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1969 R69S US Crank Balancer (damper)

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sblaylock
Posts: 189
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Location: Victoria, BC. Canada

1969 R69S US Crank Balancer (damper)

Post by sblaylock »

I'm getting an odd noise from the front on my R69S and after removing the front cover I noticed the crank damper is very loose. Is this normal, or are the washers completely worn? The hex bolt is tight so it's not an issue with that loosening off.

Next question would obviously be do I really need it. At my age I don't "ride like I stole it". I'm pretty easy on the old girl and don't run the RPMs much past 4000 - I have an original oil pump tach installed so this isn't a guess.

Thanks for the help,
Scott B.
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Scott Blaylock
Stoney Peak BMW Service
Victoria, BC. Canada
BMW Classic and Vintage Motorcycle Service and Restoration
service@stoneypeak.com

sherman980
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Re: 1969 R69S US Crank Balancer (damper)

Post by sherman980 »

Scott,
There is a rubber "ring" in the center of the damper assembly that needs replacing regularly. Been a long time since I rode a /2 with one, but as I recall, I needed to replace mine every 2-3000 miles. When they get worn, the heavy outer damper ring gets loose (it should be difficult to spin by hand when the rubber ring is new) and causes a serious out of balance situation. It WILL eventually cause damage if you don't service it. Makes a lot of rubber dust in the front cover as well. During a cross country trip I took back in the '70s on an R69S, I ran out of replacement rubber rings and couldn't find a dealer that had any at the time. I ended up just removing the damper and put another 100k miles on the bike with no issue. Still have the bike to this day. Pics below should be self explanatory but note there is an extra rubber ring shown in the pics. The proper assembly uses just one.

s-l1600.jpg
s-l1600 (1).jpg
s-l1600 (2).jpg
s-l1600 (3).jpg
Hope that helps.
Thanks.
Chuck S

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Re: 1969 R69S US Crank Balancer (damper)

Post by schrader7032 »

I understand that the neoprene ring gave up the ghost with earlier designs. Newer ones are much better. I bought a new ring from Vech and never had any issues for nearly 10K miles.

This past year or so, I was chasing a vibration and one of the first things recommended was to remove the balancer which I did. It wasn't the source of my vibration. I left the balancer off and don't plan to put it back on. As I understand it, the balancer is likely needed for situations where you are running near max RPM when the crank might flex a bit. That's not my case and never will be. So, the balancer sits on the shelf.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
Fast. Neat. Average. Friendly. Good. Good.

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Re: 1969 R69S US Crank Balancer (damper)

Post by wa1nca »

I wanted to order replacement parts for mine and Richard at bench marks also advised it was not necessary unless I was racing the bike
tommy
Tommy Byrnes
54 R51/3, 55 R50/Velorex 560 sidecar, 64 R27, 68 R69US, 75 R75/6
Ashfield, Ma
USA

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sblaylock
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Re: 1969 R69S US Crank Balancer (damper)

Post by sblaylock »

Thanks for all the feedback. It sounds like I can just leave it off and order a new, shorter, hex bolt.

Chuck, Mine is pretty much free wheeling on the rubber ring and there is a fair amount of rubber dust in the cover so it is well past it's best before date.

I'll order a shorter hex bolt and replacement parts so I have a working one on the shelf if I notice a difference in how smooth the bike is.

One quick question - is the part number ...203 the short one I need to replace the ...145 one?

Vibration damper hex bolt (60 Watt): 11 23 0 070 145
Armature hex bolt (60 Watt): 12 31 8 002 203

Thanks again for the help,
Scott.
Scott Blaylock
Stoney Peak BMW Service
Victoria, BC. Canada
BMW Classic and Vintage Motorcycle Service and Restoration
service@stoneypeak.com

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Re: 1969 R69S US Crank Balancer (damper)

Post by sherman980 »

Scott,
As a temporary (or permanent) fix, you can just remove the outer "balancer" ring, etc. and just reinstall the inner assembly with the long hex bolt. All should be good. (Ask me how I know... LOL!) Others can pipe in about the correct shorter hex bolt.
Thanks.
Chuck S

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vechorik1373
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Re: 1969 R69S US Crank Balancer (damper)

Post by vechorik1373 »

This is the part number for the standard armature socket head cap screw if you wish to remove the crank damper entirely.

12 31 8 002 205

Interestingly enough, the very early R69S was not delivered with the vibration damper. I own a 1961, the 35th off the production line, and it never had the crank damper nor the bulged cover to accommodate the damper. Nor does it have the rear fender "R69S" emblem on the rear fender.
Unless you are going to play Rodney Roadrace with red line shifts, the damper isn't necessary, and one that the internal rubber sleeve that has disintegrated in is far worse for the engine, with that out of balance steel mass flopping around, which will hit the inside of the generator cover, gouging the inner surface up pretty badly...

This is my R69S, in original paint. you can see the gen cover without the bulge.
The pin stripes are pretty worn away on the sides of the gas tank, from years of use.
Screenshot_2021-11-30_09-42-50.png
Vech
Technical Adviser, Former owner, Bench Mark Works
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sblaylock
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Re: 1969 R69S US Crank Balancer (damper)

Post by sblaylock »

Thanks Vech, and congratulations on your retirement.

With the third "Atmospheric River" pounding us on the island today, I'm a little tired from being up every few hours to check for potential flooding. The ...205 was what I meant, the ...203 is the armature.

My 1961 R50S also doesn't have one. I do see it as a listed item in the MAX BMW parts fiche, but I'm not sure it would fit under the cover on that bike.

Thanks again for the help,
Scott.
Scott Blaylock
Stoney Peak BMW Service
Victoria, BC. Canada
BMW Classic and Vintage Motorcycle Service and Restoration
service@stoneypeak.com

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vechorik1373
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Re: 1969 R69S US Crank Balancer (damper)

Post by vechorik1373 »

No, the R50S does not have one. I have a 1961 R50S. The front cover has no bulge, but it is drilled and has the cam driven gearbox mounted on it, for the tachometer, and I have the tach on it, but it is not visible in the photo. The side mounted horn is visible, however. I installed the leather swinging pillion saddle of the back of the solo seat, and metal framed Denfeld leather saddle bags on it.
By the time I built this bike, (This is one of the last ones that I built for myself) I was sick of black BMW's, so this one is Bristol Gray..
Screenshot_2021-11-30_16-14-55.png
Vech
Technical Adviser, Former owner, Bench Mark Works
662 312 2838 cell 9 am to 4pm CST PLEASE!

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sblaylock
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Re: 1969 R69S US Crank Balancer (damper)

Post by sblaylock »

Wow. That is a beautiful bike - love the color.

Mine is still in barn find rust, but is next on the list for restoration. I was thinking black, but lately I've seen several non black R50S bikes so I may go with something else to "change things up".

Thanks for the info on the damper and the photo of your R50S. That is a stunning bike.

Scott.
Scott Blaylock
Stoney Peak BMW Service
Victoria, BC. Canada
BMW Classic and Vintage Motorcycle Service and Restoration
service@stoneypeak.com

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