Driveshafts measuring T56

Discussion in 'Transmission & Driveline Topics' started by badazz81z28, Dec 29, 2015.

  1. badazz81z28

    badazz81z28 Veteran Member

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    Ok folks, checking my sanity before I buy. I measured for a new driveshaft a few times and its all comes down to slip yoke movement. I remember that the splines on the t56 are actually below the outer seal, but how much? Based on this im factoring about 1/2" exposed slip yoke which gives me really 3/4" until bottoming out assuming 1/4" of movement is past the seal.
     
  2. badazz81z28

    badazz81z28 Veteran Member

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    From here to where it stops with seal contact is about 3/4". If you try to push it forward it goes about another 1/4". Like this equates to a 42.5 CL/CL shaft

    [​IMG]
     
  3. 71RS/SS396

    71RS/SS396 Veteran Member

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    When I order from Dynotech I fill out the work sheet they have on line and they figure out the length based on the dimensions I give them. Make sure you measure it with the suspension loaded.
     
    Last edited: Jan 1, 2016
  4. JodysTrans

    JodysTrans Veteran Member

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    The area you are referring to on the rear seal is actually the dust boot and not the actual seal.

    We bottom out the slip yoke to the mainshaft, then pull it outward 3/4"-7/8", then measure u-joint to u-joint. With the rear suspension loaded as 71RS mentioned.

    We also go one step farther, if the customer weighs 200lbs, we put that approximate weight on the drivers seat.
     
  5. badazz81z28

    badazz81z28 Veteran Member

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    I'm trying to get about 3/4" because I want maximum yoke engagement on the main shaft. The problem is that dust boot. The yoke can actually go further after touching it. Do you all measure from that boot lip or do you push it in as far as it will go? How far does that lip extend past the end of the main shaft? Currently by my last measurement I'm at 1/2" movement until slight contact with that dust boot lip.
     
  6. badazz81z28

    badazz81z28 Veteran Member

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    Btw, my car lowered so I'm not sure if that makes a difference. I was told that since its lowered and the shaft would be close to horizontal I need to consider that suspension movement may actually pull out rather than compress
     
  7. JodysTrans

    JodysTrans Veteran Member

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    The boot lip is NOT the seal, your slip yoke is out too far.

    A suspension in droop will push the yoke forward, no matter what ride height your street car is.
     
  8. badazz81z28

    badazz81z28 Veteran Member

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    Jody, I understand. How much past that rubber boot in the main shaft? Do you push it all the way in to compress the boot? I just don't want to damage it, but I know it will go in further past the point of just touching. Are you saying my 1/2" of exposed metal is too much out and needs to be pushed in? Sorry Im not understanding.

    This is 1/2" from touching seal

    [​IMG]
     
    Last edited: Dec 30, 2015
  9. John Wright

    John Wright Veteran Member Lifetime Gold Member

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    I used Denny's and they have a different set of dimns that they want you to furnish. I gave them what they asked for and it fits great, even with my oddball combination of parts.

    BTW, I removed the seal to get an accurate measurement.
     
  10. badazz81z28

    badazz81z28 Veteran Member

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    John I already have the yoke. I'm trying to get a CL to CL measurement. What really need to know is how much of the main shaft is counter sunk into the dust boot. My 1/2" slip yoke visible plus was ever the hidden under the dust boot is what I'm shooting for. I'm trying to avoid damaging the boot or spill fluid all over.
     

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