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rebuilding the 700R4?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by DieselDan, Sep 7, 2003.

  1. DieselDan

    DieselDan 1/2 ton status

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    My original 700 was supposedly rebuilt before I bought the truck (Hey the case looked clean /forums/images/graemlins/smirk.gif )But it's never shifted correctly, and the converter crapped out this spring. I question how well it was rebuilt and if it was set up for a 6.2.

    So now I'm thinking about rebuilding myself, but I really need to find another core work on so I don't disable the truck. We all know the later/the better (built) the 700 is, but there also seems to be a big change mid 1987. Anybody know exactly what these changes are? Is it possible or feasable to update an earlier tranny? Also 2WD trannies are more common than 4WD, is the only difference the mainshaft length (which can be swapped)?

    OH Yeah, keep "the 700 is crap" comments to yourself. I'm a manual tranny lover myself, but I need an OD. So unless you're gonna give me a bitchin' deal on a NV4500 - save it /forums/images/graemlins/ignore.gif
     
  2. SUBFAN

    SUBFAN 1/2 ton status

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    I don't know the exact changes, but all the upgrades were useable in all the T 700's.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    There was an auxiallary valve body added later, and I believe the "mid-year" change you are talking about reflects that different casting. You can tell those cases with the half moon casting line that passes through both coolant line fittings on the passenger side.

    2WD can be converted to 4wd with the correct output shaft. Unfortunately thats one of the first pieces installed, so the donor would have to be a 4wd also, or your current tranny would have to come apart at the same time. /forums/images/graemlins/frown.gif
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    4WD tranny's also have a much thicker case, they commonly refer to them as a K case because there is a large
    (K) on the bell portion of the tranny.
     
  5. alec78

    alec78 1/2 ton status

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    Please don't take this wrong but I've never heard of a difference between 4x and 2x cases. I only say that because the dealerships I worked in. The Tech just took the tail housing off the new replacement and bolted the t-case on it. I suspose that could be a way for the dealer to make more $$$ (wouldn't be surprised either) but that's just my experince.

    I do remember that to take an older 700 and buy the updates was more expensive that just buying a SeRTA (Service Replacement Tranmission Assembly). Of course those were GM prices.
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Output shafts are different lengths between 2WD and 4wd, and also the case is thicker on a 4WD.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    I'll second the case being thicker if you are still having doubts. AFAIK it's not the entire case (or else the whole thing would be fatter) it's the bellhousing area, which is *typically* what cracks in a 4wd application. (which is also why they use the strut rods in auto applications)

    They aren't thicker like the difference between 1/4" and 1/2", but they are most definitely thicker than the 2wd ones.
     
  8. HarryH3

    HarryH3 1 ton status Author

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    The 4WD cases are thicker, at least up front. I've got an '87 Corvette 700R4 in the garage and it's obvious how much thinner it is. Especially if you look at where the dust cover attaches. On the 'vette version, the cover is a stamped piece of sheet metal that bolts into some very thin aluminum with sheet metal screws. On the 4WD versions, the cover is cast aluminum and bolts to the tranny using 3/8's bolts, which thread into much beefier aluminum than what is on the 'vette tranny.
     
  9. DieselDan

    DieselDan 1/2 ton status

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    All good info! I didn't think about the case thickness issue. 'Still picking up info on the later cases. Right after I posted I found this article Corvette Fever Guess I'll keep lookin for late model 4x4 700R4.

    My ('86) has the dreaded 4+3 Doug Nash stick /forums/images/graemlins/grin.gif
     
  10. HarryH3

    HarryH3 1 ton status Author

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    [ QUOTE ]
    My ('86) has the dreaded 4+3 Doug Nash stick

    [/ QUOTE ]
    Ugh! I remember those self destructing piles-o-dung. /forums/images/graemlins/wink.gif What part of Mass are you in? A good friend of mine lives in the Boylston/Shrewsbury area and has an '84 with absurdly low mileage (Under 25,000 miles last time I asked about it! /forums/images/graemlins/eek.gif) and it has the 4+3 in it. He ordered it before they were even available and waited months for it to come in. I don't think it's ever seen a rain drop. /forums/images/graemlins/cool.gif
     
  11. fad2blk99

    fad2blk99 1/2 ton status

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    For the rebuild help.... I know a few years back one of the off raod mags (Four Wheeler or 4 Wheel & Off-road) did an article on a 700 rebuild. There is a company who sales a video, info and tools to make the rebuild a snap; all of which is detail in the magazine article. Try serching the two mag sites for info....
     
  12. fad2blk99

    fad2blk99 1/2 ton status

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  13. SkulzNBonz

    SkulzNBonz 1/2 ton status

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    Sweet, I'll be rebuilding mine in a couple of weeks, and this is just what I needed /forums/images/graemlins/thumb.gif

    John
     
  14. DieselDan

    DieselDan 1/2 ton status

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    I live on the Mass/NH border. Don't get down to Shrewbury to often. I'm amused by low mileage Vettes /forums/images/graemlins/rotfl.gif I'ld rather drive the crap out them (mine /forums/images/graemlins/thumb.gif ) 'Had a friend that had an '86 with about 8000 miles /forums/images/graemlins/shocked.gif Hey, it's not a rare Ferrari. DRIVE IT!

    The OD on my 4+3 blew up years ago. It was so far trashed I had to pay the "a-hole from NY" $800+ for a rebuild. All DNE 4+3 owners know of the a-hole from NY; he's the only one that knows how and has the correct parts to rebuild a DNE OD (he bought up all the parts/cores when DNE went belly-up). This guy deals only in cash or bank check /forums/images/graemlins/eek.gif

    If your buddy's 84 tranny hasn't been broken yet he needs to get it modified/fixed before it craps out. The front bearing doesn't get enough oil (the carrier can be drilled) and the clutch pack end play should be checked. Quality control was so bad at Doug Nash that they were seting up the main (ball) bearing too much lash/zero lash/or a PRE-LOAD.

    I've helped build autos before (TH400). So I don't forsee a problem doing a 700. I just ordered an ATG manual. /forums/images/graemlins/grin.gif
     
  15. fad2blk99

    fad2blk99 1/2 ton status

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    I'm not doubting your skills here so please don't take offense ... but a very trusted friend of mine (I know, its hearsay) told me that's where a lot of good tranny mechanics get in trouble w/ the 700r4. Its so unlike any other tranny...
     
  16. dyeager535

    dyeager535 1 ton status Premium Member

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    Don't cut corners, and do it by the book, and you should be fine.

    I agree, the 700 has a reputation of being "finicky" (to be nice) but I think more than anything, that has to do with profit margin/time to build more than it does the tranny itself.
     
  17. DieselDan

    DieselDan 1/2 ton status

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    No offense taken (only advise /forums/images/graemlins/grin.gif )

    Ya I agree with you Dye. I've seen too many shops that are strictly concerned with the bottom line profit. I've worked (back in-the-day) in both flat-rate and hourly shops and the quality of work was clearly better in the hourly shop. That's why I'm looking for another core to work on; so I'm not under the gun to finish it before I think I got it built right /forums/images/graemlins/smirk.gif
     

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