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restoring a 1976 BMW R75/6 - Oring Cross Over

b25bsaboy

New member
Good afternoon,

Finally after several years I am getting to the 76 BMW R75/6 restoration. Just pulled the backend where the flywheel is located and placed my order with my local BMW dealer when the thought crossed my mind, in that has anyone crossed over the BMW part number to a Parker O-Ring number? I just find it frustrating in that I want to complete the reassembly, only to have to wait till the parts arrive which sometimes takes up to ten (10) days.
 
Good afternoon,

Finally after several years I am getting to the 76 BMW R75/6 restoration. Just pulled the backend where the flywheel is located and placed my order with my local BMW dealer when the thought crossed my mind, in that has anyone crossed over the BMW part number to a Parker O-Ring number? I just find it frustrating in that I want to complete the reassembly, only to have to wait till the parts arrive which sometimes takes up to ten (10) days.

Two things:

Did you order from Max's BMW? I can't imagine taking that long if ordered from them.

2) If I read the microfische from Max's correctly, the size of the o-ring is 59 x 3 which I think means 59mm ID x 3mm cross section. Their price listed is around $3.89.If this is correct, then there is no good conversion to any English sizes. However McMaster Carr has the metric version per that size. You also have a choice as to what material you would want. Presumably I would think Buna-90 (90 durometer) or Viton. I think there are others. The only drawback from McMaster is that for these types of items you have to purchase in "lot" quantities - in this case, I think it is a qty. of 10. But work out with a per-each price which is much cheaper.

I still think the best thing to do is to call Rusty at Max's and order the exact right part and have it shipped right away! That way you are sure it is the correct size and part for your application.
 
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I'm a little confused...what o-ring are you discussing? Is this the rear main seal (not really an o-ring) or the oil pump cover o-ring?
 
crankshaft o ring

Hi Kurt I believe they are talking of the o ring inside the female section of the flywheel seals the crank ,the crank seal is on the male side of the flywheel where it bolts onto the crank,this is how its set up in /7,not sure the /6 is the same
 
Jimmy -

I've been looking on the fiche pictures...I'm just not seeing it...all I see is the rear main seal that goes around the aft end of the exposed crankshaft.
 
Based on his description, this is the only O-ring I thought he could have been referring to (From Max's microfisch for R75/6):

11 22 1 337 099 GASKET RING $3.68


11 22 1 337 099 was superseded by 11 22 1 337 093, Seal ring, R60/6-R100R, 1976-1995.


11 22 1 337 093 GASKET RING - 59 X 3mm
 
He's in Alberta and says he ordered from his local dealer. I'm guessing that was not MAX.

Good morning,

Thought I should jump in here and clear up some questions that have been asked of me with regards to the o-rings questions.

As a retired manufacturer's representative I know that when machinery is designed and manufactured add on items such as o-rings and seals are usually a standard size either metric or SAE . Thus the thought being that people such as Parker as an example manufacture o-rings as a world wide standard including metric. I will be digging a bit further into my own question, as I really think there is an answer to this question and will share it with our group.

I have in the past ordered from MAX, Capital BMW and other's when I first started this project, but it was killing me for the postage to ship the items from the US to Canada. I went to my local BMW dealer here in Calgary and set up with the parts department a deal that ABC group could order parts, get a small discount and pay a flat fee of $ 5.00 for shipping and handling. The time to receive the items ordered is about what it would take to receive parts from either the UK or the US. The next question that always comes up is that it's cheaper buying from the US? Well, not really, in that by the time you add the postage, duties, taxes, exchange on the green back, etc, in some cases it it's more money.

Kurt is right in that the /7 does not have this o-ring that is set internal on the stub housing of my /6 flywheel, thus it's not in any of the parts microfiche. Also the o-ring that is used on the rotary oil pump cover needs to be replaced since your this far in. My feeling is the if the correct elastomer and size is sourced, with the savings in some cases is being 50 - 75% why not?

When I was restoring the British motorcycles I was constantly frustrated with the garbage used in area's such as the push rod tubes. Did some research and came up with a hydraulic Quad o-ring that fit perfectly and experimented with my own machine, as the garbage neoprene white sealing rings over time and especially heat oozed out of the sealing rings. The end results is that after several retorting of the heads, this area of the push rod tubes never leaked and it was bone dry. I have given other's these o-rings and they have had the same results. I am always looking at things with the idea in mind in that with today's technology and material advancement why can't we make things better in the sealing department with our Airheads?:burnout

Apologize for any confusion on my part.
 
It appears to not be used on the /7...it shows an o-ring, but the table does not list it so it means it's not needed. I've been unable to find any discussion on this o-ring in the Airheads mailing list archives. I can only find discussions about Parker o-rings as it pertains to master cylinders and compatibility with brake fluid. Catalog here:

http://www.parker.com/literature/ORD 5700 Parker_O-Ring_Handbook.pdf

Believe me, there is nothing engineering-wise that can't be duplicated, as long as it is not proprietary. I guarantee you that BMW doesn't mfg. their own O-rings, either back then, or now. They are purchasing from someone who does make them on a grand scale.

If the R75/6 microfiche is correct, and I am assuming his item correctly, the that O-ring can be duplicated.

From a person who has literally purchased thousands of O-rings for a nationally known company that uses them in hydraulic situations far more demanding than any of our BMW motorcycles require, there are only a few factors that can influence what to buy.

1) Of course the size. In this case, the size is readily available from Max's website. AND there is a perfect size match at McMaster-Carr. Most metrics, have number in the 900 series, but not all metrics are offered by a 900 series number, but are still available by size. ID x OD x cross section. The OD of an O-ring will be equal to the ID + 2x the cross section.

2) The material the O-ring is made of. This consists in evaluating the possible heat involved, and the application (i.e. abrasion verses trapped in an "o-ring groove," etc. and durometer hardness capabilities of the material of the O-ring. Some materials can only be offered in soft durometer because of the material, others not.

3) The durometer rating. This along with the material are important. For example, if an O-ring has a "friction" or "abrasion" application (like an O-ring would have if used as a seal for a rotating part like a crankshaft or wheel rotating on an axle) then the durometer needs to be harder to avoid the o-ring compound from tearing or wearing too fast. Most common use is a BUNA (material) 70 (durometer), which is popular for most uses. However, there are distinct reasons for going harder and with other material. McMaster-Carr does an excellent job of explaining applications for each of the materials they offer. One has to make an "engineering" decision based upon that data and the desired application.

Keep in mind also that the color of an O-ring means almost nothing. White is often teflon (which is largely used in high heat situations, but is not too good for high pressure). I have seen BUNA in various colors, red, black (most common), green, blue, etc. I would bet that a Viton (which has excellent properties which resist most chemicals, gas and oil, and heat) would be a good choice for this application and probably in a 90 durometer.

Manufacturers will use different colors to help users not confuse orings in various places, and then color for them has meaning, but their applications can be duplicated by other colors as long as the other data has been matched.

It is nice when one has access to an engineer, that isn't so programmed by his/her company to "sell" the company line. I have dealt with Husky (Canadian), Cincinnati, VanDorn and others (all Manufacturers of plastic injection machines) and I could call them and get their information, and they would simply tell me the three factors that I needed to know in order to purchase the correct o-ring (or bolts, washers, or nuts, etc.) so I could get them elsewhere lots cheaper. We also stocked virtually every size in both BUNA 70, Buna 90 and Viton. So...if we didn't have access to an engineer, we could use our best judgement to get the press going. We ran 75 presses, 24 hours a day, 365 days a year. No press was down for more than a few hours (we lived close enough to McMaster-Carr to have will-call purchases) unless there was serious damage and needed proprietary parts which we almost always ordered to be couriered. Yes, the company had a lot of money to spend, but they made a lot of money keeping the presses running.

Just sayin...
 
o ring

Hi guys, my 1977 r100s has an o ring between the flywheel and the crank shaft stub, checked with moto bins in England they say for airheads from 1976 on, bmw part no 11 22 1 337 099 $1.68 can,hope this assists Jimmy
 
Hi guys, my 1977 r100s has an o ring between the flywheel and the crank shaft stub, checked with moto bins in England they say for airheads from 1976 on, bmw part no 11 22 1 337 099 $1.68 can,hope this assists Jimmy

I, like Kurt, can't find it on the R100/7 parts listing, unless it is item #6 on the 11_1718 drawing. However, if it is, it is shown, but is not showing a part number (supposedly demonstrating that it is NLA from BMW).

It is on the R75 drawing, though. That is where I got the original part numbers, one obsolete number and one superseded number.

If the microfiche dimensions are correct, then a corresponding O-ring is available from McMaster-Carr.

If the original poster's issue with purchasing from a US supplier, because of the postage, is the main reason that he ordered from his local dealer, then ordering from anyone in the US would have the same problem.

jlc
 
I, like Kurt, can't find it on the R100/7 parts listing, unless it is item #6 on the 11_1718 drawing. However, if it is, it is shown, but is not showing a part number (supposedly demonstrating that it is NLA from BMW).

It is on the R75 drawing, though. That is where I got the original part numbers, one obsolete number and one superseded number.

If the microfiche dimensions are correct, then a corresponding O-ring is available from McMaster-Carr.

If the original poster's issue with purchasing from a US supplier, because of the postage, is the main reason that he ordered from his local dealer, then ordering from anyone in the US would have the same problem.

jlc

No JimmyLee it's not the postage cost, as it would be supporting your own BMW dealer here in Canada!:thumb:
 
max bmw

Jimmy -

I've been looking on the fiche pictures...I'm just not seeing it...all I see is the rear main seal that goes around the aft end of the exposed crankshaft.

just checked max bmw(for the first time),I put in R100 rolled up to flywheel ,item #6 part # superceded to 11221337093,for r60/6 to r100r ,1976 to 1995 ,hope this assists,I,m sure he has received the parts from a dealer by now ?,Jimmy
 
I hate to keep
dhorse.gif
but when I put in my VIN for my /7, #6 doesn't show in the table meaning it's not used for my application. No matter...I have no dawg in this hunt...just seeing what I could learn.
 
I hate to keep
dhorse.gif
but when I put in my VIN for my /7, #6 doesn't show in the table meaning it's not used for my application. No matter...I have no dawg in this hunt...just seeing what I could learn.

I am suspecting that you are on to something. Even though I definitely saw an O-ring in the pic of the above mentioned frame of the R100/7 microfiche, it is not listed below with a part number. Perhaps they used a common pic for the microfiche and simply didn't include any number because the R100/7 didn't actually use it? In any case, it is shown on the R75 fiche as the original poster said he had.

Just to be clear. You are not an a$$ any more than I am!!

I think questioning these types of things helps us all learn more - from all sorts of perspectives! Keep up the great work!
 
I hate to keep
dhorse.gif
but when I put in my VIN for my /7, #6 doesn't show in the table meaning it's not used for my application. No matter...I have no dawg in this hunt...just seeing what I could learn.

Or maybe the fiche is just wrong. Do you really think they used the O-ring on nearly every other bike with that flywheel but deliberately didn't install it on the R100/7? Do a 'where used' on the O-ring and see if anything clicks.
 
The smiley was a "beat the dead horse" one...that's what I was trying to say! :stick

Oops! I guess I am not into all those animations. Duhh!

I, speaking for myself alone, still do (or say) some dumb-a$$ things! Just ignore me when that happens.
 
Or maybe the fiche is just wrong. Do you really think they used the O-ring on nearly every other bike with that flywheel but deliberately didn't install it on the R100/7? Do a 'where used' on the O-ring and see if anything clicks.

Could be...can't say as I've ever found it wrong when I needed something...who knows. Here's a RealOEM cross-reference search on the part number. Interesting that the R80/7 shows up but not the R100/7.

GasketRing.jpg
 
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