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VSS question for a 91 NP241C

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Boscolingus, Mar 12, 2002.

  1. Boscolingus

    Boscolingus 1/2 ton status

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    As I recall on my previous transfer case it did not have a mechanical cable output for the speedo, however this transfer case I just purchased has a mech. output where my truck does not have such a cable.

    The question is - Is there a proper part VSS I need to put in it's place or do I just have my head firmly up my ass on this one =-)
     
  2. woody9

    woody9 1/2 ton status

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    not sure this helps, but my 91 sub with 241 has the elec speedo on it. It's not your memory!
    NFI on how to convert a mech one to elec however...
     
  3. BurbinOR

    BurbinOR 3/4 ton status

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    One place to check with is http://www.jagsthatrun.com - they have VSS units for just about every application. Not sure if you have an electronic speedo but check that out before you call them.
     
  4. Kyle89K5

    Kyle89K5 1/2 ton status

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    If your's has a mechanical speedo, then it's not a 91 case. My 89 is mechanical, they switched to elec in 90. HTH.
     
  5. Boscolingus

    Boscolingus 1/2 ton status

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    ahh, ok - just the answer I was looking for, so what all would be the total parts I would need to make it compliant and work on a 91 platform?
     
  6. Kyle89K5

    Kyle89K5 1/2 ton status

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    Now THAT is a good question. The easiest way that I can think of, since I've never seen a good teardown of them both, is to hunt a 91 case. It doesn't even have to be in good shape anymore, but see if you can find one and compare. It might be as simple as a tailshaft swap, but I'm not for dang sure. I'll look into it a little more and see what I can find.
     
  7. Boscolingus

    Boscolingus 1/2 ton status

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    so what were getting at is that there was a significant change in the cases between 89/90 and 91? If so it may not be as easy as a part replacement. Could I possibly get someone to take some pics of the VSS unit from all years ranging from 89-91 to see what kind of mess I'm in and how I can go about this, this just might be a learning process in which I'll do the homework for the next guy who gets into this situation =-)
     
  8. Kyle89K5

    Kyle89K5 1/2 ton status

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    Here's a pic of one with a SYE kit on it. You can see where the elec speedo plugs in. This is on a 90. DP90K5's to be exaact. You can compare a little right there.

    http://coloradok5.com/gallery/albuo71/aac
     
  9. Boscolingus

    Boscolingus 1/2 ton status

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    well - son of a bitch, it looks as if the entire tail housing is completely different, now Im gonna check out AllData and get some info and part numbers for this situation
     
  10. Kyle89K5

    Kyle89K5 1/2 ton status

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    That may be good news, head to a parts yard and start scrounging. The 89 is a little more rare than the 90-> because the 89 was the only year for the mech. Good luck.
     
  11. Burbinator

    Burbinator 1/2 ton status

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    The tailshaft housing IS different on a case with a SYE kit...
     
  12. BigBurban350

    BigBurban350 1/2 ton status

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    All you need is a tach and friend to chart out the RPM to Speed ratio(If /forums/images/icons/confused.gif then get another 241C with the hall effect sensor on the tail shaft).
     
  13. Boscolingus

    Boscolingus 1/2 ton status

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    haha- I took the later route, the 90-91 t-case came in 2 days ago and was in the truck 1.5 hours later, just couldnt wait to get the drive train done.

    Another thing I have noticed is that the pinion angle w/ the 14 bolt looks rather ominous - Im going to guess that it seems to be at 15+ degrees, not sure on what the max degree is before vibration and u-joint exploion, however I beleive I will machine up some 5 degree angled shims to decrease the angle.

    I am curious why this angle issue has never occured out of the thousands of 14 bolt swaps to factory drivetrains ( mine is a 91 w/ 700R4-241C setup )

    More to follow..............
     
  14. Boscolingus

    Boscolingus 1/2 ton status

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    However I do want to add that I do appreciate the input - I posted this several months ago I beleive and yet you came through w/ a possible fix, now thats just damn cool /forums/images/icons/smile.gif
     
  15. BigBurban350

    BigBurban350 1/2 ton status

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    Precision u-joints call for 1 to 3 degrees, So youd better shim it. The degree out must equal the degree in to get max life out of drivetrain components due to the acceleration/deceleration vibration due to a u-joint.

    Fun fact /forums/images/icons/smile.gif : a <font color="red"> </font color> CV <font color="black"> </font color> joint is the solution to those damaging vibrations, <font color="red"> </font color> C <font color="black"> </font color> onstant <font color="red"> </font color> V <font color="black"> </font color> elocity
     

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