Decoding part number

[chuck hahn]

This is the part number for the oring that holds the reservoir cup in the front master cylinder on my skunk. Im thinking that its telling me its a 62 MM oring but what durometer?? Am i correct assuming that it is 62MM?

59686-33620

[Nessism]

62mm ID or OD? What material? What O-ring thickness? Why not just order the OEM part and avoid these questions?

[chuck hahn]

ED its NLA and theres only 4 on ebay from Germany and i cant see buying a 30 dollar oring if i can get information to just buy a regular nitrile oring for 2 dollars.

[Nessism]

Measure the size yourself, chuck. And research. Nitrile is not good for brake fluid. You need EPDM

[chuck hahn]

Well i can at the least measure the base of the reservoir and the depth of the groove and take SWAG at it.

[oldGSfan]

The number on Partzilla (#3) is dyslexically different, 59668-33620 vs 686. Looking that up on eBay I see it's available for $8 here (and many others for around $10):

https://ebay.us/m/NJHuGM

Maybe snag it?

[chuck hahn]

Tom. I took the number from item 9 here.....
1978 Suzuki GS1000EC Front Master Cylinder (Gs1000ec | Part Shark

[oldGSfan]

Tom. I took the number from item 9 here.....
1978 Suzuki GS1000EC Front Master Cylinder (Gs1000ec | Part Shark

Could be a PN change perhaps, or a typo. Anway the 13 of them on eBay match your # and look right. I actually used the Partzilla number in the search and they appeared, maybe a 'close enough' search logic going on.

[Nessism]

O-rings are commonly sized ID x thickness. You want a little stretch, so the O-ring ID needs to be a smig smaller than the groove it fits into. Maybe 1-2mm for a 62mm O-ring? something like that. To figure thickness, you need to measure the mating O-ring groove, which in this case, will be difficult; measure the OD of the groove in the master cylinder. There is no easy way to do that. Maybe take a piece of wire, slowly cut it down to size, until it just fits inside the groove, then remove the wire and measure with calipers? Something like that.

[chuck hahn]

I discovered that with the groove Ed. The base of the reservoir cup is 45MM and i measured it a few times to be sure it was that. I like the wire idea for finding the groove depth. I will try that but im guessing its gonna be close to 2MM.