Identifying Rocker Arms and the Failed Needle Bearing debate

I have a 1977 R100S that's getting resurrected slowly (see The Punk's Bike thread). Now that I've got some miles on the bike, some problems are showing themselves. The right cylinder's tapping was louder than the left and was getting louder. Damn.



The above photo is of the rocker on the left in the photos below. Not all the needles are currently accounted for. Which brings me to the questions/observations.

1. If I understand correctly, the left rocker is a rocker original to this generation of bike and the right rocker is the subsequent '85 and on rocker. Yes?

2. What I believe is a later rocker has a small shim stack but it also has the older style blocks. This ok?

3. I can either replace the failed bearings, the rocker, or ? Is there any great benefit to upgrading both 'old' rockers to the newer style? Or do I just replace the needle bearings and call it good? I would, of course, inspect all four rockers.

4. If just replacing the bearings, how much of a pain in the ass is this? From skimming some threads with the right tools to extract and press in the bearings it doesn't appear too onerous. But I don't have those tools.

5. If replacing the rockers... cheapest/best source? Sets of used rockers, with bearings in unknown condition, are on Ebay all day long for $100-$150. But that unknown is what I started with.

Whatcha think?





I haven't yet gone looking for debris or the missing needles. And yes, I see that I've got one block rotated and installed backwards.

I can speak to #4 and #5. I had similar trouble with my '85 R80 rocker bearings:

http://www.advrider.com/forums/showthread.php?t=829938

Q#5: Don't buy used at $100-$150 when new rockers of the correct design and with bearings are only $93:

http://www.maxbmwmotorcycles.com/fiche/DiagramsMain.aspx?vid=51651&rnd=04282014

Q#4: The bearings are $27.50 each, so $55 to outfit each rocker. If there is nothing otherwise wrong with the rocker itself (pitted or worn tips, buggered adjustment screw threads, etc), replacing just the bearings is easy and will save you a few bucks. The rockers are short enough that you can use a bench vise or c-clamp if you dont't have an arbor press.

I have a picture somewhere of a home made bearing remover that I used but I can't find the tool or the pic at the moment. It's just a length of steel tube (slightly longer than the rocker) with a diameter small enough to just fit through the bearing ID. Hacksaw a few lengthwise splits into the end of that tube about 3/4" long and spread the segments out to just over the OD of the bearing. Maybe file or belt sand the flared end so the end faces are all in the same plane again, but that's getting pretty fancy!

Insert the tool into the rocker backwards (unsplit end first) until the flared end compresses, passes through the bearing, and then springs back out to rest against the end of the bearing shell in the ID of the rocker arm between bearings. Press or hammer it out, and repeat on the other shell.

You can use a socket of a convenient OD to press in the new bearing. It's an easy job.

Good luck.

Bob

Hope this helps.

The old bearings will come out with a long punch if you're careful and lightly hit once at a time, alternating 180 degrees between strikes. I'd use a brass punch and support the rocker over a hole (I would drill a hole in a board larger than the race but smaller than the rocker) so the race has somewhere to go but the rocker is protected and all of your force goes into removing the race.

Even though I have a lathe, I didn't bother making a tool to do this job and there were no marks (other than very light scratches) on the rocker I.D. when I was done.

FYI, Max sells the whole upgrade kit for the rockers.....may go that route next winter.

I believe he was stating that a WHOLE SET of 4 can be had for $100-150 on ebay, so buying 4 new ones at $93 each is quite a significant jump in price.

And of course Anton has a webpage on Rocker Arm esoterica:

http://largiader.com/tech/rockers/

One of my "Round Toit" projects is replacing a couple of rocker arms that have slight pitting on the valve tips. Be nice to get a set of four in good shape and do a pre-emptive needle bearing replacement.


--Bill

Ahh, yes .. he did say "ets of used rockers, with bearings in unknown condition". I missed the plural and that is a big difference!

Of course "bearings in unknown condition" still throws a wrench in the works. So, if option (A) is new bearings at $55 per rocker x 4 rockers = $220, presuming his rockers are in otherwise good condition. If his rockers are worn, option (B) is all new rocker/bearing assemblies from BMW at $93 each x 4 = $372 - bummer on the wallet, but fresh is good.

Option (C)(1) is risky: used set of rockers/unknown quality bearings from eBay $100-$150. Option (C)(2) is less risky: the eBay rockers ($100-$150) plus all new bearings ($220), for a total of $320-$370 - another bummer on the wallet, right on par with the $372 for all new assemblies .. but with the new bearings already installed.

Knary, I feel your pain. I've been known to squeeze pennies and push parts - really hard - to keep my bike moving, including use of used wear items like bearings. But sometimes it's just a false economy that bites you even harder later. If the bike isn't your primary means of transportation then maybe (gulp!) .. park it for a bit until funds build up?

Ok, screw that! It seems there are lots of price points: $27.50 each to replace just the individual bad bearings in your own rockers and hope the others aren't about to fail (more $$$), $100-$150 for an eBay crapshoot (real price unknown if another bearing fails and creates more $$$ chaos), $220 for preemptive replacement of all eight bearings in your own rockers, $372 for all new factory rocker/bearing assemblies, or $320-$370 for the eBay rockers and all new bearings.

Other possibilities: Skyshadow mentioned an upgrade kit. I don't know what that costs but it's probably worth looking into. Also, I could check my spares box to see if I kept any of those non-damaged used bearings (like I said, I'm 'frugal') that I preemptively replaced when I had the same issue. I'm happy to drop anything I have in the mail to you if you need them to get by with for a while. Just drop me a PM and I'll start digging.

The process of replacing them is the easy part!

Bob

Thank you, everyone.

While these machines are simple, relatively speaking, and simpler than some would make them out to be, that doesn't mean that there aren't hidden traps when parts of different generations have to work together. I'd read Anton's page as well as a bunch of other threads, but sometimes you need to just the questions.

The upgrade kit, mentioned above, is arms, buttons, etc and is what's used on airheads made from '85 on. It costs $390 from Max and is not much more than buying four rocker arms. I will not be buying that.


My likely plan is to replace bearings, as pairs, as needed. $50 or so per rocker, if the rocker is otherwise working condition is -ahem- bearable. That's if I don't have eight to replace! Then I might gamble on an set of rockers from ebay.

So that brings me to the next question:
What state does a bearing need to be in to warrant replacement? Obviously if it's like the one posted above. But needles falling out? Or? It seems some people just put needles back in place if there aren't other signs of damage and others replace no matter what.



Other Bob,
You've got it. Money is somewhat tight, but mostly I'm trying to minimize how much I pour into this machine when it still has other needs and questions. As others have said, there's nothing quite as expensive as a 'free' bike. Luckily I'm usually smart enough to at least try to not be penny wise and pound foolish, especially when there's always that other currency, time, to be considered.

If you've got working bearings in good shape...

I would think the rockers would be fine if you were able to find all the needles and just put them back. Maybe press the bearing cases in a little further and fill the space with a washer (or the like), to stop the rollers or needles sliding sideways and coming out the split in the rocker blocks again.

I'll start digging, followup report soon. - Bob

Obviously if needles are falling through the gap in the rocker block, it's time to replace. I recently found failed bearings in a bike that had the rockers installed with way too much end play. The process of those bearings getting pounded up and down with every valve actuation had damaged the rocker shafts too. I found chunks of bearing shell in the valve cover, but fortunately no bearings had fallen through. You don't have to remove the rocker shafts to check them. Just pull off the rocker blocks and push the shaft to either side to check for wear.

That is the key, catch it in time before the rocker shafts get trashed. My needle bearing rocker arms are 1982 vintage (upgrade from the /5 bushings) and I'm needing to do some preventative repairs on them. But, as I said, I've got minor pitting on the rocker arm tip that contacts the valve and I need to do something about that. Maybe I could get the tips welded, reshaped and hardened, I do need to check into that. If I could get the tips refurbished, I'd gladly spring for new needle bearings (the rocker shafts were cherry last I looked, and still should be) and be ready for another 35 years and 100K-miles.

--Bill

Knary,

It took a bit of extra digging time to locate something useful, but ..



These are out if a R60/6 which according to Max's fiche are the same rocker arm and shaft as from a R100S, hence the same bearing. Seven of the eight bearings pass the "eyeball" test, but one bearing/retainer set it shot.



Maybe you could just replace the bad bearing for now, or scavenge one from your other rockers? Anyway, these will get your wheels turning again - yours for free because you've already paid it forward so many times. Drop me a PM with an address to aim the shipping cannon at.

Also, IIRC, you could use some proper control housings, grips, brake parts, switches, fenders .. what else? I've got some more stuff from that R60/6 that I'd like to get out of my way, so send me your wish list and I send you a care package. Or two.

Bob

When do the bearings need to be replaced? Other than when the cage fails? When they get notched pretty much just like steering head bearings do. Hold the shaft in your hands and slowly rotate the rocker arm. Chances are you will feel the pits. They are almost always pitted after some miles. I always replace them during valve jobs. New rocker arm bearings are part of a valve job IMO. The shafts usually last a long time if a bearing issue doesn't get into them.

I don't have any experience with repeated excessive rocker arm end play but I do know that those bearing cages fail with minimal end play. I suspect they fail less with minimal play but . . . .

Wow. Thank you. That's very generous of you!
The list is quite small these days. Of the stock items, the parts that spurred this thread are the only things on the list aside from some seals and gaskets.

PM on the way.

Ah, the joy of learning...

Other Bob very kindly sent me some used rocker arm assemblies from a /6. The rocker with the failed bearings was also showing some not insignificant pitting and wear on its hardened tip (technical term?). I clean the best one from Bob up a bit and went to install them.

"Why won't this fit!"

My blocks. My /7 arm on the right. The /6 arm on the left.




Well, shit. The older arms are 1.5mm taller with the difference being made up for in the blocks (you can guess by how much). The /7 blocks are also shaped for the buttons.

/7 on the right


IOW, either set will work so long as they're used as a set. OTOH, the newest rocker arms with the plastic bushing and shims will work with the /7 blocks. The part numbers for the different machines are the same because BMW in their wisdom doesn't think you'll use a new rocker with old blocks or vice versa.

So do I use the old blocks for right now just to get the bike on the road? Good question.

And, yes, this information is on Anton's site which I had read about 437 times.

The yearnin' for learnin' never ends!

I took another look at the Max BMW fiche for the R60/6 and R100S and for the rocker bearings both give part #11-33-1-261-712. The fiche notes both also add: "Needle bearing for rocker arm, R60/6-R100MYS, 1974-1995. The OD of the bearing is 20.00mm."

So, maybe try gently pressing out a few of the bearings from the R60/6 rockers, pick the one least buggered up by the process, and reuse it in your R100S rocker arm. That would at least salvage some riding time this summer and you could dig deeper into it when the snow hits. That's the proper "wrenching season" in my neighborhood.

BTW, the pic of the galled R60/6 rocker block has me thinking that the slot cut into that block may be causing the bearing shell to fail. That slot is pretty wide: at least as wide as an individual needle. Thrust loads along the shaft axis could generate higher wear/friction/failure in the needle bearing shell at the location of the block slot. In the pic of the R60/6 failed bearing it looks like parts of the failed bearing shell, or a needle itself, was ground into the block near that slot.

Perhaps it would be a good general practice to relieve the edges of that slot slightly before reassembly? I can't remember (and I'm too lazy at the moment to dig out my spares) whether the ID of the shims matches the of OD of the rocker arm shaft. If it does then adding a shim would separate the bearing shell from the slot in the rocker arm block and prevent that source of failures from having an effect ... assuming shims are routinely placed on both ends of the rocker arm

Good luck,

Bob

All you need to replace them is a big vice and a couple of small sockets, just measure how far into the arm the bearings sit before you start and then use a small socket to press the bearings out so that the bearing drops into a larger socket. All very low tech and easy. A set of new bearings and you can forget about it for the next 30-40 years. Just make sure the bearing spindle is in good condition.

Low tech is good. And the same socket will be used to install new bearings-- the bearing shell should press in just below the outside of the rocker arm.

I think that the needle bearing fails when the outer lip of the bearing shell wears thin, breaks and releases the bearing needles. I think that the lip wears when the rocker arm is allowed to run with too much axial play for along time. This causes the bearing shell-- and lip-- to "slam" against the needles as the rocker arm oscillates in it's normal motion. The light little slam happening millions of times wears the lip and then, kablooey. I'd suspect that a thin shim between the rocker and the rocker block would serve as a "safety" to keep the needles from escaping through the slot in the rocker block. Or so I'd speculate. The failures occur secondarily when the needles escape through the slots and not primarily by the fracture of the bearing shell lip.

--Bill