This is why you need to clean/change your slingers!

R68
Posts: 489
Joined: Wed Aug 20, 2008 4:22 pm

Re: This is why you need to clean/change your slingers!

Post by R68 »

Use a metal dinner fork to clean the grunge in the slingers..takes awhile to get all the stuff out, but no possibility of damaging the slinger edge. If the slinger is bent, or stress cracks present, best to replace? Replace the brass R5 slingers: too soft to clean without damage?
There is no conceivable way the metal slinger can "melt"...that degree of heat would cause the motor to explode!
I'm not sure that full slingers NECESSARILY cause rod bearings to seize: the bearings still get some splash lubrication (?), and I've always wondered why so many old BMW motors (every one I've ever personally redone!) have full or near full slingers, but almost never see a seized motor? Question for Vech: what do you think?

mcsherry1328
Posts: 213
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by mcsherry1328 »

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Slingers are always a popular topic and with good reason. I totally believe slingers need to be cleaned periodically. That said with modern oils and very frequent oil changes this interval could be reduced greatly. A few years ago I had several old engines that I thought should have this service done. Having never done it before (feeling intimidated) I started looking for a shop to do this. I was quite surprised when talking to several shops that they actually didn't do the work themselves. They shipped it out. I'm an average, maybe slightly above, home garage motorcycle hobbyist. So, I ended up buying the "Many in one" tool & I already had the Barrington manual. These are both must haves in my opinion. Going step by step with Ed Korn's homemade video I did this job myself. So far having completed three engines. All are running and working perfectly. The first one was an R69S engine that I've since put on 3500 miles with no issues at all.I have two more to do and feel this is within reach of most competent home shop mechanics. In my case all the engines definitely needed slingers serviced. I opted to clean the existing slingers rather than buy new ones. I've heard several stories of out sourced reproduction parts that didn't quite fit or were just out of spec. Cleaning the slingers is actually very easy. I bought a set of small picks from Northern Tool for under five dollars. It takes about ten minutes for each slinger. I soaked them for a while in a solvent tank.
I also bought a high quality torque wrench which I feel is very important in reassembly of engine. I do have a large air compressor which made the removal of the flywheel very easy. With fewer shops offering this service and those that do,at prices that sound truly exorbitant, I think you may want to try this yourself. Feel free to contact me with questions about this very popular and important topic. Michael

R68
Posts: 489
Joined: Wed Aug 20, 2008 4:22 pm

Re: This is why you need to clean/change your slingers!

Post by R68 »

...well I just really don't know what to think about this slinger debate? Although I've not heard of too many seized con rods, there do seem to be a lot of BMW with rod knock? Maybe when the knock becomes too loud, the bike is just retired? Ed Korn and his tools are history, I think?..

mcsherry1328
Posts: 213
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by mcsherry1328 »

I have had several vintage BMW owners tell me that slinger cleaning is not necessary, because the crankshaft and rod assembly is spinning in oil. That's true they are spinning in oil and the main bearings are oiled just fine by this centrifugal splash method. However the connecting rod bearings are also supplied additional and critical oiling from the small channel through each connecting rod and bearing. If the slingers are neglected to the point this small orifice is blocked then critical oiling stops. The pictures I've included show a small pipe cleaner passing through both connecting rod journals. The factory designed and built this method of engine oiling to be adequate if maintained.
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mcsherry1328
Posts: 213
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by mcsherry1328 »

Ed Korn sold his tool business years ago to Dan at Cycle Works tools in Kansas. I have bought several tools and parts from Dan, but it's been years ago. As far as I know he still sells these tools, if not someone on this site or Ebay would offer them for sale.

Tinkertimejeff
Posts: 48
Joined: Thu Jan 20, 2022 5:49 pm

Re: This is why you need to clean/change your slingers!

Post by Tinkertimejeff »

RE R68 response: The front slinger in this 1969 R69S did in fact overheat and melt to a point where they deformed and stopped the motor in its tracks. The front bearing carrier was melted and destroyed during the overheating of the crank shaft and its components. The motor didn't "explode", fortunately but it did seize and cause a minor low side crash. The left side con-rod bushing was melted and partially pushed out to the rear due to the overheating. The connecting rods were both frozen to the crank shaft and both had to be cut in order to remove the crank shaft.
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mcsherry1328
Posts: 213
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by mcsherry1328 »

Now that is a catastrophic failure. Thanks for sending these pictures of what a comprehensive engine expiration looks like.

sherman980
Posts: 73
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by sherman980 »

Guessing there is more to that "story" than "dirty slingers"! Yes, slingers need to be serviced on occasion (more so in todays world running detergent oils), but in fifty years of riding (100's of thousands of miles!) and wrenching on BMWs (mostly /2 and earlier), I have never seen a catastrophic failure like the one shown that was a "slinger" only problem. When (not if) they fill up, yes you lose some oiling to the crank and rod bearings, and yes, this can (but does not always) cause a crank/rod bearing failure. But you will hear it long before your motor turns into the mess shown in the pic. I have seen plenty of slingers that were full come out of engines that were running just fine. So I guess the takeaway from my perspective is this example should NOT strike the fear of God into you if you don't pull your engine apart this second to clean your slingers! Just breath....
Thanks.
Chuck S

mcsherry1328
Posts: 213
Joined: Fri Oct 27, 2006 3:00 am

Re: This is why you need to clean/change your slingers!

Post by mcsherry1328 »

Just went for a ride on my R67/2 and was thinking of those terrible pictures of the R69S engine failure. My first thought was is this your engine ? What was the condition or level of the oil. Assuming the engine had some oil in it. I was thinking while riding along, there's more to this story than I know. This type of failure is way beyond slinger issues. Looks like it wouldn't have mattered if these slingers were full or clean. Would love to know if there is more that you can share.

Tinkertimejeff
Posts: 48
Joined: Thu Jan 20, 2022 5:49 pm

Re: This is why you need to clean/change your slingers!

Post by Tinkertimejeff »

It is my engine now. I really don't know the specifics of the motor lock up as it happened in 1975 long before I owned the bike. I think some of the damage was done during it long and grossly inadequate storage after to lock up. The crank case and transmission both had mud dobbers (annoying insects) nests built inside. I would have to speculate that there was a lot of noise and motor slow down just prior to the stop. The left connecting rod bushing was pushed nearly all the way out and melted to the wrist pin. Both connecting rods were cut in order to get the paper weight out so the clean up could begin.

I would think the connecting rod would have bent or snapped before the motor stopped, I think the melted slinger saved the engine block by locking it up before the rod snapped.

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