Right in the middle of re-assembly (76 KTM 250) ran out of one main seal, off to the local supplier... Chicago Rawhide has two:
CR 9705 has Nitrile material
CR 9706 has Viton material
For lack of a better explanation, they did have the Viton type, which should hold up better than Nitrile, but in thinking, long before Viton, seals were made with non-exotic materials. I don't know when Viton came into the picture. Some expert will prolly chime in here...
Of note, there is a green substance around the OD of the CR seal, when asked of the Vendor, he explained that it is a Locktite material that seals upon entry and acts as a vibration cushion. So I have come to the conclusion, do not make attempts to remove this material to aid in seal insertion...Any comments about seals in general are greatly appreciated...
Thanks in advance, Tom Brosius
Tom I have been selling Chicago Rawhide seals for for over 30 years and Viton has been around that long.... the green coating is called "Boretite" . Its actually for "sealing in" the od of seal where some machining of housings wasnt exact..Rubber OD seals are for even more forgiving on machining bores. You are correct dont scrape it off... BT
Brian Taylor
Tom: Brian T I am sure has all the specific list of chemicals that both compounds are rated for, but either will work fine in your application. Viton's main claim to fame was higher temperature toleration than Nitrile (Buna-N). Honda uses Viton on most O rings in contact with top end of engine. Where most heat is. Viton has been around since late 1950's. Viton's common draw back is it does not tolerate akalines well. So don't use it on your salt spreader.
Brian, thanks for the explanation of Viton and it's history.
Tom Brosius
Tom, Brian & Ted,
Ted makes some great points about Viton. We at Honda (before I retired) started to use Viton seals in our our water pump line mainly because people were pumping chemicals through our pumps that we didn't recomend. Also, Ted mentioned heat being a factor in using Viton seals. This was a great side benefit since the seals were in direct contact with the crank and did heat up under normal (or in most cases not normal;)) use.
I also found that the "Boretite" that Brian mentioned is great for using on the OD of bearings in hubs where the bearings were maybe getting a little sloppy. Great posts.
Ron Carbaugh
Nitrile( buna ) has a range of -40F to 225F normally ok for most things .. the Viton is -40f to 400f nice saftey factor there but a lot more money (in comparrison ) but the real benifit is Vitons resistence to most special lubricants that would attack nitrile . With all the fancy additives to oils, gasolines etc that they dont tell u about on the labels its always wise to sit back and think thru what the seal environment is going to be .. BT:)
Brian Taylor
Quotequote:Originally posted by BrianTaylor
Nitrile( buna ) has a range of -40F to 225F normally ok for most things .. the Viton is -40f to 400f nice saftey factor there but a lot more money (in comparrison ) but the real benifit is Vitons resistence to most special lubricants that would attack nitrile . With all the fancy additives to oils, gasolines etc that they dont tell u about on the labels its always wise to sit back and think thru what the seal environment is going to be .. BT:)
Brian Taylor
I have to agree with BT.
If you not sure pay more but be safe.
Speedy------>>>>>>>>>
(I am using in the hot area of the engine VITON only.)
Helmut Clasen KTM
162 Hillcrest Ave
L9H 4Y3
Dundas Ontario Canada
Ph.905-627-5349
[email protected]http://speedy_c.tripod.com
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