VITON CRANKSHAFT SEALS

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Why doesn't it work for everything on a Corvair?

If you go way back in ancient history one of the greatest discoveries for the Corvair was the use of Viton oil rings. In the 1960's Corvairs had developed a reputation of leaking oil. When the pushrod draintube o rings leak they make a real mess. Let them go long enough and they can leak a phenomenal amount of oil.

The cause of the leaks is a little misunderstood.  Neoprene actually works pretty well as originally prescribed by the factory. In fact Dr. Benzinger (the head designer for the Corvair motor) was asked in the 1970's about why GM used neoprene when , at that point in time, there was such a well known problem with the material.

Dr. Benzinger answered that he was unaware of the problem and that neoprene was an acceptable material.  You should have heard the audiences reaction!  But I think Dr. Benzinger might have been telling the truth, from his perspective at least. In the 1950's and early 60's when he had an involvement with the Corvair motor neoprene had probably worked fine.

The problem with neoprene is that age and overheating is it's enemy. If a Corvair engine was only 2 or 3 years old the odds of the neoprene O rings leaking was virtually nil.  But even more importantly neoprene O rings could be in a Corvair for 20 or 30 years and never leak - so long as the motor was not overheated.

In the late 1960's several people discovered that if you used Viton for the O rings you would eliminate these problems. Over 40 years of use in Corvairs has proven beyond a shadow of a doubt that Viton is an excellent material for O rings.

Now, let's switch gears a bit.

In the mid 1990's several companies were still manufacturing crankshaft seals for the Corvair. But things started to go wrong. One company dropped off the outer rubber which made the seals difficult to keep in place. They also could leak. Another company altered (I hope by accident) the I.D. of the bell housing seals and they leaked horribly.  Because changing a bell housing seal is a major job this became a big issue almost overnight.

My company and one other vendor made contact with an outfit that could have seals made for us any way we wanted them. I told them that there was nothing wrong with the material but that the design and dimensions had to be correct. Since the late 1990's we've been selling these seals and they have worked fantastically.

We were also offered a little later the same seals but in Viton.  The idea sounded intriguing to me but about the same time I happened to mention this to a member of our local Corvair club. This individual worked for Parker Seal as a rep and he suggested I talked to their head engineer.  I did so, and the engineer told me in no uncertain terms that, while Viton is a great material in many applications one place it is generally avoided is in "dynamic" seal applications.

A dynamic seal is where there is a rotating shaft that needs to be sealed. The issue apparently is wear. Viton is a less than stellar material when it come to wear.

At that point I decided not to avail myself of the Viton seals. I think that turned out to be a good decision as we are now hearing of Viton bell housing seals that are leaking, some after only a few years. Is it the wear issue?  We can't say yet for sure but I do know that seals made of more traditional materials have not experienced these problems and are working just fine.

Why make seals out of Viton when intelligent people advise against it?  Because Viton did so well for a serious old Corvair issue it's name has attained sort a God-like quality. If you think that's an overstatement think back about how many times you hear the word brought up as a solution for any number of Corvair problems.

Viton has become a magic word for some Corvair people. But the truth is, it's viability as proper material in Corvairs is very limited.  Viton is a very good material when it's proper realm is understood.

And even if Viton was a good material for seals would it be he only one?  Modern dynamic seal materials are much better than old materials and they are specifically designed for the application. The material our seals is made of is good for up to 350 degrees (and if you got anywhere close to that temperature in this application you'd be in BIG trouble elsewhere). The simple fact is, the 10% better heat tolerance of Viton is unnecessary in these applications anyway.

I don't use Viton crank seals and I hope you don't either.

VENDOR DISCLAIMER  Obviously as just mentioned I sell traditional material bell housing and crank seals and do not sell Viton seals. But I certainly could - the Viton seals only cost me about $2.00 more each than a regular seal and I see that I could add another $10.00. Not a bad markup.

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