How to Identify a 700r4

Discussion in 'Automatic Transmission' started by HotRodPC, Oct 27, 2011.

  1. HotRodPC

    HotRodPC Administrator Staff Member

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    First thing you want to look for is the # on the passenger side of the rear of the case just above the oil pan on the case itself. The FIRST digit denotes to year model of the transmission.

    NOTICE - First Digit 9 Denotes Both 1982 Model, and 1989 Model. There are 2 ways to determine a 1982 Model and a 1989 Model. #1 82 has 2 letter code, 89 has a 3 letter code. #2, 82 will have pressure taps, 89 will NOT.


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  2. HotRodPC

    HotRodPC Administrator Staff Member

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    Pressure Taps 1982-1988 & Early 1989

    1987 thru 1993 models have auxillary Valve Bodies that correct some issues. 82-86 Models are Single Valve Body Units.

    The more sought after cores are 88-93 model cores because they have more changes and OEM updates for a better transmission, and should be what you look for to be used for a performance build.

    1982-1988 and the early 1989 models have pressure taps on the passenger side of the case.

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    Late 1989 Models and Up to 93, will NOT have pressure taps. If you can't read a # in the proper location, but you do not see pressure taps on the case. Its a safe bet the transmission is 89 or later and one of the better more sought after cores.
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  3. HotRodPC

    HotRodPC Administrator Staff Member

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    Another sign of the later model, more sought after 700r4 for performance builds would be the rainbow on the passenger side of the case in the casting of the case. It is has this rainbow as pictured below between the blue lines, its one of the better performance choice cases.

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    Also, on the picture above, you can see the K on the passenger side of the bell housing. The K is the stronger case, most commonly found in 4x4 trucks. The K case has thicker bolt lugs at the bell housing bolt bosses. It also has more threaded holes drilled into the torque convert cover. The torque converter cover for the K case uses a much thicker cast aluminum cover with 6 bolt holes instead of 4 and said to better strengthen that section of the case when the torque converter cover is bolted on.The 2wd or Non K case will use a thin tin cover over the torque converter and 4 smaller bolts.
    If you are building a high performance 2WD 700r4 and you feel it needs that added bell housing strength, you can use a 4x4 Case, but you will also have to use the 2WD output shaft, and add the aluminum tailshaft housing from a 2WD case that is a direct bolt on to the K case.
     

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  4. HotRodPC

    HotRodPC Administrator Staff Member

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    If you see a case that LOOKS LIKE a 700r4 / 4L60, but the lack of a TV cable or provision for the cable, and a Green wire connector on the passenger side of the case then this is NOT a 700r4 / 4L60 Transmission Case. It is a 4L60-E eletronically controlled transmission used in a computer controlled vehicle from 93 and later.

    NOTICE the 4L60-E also has the Rainbow and NO pressure taps.

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  5. 89Suburban

    89Suburban Full Access Member

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    What are the gear ratios for a 700r4?
     
  6. Jims86

    Jims86 Full Access Member

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    3.06 1st gear, 1.63 2nd gear, 1.00 3rd gear, .070 4th gear.
     
  7. HotRodPC

    HotRodPC Administrator Staff Member

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    ---------------------1------2----------3------4------R

    th-350/th350C----- 2.52---1.52-------1.00-----NA-----
    th-400 (3l80)-------2.482--1.482------1.000---NA------2.077
    th-700-r4/4L60-E--3.059---1.625------1.000---0.696---2.294
     
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  8. 89Suburban

    89Suburban Full Access Member

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    This is the comparison I was looking for, and not wanting to see at the same time.

    I was pondering in my tinkering mind, if my 700r4 ever took a dive , I would like to replace it with a TH350 or TH350C. But, now reading those gear ratio comparisons, do not want to loose the lower first and 2nd gear ratios of the 700r4, they are most important to me pulling out with a 2000 LB boat and trailer.
     
  9. HotRodPC

    HotRodPC Administrator Staff Member

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    For you, yes, you're probably right. But there is also a big disadvantage to the 700r4 low first gear. Look at the wide ratio between gears on the 700r4, then compare that to Th350. That wide ratio hurts in most truck situations. I do like the ratio's of a 200r4 better. It starts at a 2.74 I think it is.
     
  10. 89Suburban

    89Suburban Full Access Member

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    In your opinion, is the TH350C stronger than the 700r4?
     
  11. HotRodPC

    HotRodPC Administrator Staff Member

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    Hell yes. It will tolerate much more abuse without a doubt. You just don't have the OD and that hurts. A stock Th350 will run circles around a 700r4 and handle double the hp, double the weight, double the towing and beg for more.
     
  12. HotRodPC

    HotRodPC Administrator Staff Member

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  13. MxRace75

    MxRace75 Junior Member

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    Hi guys and gals. I'm new to the forum and came across this thread.

    I seem to have a odd ball trans that I'm trying to figure out.

    I'm pretty sure it's a newer style 700r4

    It's a jasper rebuild - pulled out of a 89 blazer so I have to assume it was built for that.

    The numbers on the trans are 91 KR
    There is no Arch/Rainbow
    It doesn't have the pressure ports
    It's not a K case

    Any ideas ??

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  14. HotRodPC

    HotRodPC Administrator Staff Member

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    Yep, the rainbow is missing. That rainbow is just flashing from the mold. It very well could have been ground and polished off, or the mold changed too. That is most likely a 91 model transmission. There should be a few more digits too. It is possible that Jasper may have stamped it. I have a 700r4 that the stamp is so light you can't even tell what the charachters are. To the best I can tell it's a 90 or 91 case. Anything 87 up is a good one. 88 and up are even better with an update to the 1-2 shift valve which also required change to the spacer plate so they are not backwards compatible. The #9 checkball is also eliminated in the 88 up and if used will fry the Low clutch pack. And the 3-4 clutch release springs were also added to pull the 3-4 clutch off faster and slow down the wear of the 3-4 clutch pack. Many times, builders will leave those 3-4 release springs out saying they actually affect something else blah blah blah. I choose to use them on a build, but I do use the Sonnax springs instead. Those springs will retrofit back to 87 models too, but not 86 and earlier. A better filter design and O ring method is also used on 88 and up models. Bottom line, try for the 88 and up models for cores. And don't think the earlier ones are junk just yet. Many of the 88 and up models are VSS or Reluctor wheel output shafts, so if you have a manual speedo, and want to upgrade to an 88 up model, you'll probably want to grab that manual speeo output shaft out of the older one for your 88 up build.

    Sonnax spends alot more time engineering and testing, or R&D than GM does for their aftermarket parts. In fact, it takes several years, but GM usually does eventually have an Ohh yeah moment and upgrades to match Sonnax. ie the GM Smart Shell for example and Sonnax had come out with The Beast many many years ago.
     
  15. MxRace75

    MxRace75 Junior Member

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    Thanks for the info. It's a 4wd so my speedo cable is on the transfer case. I'm just picking up a few cores right now. I've got this one and a 89 k case.
     

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