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700R4 problems

Discussion in 'Chevy Trucks' started by Cordarin, Dec 13, 2001.

  1. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    Ok guys I know this is gonna be a bit long but any help would be appreciated. I just bought an '86 Blazer(full-size,4X4) from a guy who got it from another guy and never drove it....(I know). Now the kid who owned it previously had just (and I mean just) put a rebuilt hi-po 350ci in it(apparantly he didn't drive it afterwards either). I don't know what if any mods he may have made to the tranny ( race-only shift kit?) Ok..now for the problems
    1)It only seems to up-shift during hard acceleration and at high RPM..I'm talking like 4-5 grand.....when it does shift, it shifts hard (no complaints there).
    2) In any gear other than 1st or reverse, if I let off the throttle, the RPMs drop (to idle!) and it seems to be in neutral...until i get back to the appropriate RPM for my speed, at which point it will accelerate fine again.
    From park it shifts positively and firmly into drive or reverse. I have tried adjusting the TV cable (could a bad/mis-adjusted TV cable cause such problems?)...I have disconnected the electrical connection to the tranny..neither made any difference.The torque convertor looks new...(could it be the wrong one?) The fluid is dark and smells a little burnt(wince), but I do not know how old it is or if the wear has been caused by the tranny working so hard. I am prepared to replace/rebuild the tranny if that truely is the problem...but I am hopeing for some other possibilities...?
     
  2. Sndun

    Sndun Member
    Messages: 56

    I would start off by dropping the pan and changing the fluid and filter. While you're in there, poke around and see if anything seems unusual. Could be covertor/ tv adjustment related or it may be time for a rebuild. Your local trans shop should be able to tell you after a quick spin and it won't cost you anything for the estimate.
     
  3. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    Thanks for relpying

    I was plannin on doin the filter change.....and last night i tried another adjustment to the TV...and while I was drivin' it around the block, I started to hear a constant 'clunking' noise that seemed to be comming from the transfer case....could a bad transfer cause my seeming to go to neutral problems?? it doesnt seem that the linkage is adjusted right..could it be between 2wd and 4wd?...It is starting to look like I should start looking for a new transfer AND tranny...! :(
     
  4. MTCK

    MTCK Senior Member
    Messages: 346

    I wouldn't start throwing parts at it just yet. :) That gets expensive in a hurry. First I would go ahead and pull the pan and see waht it looks like. Mud in the bottom is bad, as those are your clutches. I've never had mine do the neutral thing, when you take your foot off, but I have had mine not engage third or fourth gear until it was revved really high, tranny gone. You could also drain your t-case fluid, and when it's draining, let the fluid run through a pair of panty-ho's. If you have problems, you'll probably have metal shavings in there. Hope this helps.

    Marcus
     
  5. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    Thanks marcus

    Yes..I guess begin at the beginning is the right thing to do, I was just hoping someone had seen this kind of behavior before...does anyone know if a bad transfer case could case the neutral problems? thanks in advance for any replies,
    -Tom
     
  6. Dave mcjr

    Dave mcjr Junior Member
    Messages: 10

    well it sounds like you have a problem.
    sounds to me like the kid who installed the
    engine also installed a high stall torque
    convertor, solves the neutral problem.
    as far as the shifting at high rpms, sounds to
    me like you have a stuck or a govenor that is
    haning up. also lets not forget that if this
    transmission has not been replaced it more than
    likely has not been updated with the rather
    large update that took place after 1986.
    personally if I were you I would remove the
    transmission and the only thing I would use it
    for would be a core......
    I am about 99.9% sure that the problem is
    internal with the transmission and it will have
    to be replaced..
     
  7. DaveK

    DaveK Senior Member
    Messages: 420

    It doesn't sound like that to me. Because he says that "From park it shifts positively and firmly into drive or reverse." Which it wouldn't do with a high stall convertor. It would do nothing when shifting from park to drive or reverse until you rev the engine high enough.

    It sounds like the "kick down" is always on. Basically the tranny thinks that you are at heavy throttle which delays the shifting. Like when you suddenly give it full throttle and it kicks down into "passing" gear.
     
  8. MTCK

    MTCK Senior Member
    Messages: 346

    Kickdown still wouldn't explain the motor acting like the tranny is in neutral when you take your foot off the gas. When the TV is stuck, it stays in the gear, keeps revs up, whether on the gas or not. I think the problem may be more serious.........

    And to answer your t-case question, no I cannot think of a way a chain drive t-case could act like a 1-way clutch....... So I think that problem is in your tranny.

    Marcus
     
  9. DaveK

    DaveK Senior Member
    Messages: 420

    The TV could actually be sticking and not just out of adjustment. There are aftermarket companies that make replacement TVs. You can change the whole valve when you take the pan off to change the fluid and filter.

    Also the 700R4 uses a lockup torque converter. And since you also said "I have disconnected the electrical connection to the tranny..neither made any difference." Maybe it isn't a lock up converter he put in, or maybe it isn't working correctly. Try to determine if it is the correct or incorrect convertor.


    I found a thread on another forum that describes your problem exactly. And he did not have a questionable convertor. http://web.camaross.com/bb/Forum12/HTML/011776.html

    The best offered solution was the same as mine. Bad/mis-adjusted TV. (And then you also have a convertor that may not be locking up)

    Of course there is also one guy that suggests that the tranny is ----ed up. There is always one of them.
     
    Last edited: Dec 18, 2001
  10. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    many thanks

    Hey..thanks alot man, you are about the only one who has givin me some real alternatives to just buying a new tranny. That still may end up being the case, but at least now I have some things to try first. I'll let you know the results -Tom
     
  11. John DiMartino

    John DiMartino PlowSite.com Veteran
    Messages: 2,154

    I agree witth Dave K,the Kickdown cable may be working but the valve in the trans may be stuck or not hooked up right.If you are in OD,the tranny will act as if its in N,since the overrunning clutches will let the output shaft freewheel when the input speed is lower,try selecting manual 1st,accerlate,then let off,you should have engine braking,try it in 2nd,and drive,you should have engine braking in each gear,if you do,there 's no problem there.It just sounds like a simple adjustment at this point,there are very few non lockup convertors made for the 700r4,so its not likely that he has one,getting that working shouldn't be to hard,1st thing,get the kickdown working,its hung up at about 3/4 -full detent from the sound of it.This is why it goes into gear so hard too.To confirm what Dave,and I think ,you'd need to buy a universal trans oil pressure guage,hook it to main line preesure,get a reading,if its normal you have other trouble,if its high your kickdown is stuck.Dont be afraid to spend 30 bucks on a trans repair book,for the 700,they will guide you thru the testing and repair of this from start to finish.
     
  12. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    thanks john

    Ok...how about if I get engine braking in 1st but not 2nd,3rd and I have never seen 4th? -Tom
     
  13. MTCK

    MTCK Senior Member
    Messages: 346

    What did this turn out being?
     
  14. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    Bad news

    It turned out to be...crap, LOL. I changed the filter, found a bunch of mud and black tranny fluid in the pan, refilled it and drove it around town. It shifted a little better on a short trip, so I tried again the next day....shortly blew out all foward gears and had to drive it off an exit ramp..in reverse! So needless to say...I am gettin a new tranny. Thanks for all the help anyway guys!
     
    Last edited: Jan 20, 2002
  15. MTCK

    MTCK Senior Member
    Messages: 346

    Sorry to hear that....... I think we're in about the same boat. I'm planning on ordering a new one from this place http://www.transmissioncenter.net/performance_automotive.htm in the next couple days. The price is pretty steep, but I've had good recomendations, and the parts list is impressive. Also gunna bite the bullet and go for the new ring and pinions also. Still haven't decided if I'm gunna go 3.73 or 4.10 yet, but with the overdrive, figure, what the hell, 4.10. The 2.73 just isn't working any more....
     
  16. Cordarin

    Cordarin Junior Member
    from NJ
    Messages: 7

    sounds good

    Yeah that raptor looks pretty mean....your right about the price though...Whoo! It is alot more tranny than I need right now, I found a local place that has mild HD rebuilds for about $450.00.
    As far the gears go...you should really check into what the end result with tire size is gonna be, don't just guess, otherwise you might be real unhappy.... I would say that if you are runnin 33" or larger tires 4.10 would prob be fine, any smaller than that though and you'll probably be crankin close to 3000 rpm's @60mph....(I am assumeing your gonna drive this on the street...) Well, however it turns out Good luck to you.
     
  17. MTCK

    MTCK Senior Member
    Messages: 346

    Tire size is right there. I'm running 32 inch now, may go to 33 when these wear out, or just keep it the same. I already dropped a healthy chunk of change on chains for these tires, so probably stay the same. My calculations show (ok, richmond gear's calculation www.richmondgear.com) 1808 RPM at 60 mph with 4.10 gears, 32 inch tires, and 70% overdrive. And 450 bucks is a hell of a deal for a rebuild! There's no place in town that does it in house here I don't think, and I spent about 1600 last time to have it shipped out by a local shop and rebuilt. That didn't last too long, so I'm gunna try this raptor I think....

    Marcus