Page 2 of 4 FirstFirst 1234 LastLast
Results 16 to 30 of 57

Thread: 700r4 lock up

  1. #16
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    You need to look at the plug on the tranny to see what I am referring to. It is a 4 prong plug labelled A,B,C,D and only 3 are used.

    A ... +12 input from the fuze box routed through the brake pedal switch and vac. switch.
    B ... -12 output usually to a computer to tell it that the tranny is in 4th.
    C ... NOT USED
    D ... -12 input usually from a computer. Computers like to switch grounds rather than positives.

    *input means power or ground is applied to the tranny.
    *output means the tranny provides something to the computer.
    *Computer means the fuel injection control computer or eletronic control module or ECM.

    Internal to the tranny is a solenoid which connects the the case of the tranny pin B. So since the case is ground ... it provides a ground to the computer

    My choice was to connect pins D and B.
    Then I connected A to the regular power.

    The covertor would only lock up when in 4th, and the engine is not under load. The only down side to this is that if your driving around at 30-40mph, your tranny will usually reach Overdrive. Once it shifts into overdrive it will instantlly lock up the convertor. In stop and go traffic this is sort of annoying. A delay would be a nice addition.

    I have also done with with a relay. Same setup ... I just used the -12 out from the tranny to flip a relay and provide +12 to the tranny.

    As mentioned ... READ THE MANUAL FOR YOU TRANNY. There is minor differences from year to year ... so make sure you understand your wiring and the internals of YOUR Tranny.

    I take no responsibility for how you use the above information.

    Mark.



    Originally posted by wasteomind
    i want to try that method mark. can you explain the process for hooking it up? i have a 350 in my blazer with a 700r4 tranny and a b&m lockup converter. my gas milage is horrible and i am wondering if the lock up has anything to do with it. i still have the transmission plug hooked up in the vehicle, but the computer is no longer in it so i don't think the lock up is working. so where on the brake wiring should this 12+ be connected?

    should the power flow be like this:

    12+ from brake switch (only when pedal is pressed)
    wired to a pressure switch connected to a constant or ported vaccum on the engine
    and ending at the transmission 12+ input

    then
    the 12- input is connected to a grounding spot, say the chassis somewhere

    and then
    the 12- output is connected to the same grounding spot as the 12- input?

    if anyone is good at paint, can they draw up a quick diagram to illustrate how this wiring should look? thanks.
    Last edited by Mark_ZZ3; 01-26-2004 at 01:07 PM.

  2. #17
    Registered User Yenko's Avatar
    Join Date
    Nov 2001
    Location
    Kentucky
    Posts
    1,736
    Originally posted by Mark_ZZ3
    You need to look at the plug on the tranny to see what I am referring to. It is a 4 prong plug labelled A,B,C,D and only 3 are used.

    A ... +12 input from the fuze box routed through the brake pedal switch and vac. switch.
    B ... -12 output usually to a computer to tell it that the tranny is in 4th.
    C ... NOT USED
    D ... -12 input usually from a computer. Computers like to switch grounds rather than positives.

    *input means power or ground is applied to the tranny.
    *output means the tranny provides something to the computer.
    *Computer means the fuel injection control computer or eletronic control module or ECM.

    Internal to the tranny is a solenoid which connects the the case of the tranny pin B. So since the case is ground ... it provides a ground to the computer

    My choice was to connect pins D and B.
    Then I connected A to the regular power.

    The covertor would only lock up when in 4th, and the engine is not under load. The only down side to this is that if your driving around at 30-40mph, your tranny will usually reach Overdrive. Once it shifts into overdrive it will instantlly lock up the convertor. In stop and go traffic this is sort of annoying. A delay would be a nice addition.

    I have also done with with a relay. Same setup ... I just used the -12 out from the tranny to flip a relay and provide +12 to the tranny.

    As mentioned ... READ THE MANUAL FOR YOU TRANNY. There is minor differences from year to year ... so make sure you understand your wiring and the internals of YOUR Tranny.

    I take no responsibility for how you use the above information.

    Mark.
    I started pulling the 2.8 w/ 700R4 last night for the V8. My 85 2wd blazer has a 2.8 700R4 overdrive transmission in it . Since its already wired for a overdrive tranny, would there be a problem getting a V8 700R4 to work since its already wired for a 700R4? I pretty much got everything unbolted for the motor to come out, just ran out of time for the transmission. I can see up top looking down, there is a few wires going to the transmisson. I will get a better insite on this once I get down there to see what wires are going where. What are your thoughts on this if you don't mind me asking? Thanks for any info that you might have.

    By the way, I'm not 100% sure about that overdrive tranny being a 700R4. For all I know, it might be a 200R4. Just thought I'd say that cause I'm more of a manual trany gu-roo...lol.
    ISRA# 18696

    CMA

  3. #18
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    When I first did my V8 swap on my 1985 ... I re-used the existing 700R4 wiring for the V8 700R4. Worked fine.

    Best to check a wiring diagram and make sure the pins are the same.

    GM was pretty good about keeping the wires the same. If they changed, then GM would change the plug such that you could not re-use it ... to help dummies like us when converting things!

    Mark.

  4. #19
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    just to add ... I original swap was on a 1985 Jimmy with a 2.8 700R4. I used a 700R4 from a 1988 Suburbon.

    Mark.

  5. #20
    Registered User Yenko's Avatar
    Join Date
    Nov 2001
    Location
    Kentucky
    Posts
    1,736
    Thanks, that was my next question. I just hope I stick to this 700R4 plan. My luck, I'll have second thoughts toward a manual tranny. I need to find a 700R4 before I change my mind. My brother has a few laying around in his basement. I just might talk to him about buying/using one of his.

    You said 88, is that a better year tranny to use? I've heard pre-86's 700R4's has had allot of problems. A friend that I work with, has a 400 sbc with a 88 700R4 in his S10 truck and that is what he said.
    ISRA# 18696

    CMA

  6. #21
    Registered User Yenko's Avatar
    Join Date
    Nov 2001
    Location
    Kentucky
    Posts
    1,736
    I forgot to ask, are you using the stock column shifter? I'd like to keep the stock shifter with the V8 700R4. If its possible.(?) I'm using manifolds, by the way.
    ISRA# 18696

    CMA

  7. #22
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    Yes the 1982-1985 were not the best for any performance stuff.

    1986 they made a series of changes. 1986-up is the best choice
    1989 they added an aux. valve body. 1989-up is even better.

    The key to watch for is the speedometer output. Sometimes there is provisions for a cable, other times it is eletronic. You can switch between the different styles, but it involves removing the tail housing and swaping parts.

    It is also a great time to swap the servo with one from a corvette. Aftermarket tranny shops carry these parts typically called a "corvette servo". It is a larger piston which has more application force. The 1-2 shift usally seems firmer and the 4th gear holds better. I'm sure there is a more techhnical description for what it does. It's been a while since I traced the fluid diagrams (Ok I was really bored).

    Just as an FYI ... there is typically 3 different stalls found in stock 700R4's. The flash points are 1450, 1650 and 1950 rpm. Weight, gearing and torque will change these. Most passenger cars got the 1450. Trucks typically got the 1650. The 1950 was only offered in 1986 F-bodies with a TPI and high performance vehciles like the vette or police duty caprices. I run the 1650 version and I am quite happy with it. I have had the 1950 before as well.

    FYI #2. There are all sorts of govenors that came in 700R4's. If you want to adjust your shift points, you can mix and match springs and weights to achive your shift points. You can go to GM buy a Vette govenor and in will shift from 5500-6300 depending on your gearing, weight, torque, etc. Most non-vette ones will shift at 4300-5200. The ones with the smallest inside weights will have a higher shift point. I ended up using the stock truck version (heavy weights), and changed the springs (even cut one!) until I got it to shift exactly where I wanted. I tried to vette version out but it shifted at 6300 and floated my valves! BTW ... GM sells the Vette one ... or any govenor for about $25 bucks. They are rebuilt units. I was very surprized.

    You can buy the B&M kit and do it yourself ... but be aware it will probably take you 6-8 tries to get it just the way you want it.

    Mark.

  8. #23
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    Yes I am. I understand the shift linkage you WANT to use should be from a 4.3 truck. It is not the round stock, but a flat piece of steel.

    I used a large round shift rod from the column to the tranny and I had to grind, twist, curse, etc. to get it to fit without hitting. I can't really get L1 that well ... but since I have my shift points where I want them ... it is not that big of deal. I will be picking up a 4.3 rod when I get a chance. Low on the priority list.

    Mark.

    Originally posted by Yenko
    I forgot to ask, are you using the stock column shifter? I'd like to keep the stock shifter with the V8 700R4. If its possible.(?) I'm using manifolds, by the way.

  9. #24
    Registered User Yenko's Avatar
    Join Date
    Nov 2001
    Location
    Kentucky
    Posts
    1,736
    Thanks, Mark

    You've given me some really good info to go with. I sure do appreciate it.

    Thanks,

    Yenko
    ISRA# 18696

    CMA

  10. #25
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    ... anytime.

    This is what makes these boards good ... information exchange!

    Mark.

  11. #26
    Registered User Yenko's Avatar
    Join Date
    Nov 2001
    Location
    Kentucky
    Posts
    1,736
    Originally posted by Mark_ZZ3
    ... anytime.

    This is what makes these boards good ... information exchange!

    Mark.
    PRICELESS

    Sorry....had to say it. :roll:
    ISRA# 18696

    CMA

  12. #27
    Registered User oldcarguy85's Avatar
    Join Date
    Aug 2002
    Location
    west chester, PA
    Posts
    1,369
    just sometign to add.. to identify the 87 1/2-up transmissions with teh aux. valve body, look on teh passenger side of teh trany. going aroudn the cooler line connections there will be a rainbow shaped casting line. also, i beleive the 88 or 89-up have no plugs ont eh side of the pasesnger side of teh trans. the older ones have little plugs ont eh side where u woudl liek connect a pressure tester or something. id strongly reccomend getting an 87 1/2- up trans. considerably stronger like was said before.
    1988 s-15 jimmy
    500hp 383
    700r4
    4.10s posi

  13. #28
    Registered User wasteomind's Avatar
    Join Date
    Oct 2002
    Location
    New Hampshire
    Posts
    188
    i know my tranny is out of a late 80's camaro, the problem though is this, the previous wiring for the v6's 700r4 was not altered and was just plugged into the v8 700r4 tranny thats in there now. if i have no computer in the truck anymore, then the lock up is not functioning correct?
    nipples

  14. #29
    Registered User Mark_ZZ3's Avatar
    Join Date
    Sep 2003
    Location
    Alberta
    Posts
    44
    It depends ... was the truck originally fuel injected? If not, then the existing wiring should be OK.

    It all depends what was controlling the lockup. Typically, fuel injection engine had the computer controlling it. I am unsure what sort of hybrid computers they used in the carb'd 2.8's. You would have to consult a wiring diagram for your truck to be sure.

    Mark.

  15. #30
    Registered User oldcarguy85's Avatar
    Join Date
    Aug 2002
    Location
    west chester, PA
    Posts
    1,369
    as long as it was FI, the compotuer controlled the GROUND on the trans. the 12v+ is alreday there adn wired into ur brake swithc. its the ground tha u have to mess with
    1988 s-15 jimmy
    500hp 383
    700r4
    4.10s posi

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •