700R4 Information Thread

[Ricko1966]

@nick Transmission, Strange question ,I know. But is there any reason I can't use a 4l60e as a donor to rebuild an 85 700r4 use all the 4l60 internals ,minus pump,use the 85 valve body. I'd think that would give me a decent transmission. And 4l60E cores are lots easier to come by than 88-92 700s

 

[NickTransmissions]

@nick Transmission, Strange question ,I know. But is there any reason I can't use a 4l60e as a donor to rebuild an 85 700r4 use all the 4l60 internals ,minus pump,use the 85 valve body. I'd think that would give me a decent transmission. And 4l60E cores are lots easier to come by than 88-92 700s

You can but your 1985 unit was designed to use a drum with a 2mm forward feed orifice in the forward drum. The 87+ 700s and 4L60Es all have drums with 6mm orifices as they were designed to work with a forward accumulator circuit. So your engagement into drive would be particularly harsh, especially when the vehicle is cold (i.e. sitting overnight). The reverse drum from the 60E is backwards compatible but likely not usable as nearly 100% of them are warped on the band surface so you're buying a new one anyway.

The pump can be installed however a couple mods have to be done to make it work in the early non-aux VB 700r4 (it's easier to retro the 4L60E pump into an earlier 700r4 than a late given the aux VB feed pipe to the forward clutch circuit has to be accounted for and circuitry re-routed). All other case components gears, shell, etc are interchangeable - just keep your 700's input shaft since the 60E shaft has no worm gear for the governor.

 

[TDoc]

86 K5 700R4 3:73 gears. Did a driveway complete trans flush 2k miles ago with maxlife dex full synthetic. Shifts great! Fluid was very dark when I got the blazer. Put 2k miles on it and dropped pan. Looks great! Magnets had a decent amount of black goo but hardly anything in bottom of pan. The two little rings of clutch material in the corner are from a magnet I have outside the pan.

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@NickTransmissions
I also got the torque converter to lock. Who knows how many years and miles it’s been not locking. Now it locks in 2,3,4th. Like immediately when vacuum levels are high. Almost to the point it’s annoying. Is that ok or am I going to cause premature wear? I hooked it to manifold vacuum.

I’m sure this trans has been rebuilt or replaced. It has the gmt400 red dip stick, not sure how to tell what year the 700r4 is, I thought the pan was leaking but it’s two of the pump bolts. I tried to stop or slow it. You can’t get the bolts out without removing or moving the transmission back.

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[HotRodPC]

86 K5 700R4 3:73 gears. Did a driveway complete trans flush 2k miles ago with maxlife dex full synthetic. Shifts great! Fluid was very dark when I got the blazer. Put 2k miles on it and dropped pan. Looks great! Magnets had a decent amount of black goo but hardly anything in bottom of pan. The two little rings of clutch material in the corner are from a magnet I have outside the pan.

You must be registered for see images attach

@NickTransmissions
I also got the torque converter to lock. Who knows how many years and miles it’s been not locking. Now it locks in 2,3,4th. Like immediately when vacuum levels are high. Almost to the point it’s annoying. Is that ok or am I going to cause premature wear? I hooked it to manifold vacuum.

I’m sure this trans has been rebuilt or replaced. It has the gmt400 red dip stick, not sure how to tell what year the 700r4 is, I thought the pan was leaking but it’s two of the pump bolts. I tried to stop or slow it. You can’t get the bolts out without removing or moving the transmission back.

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Nick can respond too, but not sure when he'll get here. I'd say, you're not getting lock up in 2nd I wouldn't think. Pressure switches should only allow that in 3rd and 4th sometimes just 4th. But I've never heard of a lock up in 2nd. But hey, maybe your set up and hook up doesn't require or depend on pressure switches and I guess that's possible, all in how you hooked it up and wired it. Obviously it's electronic. I'd have to say NO, you will NOT get them bolts out, even if they are exposed. They're to long and not going to clear without hitting the torque converter would be my thought. BUT, is it possible the bolts are loose? Can you get a wrench in there to reach them and get an idea of the torque on them? Don't overtighten whatever you do, you can easily stip those threads if that's not the problem already. Whoever built it, might have forgotten or didn't use the bolt washer gaskets, or under tightened or over tightened and stripped out the alluminum, which is easly fixed with helicoils but then you have to have the whole transmission out, and do it in a way you don't get shavings in the transmission. That won't be good either. But see if you can get a wrench in there and see if maybe a little snug if they are loose will correct the leak. Then you at least know what it's going to take to fix it.

BTW, don't change it now, but for that transmission, I probably wouldn't have used synthetic fluid. If it's been freshely rebuilt and in good shape, you have a good chance of it being OK, but if it was well worn, it's not going to last any longer in fact likley less. good fluid high in detergents, thinner will tend to get around worn seals and parts where as standard fluid may have been better. Once a transmission is badly worn if it hasn't been maintained, don't think a fluid change will fix it. That'll probably kill it at that point and that's usually when people decide to maintain it, is when it's ailing and they think a fluid and filter change will help when it when in fact, total opposite. Clean all that gunk built up in the drums out of it, now your tolerances just increased by all the space you just created getting all the built up gunk out of it. New Clean Trans fluid is a great detergent. It does clean things and sometimes, the damage has been done, you don't want it cleaned out. That does NOT seem to be in your case, so YOU are probably good thankfully, but keep it in mind in the future or on other transmissions.