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Replacing 700r4/Np241 with SM465/205. What should I know?

Discussion in 'The Garage' started by bigredblzr, Apr 29, 2004.

  1. bigredblzr

    bigredblzr 1/2 ton status

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    Just like the title says I'm replacing my 700r4/Np241 with a SM465/205 setup. I know I'm prolly gonna have to do some drive shaft work, but what else should I know about the swap? The 700r4/241 are stock outta my 91 K5 (just in case it matters). Please say so if you're speaking from experience /forums/images/graemlins/wink.gif.
     
  2. big83chevy4x4

    big83chevy4x4 3/4 ton status

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    ive started the swap on my k10.
    you will need to move the crossmember.
    the front drive shaft becomes way to long
    go with a hydro clutch, its worth it.
    other than cutting a hole for the shifter, thats about it /forums/images/graemlins/waytogo.gif
     
  3. 75-K5

    75-K5 3/4 ton status

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    Will you be doing linkage or hydro clutch?
     
  4. bigredblzr

    bigredblzr 1/2 ton status

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    I was just going to put it in however I bought it. What is the difference between the linkage and the hydro-clutch? Sounds like the hydro-clutch may provide a smoother shift? /forums/images/graemlins/dunno.gif
     
  5. lifethroughdeath

    lifethroughdeath 1/2 ton status

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    i'm going to be doing this soon also, and was wondering if there are any comp problems since the 700r4 is no longer connected to it. What do you do with the wires, just cut them out?

    Nate /forums/images/graemlins/k5.gif
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, if I remember the later stuff right, you'll need to run VSS off the t-case (that was only on the 90-91 1 tons) and get a different (manual trans) PROM for it to run right, since it WILL be looking for the Park/neitral switch, among other things.

    Don't even waste your time with mechanical clutch on that truck, they are designed for the hyde. stuff, and it is MUCH easier to retrofit than the mechanical stuff. Plus it's superior, at least IMO.
     
  7. bigredblzr

    bigredblzr 1/2 ton status

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    What's a PROM? What is the big difference between the mechanical clutch and the hydro-clutch? Are the hydro-clutchs any harder to find?/forums/images/graemlins/confused.gif
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    PROM is the engine-specific calibration in the ECM. (It's what is talked about when companies try to pawn "performance chips")

    Big difference between mech clutch and hyde. is technology. One was probably designed about 150 years ago, one was designed maybe 40 years ago. /forums/images/graemlins/smile.gif

    Really, there is less to do with that swap (especially on a newer truck) and the hyd. clutch is not affected by movement of the body/frame, etc. Ask people that have driven both on these trucks, and I believe you'l see the hyd. reigns supreme for driveability.

    Not that mech. clutches can't be good to drive, just less likely from what I've seen.

    I'd really be focusing on the problem with VSS/Speedo though, instead of the clutch, these clutch assemblies aren't too hard to find, as long as you can get a bellhousing and pedal assembly, the rest can be purchased new. Converting a 205 to a tone ring setup (or finding a 90-91 K30) is more time consuming.
     
  9. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    [ QUOTE ]
    I'd really be focusing on the problem with VSS/Speedo though,

    [/ QUOTE ]
    I'm doing the same swaparoo on an '89 (no tone ring) Will I need the PROM from a std. tranny vehicle? I swapped out the steering column with one from a std. so I have no neutral safety switch in the column now /forums/images/graemlins/dunno.gif I figure if it doesn't run right I'll end up bashing it with a hammer until sparks catch the leaky oil on my driveway on fire and the whole rig burns to the ground... oooooor it will know what's best for itself and run like it's supposed to. /forums/images/graemlins/weld.gif
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    I'm sure it will run, but it won't be running right. Injection needs to know when the vehicle is in gear/moving, and when it's not.
     
  11. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    The speedo will be hooked up so the VSS will be working. That ought to be enough, right?
     
  12. 75-K5

    75-K5 3/4 ton status

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    If you're just going to be driving this on the road, then a linkage is just fine. If you will do any offroading, you NEED a hydro setup...just ask Tim. /forums/images/graemlins/rotfl.gif
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Nope. ECM "knows" it's in gear with the P/N switch. Not likely to be going 60MPH in neutral very often, right?

    I know there are a few "conditions" that govern whether a code is thrown, and how the system runs, but I'm not positive what will happen if you disconnect P/N switch and still have a VSS signal. Seems the different systems (year differences perhaps) react differently with the same problem.

    Stands to reason the setup is programmed to know that speed in neutral or park for along period of time is a problem, and likely a failure of the system. (thus, a code might be generated)
     
  14. TruckNutzDude

    TruckNutzDude 1/2 ton status

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    I think this topic is worthy of it's own post so I'm starting one in the "'73-'91 K5, Suburban, truck" section.

    Finished... here's the Link /forums/images/graemlins/deal.gif
     
  15. bigredblzr

    bigredblzr 1/2 ton status

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    I feel like an idiot, but what is VSS? /forums/images/graemlins/confused.gif

    Should I try to get the chip from the guy that I'm getting the rest of the setup from?
     
  16. lifethroughdeath

    lifethroughdeath 1/2 ton status

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    VSS = vehicle speed sensor, i believe. And since i'm going from a 700r4 to a sm465 and i will need a PROM for a stick truck, is this something i can go and pickup at the parts store, or GM directly or what, and any idea how much $$$ ? /forums/images/graemlins/1zhelp.gif Thanks

    Nate /forums/images/graemlins/k5.gif
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

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    You can probably get it from multiple places online, just have to search around.

    Don't ask on www.thirdgen.org forums, but I bet there are links to people/companies that can supply you with what you need.
     
  18. bigredblzr

    bigredblzr 1/2 ton status

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    Would a mechanical clutch be any harder to setup than a hydro-clutch, or vice versa?
     
  19. lifethroughdeath

    lifethroughdeath 1/2 ton status

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    700r4/241 to sm465/208 PROM Q

    [ QUOTE ]
    get a different (manual trans) PROM for it to run right, since it WILL be looking for the Park/neitral switch, among other things.

    [/ QUOTE ]
    [ QUOTE ]
    PROM is the engine-specific calibration in the ECM. (It's what is talked about when companies try to pawn "performance chips")

    [/ QUOTE ]

    I've got a 1990 K5, 700r4/np241 getting swapped with a sm465/208(eventually 241) and in the other "swap" post it was said that i'll need a new PROM from a manual trans truck. So what i gather is the PROM is like a stock version of a "performance chip" ?? if yes, then can i just buy a performance chip for a manual trans truck and be good to go? Thanks

    Nate
    /forums/images/graemlins/k5.gif
     
  20. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: 700r4/241 to sm465/208 PROM Q

    You probably can, but the "performance" chips are crap, and not worth the money, unless you like running premium gas for a few degrees extra timing. I'm sure the manufacturer or seller could tell you if thats all you need to change.
     

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