Just Another U-Joint Failure

Discussion in 'GS Boxers' started by grantsdad, May 24, 2014.

  1. grantsdad

    grantsdad Been here awhile

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    Last week I heard a knocking sound from the driveline as I turned the rear wheel by hand. After reading countless stories of u-joint failures I figured it was my turn to face the inevitable.

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    I removed the driveshaft to properly inspect the u-joints



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    The trunnions attached to the fixed yoke were very stiff, not moving freely like the splined yoke. They also had grease weeping from the seals.




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    It takes a bit of patience to seperate these little pieces.



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    Eventually I managed get them apart



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    The end of one of the trunnions is discolored, likely from excessive heat.
    #1
  2. bemiiten

    bemiiten League of Adventures

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    If the plan is to have the shaft rebuilt by Bruno, then grinding out the stakes with the U joint in place is not the best idea as their is not much material their and removing too much can leave not enough to machine a groove for the clips. Best to cut the joint out from the inside with a cut off wheel and remove the stakes once the joint is out of the way.
    #2
  3. GSABest

    GSABest El Aventurero

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    Welcome to the club! The front ujoint failed on my 2008 adventure at the 83,000 km mark. Left us stranded in northern Argentina. Eventually installed a used replacement which had one new u-joint in it, as new BMW parts availability is rather poor largely due to onerous customs clearances. I intend to replace it with a new one once the bike has been shipped to the US next week.

    Sent from my HTC One using Tapatalk
    #3
  4. aculate

    aculate Herk, herk,...Ptooey

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    OP, how many miles on the bike?
    #4
  5. Kawidad

    Kawidad Long timer

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    From the photos I've seen that is the method used to remove the U joints and then metal is added via a welded seam in which the groove is machined. :augie

    To the OP, good catch.
    Year and mileage?
    So what's the plan now? :ear
    #5
  6. grantsdad

    grantsdad Been here awhile

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    My plan is to rebuild them myself, with the help of friends at work. I bought replacement u-joints HERE and a colleague will perform the machining. We work for a company that designs and manufactures gear-driven transfer cases for the automotive aftermarket. We also make yokes and companion flanges for various applications. After examining photos of Bruno's work and photos of the welded-washer method, we along with our Senior Engineer hatched a plan for rebuilding the driveshaft.

    I removed the stakes from one side with a diamond-point grinding tool mounted in a Dremel. It's a delicate and time consuming task because I could not remove any more material than was necessary to release the cap. To be safe, I left a small edge of stake material that sheared off under pressure from a bench vice.

    Once one cap could be pushed through it's ear of the yoke there is more working area to get at the stakes of the opposing cap. Again cautiously not exceeding the bore diameter of the yoke, in this case 19mm.

    Next week we'll make a fixture to support the driveshaft on the table of a Hass VF-5ss where the snap ring grooves will be cut into the yokes.
    #6
  7. grantsdad

    grantsdad Been here awhile

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    My bike is an '07 GS with a scant 43,000 miles on the odometer. This is my first shaft-driven motorcycle and my first BMW.

    I bought the bike second-hand with 7500 miles on it. Though I can't speak for the original owner, I have never ridden the beast on anything rougher than a graded forest service road. Well, I did venture off on a Jeep trail for 6-8 miles but I took it easy, pick-poking along in 1st or 2nd gear.

    The yokes, front and rear have never been wet as far as I know.

    I am guilty of launching the front wheel from time to time. :D

    One of the bearing caps was very dry. It's obvious that the small amount of grease from the factory had escaped, thus causing the failure.

    It's not surprising BMW uses non-greaseable u-joints; they're fairly common in the automotive world. I just wish they made them replaceable. Throwing away a perfectly good driveshaft because of a failed u-joint is just wrong on so many levels.
    #7
  8. bemiiten

    bemiiten League of Adventures

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    :thumb I agree, the clips are worth the extra cost/work. Not much of a fan of welding a washer over the cap due to the heat and difficulty of fixing it in a pinch somewhere. If your friend at work can offer this service, I'm sure plenty of other inmates will have shafts to send. Yours lasted 5K longer then mine.
    #8
  9. JetSpeed

    JetSpeed Naviator

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    I'm a little surprised that the engineers at BMW are still using Cardan (U-) joints on these bikes and not CV joints, even though the drive angles are not all that great the CV (in my opinion) is better suited for this application.
    #9
  10. bemiiten

    bemiiten League of Adventures

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    Considering how many fail, some catastrophically, in under 50,000 miles, only a matter of time before someone is involved in a accident. At that point we'll get a 'Replace at 40,000mi' sticker for the owners manual. :lol3
    #10
  11. _cy_

    _cy_ Long timer

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    dead on comments .. switching to non-serviceable U-joints, tie rod ends, ball joints, etc. has long been a tactic for automotive mfg from all over the world.

    now which is better for BMW? selling two tiny u-joints for $50 each or selling an entire driveshaft for $735?
    specifying C-clips for serviceable u-joints makes little to no difference in terms of manufacturing costs.

    OEM wants major components to last past warranty period .. but not much too longer. this accelerates new model buying cycle .. especially when costs to fix major component starts approaching 1/2 valve of motorcycle like on R1200 series.

    this may sound like tin foil hat theory's but it's not ... look at how many years final drive issues has plagued R1150/R1200? this is not by accident .. BMW engineers are not stupid in the least.

    it's not like BMW doesn't know how to make a driveshaft last ... R80G/S driveshaft and final drive are bathed in oil and typically last entire life of bike. but that would not do .. R100GS switched to non serviceable driveshafts not bathed in oil .. service life is typically not much more than R1200 series. a home run from BMW's point of view :D

    it is possible to avoid failure by injecting grease into joints with a grease needle. have been doing this on all non-serviceable joints for many years. some bearings are located in inaccessible locations making pumping full of grease impossible. this was NOT by accident!

    when any bearing goes dry ... game is over .. bearing is toast!!! if internal grease is not refreshed ALL bearings have a finite life.
    kept full of grease with proper preload .. most bearings will last life of vehicle.
    #11
  12. cardoctor1

    cardoctor1 Been here awhile

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    been thinking about u joint maint for a while couldnt the caps be drilled and taped for a grease fitting and then put a screw in plug when finished.
    #12
  13. Wallowa

    Wallowa Diver Down

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    The u-joints with zerks to lube them are not as strong as sealed u-joints...but then again..I have a very high Hp vintage car with zerk fitted u-joints and none have failed...

    Zerks are in yoke, not caps.
    #13
  14. orgo

    orgo Been here awhile

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    #14
  15. JetSpeed

    JetSpeed Naviator

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    Assuming that the bearing cross journal is hollow on a grease-able u-joint and solid on a non grease-able unit this statement may be true, but it is mute to even bring up since most all u-joint failures occur at the bearing/cap and are caused by lack of lubrication, I have never seen a cross journal fail.

    I have also not seen a Zerk on a yoke as there would be no point, it would have to be on the cross journal or cap for the grease to reach the needle bearings.
    #15
  16. _cy_

    _cy_ Long timer

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    not room for zert to stay in place. but there's room for a service port in center of yoke.
    in other words if BMW wanted to they could have made driveshaft Ujoints replaceable and serviceable.

    BMW engineers did a really good job making these driveshafts all but impossible to service without a service facility.

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    then there's a rubber mounted shaft bushing that can fail
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    #16
  17. mwhite5471

    mwhite5471 Been here awhile

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    Instead of the regular male zerk you could use a female needle zerk and this would only protrude an 1/8th.

    Also need a very dense tacky grease like a complex lithium blend...I use Caterpillar Gold in my off road buggy.
    #17
  18. Wallowa

    Wallowa Diver Down

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    When I said that I have only seen zerks IN the yoke, I should have stated that you found them inside the yoke on the u-joint; getting to them with a grease gun is always a bit of a challenge...since the non-sealed [with zerks] do have a channel to allow the lube to move from the zerk to the bearings in the caps they are not as strong as a solid u-joint without channels...but again this is a moot point and not really answering the OPs issue.

    Even sealed u-joints should last a very long time if they hold their lube.
    #18
  19. _cy_

    _cy_ Long timer

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    ok .. enough bitching ... here's what you can do to refill your ujoints full of grease.
    take a grease needle, then carefully insert needle into tiny grease seal. then pump full of grease. repeat for each bearing cup. if you damage seals doing this .. not a big deal since spinning forces grease into cup.

    or you can drill a tiny hole in bearing cup. not likely there's a hollow passage to allow easy filling of all bearing cups in one go. seal back up with JB weld or what ever.

    if you've got say 45k miles .. it's coming .. repack your Ujoints or get ready to pay $$$ when it goes down in the middle of a trip.

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    #19
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  20. grantsdad

    grantsdad Been here awhile

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    When I placed my order with drive-lines.com I expected to receive Elbe-106 u-joints. What I actually received were equivalents from INA. I had no problems with this since our company has years of success with other INA bearings. The INA u-joints are 19mm x 48mm with a zerk fitting in the center of the trunnion. The trunnion is cast (or forged?) with a protusion to place the zerk at 45°. This might make clearance while rotating a problem. I replaced the snap-on zerk fittings with a flush-mount style from McMaster-Carr

    I had the old u-joints removed, new u-joints on my desk alongside a carbide key-slot cutter. Then reality set in. I manage a small factory with 7 mills, 5 lathes, 3 gear hobbers and 2 gear shapers. Our mills are booked-solid with work through July. As much as I wanted snap-ring grooves, there was no way I could pull paying jobs off the machines for myself.

    4th-and-10 from my own end zone I opted to punt. Our lathe team turned 18.8mm x 2mm discs in mere minutes. I spent an hour or more with an arbor press, V-block and heighth-guage centering the trunnions within .003". The fabrication shop was happy to help out as well by TiG-welding the discs into place. The job was done Friday afternoon.

    Some kind of cold virus going around? No! Really? Yep, I was sick all weekend. I slept 17hrs between Friday evening and Saturady afternoon. Sunday moring came around and I was alert enough to reassemble the drive train. Everything was inplace and torqued to spec when I realized pictures had not been taken. Damn.

    I took it apart and snapped a few:

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    #20