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Discussion Starter #1
is the 700r od transmission out of a 86 surburban 4 wheel drive the same as a 2 wheel drive 86 pickup and will they fit
 

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No. The basic transmission is pretty much the same (a few minor differences, mainly due to the fact that they are different years), but they aren't interchangeable without quite a bit of work.

The difference between a 2WD transmission and a 4WD transmission is in the tailshaft housing and tailshaft itself. The 4WD is made to bolt to a transfer case while the 2WD is made to go directly to a driveshaft.

A 4WD tranny can be converted to work in a 2WD, but you would probably be better off finding a 2WD tranny to start with because you would basically have to rebuild the transmission to convert it... You could just take it all apart and convert it to 2WD, but while you've got it apart you might as well install new clutches, steels, seals, etc.

Hope this helps! :)
 

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Discussion Starter #3
that answered my ? thanks is it a big job changing the block heater it seems mine is'nt working on the 86 gmc
 

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micvale1;1578704; said:
that answered my ? thanks is it a big job changing the block heater it seems mine is'nt working on the 86 gmc
You need the truck up in the air and you have to completely drain the block. But, most of the time - it's not the heater that's bad, just the cord. I've had to buy several. They tend to burn out at the connector where they plug onto the heater-prongs.
 

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Changing the heater isn't very difficult. If you've ever changed a freeze plug you've pretty much changed the heater. You don't have to have the truck raised although it does make everything much easier.

Jdemaris is right... The heater rarely fails while the cord is a common source of trouble. The cord can be unplugged and changed without removing the block heater.
 

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Discussion Starter #6
thanks alot for the info on the block heater cord bought a new cord today and its working fine and i found a 700r4 tranny and transfer case today its out of a 85 jimmy 4x4 it was bolted up to a 305 but the guy said it was the same as my 86 surburban 4x4 he want $350.00 for the pair
 

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$350 sounds like a lot of money unless the tranny has been rebuilt recently. If it's just some unknown tranny that "works good", be careful not to pay too much for it... They aren't worth much unless they have some history that shows a recent rebuild... I paid $100 for a so-called "good, working, functional 700R4" with unknown miles. And it did work fine... For 17 miles...
 

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micvale1;1580878; said:
thanks alot for the info on the block heater cord bought a new cord today and its working fine and i found a 700r4 tranny and transfer case today its out of a 85 jimmy 4x4 it was bolted up to a 305 but the guy said it was the same as my 86 surburban 4x4 he want $350.00 for the pair
When you say "pair" I assume for the $350 you're also getting the transfercase and intermediate adapter?

I don't know what kind of trans. your truck has now. If you're changing from a 3L80 a.k.a. TH400 - you'll need a different adapter where the trans. bolts to the transfercase, a flywheel/flexplate specifically for a 6.2 700R4 setup, and whatever parts are needed to hook the TV cable to the injection pump. In regard to the 700R4s in general, the 85s and up were upgraded and are better than the 83s and down.
 

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Discussion Starter #9
i have a 700r4 in the truck now but the clutch seal are going its has a hard 1st and second shift when cold its ok when warmed up,, the $350.00 1 the transfer case is still bolted to the tranny,,, tranny shop wants $1300.00 to rebuild the 1 in my truck
 

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Well, I suppose it might be worth it with the transfer case still on it depending on what model transfer case is installed on it... Some are worth more than others.

Have you considered rebuilding your existing tranny yourself? It isn't complicated if you are careful, have a clean area to work in, and are willing to spend the money on the necessary parts, although I will say it isn't something you want to try if you don't have much mechanical experience...
 

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micvale1;1580957; said:
i have a 700r4 in the truck now but the clutch seal are going its has a hard 1st and second shift when cold its ok when warmed up,, the $350.00 1 the transfer case is still bolted to the tranny,,, tranny shop wants $1300.00 to rebuild the 1 in my truck
The hard shifting ought to be easy to fix - sounds like a simple TV cable adjustment. A seal leak is a different story. I've never had a 700R4 actually go bad as far as running goes - but I've had several lock-up converter clutches go bad and MANY 700R4s leak oil out the front so bad - I had to pull and fix.

If your trans is an 85 or newer - too bad you can't find someone who can fix your trans. more reasonably. A good seal/clutch kit plus a few HD upgrades for your trans. would cost around $200. The labor is the issue - plus - I suspect no trans. shop will do your trans. without replacing the lock-up converter.
 

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Discussion Starter #12 (Edited)
how do u adjust the tv cable i'll try that,,, i'll even try rebuilding it myself i always thought it was a hard job .. they told me that the clutch seals inside the tranny were getting weak and it was just as much work fixing the seals as it would be to rebuild it,, it was just going to more money for the rebuild parts
 

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It is a semi-automatic adjustment...

With the engine off...

Open the hood. Remove the air cleaner. Climb up on top of the engine (or do whatever you have to do to get up behind the intake). On the back of the engine right near the glowplug controller and the vacuum pump there is a cable. This is the TV cable. It goes into a black plastic cable housing. Right where it goes into the housing you will see the adjustment button. Push the button down and hold it. Push on the end of the cable housing (it sticks out of the adjuster a bit) until it is pushed in all the way. Release the button. Manually open the throttle to the full throttle position. You will hear the adjuster make a "click" noise. This means that the cable has self-adjusted.
 

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Discussion Starter #14
that sounds easy its snowing and blowing real hard here but lucky for me my truck is in side my shop nice and dry so i'll go out and try it thanks again for all the info all u guys r a real BIG HELP
 

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micvale1;1580995; said:
how do u adjust the tv cable i'll try that,,, i'll even try rebuilding it myself i always thought it was a hard job .. they told me that the clutch seals inside the tranny were getting weak and it was just as much work fixing the seals as it would be to rebuild it,, it was just going to more money for the rebuild parts
I do all my own auto-trans. now - it is MUCH cheaper and I like to know what's going in. A few years ago - I lost my 4WD function in my Subaru. Went to a shop - guy shook his head - and told me it was a common problem that would cost $1500 to fix. I came home, ordered a trans. kit and book from Matco. Ended up - after some education - I fixed the trans with two hours works and only used a small portion of the kit. Total job cost me $135. What ticked me off is - the shop had to know that my 4WD clutch pack was accessible without removing the transmission - but they failed to mention that.

With the 700R4, there is a lot to know because it is a very popular transmisson - and it also had many problems early on - that got corrected along the way. A cheap book with all the update info is a God-send.

There are many places to buy parts and repair info - it's pretty competitive. I've been using Matco and they've been great. You can buy a good book from them on rebuilding and upgrading the trans. for around $15. Their URL is: http://www.bulkpart.com/Merchant2/merchant.mvc?Screen=SFNT&Store_Code=2
 

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Discussion Starter #16
one time many years ago i had a 71 mach 1 mustang it was'nt shifting very good so i took it to a transmission shop he told me 1800.00 to fix it with out even looking at it so i did'nt have the money for that so i went down the street to canadian tire and had the rear brakes done i did'nt know alot back then so when they finish i was backing it out of the bay and the mechanic said he can hear an air leak so he put it back on the hoist and found the rubber line to the modulater valve was split and fix it for free i tell u i was soooooooo happy so that tells you how much faith i have in tranny shops
 

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Yeah, I've never had much faith in tranny shops. That's not to say that none of them are any good... There are plenty of them that are perfectly honest and will work with you to get your car fixed, but it is an area where you can make a lot of money doing unrequired repairs... After all, not too many people would know the difference...

Good luck with your project!:)
 

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By the way, there isn't that much inside one of these transmissions. Most tranny shops make it sound more complex than it actually is. In my opinion, it doesn't take a rocket scientist to disassemble the tranny, install new clutches and seals, and put it back together. You can buy manuals to help you do it. The trick is that you have to work in a clean, organized way with lots of time and space and you have to be ready to spend money to buy parts.

Of course, this all comes from the guy who quit messing with 700R4s, but the truth is that if I'd had any money at the time when I was going around in circles with my 700 I could've built a nice tranny... Both the transmissions I built with used junkyard parts went through all four gears just fine and the torque converter lock up worked. The problem was that they didn't last very long... I'm not surprised, really. I remember sitting at my kitchen table with two clutch packs with all the discs burnt to a crisp and sorting through them and trying to put together one set where all the discs still had most of the lining on them... The discs were so thin I had to add an extra couple of discs to make up for the slop... :eek: I knew at the time that it wasn't going to be a great tranny and that it probably wouldn't last, but the one I finally ended up with worked fine until the pump siezed one day (looking back now, I see that that was probably due to a sloppy mistake on my part when I was putting the tranny in)...
 

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High Sierra 2500;1581649; said:
By the way, there isn't that much inside one of these transmissions.
Problem is - there is a LOT of know in regard to needed modifications, new parts, updates, etc. A person working on auto. transmissions every day - is usually aware of these things. Some of the mods. are considered - sort of - "trade secrets." Sometimes a double-thickness gasket added here, or an oil relief hole drilled there, can greatly add to reliability. So, to a good overall mechanic - who does NOT usually work on automatic transmissions - recent knowledge is the key to getting the "best bang for the buck."

Same goes with buying parts and knowing if any brands or types are more reliable than some others. A high volume shop will be more aware of these things (hopefully). That is why, I used to avoid doing auto. transmissions myself. The need comes up so rarely - in my case - there were times I did not want to conduct an involved research project just to fix one transmission. But - prices have gotten so high - I now take the time and do my own. I got stung once by a "reputable" shop once, and it won't happen again.

I was on a trip when my TH400 broke a gear. So, I had to bring it to a shop. Problem #1 - the repair was twice the estimate - yet - nothing unsual was found to be wrong with it - i.e. it was a standard rebuild. Problem #2 - once fixed it would not shift properly. The head of the repair shop jerked around for awhile with the modulator and VRV valve - and finally announded "auto transmissions don't work with diesels." Well that's a pretty ridculous statement. I got $200 taken off my bill - I was told to "never come back" and took my Suburban home. I still don't know what they did to it - to make it shift so lousy. But, I bought a HD shift kit from NAPA for $30. It came with an array of springs and gaskets and about 10 different choices of levels of improvements. I was pretty disgusted since every attempt required draining the oil, pulling the pan, etc. I took my best guess - picked a spring - and a gasket - put it together - and it shifted better than it ever did - even from when it was new. That was PURE luck. I could of wound up doing the process, over and over, 20 times. Well, no more transmission shops for me - unless I'm dead on the road somewhere.

When the good-old cast-iron Powerglide first came out - it had MANY failures and many updates before it became reliable. When the turbo-350 first came out - it was a dismal failure - worse than the first 700R4s. But, after many improvements, the TH350 became very reliable. The 700R4 is basically a TH350 with an extra gear and lock-up converter added. It has the same engine torque rating - which I believe is 350 lb. ft. in stock form. When the 700R4 first came out, the small local Chevy dealership in my town refused to sell trucks with it - since the failure rate was so high. But, by 1985 it was greatly improved. And since then, improved to a point it can be built with over a 500 lb. ft. torque rating - if not using the lockup converter. That exceeds the heaviest stock TH400 - which is technically a TH475. The TH400 that first came out in 1964 seems to be one of the few GM automatic tranmissions that worked great right from the start and exceeded expectations.
 

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Discussion Starter #20 (Edited)
i found a 89 k5 blazer he has the 700r4 and 2 transfer case NP241 and the NP208 now i have an 86 surburban with the 700r4 tranny will the 89 tranny and tranfer case fit the 86 surburban and which transfer case should i get ,,,and is there a tag or stamping on the tranfer case to see which 1 i have on the truck already
 
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