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R69S hydraulic vs friction damper

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skychs
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R69S hydraulic vs friction damper

Post by skychs »

While restoring my R69S I have been reading mixed reviews on the hydraulic vs friction damper. A lot are saying the hydraulic system is worthless and they recommend changing it to a friction damper, especially if you're considering mounting a side car. I have a sidecar on my R60/2 and was considering mounting it to the 69S. My guess is the hydraulic damper doesn't tighten the front end enough. Has anyone converted their system and/or recommend the swap?
Thanks
Chuck
1966 R60/2, 1967 R69S, 1975 R90S, 2020 R1250GSA

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vechorik1373
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Re: R69S hydraulic vs friction damper

Post by vechorik1373 »

The hydraulic damper is useless with a sidecar. You must have the friction type used on R50 - 60/2, because as you know, (since you have a side car) you must tighten the friction damper to the point that if the bike was solo, it would be totally unridable. The Hydraulic system is not near effective enough with a side car, (as you will discover if you try it, and the front end will oscillate wildly).

Even with a solo R69S, the hydraulic damper is pretty useless, because all of that complicated linkage is usually worn out, and you have excessive amounts of slop. The very spot that you want to damper to be effective (if needed) is just very slightly off the straight ahead orientation, to stop a front end oscillation before it can start. And because of all the slop in the linkage, an oscillation can start anyway.. That is not to say that you cannot rebuild the hydraulic linkage to get rid of all the play at the various pivot points in the linkage. You can, (I have done it, many times) provided you have a lathe and custom make the bushings to fit all the pivot points.
But in truth, if you have to use either system on a solo bike, then there is something wrong. Low tire pressure, or loose steering head bearings are the most common reasons for an oscillation to begin.

I always lectured my customers, when I turned a freshly restored bike back over to them, and told them that every time you take your solo bike out, and run it down the road, get it up to 40 mph or so, and then shut the throttle down, and take your hands off the handlebars. Yes, the bike will drift to the side as it is slowing down, but if you see any tendency for front end oscillation, grab the bars, stop, turn around and go home. If the bike slows with no oscillation, grab the grips and ride wherever.
If it oscillates at all, you have to find out WHY the front end is doing this. It is a dangerous condition, and can kill you if it gets out of hand. Tank slappers, (or in a BMW's case valve cover slappers) are not something you want to experience!
Loose steering head bearings, loose wheel bearings, low tire pressure can allow this to happen. Figure it out and fix it before you ride it again.

What is involved to install a friction damper on an R69S?
If you look under lower triple plate of the front end, where the damper linkage is, you will see two steel limit pins for the linkage, that are pressed into the triple plate. They must be removed in order to install the friction type damper. The rest is straightforward, and not difficult to do.
Vech
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Re: R69S hydraulic vs friction damper

Post by jwonder »

Vech is 100% correct as usual!

I have restored both my R 69 S and R 50 S with the original hydraulic dampers and I am happy with them. I have a lathe, and I have made sure that all the linkage is tight, lubed, and in perfect condition! Both linkages for both of those machines came to me loose with worn bushings and it took some effort to bring them back into specifications. I made extra bushings in case I need to replace them.

I do not use those two motorcycles for a sidecar, solo only!
James Wonder
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Flx48
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Re: R69S hydraulic vs friction damper

Post by Flx48 »

Agree the stock hydraulic damper was mostly ineffective, at least on the 69S bikes I've owned.
(that said, I never tried making improvements, such as James has)

My outfit (R69) uses the friction damper at a very moderate level, same as I use on the solo.
I try to be very careful to maintain suspension and alignment, most of the wiggles I have are reminding me I've forgotten to check on the tire pressure for the last week or two.

But I think the friction damper is pretty useless, too, especially with the sidecar.
Steering a sidecar is enough work without adding the resistance of the friction damper.
Installing a sidecar specific hydraulic damper is on my to-do list.

To me there is no question a hydraulic damper is superior to a friction damper as a safety feature.
A friction damper takes effort to overcome, but once it's moving, it moves easily.
Conversely, a hydraulic damper can move easily at low speed, but when moved quickly, the resistance to movement is strong.
Exactly the same action as a hydraulic shock absorber.
That's why modern bikes use hydraulic shock absorbers and hydraulic steering dampers; the friction versions of both are obsolete.
Best-
George

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skychs
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Re: R69S hydraulic vs friction damper

Post by skychs »

Thanks guys. I appreciate all the input. To keep the bike original I think what I'll do is set the bike up with the hydraulic damper and see how it handles. At the same time I'll start gathering all the parts to switch it over. If and when I ever attach a sidecar I will have both systems to evaluate.

Does anyone know where I can find the infamous bushing for the hydraulic system? I cant seem to find them anywhere.
Thanks
Chuck
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1966 R60/2, 1967 R69S, 1975 R90S, 2020 R1250GSA

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Re: R69S hydraulic vs friction damper

Post by jwonder »

Chuck,

I made two extras (I always make extras) out of Delrin and will ship you one of my spares if you wish. They are not hard to make and I will make more if I need to, but your welcome to one of my spares. Members helping members!! :D

PM me with your address and I will send it.

The other area that you may need to tighten up is the set pivot/rivet for both of mine I put that in the press to tighten that up a bit but be VERY careful with that as you can tighten it too much!

Also adjustment is KEY! Go to the workshop manual in our library at https://vintagebmw.org/library_data/sla ... l_1972.pdf on page 122 shows you how to install it. THAT is VERY important and it makes a huge difference to do it right! Don't ask me how I know! :shock:
James Wonder
Vice President, Vintage BMW Motorcycle Owners
2022 BMW Friend Of the Marque
Long Island, New York

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skychs
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Re: R69S hydraulic vs friction damper

Post by skychs »

Thanks James. PM sent.
1966 R60/2, 1967 R69S, 1975 R90S, 2020 R1250GSA

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Re: R69S hydraulic vs friction damper

Post by malmac »

jwonder wrote:
Tue Jul 26, 2022 10:23 am
Chuck,

I made two extras (I always make extras) out of Delrin and will ship you one of my spares if you wish. They are not hard to make and I will make more if I need to, but your welcome to one of my spares. Members helping members!! :D

PM me with your address and I will send it.

The other area that you may need to tighten up is the set pivot/rivet for both of mine I put that in the press to tighten that up a bit but be VERY careful with that as you can tighten it too much!

Also adjustment is KEY! Go to the workshop manual in our library at https://vintagebmw.org/library_data/sla ... l_1972.pdf on page 122 shows you how to install it. THAT is VERY important and it makes a huge difference to do it right! Don't ask me how I know! :shock:
James, when you refer to Delrin, are you using the Delrin to replace what I assume were some type of fibre friction washer.
I was going to turn some up out of clutch friction material. Or were the washers actually meant as as a low friction bush?
It seems I have the system all wrong in my head.

Mal
mal - R69s
Toowoomba- Australia

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Re: R69S hydraulic vs friction damper

Post by vechorik1373 »

Skychs,

If you are going to use the stock R69S damper system with a side car, promise me you will put a pair of Depends on under your jeans, just in case you have a pants filling oscillation experience! :lol:
Vech
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Re: R69S hydraulic vs friction damper

Post by skychs »

vechorik1373 wrote:
Tue Jul 26, 2022 7:31 pm
Skychs,

If you are going to use the stock R69S damper system with a side car, promise me you will put a pair of Depends on under your jeans, just in case you have a pants filling oscillation experience! :lol:
:D :D :D I promise ... if I add the sidecar I will switch over to the friction damper. :D :D :D
1966 R60/2, 1967 R69S, 1975 R90S, 2020 R1250GSA

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