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Convert manual to Auto?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Rolled, Jun 16, 2002.

  1. Rolled

    Rolled 1/2 ton status

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    I have an 87 k5 with a 305 TBI, 205, and some 4 speed (L,1,2,3,R). I want to put in a 4 speed auto.

    Anybody out there know what all is involved with this? What I am unsure about is:

    1.Will the transfer case, drivelines and any mounting brackets bolt right up or do I need to do some parts chasing?

    2.What about wiring? I have seen an 85 that had a 700 but was replaced with a TH350 and you could see the old plug hanging down. What all does this plug do and where does it go? Is it an electronic kick down or does it communicate with the computer?
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Swapping a 4 speed auto in place of the 4 speed standard is a step backwards in my opinion. You'd be going from bulletproof reliability to a tranny with a shaky rep (depending on what year it was...and many other variables)

    The 700R-4 is expensive to rebuild as well, and the track record for rebuilds is probably worse than factory units unless some serious money is thrown at it. The Jet T700 and the Raptor are two that come to mind and neither one is cheap.

    Anyways, to swap over a few things need to be determined first. Four t-cases generally were mated to the SM 465...you'll need to confirm which one you have. If you're sure it is the 205 then you have a 10 spline 205. The 700R-4 is a 27 spline output tranny. Check with Advance adaptors for a T-case adaptor, as for the t-case input I believe a 27 spline input can be swapped in.
    Your drivelines will need altering. The front will need to be lengthened and the rear shortened. You'll need a TV cable bracket at the throttle body. You'll also need some sort of lock-up convertor control...
    You'll need a the pedal hanger assembly from an auto equipped truck and a steering column from the same (or a floor mounted shifter)

    That's all I can think of at the moment...

    Rene
     
  3. Rolled

    Rolled 1/2 ton status

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    Thanks for the reply Rene.

    I want to go with the auto since this is going to be a vacation vehicle and possibly a daily driver. I hate shifting all the time :-)

    I think I might buy a parts truck with the auto and just swap out the parts.

    I was told a good rebuild in my area, PHX AZ, would run about $300. Does this sound right? Can anybody tell me or point me to a good site that has all the tech info on a proper 700R4 rebuild?


    Thanks
     
  4. Chaz88K5

    Chaz88K5 1/2 ton status

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    300 to rebuild a 700r4...man thats cheep...i just converted my daily driver to a manual from a 700r4...i was trashin a tranny per year...when i pulled it out for the swap...i was on my 4th 700r4...but also i have put on about 100,000 hard miles on the truck since i bought it 4 years ago..but i would just stick to the manual...like rene said...its more of a step backwards..shifting cant be all that bad?..i do it everyday /forums/images/icons/grin.gif /forums/images/icons/grin.gif
     
  5. 70~K5

    70~K5 1/2 ton status

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    With that setup you don't have to shift very much. Come drive my Peterbuilt with the 15 speed trans. I could live with a 3 speed, you don't use low on the road much.
     
  6. Greenblazer-AZ

    Greenblazer-AZ 1/2 ton status

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    I think you will regret that swap, unless it's only going to be driven as a stock on road vehicle. Manual K5s are rare so I bet you could sell it for more than one with an auto trans. Sell it to someone that want's a manual and buy one with an auto, You might even end up with a few extra dollars in the process. Doing the swap will cost you money, and decrease the value of what you have. Just my opinion.
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    I know you are getting ganged up on here, and I want to join the mob : )

    Someone else mentioned just buying another truck. They are right. If this is a straight truck, you are FAR better off selling it to someone that wants a manual trans (which is quite rare the later the year) and finding one of the oh so common 700R4 trucks. (with an inferior t-case to boot I might add)

    I did chime in though because you mentioned daily driver. Mines driven daily, with 33's and 3.42's. 13/18MPG consistently, and after about 1 day of driving in traffic, the shifting *is* automatic. You quickly get to the point you aren't focusing on shifting at all.

    If I were running larger tires in a heavier truck daily, there is no WAY I would consider a 700 over the 465. Scan the list back a few weeks, months, year, however long you like, and compare how many people have actually been stranded by the SM465, compared to people stranded by auto trannies.

    $300 sounds WAY to cheap IMO, except maybe best case scenario that the 700 actually just wore out from use and needs new seals and clutches. Probably 75% of the time thats not the case, and hard parts need replacing which gets pricey. When my '83's 700 went out, I had to go to Aamco (stranded in Flagstaff AZ almost 10 years ago) and I shelled out $1500 to replace all of the components that had welded themselves together *in constant, no traffic, freeway driving*.


    If your 465 holds true to most everyone elses, it should have at least 13 more years left until you might think about freshening it up inside.

    I've got a 200-4R rebuild manual in e-version if you'd like to see what you are thinking about getting into. (I "freshened" mine up to last behind an Olds 403....the freshening up cost me $500 in parts alone to make it strong enough to be fairly reliable) Not a 700 exactly, but still a GM 4 speed OD tranny from the 80's, and thus quite similar.
     
  8. Sandman

    Sandman 3/4 ton status Author

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    You would be better off putting in a TH350. I just did this conversion from a manual for Mud Racing reasons. If you can find a complete setup of a Th350 and a 205 you will not have to modify your drivelines. The transfer case adapter for the four speed is pretty long. The same adapter for the automatic is much shorter and eats up the difference in length. You also do not have to worry about the electronics and it will last better. You should give the manual a chance. The only reason I swapped was to race. Other than that, I liked it.
     
  9. AussieK5

    AussieK5 1/2 ton status

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    When I needed to replace my blazer with a pick up there was no way I was going to go with an auto again. Yep city driving could be easier with the auto but nothing beats the manual for reliability. Manuals rarely (i know I know... there are exceptions) let go all at once, you usually can limp along with what gears you have left. I havent done alot of hardcore offroad but I have done alot of car racing and one thing you rarely see in a racecar is an auto, as a whole they just are not as robust and hate abuse. I don't like being in a position where I have to worry about a critical drivetrain components when just doodling down the highway pulling a car trailer or whatever.
    I been involved in some logistical nightmares getting mates auto rigs back to home after the g/box lost it. Like Dorian both instances were a very long way from home and in very remote areas...with out good support it can cost a fortune to get a rig back to somewhere that you can do repairs, then even more if you have the bits freighted in. You've probably guessed I'm a one eyed supporter of the manual option. /forums/images/icons/grin.gif My DD has 4.11s on 33s and around town I rarely use the low gears, I just flick between 3rd and 4th and if I treat it right she even lets you change without the clutch! almost an auto! but seriously a cheap 700 will cost you eventually, its just a matter of time or loud pedal. I think Ive bumped my gums for enough long now /forums/images/icons/laugh.gif and will get back in my box! /forums/images/icons/wink.gif
     
  10. Rolled

    Rolled 1/2 ton status

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    Standard is out of the question for me. Most of my cars/trucks are standard and they require 2 hands and 2 feet. I like drinking and eating while I'm driving and my third arm is on the blink right now lol.

    If I keep this truck it will be used for vacation, pulling a boat to the lake and maybe a commute accross town a couple times a week. I wont be taking it off road unless I absolutely have to.

    I have a TH400 and a TH350 here at the house that I could use but I thought I would go with the latest version I could get my hands on.

    Before I ask I'll do a search in the forums on what it takes to do a swap to the old 3 speed autos.

    Thanks for the help guys.
     
  11. 70~K5

    70~K5 1/2 ton status

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    It's your Blazer and you can do what ever you want, but why buy a stick if you wanted an auto? And why change one that's kinda rare when there's lots of one with auto out there? /forums/images/icons/shocked.gif /forums/images/icons/confused.gif
     
  12. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I'm going the other way. In 2-4 weeks I'm going to have my '84 back on the road and for the first time in its 18 year existance, it's going to be a REAL truck with a granny gear 4 speed like they all should be.

    Only LAZY people prefer automatics. Nobody that isn't handicapped should have one unless it's for racing or something in my opinion.

    I can't wait to drive my '84 as a 4 speed truck!!
     
  13. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    LOL, tell us how you really feel Tim! /forums/images/icons/grin.gif

    As for swapping in a slush box...if you're gonna do any towing I'd swap in the TH400 or Th350 over the 700R-4.

    Rene
     
  14. ftn96

    ftn96 1/2 ton status

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    Ok, here's the deal. You send me your tranny and T-case and I'll send you my TCI 700R4 and Fixed yoke 241 and you pay shipping for both. That should equal things out as far as the price difference. Im being serious here. I dont really need that 465 but the 205 is /forums/images/icons/grin.gif and should I not be able to find a 4500 I'll use your 465. PM me if you are really interested.
     
  15. m j

    m j 1/2 ton status

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    interested in the 200r4 rebuild info, please!
    lil brother has a 67 LeMans ragtop and he wants a 200r4 for the new 70 Gran Prix B&B 400.
    I want to stuff a Tremec in it, but it is his car.
     
  16. WakeBoard&4X4er

    WakeBoard&4X4er 1/2 ton status

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    Just FYI

    w/ 700r4 you should not tow a boat in O/D
     
  17. m j

    m j 1/2 ton status

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    thank you for manual!
     
  18. dyeager535

    dyeager535 1 ton status Premium Member

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    Least I can do, you have a nice library up for all to use, and I've used it myself a few times. Only fair!
     

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