U-joint replacement

Engine, Transmission & Driveline

  1. thethee

    thethee Active Member

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    When I dropped my trans I noticed that there was play in the u-joints and they needed to be replaced. Got some new ones through rockauto but I have a couple of quick questions about it.

    1. New ones have a grease fitting, do I need a specific grease or is multi purpose EP2 okay?

    2. Read about mounting the u-joint so the fitting is "under compression", what does this mean?

    Thanks in advance
     
  2. Jon O.

    Jon O. Well-Known Member

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    Each of the four inner corners are either being forced together or apart. Two together, two apart. The differential puts force on the driveshaft opposite of the engine. You have to find one of the two corners that would be forced together and put the grease fitting in that spot. Therefore it will be under compression. Less chance of failure if the hole is compressed instead of pulled. I hope that makes sense.
     
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  3. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    If you look at the grease fitting, you want to do a couple things. First is to point the grease fitting so it slants towards the driveshaft on both ends That makes it easier to get the grease gun in place. You also want to orient them so you can get to both fittings without having to spin the shaft.

    For the most strength, you want to compress the web between the fitting as the driveshaft turns. That is if you are looking at the rear axle, the shaft runs clockwise (CW). So, you want the grease fitting to be on the right side of the bore. Visualize it as the driveshaft pushing against the rear flange.

    On the front of the driveshaft, visualize the trans yoke driving the shaft CW. So, that means you would place the grease fitting on the right side of the bore again on the driveshaft as you face the trans. Basically, it would be inline with the grease fitting on the other end. I tried to find a picture, but couldn't.

    The important thing is that it really isn't going to make any difference in your car. You aren't making enough power or dumping a clutch so that you break u-joints. If that was really a consideration, you'd be looking for some Spicer solid u-joints without the grease fitting. Actually, it isn't the u-joint that usually breaks. It's a yoke or the shaft itself twists. I twisted the driveshaft in my A12 car a couple times ... and broke the flange bolts off in my bracket race drag car. Never broke a U-joint.

    So, you can put them in like I described, or not worry about it.
     
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  4. thethee

    thethee Active Member

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    Thanks for clearing that up about the compression.

    Then about the grease, I'm not familiar with different types of grease, would this be okay?
    Kroon Oil Lithep EP2
     
  5. Jon O.

    Jon O. Well-Known Member

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    Really any good grease will work. I personally like red n tacky. Just don't use the cheapest grease and it should last a long time.
     
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  6. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    I use the grease that's in my grease gun that I use for front suspension etc.
     
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  7. thethee

    thethee Active Member

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    All I need to know for now, thanks
     
  8. thethee

    thethee Active Member

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    U-joint replacement was successful!
     
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