Is there a part number for the o-ring between the plastic reservoir and the metal body on 1977 and later front brake master cylinders?
Is there a part number for the plastic reservoir?
Is there a part number for the plastic reservoir?
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front brake M/C Reservoir O-Ring part # ??
- Thread starter DogBunny
- Start date
Skull, thanks for replying, however that diagram does not show the o-ring that I am looking for information on.
This is the o-ring that goes between the plastic reservoir and the metal body on 1977 and later front brake master cylinders. Looking for a part number, a substitute that works, or a way to make a leaking reservoir stop leaking.
Also interested in a part number for the plastic reservoir.
This is the o-ring that goes between the plastic reservoir and the metal body on 1977 and later front brake master cylinders. Looking for a part number, a substitute that works, or a way to make a leaking reservoir stop leaking.
Also interested in a part number for the plastic reservoir.
Hey man, how's the old hood? I would clean everything well with non-chlorinated brake cleaner, incl. the o-ring, then give the o-ring a hefty coat of something like Permatex Motoseal or Yamabond and reassemble. While the reservoir is off it would be interesting to see if it could be buffed to be more clear. Cheap paint swirl remover might be a good last pass; a friend uses it to buff headlights to new-looking. Must keep the buffing pads separated...
I don't think Yamaha ever sold either of them separate.
I know back in April I was looking for the same thing, oring part, and I ended up going to a local hydraulic repair shop and guy there matched up the oring to a metric size of 39.7 mm id with a 3.5 mm cross section. Now back then some here said if the oring was not the correct material I was looking to have a problem down the road. Was told it should be EPDM material. Really not sure if that was what the ones I got were but as of this morning brakes still work fine and not a sign of leaking.
I know back in April I was looking for the same thing, oring part, and I ended up going to a local hydraulic repair shop and guy there matched up the oring to a metric size of 39.7 mm id with a 3.5 mm cross section. Now back then some here said if the oring was not the correct material I was looking to have a problem down the road. Was told it should be EPDM material. Really not sure if that was what the ones I got were but as of this morning brakes still work fine and not a sign of leaking.
I found a matching o'ring at my local hardware store.
All parts files have the plastic reservoir and the base as Part #1..........assembly...........That's why i posted the parts file. I had looked at several of the later years to see if they did later....No......
A good engineering parts supply shop will have the O ring
A good engineering parts supply shop will have the O ring
Finding O-rings can be maddening.
I've resorted to getting a Napa o-ring kit. Make yer own...
I've resorted to getting a Napa o-ring kit. Make yer own...
I've used this chart some, more for reassurance than selection 
https://www.marcorubber.com/o-ring-material-selection-comparison.htm
The info for Motoseal 1 says "resists gasoline and other damaging fluids". If I'm worried what the effect of some fluid will be on something, I will put some in a jar of the fluid for a few days to see what happens.
https://www.marcorubber.com/o-ring-material-selection-comparison.htm
The info for Motoseal 1 says "resists gasoline and other damaging fluids". If I'm worried what the effect of some fluid will be on something, I will put some in a jar of the fluid for a few days to see what happens.
Thanks to all who have replied.
That kshansen and marty found o-rings locally was encouraging.
I did my own measuring, and I agree that the old o-ring has a 3.5 mm cross section. The o-ring sealing face of the plastic reservoir was slightly ovoid, and may have shrunk over time, so I interpolated a measurement for it. I cut into a useless donor M/C metal body so that I could get an accurate measurement of the o-ring seat diameter on it.
I think I know what to look for. What I don't know is how much "squish" there is supposed to be. That's why I was looking for an o-ring part number, on the remote chance that with an ADP Lightspeed parts search I might find one sitting on a dealer's shelf somewhere that I could buy and measure.
There are lots of parts that have numbers but don't show up on the parts diagrams. One of the best known is the BS38 and BS34 throttle shaft seal.
McMaster-Carr has kshansen's 3.5 x 39.7 o-ring. It also has what may be a better candidate, a very slightly thicker 3.53 x 39.69 version. Both are made of "Oil-Resistant Buna-N," and tout "excellent resistance to hydraulic oils. Does brake fluid count?
Before I order from McMaster-Carr I am going to see what I can find locally, tomorrow.
TwoMany, that is a cool DIY o-ring kit. I never would have imagined it. Have you used it? Maybe that's an old pic from when you got it, but hadn't used it yet?
xjwmx, Austin is still great, but promise not to tell any one. Good idea on testing parts in fluids before use. Some o-rings expand in contact with some fluids -- this can actually be beneficial according to member bluebikerblan who worked on silcone rubbers for DOW.
I looked at your chart, Buna-N gets low marks for brake fluids, but as I just said, it might not matter.
That kshansen and marty found o-rings locally was encouraging.
I did my own measuring, and I agree that the old o-ring has a 3.5 mm cross section. The o-ring sealing face of the plastic reservoir was slightly ovoid, and may have shrunk over time, so I interpolated a measurement for it. I cut into a useless donor M/C metal body so that I could get an accurate measurement of the o-ring seat diameter on it.
I think I know what to look for. What I don't know is how much "squish" there is supposed to be. That's why I was looking for an o-ring part number, on the remote chance that with an ADP Lightspeed parts search I might find one sitting on a dealer's shelf somewhere that I could buy and measure.
There are lots of parts that have numbers but don't show up on the parts diagrams. One of the best known is the BS38 and BS34 throttle shaft seal.
McMaster-Carr has kshansen's 3.5 x 39.7 o-ring. It also has what may be a better candidate, a very slightly thicker 3.53 x 39.69 version. Both are made of "Oil-Resistant Buna-N," and tout "excellent resistance to hydraulic oils. Does brake fluid count?
Before I order from McMaster-Carr I am going to see what I can find locally, tomorrow.
TwoMany, that is a cool DIY o-ring kit. I never would have imagined it. Have you used it? Maybe that's an old pic from when you got it, but hadn't used it yet?
xjwmx, Austin is still great, but promise not to tell any one. Good idea on testing parts in fluids before use. Some o-rings expand in contact with some fluids -- this can actually be beneficial according to member bluebikerblan who worked on silcone rubbers for DOW.
I looked at your chart, Buna-N gets low marks for brake fluids, but as I just said, it might not matter.
I take it campfires are allowed in Texas now
The chart differentiates between hydraulic and brake fluid, with marked differences in performance. I agree swelling might not be bad -- wouldn't want to see any dissolved black in the jar of fluid though, personally.
If you want to get really deep into it, think geometry. The circular cross-section of an o-ring can deform, but can't fit into an area that's less than its area. A good limit would be to choose an o-ring diameter that's less than 110% of a square groove's width, or depth. Ex, suppose that you have an 1/8" wide by 1/8" deep groove, and the parts fitment is close. 110% of 1/8" is 0.138", so an o-ring of 0.138" thickness would be about as far as you'd want to go. Another method is to use 0.005" as the wall deflection limit. That would take that 1/8" (0.125") groove, add 0.005" to one side, 0.005" to the other, making the maximum o-ring diameter 0.125" + 0.005" + 0.005" = 0.135" diameter. Then, it's your choice on what's available for thicknesses.
Oh, yeah, got that long ago. I have *lots* of o-rings, but still not enuff to cover all bases. Among other things, I used it to make those goofy squashed diamond shaped petcock o-rings for the XS1B.
Tip: You can make o-rings from oversized o-rings. Cut to length, using angled bologna cuts, join the ends with that "Gorilla Grip" super glue (it has rubberized plasticizers, works well with rubbers). The kit comes with a guide tool (plastic block with grooves) to keep the ends aligned. Remember doing splice repairs on magnet tapes and films?
Attached is another o-ring material selection guide...
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Well, I can definitively say that the correct size for an XS650 M/C reservoir o-ring is 39.7 x 3.5.
AND I found a part number for it, AND it is still available:
45516-422-006
That is a HONDA part number. I think that Nissan makes our XS650 master cylinders. And whoever makes ours must also have made Honda master cylinders. And they spec'ed the same o-ring for both.
http://www.partzilla.com/parts/detail/honda/HP-45516-422-006.html
The above link shows Honda master cylinders that use the o-ring. Click on any of the models, and you'll see how similar the Honda reservoir is:
http://www.partzilla.com/parts/detail/honda/HP-45511-463-006.html
The Honda reservoir is still available, but unfortunately it is rectangular, while ours is sort of oblong, so no interchanging.
I went to Harbor Freight, and for 8 bucks I got an assortment of 240 metric o-rings, including ten 39.7 x 3.5s. I put one in my leaking reservoir and it works fine. These are nitrile o-rings, which is the same thing as Buna-N. I'm running a test on one of the small o-rings in brake fluid to see how it reacts.
If you can't find a 39.7 x 3.5 locally, and don't want to buy the Honda part, there are several available very reasonably on eBay.
McMaster-Carr sells an over-size version of the 39.7 x 3.5:
https://www.mcmaster.com/#9262k23/=19gtpka
There is a LOT of squish area in the o-ring seat, and I think this over-size o-ring is a very logical choice to pop into a 40-year old reservoir. I'll be buying a pack next time I order from McMaster-Carr.
AND I found a part number for it, AND it is still available:
45516-422-006
That is a HONDA part number. I think that Nissan makes our XS650 master cylinders. And whoever makes ours must also have made Honda master cylinders. And they spec'ed the same o-ring for both.
http://www.partzilla.com/parts/detail/honda/HP-45516-422-006.html
The above link shows Honda master cylinders that use the o-ring. Click on any of the models, and you'll see how similar the Honda reservoir is:
http://www.partzilla.com/parts/detail/honda/HP-45511-463-006.html
The Honda reservoir is still available, but unfortunately it is rectangular, while ours is sort of oblong, so no interchanging.
I went to Harbor Freight, and for 8 bucks I got an assortment of 240 metric o-rings, including ten 39.7 x 3.5s. I put one in my leaking reservoir and it works fine. These are nitrile o-rings, which is the same thing as Buna-N. I'm running a test on one of the small o-rings in brake fluid to see how it reacts.
If you can't find a 39.7 x 3.5 locally, and don't want to buy the Honda part, there are several available very reasonably on eBay.
McMaster-Carr sells an over-size version of the 39.7 x 3.5:
https://www.mcmaster.com/#9262k23/=19gtpka
There is a LOT of squish area in the o-ring seat, and I think this over-size o-ring is a very logical choice to pop into a 40-year old reservoir. I'll be buying a pack next time I order from McMaster-Carr.
