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Sourcing (Metric) oil seals by size, not application

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pebbleworm

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#1
I am rebuilding a 1938 German Adler bicycle, with a 3-speed gearbox in the the bottom bracket and need to replace 3 fossilized rubber oil seals. I can't just go up to a parts counter and ask for Adler Par numbers F 625 E, F 625 F, and F 625 D. Random web searches and McMaster Carr are turning up some seals that are close, but not exact for some and absolutely nothing close for others. There are a lot of reproduction car and motorcycle seals, but they are all listed by application, not dimensions. Does anyone have suggestions on how I should be searching for these?
I tried soaking them in oil of wintergreen and alcohol which softened them up temporarily, but are rock hard again a few weeks later. I could probably get away with cutting my own out of sheet rubber for some and replacing one with a rope oil seal, but I'd rather get closer to the original. I'll be running 00 grease in the gearbox so leakage should not be too bad. Thanks in advance!
 

dave_r_1

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#2
Search for a local bearing or seal shop.

Locally, my dad, a longtime mechanic, told me about a place called Commercial Bearing, now called Motion Canada, and they were able to find a seal only based on dimensions for a worm drive I have (that the manufacturer didn't sell parts for it, just pony up $600+ for a new one when the seal blew out).

You might even be able to find it yourself on their web site:
motioncanada.ca
 

Bob Korves

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#3
Motion Canada may be related to Motion Industries in the U.S. I used to deal with Motion all the time, and they are very helpful in finding seals, bearings, etc. in my experience. Try Motion Industries, with samples of the seals and where they fit. Take the bicycle with you if necessary. If you do not find a helpful counter person in one store, try another. Here are some locations local to you:
https://www.yellowpages.com/search-map/san-francisco-ca/motion-industries

Some good photos of the applications and dimensions may get you some help here as well.
 

pebbleworm

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#6
Thanks for the suggestions! I am finding things that are closer to what I need online thanks to your help. There is a Motion Industries near where I am staying, but I'm working hours that would be illegal in the EU so won't be able to bring the brittle pieces inn while they are open. Taking pictures of small black objects is a little challenging for me. One seal has a lip around the outside like a small brake wheel cylinder seal, the other is flat with a lip on one side of the ID and a recess on the other. The third is a ring of metal channel filled with Buna rubber. This last one I think can be repacked with string packing fairly easily. I am basically in a motel room, and I don't trust my Harbor Freight digital calipers, which seem to consistently read .1mm too small. Most of the measurements I take seem like an odd size. Since this is a bicycle some but not all of the parts are Imperial bicycle standard, and some others are Metric. If anyone is interested, I have a thread on the bike on a bicycle nerd board at:
https://thecabe.com/forum/threads/c...-3-gang-german-bottom-bracket-3-speed.106395/
 

Downwindtracker2

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#7
Metric oil seals # are super simple, OD x ID x thickness. in mm. And that is the seal #. Engineers are mentally lazy in designing, you'll get something like a 20mm shaft in a 30mm housing opening.
 

Bob Korves

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#8
Most bicycles do not have seals for the bearings, only shields at best, and I would imagine that many seals that may have been designed and used in the era of the bicycle in question would not be anything designed so a standard metric shaft seal would work on it. Just guessing, without some pics it is impossible to know what the bicycle was built with.
 

pebbleworm

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#9
It's more of a motorcycle type gearbox. All of the seals are around the pedal axle. Part 147 is like a crankshaft main seal, 156 is the one like a brake wheel cylinder seal, and 111 is more of a flat sealing washer.
 

Bob Korves

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#10
It's more of a motorcycle type gearbox. All of the seals are around the pedal axle. Part 147 is like a crankshaft main seal, 156 is the one like a brake wheel cylinder seal, and 111 is more of a flat sealing washer.
OMG! A great example of Germanic over engineering! (disclaimer: I am half German from both parents, and have the same tendencies to over engineer stuff...)
Still, it does not look like ordinary types of standard shaft seals are going to do the job here... It does look like that gearbox was borrowed from another application, probably something like a motorbike. I still think a trip to Motion Ind. would be a good choice, bring samples...
 

pebbleworm

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#14
Thanks for all the help! After looking at the links you all have provided, the rubber bits I need are not standard parts. BUT I have been able to piece some parts together that should work from orphan OEM seals from eBay and sheet gasket material. Next step is to find a replacement "gegenmutter", part No.112. If I measured it correctly, an off the shelf camera lens adapter could work, One is on it's way from the Far East.
 
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