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TH350 to 700r4 swap questions???

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 82TOYLB, Dec 7, 2001.

  1. 82TOYLB

    82TOYLB Registered Member

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    I just purchased a 700r4 transmission mated to an np208 with a solid output yoke from an '88-'89 blazer. The tranny was new from GM like 1 year ago. Everything appears like it will bolt up just fine to my '79 350 and crossmember. I have a front driveshaft from an '84 that I believe is the correct length and I will have the rear lengthened or shortened as needed. The question I have is reguarding a four prong plug that is located on the topside of the transmission just above the left rear corner of the tranny pan. How should I hook this up? My '79 has no provision for electronics in the tranny. Do I need to rig up some kind of switch? Can I just place a dust cap on it and run the tranny without the electronics? What does it do? Is it just a neutral start/ backup switch? Is it a VSS or something I can ignore? Any help would be appreciated. Thanks.
    Michael.

    82 Toy LB with Marlin, locked, 36's,38's,35's depending on month/mood. 79 K5 with 3/4 ton running gear, 36's.
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Torue COnverter CLutch lockup. Not running an auxiallary cooler and leaving this unplugged will likely kill the tranny in short order. Only benefit to running TCC is tranny runs cooler and your RPM's will decrease a bit. Mileage also will go up a tad.

    You can run the setup off of an (here we go again) early 80's K5, up to at least '85, equipped originally with a 700. You need the speedo, and the harness including VSS. Find one being parted out thats complete, take the entire harness..just follow it from the tranny and take everything that is attached to it. IF you want to run it with lockup. Either that or buy an aftermarket kit. Most of them aren't very good compared to the stock system, which I had no complaints about.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  3. 82TOYLB

    82TOYLB Registered Member

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    I take it this question has been covered before. I would like more information about how to hook up this wiring harness to my computerless '79 harness. Also you mentioned the speedometer from an 80's blazer??? I am not sure why the speedometer is involved in this harness, wouldn't the harness go straight to the computer and the computer control the lockup by analyzing data from the tps and vss? Am I way off base? Could I just put in a switch that I actuated once I was out on the highway and wanted to lock up the converter? Similar to the Overdrive buttons on ford contours and Nissan Maximas? Help me out if you can and don't mind. Thanks.
    Michael.

    82 Toy LB with Marlin, locked, 36's,38's,35's depending on month/mood. 79 K5 with 3/4 ton running gear, 36's.&lt;P ID="edit"&gt;&lt;FONT class="small"&gt;&lt;EM&gt;Edited by 82TOYLB on 12/07/01 05:51 PM.&lt;/EM&gt;&lt;/FONT&gt;&lt;/P&gt;<P ID="edit"><FONT class="small">Edited by 82TOYLB on 12/07/01 05:53 PM.</FONT></P>
     
  4. Blazer79

    Blazer79 1/2 ton status

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    Buy a harness from Painless wiring. It's made especifically for this application, so it would be the best solution, only it's about $75.

    <font color=purple>//////
    <a target="_blank" href=http://blazer79.freeyellow.com>blazer79.freeyellow.com</a></font color=purple><font color=black>
    Soon a 454 K5!!</font color=black>
    [​IMG]
     
  5. 82TOYLB

    82TOYLB Registered Member

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    Thanks guys. I just looked in Jegs and found 3 kits for controlling the lockup converter when placing this tranny in a non-ECU vehicle. I'll go with the TCI kit that is $73. Thanks.
    Michael.

    82 Toy LB with Marlin, locked, 36's,38's,35's depending on month/mood. 79 K5 with 3/4 ton running gear, 36's.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    The TCC harness is standalone, besides voltage. You aren't dealing with a computer, there isn't one. VSS is part of the speedo/cable assembly, thus the gauge. No TPS, hence, no computer. YOu can definitely wire in a switch, but you forget to unlock it, you'll stall at lights : ) Only speaking personally, if I'm going to have an automatic, it will stay that way. Automatic. Meaning I put it in whatever gear I want, and it does all the work, no further input required from me. (within reason, not towing or wheeling, etc)

    I think there is ONE aftermarket harnes that folks have had luck with, and I believe it is about double everyone elses. Running off of vacuum alone will net you lots of locks and unlocks, thats why GM used VSS from the beginning of the 700, and probably why everyone complains about the lock/unlock problems of the vacuum dependent aftermarket kits.

    The factory harness is plentiful (relatively speaking) and a bolt in. Why not use it?

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  7. 82TOYLB

    82TOYLB Registered Member

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    Thanks for the more detailed information. I will try to find a truck being parted out in this area soon. If unable then I will go with the B+M kit that seems to be the only one that does not rely on vacuum. Thanks again.
    Michael.

    82 Toy LB with Marlin, locked, 36's,38's,35's depending on month/mood. 79 K5 with 3/4 ton running gear, 36's.
     
  8. taterblazer

    taterblazer 1/2 ton status

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    Does the 700R4 tourque converter ever lock when it's in drive or does it just happen when it's in overdrive?
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Drive as well as OD


    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     

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