Rocker Bearings Coming Apart!

Discussion in 'Airheads' started by Pica Hudsonia, Jul 10, 2012.

  1. Pica Hudsonia

    Pica Hudsonia Super-dupergenius

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    I'm about 2 weeks into ownership of my first BMW, a '93 R-100GSPD. You can see pics and a day trip report here:

    http://advrider.com/forums/showthread.php?t=805255

    For the past several days, I've been spending most of my free time carefully going over the bike, replacing fluids, cleaning and adjusting stuff, and getting to know all its parts. This is not a burden to me, but one of my favorite hobbies. I'm kind of glad to learn the Beemer lends itself well to tinkering. It seems pretty easy to work on, and it has enough pieces deserving of some TLC to keep me busy for a while.

    This morning on the agenda was valve adjustment. I took off the left valve cover and everything seemed A-OK. The exhaust was exactly .008", so I left it alone, but the intake required a tiny adjustment to bring it to .004.

    When I opened the right cover, I found a little pile of scrap metal inside. Back when I was working on helicopters (German ones, no less!), if we found a gearbox with debris like this in it, we said it was "making metal." :huh

    [​IMG]

    [​IMG]

    [​IMG]

    (The penny wasn't there. I added it.)

    I took a few pictures to show you, and then started investigating to find out where this junk came from. Since it sat right below the intake valve rocker shaft, I looked there first. Here's what's going on:

    [​IMG]

    [​IMG]

    Seems as though a bearing is coming apart, and at least one and a half of the needles are trapped in the slot of the shaft mounting block. On seeing this, the first thing I thought was, "Bingo! So that's the source of the metal pieces." About two seconds later, I thought, "Nuts! This looks like it's gonna be expensive." :cry

    At this point, I ran out of time and had to get cleaned up and ready for work. This whole business of keeping a full time job is really cramping my style. :puke1

    So tomorrow morning I'll tear into it further to see just how much damage there is. I suspect I'll need to replace at least the bearings, rocker, and shaft. I've been reading up on how to properly shim it. I'll also drop the oil pan to see if any pieces made their way into there, and look closely at the oil filter.

    I've never ordered from A&S BMW, but I like their website, they seem to have a good selection of parts, and their prices are reasonable (a relative term when we're talking about BMWs). Does anyone have experience with them, good or bad?

    Any ideas on what might have caused this failure, or advice on how I should proceed? :ear

    There's a reputable shop 40 minutes from my house. I could pull off the entire head, take it to them, and tell them to just make it right. But then I'd be paying for labor as well as parts, and besides, I find it more fun to fix stuff myself. What a way to be initiated into airheads, eh?
    #1
  2. batoutoflahonda

    batoutoflahonda Long timer

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    Yeah, they are stupidly expensive and proprietary.

    Just curious, how was it running? If you say great, I'll chalk that up to my "robustness of the airhead" log. "Why I once new a guy....."
    #2
  3. disston

    disston ShadeTreeExpert

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    If you are capable of removing the cylinder head and taking to somebody else I think you are capable of doing the repair yourself. It can be done with out actually removing the head.

    Take off rocker arms one at a time. Make tool from all thread rod, available at neighborhood hardware store, and assorted nuts and washers and sockets from 3/8 socket kit. The all thread goes thru the rocker arm with bearings to be removed. One of the sockets of a diameter to push thru, small enough to fit easily inside the rocker and contact side of bearing. Another socket larger than the hole but small enough to make receiver chamber at other end. I made this tool from a long threaded carriage bolt. A little simpler than using the all thread. A carriage bolt is one with a round hole and a square head under the round portion. These are the bolts used on older car bumpers. All you see is the round part. It helps to have a large vise to hold your tool in as it takes a lot of force to push the old bearings out. A variation will suffice to install new bearings. The new bearings are installed only 1 or 2 mm deep.

    There was a thread only a week ago about doing this with a larger vise and making a driver to use in vise. I've forgotten where this thread is, I looked.

    There are 8 bearings to be replaced. They are not cheap. They are only available at your friendly dealer. Lots of shoppers have tried to find some cheaper generic bearing. Hasn't been one found yet. It is an odd size.

    I believe in doing all 8. Some may want to do only the few needed at this time. I think the rest will fail soon so I do them all.

    It's a standard failure of these bikes. Maybe some never fail but I think most do.

    I get to use one of the primer dealers in the country, one with the best Airhead parts and service reputations and a friendly place, I shop at Bob's. But he is 35 miles away and where as I do use this as a destination so I take the bike sometimes I don't want to or have time. Of mail order houses among the dealers Max BMW seems to be the most popular. Bob's also has a robust mail order business. But since these items are going to cost so much if you buy all 8 now it might be a good idea to check Moto Bins. Even after shipping their prices can save you some money, especially if there are other things needed now also.
    #3
  4. bernardofeio

    bernardofeio Bernardo Feio

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    hello<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:eek:ffice:eek:ffice" /><o:p></o:p>
    <o:p></o:p>
    does it make sense to change the roller bearings by some bushes? <o:p></o:p>
    <o:p> </o:p>
    The bearings are difficult to change and most of the time the final result is worse than the worn old bearings <o:p></o:p>
    #4
  5. adventure950

    adventure950 Anglo-Saxon

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    It looks to me like your missing the black plastic AX bearing - part number 11331337717 and the shim to take up the axiel play on the valve gear. There should be one pushed into the ends of each rocker arm shaft then a shim fits into the gap between the platic cap and the rocker gear clamp if needed ( and in my experience they always are needed). I would also drop your sump to make sure non of this debris has moved down into the block, remove the oil filter cut it open and see if there is any metal fragments inside it -belt and braces and all. If there is debris in these parts of the engine then sorry to say but I think your in for a strip down.
    #5
  6. noman

    noman Long timer

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    you will find replacement rocker (with needle and AX beaing) for your bike at max bmw. $96.

    easier to replace as a complete unit. remember to re-torque the head bolts at some point; orient the shaft correctly for proper oilflow; check the pan for bits; check the other valve cover for needles/bits, too.
    #6
  7. boxermoose

    boxermoose Now fully goosed

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    Ugly - PO probably did the side lash to quiet it down before sale and lost a needle or destroyed the seal during re-assembly

    Can you post up a pic of the top clamp and rocker pin so we can see which way the dimple on th epin is facing
    #7
  8. Grayghost66

    Grayghost66 Been here awhile

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    "I've never ordered from A&S BMW, but I like their website, they seem to have a good selection of parts, and their prices are reasonable (a relative term when we're talking about BMWs). Does anyone have experience with them, good or bad?"

    I've had nothing but very good experiences dealing with A&S BMW. Great customer service and fast shipping.
    #8
  9. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    The rocker arm needle bearings do fail. And the replacements are criminally expensive because the bearing size is unique to this application and there is no generic standard size. One mm either way on the ID or OD and you'd have a $5 Torrington cross-match.

    The rocker bearing fail, I think, because the rocker axial- (end-) play gets to be too much and as the rocker moves up and down axially on the rocker shaft the needles are slammed against the rolled end lip of the bearing shell. The lip is very thin and brittle (from the hardening process) and the needles tapping for millios of cycles fracture the lip. The needles escape thru the slots in the rocker blocks. The rest is history.

    This is not optimum, but the old rockers with bushings (/5 and earlier) had more wear with less mileage and were as expensive to repair. I had the bushed rockers in my /5 wear slap out in 1981 and I replaced them with the (then) new-fangled roller rockers from the /6 models. They've worked fine for 90K since then.

    I think that the trick is to make for absolute certain that the axial play on the rockers is as close to -zero- as possible. That seems to work. But check for frags during valve adjustments, and periodically do a visual inspection of the rollers and shafts. This can be done when the heads/cylinders are off (for pushrod tune seals, etc) or even when the cylinder head nuts are slackened for a head re-torque. I suspect that you can spot incipient cracks in the lip, and see how the shaft looks-- no pitting, galling or scoring, please.

    Depending on the OP's budget, all rollers could be replaced or, if the others check out, just the failed bearings and flag the others for later. AT $30 a pop times 8, plus the possibility of the a rocker shaft, $$ can be juggled.

    And get a magnetic engine oil drain plug. That will pick up the swarf and give you a warning at 3000 mile oil change intervals.

    Two recent threads on Rocker Arm Failure are:

    Rocker Arm Needle Roller Bearings Failure
    www.advrider.com/forums/showthread.php?t=805601
    (The bearing drift in the first thread is a good idea. Removal/installation and be done otherwise, but it's risky)

    r100gs - cooked - overheated - dead?
    www.advrider.com/forums/showthread.php?t=645324
    (towards the end of the thread-- most of it deals with Little Brothers and Airheads)

    Good luck!
    #9
  10. jimbee

    jimbee Airhead Intermediate

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    The plastic bit and the shims sit above the the rocker assembly, and the pictures are of the bottom, so likely they are still there.

    Agree with others that it takes some trial and error to get the right amount of end play. I recently aso replaced the black plastic bits (are they really bearings?), and found that after a few hundred miles, they settled in and the rocker end play opened up, so I had to re-shim.

    Perhaps obvious, but when re-shimming, don't just rely on the thickness specified by the part number (they are not always that accurate). Use a feeler gauage to measure end gap (with valve adjusters backed all the way out), then use a caliper to measure the feeler gauge thickness, then build the appropriate stack of shims using the caliper. I used a stack of shims approx 0.04mm less than the largest feeler gauge I could fit. Afterwards, just had a bearly perceptable amount of visible oil film show up when moving the rocker shafts up and down. Please take this with some large grains of salt. As has been pointed out elsewhere, I've only done this once. :D

    Good luck, bon chance, and buena suerte! (but not that tough)
    #10
  11. disston

    disston ShadeTreeExpert

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    If the rocker that has failed is missing it's shim(s) or thrust bearings then it is likely you can get away with fixing only this one. However, if it is nothing but high mileage then I see no way around replacing them all to be sure. Sure you can fix just one but then do another one 500 miles later and do this for the next 6,000 miles. So make the determination if this one failed for some reason that would indicate it has a special problem.

    I like that price on complete rockers. If I wasn't so poor I'd do that. Then again if I wasn't so poor everything on my bike would be brand new.

    Generally the needles that work their way out of the rockers fall in the valve cover. They have no where else to go. They then will be washed down the pushrod tubes and into the oil pan. Here they will stay, should stay. The oil pickup is pretty strong but it doesn't want to suck these needles at the angle they would need to pass. I've never heard of them going anywhere other than the oil pan. Check the pushrod tubes and pick up the needles in the pan, you should be good to go.

    I've always thought that the bushings instead of the bearings would be fine. But no idea how much this would cost you. Do the bushes have to be reamed with a special reamer? The needle bearings have always been over kill in my opinion. And if it was such a good idea maybe it would be touted around this here place how it works, see? Nobody else every did it. Not that I ever heard of. Maybe you could be the first?
    #11
  12. supershaft

    supershaft because I can

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    I have worked with quite a few BMW motorcycle mechanics that adjusted rocker arm play on the later bushed arms just like you do on the earlier ones. That's how I do it too. I don't think I have read anyone else mention it on the web. I have adjusted literally hundreds of the them. I have almost never need a shim. I just finely adjust my CC products style modified Vise Grip C clamp till the play is all gone and they still rotate freely with the head bolts tightened all the way down. You can adjust the play down to a gnat's ass with those Vise grips. Minimum play is best but they still sometimes break in the best of conditions. The bearings are still night and day better than the bushings setup. I rarely come upon a set of those that are not completely toasted. The bushing spin and toast the rocker arms AND the shaft at the same time. Expensive repair!
    #12
  13. Pica Hudsonia

    Pica Hudsonia Super-dupergenius

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    Thanks for all your tips and ideas, folks. I really appreciate it.

    batoutoflahonda, The engine was running fine. I didn't hear or feel any indication that something was amiss. A rubust overall design, indeed--despite some individual parts that are obviously weak. I have no way of knowing how long it ran in this condition... perhaps thousands of miles. The bike has 57k on it.

    disston, Thanks for your input on the homemade bearing tool. I've made things similar to this before, and will probably use this method when I get around to replacing the rest of the bearings. More on this below...

    Adventure950, as jimbee pointed out, the plastic AX "bearing" is only on the top, and it was still in place where it belongs.

    noman- Thanks for the tip on Max BMW. A&S has the part for the exact same price, and I think I'll order it from them. I called to verify that $96 will get me a complete assembly: rocker arm, 2 needle bearing sets (installed), and the plastic AX spacer. Since my rocker is damaged, I need to replace it anyway. You can get the bearings separately, but not the rocker--it only comes as an assembly. The part # for the assembly is 11-33-1-337-715 for the No.2 arm (the one that failed on my bike) and -713 for the No.1 arm. On the right hand cylinder, No.1 is exhaust and No.2 is intake, and it's vice-versa on the left hand cylinder. The numbers are cast right into the part in Roman numeral format, so you can easily see which one you're dealing with. Also, thanks for the tip on correct orientation of the shaft. I was aware of this, but I appreciate it anytime someone reminds me of these important details. It was previously installed correctly, with the dimple at the top and facing out.

    Bill Harris, now that I've examined the damage closely, I agree with your theory: axial play of the rocker on the shaft subjects the brittle needle cage to lots of stress over time, and it breaks, allowing the needles to escape. See pics below.

    jimbee- I'll take careful measurements and use some trial and error to get the the axial play as small as possible without actually applying any drag to the rocker. My goal will be .001" or less gap. I'll be sure to check it again after 500 miles, and re-shim if necessary.

    supershaft, I was not aware that it's possible to eliminate all axial play by pinching the shaft blocks together while tightening their nuts. I know that's how it's done on the pre-1984 models, but I took it as a given that I'd need shims on mine. I will still shim it, but I think your idea is worth trying in the future.

    Here is what I found today when I pulled off the rocker assembly:

    [​IMG]

    The shaft mounting block got damaged where the broken needles rode against it. I was afraid I'd need to replace this, in addition to all the other pieces, but I think I can get away with swapping it to the top position, where this damaged area will not contact anything. The one currently on top has a nice upper surface for the rocker to contact.


    [​IMG]

    [​IMG]

    The cage's lip is missing around roughly half its circumference, and 3 or 4 needles escaped.


    [​IMG]

    These are the pieces that fell free as soon as I loosened the assembly from the cylinder head.


    [​IMG]

    I don't think this rocker is worth trying to save. Without some very precise machining to remove the burrs, it will damage a new bearing cage during assembly.

    [​IMG]

    I will likewise condemn the shaft, because a replacement is not very expensive.


    [​IMG]

    Notice that the pattern burnished into this area is not parallel to the shaft's length. This shows the angle at which the remaining needles sat. It is superficial damage that I cannot even feel by dragging a thumbnail across it, but I don't get a warm fuzzy feeling when I contemplate refurbishing and re-using it to save a few bucks.

    I will get a complete rocker arm, shaft, and AX spacer. I can't afford to do the remaining 6 bearings now, but I'll probably replace them later this year. Maybe I'll pull off all the rocker assemblies to inspect them and reshim them for minimum play at this time. The bearings are about $27 each, and the bike needs attention in some other areas too, so they'll have to wait. In the meantime, I'l be able to assemble a tool, as described by disston, to press the bearings in and out. Maybe I can do two at a time, as my budget and schedule allow.

    I drained the oil and didn't see anything troubling in it. The bike does not have a magnetic drain plug, but that's something I will get now. I pulled the oil filter, cut it apart, and examined it closely--nothing in there that shouldn't be. I probably will not drop the oil pan. I looked at the debris that I recovered, and I can account for probably all of the broken bearing cage, and definitely all of the needles (there are 31 in each set).

    Now it's time to order parts, wait a few days, then start putting this back together.:clap

    By the way, I checked the valve lash adjustment on the damaged side while it was still together. Guess what... it was almost dead-on, at a loose .004" !
    #13
  14. disston

    disston ShadeTreeExpert

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    I know we all rationalize these things and do the best we can. Good Luck.

    It might be a good idea to inspect each of the rocker shafts as they are assembled now. Just look see if any other cages are broken or cracked. I hate to see the others start breaking right away. If not cracked you have some time I guess.

    When you do them you will have to do at least two bearings, one rocker arm, at a time. The new bearings go in one at a time but they come out in pairs.

    I've seen many other engines with this same damage. Yours seems to have suffered more than most.
    #14
  15. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    Here is a very good discussion on Airhead rocker arms at Anton Largiader's website: http://largiader.com/tech/rockers/ . '85-on up the rocker blocks are indexed and axial play is shimmed. '84-down, adjust by the ole squeeze-play.

    Also a wealth of other info at his site-- recommended reading!

    You may not have caught things early enough to save the rocker shaft, but now you're bumped off the steep part of the learning curve and you'll be able to cut your losses. Doing it bit-by-bias the budget allows is do-able.
    #15
  16. noman

    noman Long timer

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    discovered a failed needle bearing on my left cyl/intake earlier this season. got a perfect used complete set-up (rocker/bearings/shaft but no mounting blocks) from bud p at a damn good price. so i have a spare rocker that needs needle bearings removed, and a shaft too. both in nice shape.

    max bmw parts fiche says same part nmber for your/my bike. if interested, pm your address and i'll send pics and/or ship the assy out. gratis, of course.
    #16
  17. Pica Hudsonia

    Pica Hudsonia Super-dupergenius

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    That's very generous of you, sir. A PM is on its way, but I will insist on at least paying for the shipping.
    #17
  18. patanga

    patanga BMWAirheadsDownunder

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    Hi Pica Hudsonia. If you've done hands on chopper work then you can fix an airhead. As already mentioned, the head won't need to come off. Looking at your photos though, there's a little more than just the bearings damaged. Replace all of the unserviceable bits and during assembly check all of the rocker end float shim clearances against specs to minimise lateral movement. I've only ever seen these bearings fail through too much lateral movement, or the rocker pivot shaft oil galleries being installed 180 deg out and restricting oil flow. Be sure to drop the sump and clean/check for metal as well as check/flush any scrap that might be on its way down the down the push rod tubes as well.

    Here is a link to a thread I posted about a week ago re this very topic. Good luck.
    http://www.advrider.com/forums/showthread.php?t=805601

    ____________________
    "The only reason people get lost in thought is because it's unfamiliar territory" (Joe Garcia)

    Check us out on facebook at "BMW Airheads Downunder", (The Australia and New Zealand Airhead Community). "B.A.D" :wink:
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    #18
  19. 100RT

    100RT Long timer

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    Pull the push rods and run a pencil magnet down the tubes carefully.
    #19
  20. Pica Hudsonia

    Pica Hudsonia Super-dupergenius

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    Well, I think I have my bearings sorted out, mostly. I ordered new parts from Max BMW, and John Martin there was very helpful. (I started out with A&S BMW, and I still have some other parts coming from them, but they didn't have my rocker parts in stock.) At first, it appeared that Max had everything I needed, but Mark called me back to say the computer was wrong about their inventory on the rocker arm assembly. Apparently, not one of those is available is the U.S., and it would have to be ordered from Germany, taking about 10 days to get here...

    I decided to go with Plan B, which is to press new bearings into my rocker. The bearings were in stock. (Plan A was to get a complete assembly, ready to install in the bike, for quite a bit more money but much less work.) While waiting for my parts, I assembled a bearing remover/installer tool, as described by Disston, out of threaded rod, sockets, washers, and nuts. As shown in pics above, there was some damage to the bore of the rocker that caused me some worry--I thought it would harm the new bearing as it's pushed into place. As it turned out, the old bearing cage smoothed out the burrs on its way past, and I then felt comfortable reusing the rocker. Of course, I used a piece of fine sandpaper to smooth things out a bit further.

    A generous inmate sent me a spare rocker with one bad bearing and one intact, in case I could use any of it--a very kind act. Unfortunately, it was a rocker for the wrong side. I needed a Number 2, and it was a Number 1. Still, I used it to practice with my newly fabricated tool, and I discovered something interesting. Disston said he believes that if one bearing comes apart, the others will probably soon follow. I was a bit dubious of that notion, but now I'm more of a believer. Once removed, the supposedly good bearing cage in this rocker showed some tiny cracks. They were not obvious, but noticeable through careful inspection. I think there was an impending failure here:

    [​IMG]

    Anyway, I eventually got my new bearings, and they were not difficult to install. Put everything back together with a new shaft, and switched places with the upper and lower shaft supports, so there's a smooth, undamaged surface for the rocker to ride against:

    [​IMG]

    Here's a view of the damaged support in its new position. Sorry about the coloration here; the red of my fuel tank and side cover is reflecting off the oily metal parts:

    [​IMG]

    I carefully shimmed the rocker to make it fit as closely as possible without having any interference between the supports. It's not perfect, because I don't have a very good selection of shims. More are on the way, and as soon as I can, I will look at re-shimming all four rockers. I'm also going to replace all of the remaining needle bearings.

    After everything was back together and the valves carefully adjusted, the engine makes more ticking/tapping sounds than I'd like. Hopefully, a more exacting shim job will cure this. The important thing is that it runs, and pretty smoothly at that. :clap

    I rode it to work and back yesterday, happy to be on two wheels again. Tonight I went for a casual ride around town, maybe 10 or 15 miles, and new problems have arisen. It seems the gremlins knew that I corrected the bad bearing, so they've thrown another issue at me.

    When I pulled to a stop to watch the sunset, the engine began running quite rough and almost died a few times. I shut it off and took a peek to see what's going on. Gas is dripping out of the left carb almost in a steady stream. It's coming from the overflow, so I suspect there's a bad float needle or seat. I got it home and shut the petcock before all that expensive fuel could return to the ground from whence it came, but it was dark and starting to rain, so I haven't looked into the carb yet. Wish I had a garage. I work on the bike under a shade tree in my backyard. Hopefully, I will find a piece of grit or something, and when I remove it the needle will seal again. I'll order new parts to make a permanent repair, but while waiting for them, I hope to get by through a simple cleaning/fiddling with it. A few days ago I pulled the carb bowls to drain them so I could crank the engine to pre-lube everything after an oil change. I of course looked closely in the bowls, and there were in fact a few spots of grime settled there--not a lot, but enough to make me suspect something could be trapped under that needle. There are no in-line fuel filters, so that's something I'll be adding. I recall that the previous owner told me to be sure to shut off the petcocks when I park the bike, otherwise a carb might leak. He was right about that--tonight it was leaking even with the engine running, so the needle lets gas through even faster than it can be atomized and burned.

    I keep telling the missus it's a good thing I like tinkering with machines so much. If I had one of those ultra-reliable Hondas, I don't know what I'd do with all my free time... probably just ride. :huh I'm starting to think that when you buy an airhead beemer, you don't just get a vehicle to take you from here to there, you get a new hobby.
    #20