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4L80E vs TH400

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Brian 89KBlazer, Jul 17, 2001.

  1. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Which one should I go with?? I'm sloooowly accepting the fact that the 700R4 might be out of it's league for my application of 4.88's in a D60/14-bolt on 37" SSR's pulling a 6000lb trailer. I had myself decided on the TH400 but can't shake the Overdrive idea. I can get a 4L80E for $1500 plus the cost of the computer for it to be stand-alone (another $6-700).
    I can get a TH400 completely rebuilt with B&M Shift kit for $650. Will the gas mileage difference justify the extra cost or should I just take the TH400 & run??

    Who sell's the Stand-alone kits & for how much??

    Thanks
    Brian
    89KBlazer
     
  2. J.R.

    J.R. Guest

    take the TH400, you can always add an electronic overdive to it down the road if you want to. besides we dont own a k5 for good mpg.LOL

    BIG BLOCK MAN
    "MORE POWER"!!
     
  3. 88streetblaze

    88streetblaze 1/2 ton status

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    i don't know but i like the 4L80's they may be expensive but you can get a controller where you can change the shift points which really comes in handy and think of all the money saved from gas.....supposidly the 4L80's are reworked 400's with electronic control and an overdrive.
     
  4. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    How much are the Allison 5 speed autos? And will they work?

    Dave

    If You Drink Don't Park, Accidents Cause People.

    91 K5 - in the process of 4" lift with D60/14FF plus LOTS of extras. ETF August 1.
     
  5. talldogg

    talldogg 1/2 ton status

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    You can add "electronic overdrive" to a TH400?????? What exactly are you talking about?

    It's not what you buy, it's what you build!
     
  6. Boss

    Boss 1/2 ton status Author

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    What exactly needs to be done inorder to put a 4l80e into our K5s? I'm sure it aint an easy bolt on affair, but Just wondering what needs to be done. I may consider one down the road :)
    Boss

    89' 1 TON of FUN K5
     
  7. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Boss

    According to Steve Holmes at Bowtie Overdrive, he can sell me a beefed 4L80E complete with low stall torque converter & the stand alone computer kit for $3300 US. He said the hookup would only involve 2 wires; one to keyed 12V power & the other to ground. The only other hookup was plugging a harness into the Throttle Position Sensor. That's it!!

    Thanks for the replys so far.

    Brian
    89KBlazer
     
  8. 88streetblaze

    88streetblaze 1/2 ton status

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    ouch isn't 3300 a little pricey? i've seen jet proformance(which are dynoed and garanteed to take something like 450 horses and 600lbs of torque) 4L80's for 1800 minus the torque converter and computer but the stand alone computers weren't but $400 and that was the one that came with easy to adjust shift points.
     
  9. Emmettology 101

    Emmettology 101 3/4 ton status

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    Jet also sells the 4L80E, have you checked with them?

    I like OD, wish I had it!!

    <font color=green>MIKE</font color=green> - "Hukd on fawnics,werkd fer me!"
    <a target="_blank" href=http://www.geocities.com/emmettology101>http://www.geocities.com/emmettology101</a>
     
  10. Zepplin

    Zepplin 1/2 ton status

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    What was that coffee can size unit they put in that new Furd in last month's Petersen's? Wasn't that some overdrive unit?
    I think it only costs $790 and it went between the tranny and transfer case.

    74 Blazer
    Zepplin
    Check out my Blazer <a target="_blank" href=http://community.webshots.com/user/zepplin1976>http://community.webshots.com/user/zepplin1976</a>
     
  11. Scooter

    Scooter 1/2 ton status

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    I think that was a KluneV under-drive not an overdrive unit.
    They (or at least one of the mags) did a story on a bolt in OD unit a few months (maybe upto a year) ago that went in after the t-case .. if I remember right they said that the company made one that went between the tranny and t-case but it was more expensive .. could only use OD in 2wd but then again you really shouldnt need it in 4wd

    Scot in KC, MO.
    Blue 87 GMC Jimmy
    Red 86 Toyota 4Runner (for sale $2000 obo)
     
  12. Zepplin

    Zepplin 1/2 ton status

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    That's right it was a KluneV. It helps if you don't want to change the gears. It makes it feel like you have lower gears.


    74 Blazer
    Zepplin
    Check out my Blazer <a target="_blank" href=http://community.webshots.com/user/zepplin1976>http://community.webshots.com/user/zepplin1976</a>
     
  13. Triaged

    Triaged 1/2 ton status

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    The add on over drive that I have seen is made by gear vender

    '71 Blazer CST w/ a 400sbc, 4" lift, 36" Supper Swampers, and alot of rust
     
  14. HarryH3

    HarryH3 1 ton status Author

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    The Klune V low range unit costs around $2,000. The Gear Vendors overdrive is around $2,400. [​IMG]

    Let's see, a built Turbo 400 for $650 or a 4L80E for $3,300. At $1.70 per gallon, and assuming a 1 MPG improvement using the overdrive, you'd break even on fuel savings vs. tranny cost at just over 243,000 miles. [​IMG] Keep in mind that you probably can't use the overdrive while towing 6,000 lbs, so any savings during those miles would be zero. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  15. 502Burban

    502Burban 1/2 ton status

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    I have a Jet 4L80E in my Suburban. I think the $1800 price tag you've seen may be for the 2WD version. Last September, I paid $2,150 for the 4WD transmission and $360 for the torque converter.

    Jet's trans control ECU isn't as nice as some, although it is less money. I like the TCI (formerly SpeedPro) version, which goes for $741 at Summit Racing. The TCI ECU gives you all the control to change things; Jet's ECU requires them to burn you a chip. If you want to change things, you have to have them burn another chip. I like to have the control, myself. [​IMG]

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  16. 502Burban

    502Burban 1/2 ton status

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    Installing the 4L80E requires a few changes. You use the same adapter that is used for the TH400 to NP205 combo. The NP205 input shaft needs to be swapped for the longer version to get the proper engagement between the two pieces. You also need to machine the adapter to accept the o-ring seal from the 4L80E, and shave about 3/8" from the output shaft on the transmission so that it won't bottom-out in the t-case input shaft.

    Other than that, the trans is an inch longer than the TH400 and over 2.5" longer than the TH350, so you'll probably need to shorten your driveshaft. Only other things I can think of is that the crossmember will have to be moved back a few inches, and you may have to customize your shift linkage. I'm changing mine over to cable-shift, using the stock column shifter (don't want another shifter stick on the floor). [​IMG]

    Robb
    '73 GMC Suburban - 502DFI
    <a target="_blank" href=http://community.webshots.com/user/robbrj>community.webshots.com/user/robbrj</a>
     
  17. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Harry

    Do you think that's all you'd see for an improvement in mpg??? I thought the OD would give somewhere in the 20-30% improvement range. Yes?? No??

    Thanks ot everyone else for the replys; very helpful info 502.

    Brian
    89KBlazer
     
  18. Blazer79

    Blazer79 1/2 ton status

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    Go check my post about a video of a 4L80 swap. That website sells the computer kit that lets you use a standalone 4L80. Here's the link: <a target="_blank" href=http://coloradok5.com/forums/showthreaded.php?Cat=&Board=blazer4x4&Number=175355&page=&view=&sb=&o=>http://coloradok5.com/forums/showthreaded.php?Cat=&Board=blazer4x4&Number=175355&page=&view=&sb=&o=</a>

    <font color=purple>//////
    <a target="_blank" href=http://blazer79.freeyellow.com>blazer79.freeyellow.com</a></font color=purple><font color=black>
    Soon a 454 K5!!</font color=black>
    [​IMG]
     
  19. Brian 89KBlazer

    Brian 89KBlazer 1/2 ton status

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    Thanks Blazer79
    I already saw the post doing a search prior to my post. I also saw the show when it aired on Shadetree a long time ago. I'll recheck the post but I don't remember it naming companies other than JET.

    Brian
    89KBlazer
     
  20. HarryH3

    HarryH3 1 ton status Author

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    Yeah, I think that 1 to 2 MPG is about all the improvement you'll see. [​IMG] It takes a lot of fuel to move a 6,000 pound barn down the road. [​IMG] 2 MPG would be a 20% improvement if the baseline is 10 MPG. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     

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