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Thread: Is my driveshaft too long?

  1. #1
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    Is my driveshaft too long?

    So I was having difficulty installing the driveshaft because it would contact the IRS differential. I ended up needing to lift up the engine to get it installed. I got it all bolted down and even the driveshaft safety loop installed, when I looked at the inventory list that FFR sent stating that the driveshaft they sent me was a 31 spline 9.25". My original order form listed a driveshaft that was 8.375". Oops! Did they send me the wrong driveshaft? Do I need to take it all out? Those bolts now have blue loctite on them... Here are the photos below. I have a Blueprint 427 with IRS. The gap on the yolk is about 1/4 inch. From what I have read, that should be more like 3/4 - 1 inch. If my only problem with this setup is that I would need to lift the engine again if I have a problem with the driveshaft in the future, then I may just leave it alone. But if there will be interference problems with a gap this short, then it would make sense to correct it now.
    Thanks for your advice on this!
    -David



    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

  2. #2
    Senior Member edwardb's Avatar
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    With IRS, the diff doesn't move. So there shouldn't be any operational issues. Like you explained, the main issue would be removing in case of required repair/replacement. The more normal 3/4 - 1 inch of exposed slip yoke allows it to move with a solid axle, and also provides the needed clearance to push the slip yoke all the way in and then drop out the driveshaft without taking anything else apart.
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  3. #3
    Senior Member CraigS's Avatar
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    I'd leave it as is.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  4. #4
    Senior Member rich grsc's Avatar
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    Looks like you have 3/4", measure from the transmission, not the dust seal lip. It's fine just as it is.

  5. #5
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    Perfect, thanks guys!! I will move forward!
    David
    MK4 Roadster #9138
    Blueprint 427 with Sniper EFI, TKO600, IRS, complete kit
    https://thefactoryfiveforum.com/show...8-Build-Thread

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