Driveshaft Repair

Solving a Strange Vibration Problem


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Replace That U-Joint Without Breaking The Bank

The need for U-Joint replacement on shaft drive bikes like the Vulcan 1500/1600's usually becomes apparent in one of two...oops, make that three ways.

  1. You are doing normal maintenance, lubing the swingarm and/or driveshaft and you notice the U-joint is kind of notchy feeling when turned from one side to the other. That's not normal, the movement should be smooth in both directions. Replacement time.
  2. ujoint_galled.jpg (35920 bytes)You have a strange vibration that used to be felt only at certain speeds but now you feel it all the time and it's worse as speed climbs. That 'might' be your tires but if you've eliminated that possibility with new ones it won't hurt to check the U-joint. If it has gotten stiff it won't rotate smoothly and will create vibration. The photo (right, courtesy of Jim Mann) shows a U-joint that went bad on a Nomad. Just one of the four sides was bad but had become so galled that the driveshaft wouldn't even move in one direction. Suffice to say the vibration was fairly severe.
  3. This is the one you don't want. You've ignored the symptoms and just kept riding then one day you snap off a shift and faster than you can say "wham bam what the heck happened!" you've lost the connection between your engine/transmission and the rear wheel. The U-joint has finally snapped.

nomad_dshaft.jpg (94853 bytes)If you've experienced any of the above you've probably called your local Kawasaki dealer to price a new U-joint only to be told you can't buy it separately, Kawasaki only sells it as a part of a whole driveshaft and that assembly (see photo right) is going to set you back a cool $240 (best price I could find at Ron Ayers). There goes the rent money.

Well cheer up, there's another fix that your dealer won't tell you about, probably because they don't know about it.

An exact replacement part is in the Kawasaki dealers parts catalog shown for a Prairie 400 prarie_dshaft.jpg (120352 bytes) ATV. It's part number 49050-1002 (shown in the microfiche as a "spider" in the event your counter guy gets confused). Now, that part from Kawasaki is listed at $65. You could pay that and save $175 but wait!

Ask your dealer to check the Tucker Rocky ATV catalog and specifically part #57-8236. That is the equivalent of the Prairie 400 part (49050-1002) (see photo left) and costs about $30 including four snap rings. Cool eh? You've now saved $200.

Once you have your new U-joint and snap rings in hand there are two ways to remove and replace the old one.

 
  1. The preferred method. Unless you have a hydraulic press, take your driveshaft and new U-Joint to an auto repair shop and have them press the old out and the new in. They'll probably charge you $10 or so but even at double the price it saves you a lot of sweat and worry.
  2. The money saving way which is what you'd probably do with a pickup truck in the back yard.
    1. ujoint_circlip.jpg (145278 bytes)Remove the circlips from all four sides using circlip pliers or, if you don't have any, a flatblade screwdriver and a pick as shown at right. There's some chance (pretty good one actually) that at least one of the clips will fly across your garage while you're doing this so either make sure your new U-joint comes with new clips or cover the original with a towel while you're removing it to prevent loss.
    2. Prop the yoke up on something so the bottom cap has a place to escape then with a socket the same size as the cap (or slightly smaller) start tapping with a hammer as shown at right. It shouldn't take too much effort to get things moving.ujoint_removecaps.jpg (108009 bytes)
    3. When the bottom cap is almost all the way out the U-joint is going to bottom out against the yoke. At this point grab the bottom cap with some Vice Grips and twist that puppy outa there. If it won't twist you may have to get out your 'persuader' hammer and tap it out. This is when it's good to be using the cheap Harbor Freight vice grip rather than the good Craftsman pliers <g>ujoint_vicegrips.jpg (93249 bytes)
      ujoint_punch.jpg (112810 bytes)
    4. Once the bottom is out flip the shaft over and drive the other cap out with a punch as shown at right. Turn the assembly 90 degrees and do the same removal for the other side.

When everything is apart you can re-assemble in pretty much the reverse except the use of a punch won't be required. Place the spider (center part of the U-joint assembly) in the driveshaft yoke and press in new caps as far as you can with your thumbs. Be sure the needle bearings stay against the walls of the caps and tap the caps gently into place using the small hammer/socket combo shown above. Most replacement U-joints will come with a zerk fitting for lubrication. If you haven't already put the fitting in place do it now and inject some grease. In the future you'll be able to pull the dust boot back and lube the joint no muss, no fuss.

Before you put the circlips back in make sure the assembly is moving freely, no binding in any direction. Add the circlips and check for binding again.

Now, while you have everything apart and the swingarm off the bike would be a great time to lube those swingarm bearings. When that's done re-assemble your bike and go ride. Enjoy the lack of vibration for the first time in probably many miles.

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