make them run a little warmer.
     
  6. TorkDSR

    TorkDSR 1/2 ton status

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    maybe i should re-word my question. why buy a non lockup tork converter, when you can just un-plug the stock one? i was just curious to see if there was some sort of mechanical advantage etc

    Ryan
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    No, there really isn't, and if you keep it in 1st or 2nd, it would never lockup anyways. (at least I'm 99% sure no 700's lock up in 2nd, my '83 did not)

    Theres NO penalty to running one IMO, they should unlock at WOT anyways, so I'm not sure why you'd not want one, except to increase freeway fuel consumption and engine wear.
     
  8. 84_Chevy_K10

    84_Chevy_K10 Banned

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    My '84 locked in 2nd, 3rd, and 4th gears when it had a 700R4. I love lockup automatics--it's like having a 7 speed!
     
  9. TorkDSR

    TorkDSR 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    so I'm not sure why you'd not want one

    [/ QUOTE ] i dont do enough freeway miles to wire it up, with the vacuum and all. i do have a schematic, there are only 4 wires coming out of the tranny, so i may get around to a fully manual lockup controll switch. i like the convenience of compression braking.
    Ryan
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    I guess I can see it in that case. But in any case, were you wanting to completely eliminate it (like for racing) it gets fairly expensive with the new parts needed. If you don't already have the wiring present, it would be a bit more of an effort, but I'd still want it working.

    Not sure I like the lockup in 2nd part, I have a feeling thats certain models only, I see *no* need for lockup in 2nd with 3.73's and 31" tires for example.
     
  11. trailblazer87

    trailblazer87 1/2 ton status

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    In the late eighties they were designed to lock up at 35mph, except at WOT. The reason I didn't get a locking converter is the fact that I run desert roads at speed and I don't like to shock anything that hard as junping with a locking converter would. My u-joints tend to last a little longer this way.
    I guess I could have wired it so that it wouldn't lock up in 4x4 but I didn't think about it at the time.
     
  12. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Mine will lock in 2-4 but I set it up so that I have full control over lockup (lit switch). Around town I never use it (especially since it will lock in 2nd), but I almost always use it on the highways, and love how it will aid in braking when decelerating for an offramp (with the converter locked you do get added compression breaking since the tranny is "locked" to the motor) otherwise it is more like a traditional auto "freewheel" effect when braking without the converter locked. Most stock setups force the converter to unlock when braking which I do and don't understand, but since it unlocks in first gear anyways, I don't see it as a problem (i.e. clutch slip) even in panic stops. As soon as I stop/slow down, I hit the switch again and it is on to unlocked town driving. It takes a little more driver awareness, but I enjoy that.
     
  13. Blue85

    Blue85 Troll Premium Member

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    Going between a lockup and non-lockup torque converter generall requires a new input shaft on the tranny. Don't bother. Just keep the lockup, but put in a toggle switch to keep lockup from happening. Keep the stall speed close to stock unless you live for sand or mud (around 1700rpm). Even then, don't go above 2000 because a K5 is heavy. This will also raise your shift points with heavy throttle.

    But DO KEEP lockup in O/D. These things hate heat, make a lot of it when unlocked in O/D and don't cool very well in O/D. No serious off-roading should be done in O/D anyway. It's as simple as that.

    As for the original question: A lot of good aftermarket parts can be found, but the most important one is an auxiliary cooler. Shift kits can be OK, but don't really give that much performance. Corvette servos are good, but may require some valve tuning to get the shifts right. One mod I really do like is the modified 1-2 valve that lets you downshift back to 1st without coming to a stop. That is a real performance boost. A 10-vane pump is a good idea if you have an pre-86 unit with the 7-vane pump, but is not mandatory. "Performance Rebuilds" are only as good as the shop selling them. Usually they don't do too much and if the builder doesn't have a deep understanding of 700's, they can actually shorten it's life. Definately go with high performance frictions if they are going to be changed. If you want higher shift points, a governer kit is cheap and easy and can even be done later with the tranny in the truck. Also see about getting this little cone-shaped spring on the T.V. valve to keep it from sticking.
     

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