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Can either of these adapters be made to fit a 4l80 to a np205?

Discussion in 'The Garage' started by LoggieStyle, Jul 10, 2003.

  1. LoggieStyle

    LoggieStyle Registered Member

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    Hi, if anyone has a 4l80/205 setup and knows what adapter I need or how to modify an adapter to work please let me know. Also, does the year of the np205 case make a difference in this setup, if so what years are easiest to do this with? These are the adapters I have at the moment I'm pretty sure one is a th400/205 adapter don't know the year though and the other I took off the 4l80 so it's probably a 241? or whatever they used in 1996.

    Anyhow thanks for any information you can provide, I am in way over my head with this project and the only person I knew with a lot of mechanical knowledge moved to washington but I don't want to give up so I apologize if I am leeching information off of you guys. If there is anyone in the los angeles area that knows about this stuff and would be willing to mentor me a bit I would pay what I can.
    Thanks,

    Logan

    [​IMG] [​IMG]
     
  2. Don

    Don 1/2 ton status

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    Bottom pic. is for a TH400 to a 205, I don't know what the top pic. is other than Th400 to???
     
  3. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    PM / email <font color="orange">U2Slow</font>, he is THE MAN when it comes to compatability info. /forums/images/graemlins/deal.gif

    Also can you post a pick of the other side of the short adapter? /forums/images/graemlins/thinking.gif
     
  4. u2slow

    u2slow 1/2 ton status

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    The top adapter is used to mate a 4L80E to any of: NP241, NP243, BW1370, BW4401, or BW4470. The main problem with using it with an NP205 is the lack of a shifter boss, and the notch required for the shift rail. If you can overcome those two obstacles, you could use an 85-91 NP205 (round pattern) with a "short" 32-spline input gear from a 77-84 NP205.

    The second adapter is one of the few I haven't had my hands on. How long is it? If its about 4" long, you need a 70-84 NP205 with a "long" 32-spline input from an 85-91 NP205. The lip on the tranny side of the adapter will need to be turned down slightly so it can fit into the back of the 4L80E.

    Here's an 85-90 Th400/NP205 adapter that's been modified for 4L80E use. Notice how it looks like the lip is "stepped" compared to the previous photos.
    [​IMG]
     
  5. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    THAT'S what I was talking about! /forums/images/graemlins/deal.gif /forums/images/graemlins/thumb.gif
     
  6. azblazor

    azblazor 1/2 ton status Premium Member

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    My K5 4L80E is mated to the old style Th400/Np205 adapter. I have a alum spacer between the back of the trany and the front of the adapter - its close to an inch long. No changes to the trany output shaft or the NP205 input shaft.
     
  7. LoggieStyle

    LoggieStyle Registered Member

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    You guys are awesome, hope you don't mind if I PM a couple of you to ask some questions so I don't keep kicking this thread to the top. Also I will post a pic of the other side of the short adapter for nvrenuf when I get home from work.

    Thanks

    Logan
     
  8. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    If they're tech type questions I'd suggest keep posting them here so the info will be available in the future via search.

    Just a thought.. /forums/images/graemlins/thinking.gif
     
  9. LoggieStyle

    LoggieStyle Registered Member

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    good point nvrenuf, I will make sure to post all tech questions here.

    From the information you guys gave me it seems like there are two good ways to do this.

    1. Get a 85-90 np205 and 85-90 th400/205 adapter and modify it to fit the 4l80, seems simple enough with a little machining. No further modifications necessary?

    2. Get aluminum spacer like azblazer's to fit between 4l80 and old style th400/205 adapter. No further modifications necessary? My question on this one is where do I get a spacer like this? or at least where can I find the information on how to make one provided I have access to a machinist and tools? Is it just a round piece of aluminum with the proper bolt holes and a hole for the tranny shaft or is it more intricate than that?

    Thanks,

    Logan
     
  10. azblazor

    azblazor 1/2 ton status Premium Member

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  11. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    [ QUOTE ]
    One option: Using a NP205 adapter
    Another option: doubler considerations
    Yet another post: more on doublers
    Good one on crossmembers and spacers
    one more: last one


    [/ QUOTE ]


    What a nice list of links! Thanks! /forums/images/graemlins/thumb.gif




    One question (because I'm a little slow today)....

    A lot of those threads seem obsessed with finding the 4L80E to 205 adapter. In these instances, they are not referring to putting together a "Doubler" setup, right?

    From my limited understanding, the sequence (if you ARE talking doubler) is:


    4L80E -&gt; Trans Adapter -&gt; NP203 -&gt; ORD Doubler -&gt; NP205


    The "Trans Adapter" therefore needs to connect the output shaft of the 4L80E (which can be either 1.5" or 2.5"? stickout?) to the NP203. It sounds like there is a "thin" solution that uses a factory adapter, but requires the small stickout from the 4L80E (which might not be that common)....or, you can use a factory 4WD NP241 adapter which works perfectly for the 2.5" stickout versions of the 4L80E, but has the wrong hole pattern. This requires you to re-drill the NP203 to match, but apparently isn't too difficult or expensive.

    Have I captured things correctly? (or at least somewhat?) /forums/images/graemlins/tongue.gif
     
  12. azblazor

    azblazor 1/2 ton status Premium Member

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    Your assesment of the various threads is correct as far as I can tell. The two issues regarding the 4L80E that pop up most often are mating it to a NP205, and mating it to a NP203 for a doubler.

    I'll have additional information with pictures in the next few weeks.

    I now have at home:

    uninstalled:
    4L80E (4x4) with NP241 and adapter
    Np203 adapter to TH400
    Np203 range box from Th400

    Projects:
    1978 Suburban with Th400 and NP205 with adapter (Old style) - will be getting a 6.5TD with 4L80E (from my 93 K2500) and NP205 .

    1979 K5 with 4L80E with spacer and old style NP205 adapter and NP205 - will be getting the 4L80E doubler setup

    1986 K30 with TH400 and Np205 new style - will be getting 4L80E mated to Np205 (might use the NP241 adapter or the old style Np205 and spacer from the K5)

    Just have to get my "stick outs" figured out if you know what I mean :-)
     
  13. K5 NUTT

    K5 NUTT 1/2 ton status

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    Mark...what do the 4l80e's going for in used shape? I did see a link somewhere to a company who has made a 4l80e without the electronics....yet shaving even more off the cost of the swap...and worth lookin into if the core value isn't to bad...

    DW
     
  14. doctor4x4

    doctor4x4 1/2 ton status

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    WOW what a great post and INCREADIBLE -- CREDIBLE info
    and well i 1/2 ass iknow what im doing but noting like these guys and im in burbank and have a neibor with a machine shop so if i can help ya id be happy 2 as this is the same kind of set up i want to go with on 1 of my projects
    Randy /forums/images/graemlins/thumb.gif
     
  15. JDNobodi

    JDNobodi 1/2 ton status Premium Member

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    I have a question. From looking at pictures of a 4L80E, I notice the tranny pan goes all the way to the back of the transmission. The factory TH400 adapter has the mounting foot towards the pan. Won't the mounting foot hit the pan? /forums/images/graemlins/confused.gif
     
  16. LoggieStyle

    LoggieStyle Registered Member

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    Hi Doc, I'm still not completely sure which setup I am going to to go with yet. When I do I will send you a PM and take you up on your offer, thanks! It's cool to find someone living so close. Burbank is only 10-15 minutes from me.

    Thanks,
    Logan
     
  17. azblazor

    azblazor 1/2 ton status Premium Member

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    Doug,
    I paid 700 for the low mileage 4L80e/adapter and Np241. But most places seem to be getting 500-700 core charge. I picked a used aftermarket standalone controller (TCI I think) for about 250. Those manual control ones don't lock up do they? Kind of takes away some of the benefit of the overdrive if they don't. Aren't they like $2500-3000?
    Mark
     

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