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Old 07-10-2012, 11:18 PM   #1
Pica Hudsonia OP
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Rocker Bearings Coming Apart!

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."







(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:





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."

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.

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?

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?
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Pica Hudsonia screwed with this post 07-11-2012 at 11:25 PM
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Old 07-11-2012, 12:37 AM   #2
batoutoflahonda
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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....."
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Old 07-11-2012, 12:47 AM   #3
disston
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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.
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Old 07-11-2012, 03:51 AM   #4
bernardofeio
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hello

does it make sense to change the roller bearings by some bushes?

The bearings are difficult to change and most of the time the final result is worse than the worn old bearings
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Old 07-11-2012, 04:10 AM   #5
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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.
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Old 07-11-2012, 05:28 AM   #6
noman
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replacement

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.
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Old 07-11-2012, 05:29 AM   #7
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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
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Old 07-11-2012, 05:38 AM   #8
Grayghost66
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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.
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Old 07-11-2012, 07:43 AM   #9
Bill Harris
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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!
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Old 07-11-2012, 09:59 AM   #10
jimbee
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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.

Good luck, bon chance, and buena suerte! (but not that tough)
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Old 07-11-2012, 10:20 AM   #11
disston
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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?
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Old 07-11-2012, 01:38 PM   #12
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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!
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Old 07-11-2012, 05:34 PM   #13
Pica Hudsonia OP
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More Details Revealed...

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:



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.






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




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




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.



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




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.

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" !
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Pica Hudsonia screwed with this post 07-14-2012 at 09:19 PM
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Old 07-11-2012, 07:12 PM   #14
disston
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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.
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Old 07-11-2012, 07:34 PM   #15
Bill Harris
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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.
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