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Discussion Starter #1
To all the technical dudes out there like Beach and jzeller and anyone else who has gone and boughgt Viton replacements.

I have been looking around for the infamous O-ring and have come across several sources so getting it is not my question. I have noticed that there are several different specs for this size Viton O-ring anywhere from a 70A, 75A to a 90A on the durometer.

For those that have not heard this term before, it is a scale of durability of the O-ring to withstand a depression or deformation due to pressure on its surface and return to the original shape without leaving a dent. The higher the number, the less likely it will maintain any deformation from pressure.

I have not seen anyone mention any durometer spec for this part so I am asking, what are you using or does it even matter in this application seeing the original just doesn't hold up and any of them would be better than the original BMW part.

I just bought a bag of 10 with a durometer rating of 75A and am hoping this will be adequate as a replacement. I can hand them out locally if needed as long as they will do the job.

I am interested in what others have used in their repairs.
 
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I was pointed to this one by Hilton, so bought several.
Viton O-Ring 75 Durometer 4mm x 19mm V75 so that's what went into my and Axle's bikes. A whole US$2.36 per o-ring.... postage was probably 50x that... along with the other bits and pieces :p
 

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Just got my o-rings and they are smaller than I thought. Can someone confirm that these look correct? they are just slightly larger than a quarter. I thought it would be bigger from watching the videos.
 

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From the pic of the vernier and converting back to inches, yes it looks correct to me. 19mm ID plus 2 x 4 mm section = 27 mm and that converts to 1.063", about right. As for the Duro, we never specify it in my industry but never have O ring failures when upgrading to Viton, it just solves the problem of memory loss due to heat/compression.
 
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From the pic of the vernier and converting back to inches, yes it looks correct to me. 19mm ID plus 2 x 4 mm section = 27 mm and that converts to 1.063", about right. As for the Duro, we never specify it in my industry but never have O ring failures when upgrading to Viton, it just solves the problem of memory loss due to heat/compression.
Thanks Dennis. Looks like I am good to go on that aspect and so are the next 9 people I can hand one off to :grin:
 

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You are good to go on a rating of 75. This o-ring slides over a splined shaft and gets the crap compressed out of it with a special washer to seal the shaft. Any of those would have done well in this application. The key is the Viton will not dry out and crack like the stock one.
 
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You are good to go on a rating of 75. This o-ring slides over a splined shaft and gets the crap compressed out of it with a special washer to seal the shaft. Any of those would have done well in this application. The key is the Viton will not dry out and crack like the stock one.
I remember reading about a "bounce test" for the viton O-ring but I can't find that thread. I toss one of these end-wise down on the table and it doesn't bounce at all. I would suspect rubber compound ones would bounce. I was surprised it didn't bounce at all. I am guessing that this would be the proper result if it is Viton.
 

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So when you slide the oring over the splines put some paper around the splines to keep from nicking it.
The types of Viton are interesting. I'm pretty sure the ones I have from Maryland Metrics are type A, common, and okay. I wonder if type F would be better as it has a better rating in resistance to the new types of engine oil. Rather than hardness, I think compression spring back is a better way to consider a type. They are all good seals but over spec is probably not the way to go. (my wife says I over think things :nerd:)Anyway, here is an indepth description of the different Vitons:
http://rainierrubber.com/wp-content/uploads/2014/01/Viton-Selection-Guide.pdf

As mentioned previously, I have some for free if you need one. They are cheap if you buy a bag from Maryland Metrics. And you could get whatever type you want. They have everything.
 

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So when you slide the oring over the splines put some paper around the splines to keep from nicking it.
The types of Viton are interesting. I'm pretty sure the ones I have from Maryland Metrics are type A, common, and okay. I wonder if type F would be better as it has a better rating in resistance to the new types of engine oil. Rather than hardness, I think compression spring back is a better way to consider a type. They are all good seals but over spec is probably not the way to go. (my wife says I over think things :nerd:)Anyway, here is an indepth description of the different Vitons:
http://rainierrubber.com/wp-content/uploads/2014/01/Viton-Selection-Guide.pdf

As mentioned previously, I have some for free if you need one. They are cheap if you buy a bag from Maryland Metrics. And you could get whatever type you want. They have everything.
A good read on the different types. I found them on Amazon and even thought they were listed as temporarily our of stock, I went ahead and placed the order and waited for them to restock. I had them in a week anyways so no biggie. $1.40 each with Prime free shipping ( bag of 10 ). I will hand some out at the Spring training meet. :laugh:

M4x19 Viton O-Ring, 75A Durometer, Round, Black, Viton, 19 mm ID, 27 mm OD, 4 mm Width (Pack of 10): Amazon.com: Industrial & Scientific
 
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