CV boot sniff test...

[DanHoug]

here's Samba member dhaavers giving 3 different CV boots the sniff test while over for a visit on his way to Synco Solstice.

Test Results:

Boot A - Chinese boot, most non-compliant rubber, smelled vaguely like poop.

Boot B - GKN/Lobro boot, made in Italy, somewhat more compliant rubber, smelled like plastic

Boot C - genuine NOS VW boot, very compliant rubber, smelled just like rubber!! seriously, it smelled like an inner tube even tho 20 years old.

so there ya have it. if in doubt, smell it.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[ALIKA T3]

I'm glad to see I'm not the only weirdo smelling parts.

I can smell chinese plastic packaging tape, the one that is brown but more on the yellow side, Aliexpress special. Smells toxic. Some parts smell like it too.
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Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[raygreenwood]

While this is humorous.....and there are a great many chemicals and plastics that you can discern differences in by smelling.....rubber....especially synthetic rubbers that are injection molded (which all of these are).....smell will not really help you.

I work with rubber, plastics, chemicals etc. During the molding process....sure....the smell can tell you the difference between Buna-N, Viton and Neoprene.....but not once they are out of the plant for a while.

The best way to tell is to take a cutting or sample of each one. Get an ACCURATE small scale. Minimum is two digits below 0.

While viton is normally tested by using a small container with an 80% sulfuric acid solution in it and dropping the viton part into it (it will not hurt the rubber)....and if it sinks it's viton (at least one of the 6 grades of viton)....if it does not it's not Viton......you do not have to use acids.

The gist is that sulfuric acid is a known specific gravity that is lower than the specific gravity of any of the viton family. So you drop it in and it sinks. Neoprene and Buna-N will float.

You can do this with saline solutions and sometimes light acids like acetic acid, muriatic acid etc as well. You need to make the solutions and then 0 the weight of a volume of them in a glass jar on a good scale. You can calculate the specific gravity (formulas and methods on line).

There are charts of specific gravities of all of the major rubbers on line.

Make a solution that is a specific gravity at least say....8-10% lower than the rubber you want to test for and then drop a piece of the rubber in and it will sink if it's what you think it is.

Examples:
In the viton test, the sulfuric acid has a specific gravity of 1.72. Vitons are somewhere are 1.85 to 1.88.

EPDM is 0.86 specific gravity
Buna-N is ~1.0 specific gravity
Chloroprene is ~1.25 specific gravity (chloroprene is chlorinated neoprene)

In most cases, anything you can smell.....if it has a strong smell.....is either the mold release agent or sadly.....it may indicate that the product is "under cured" even if it is the right product t.
Even more sadly, you can find rubber products that fail even when they are the correct TYPE of rubber.....because they have crappy formulation, crappy raw ingredients or as already mentioned, we're poorly processed during the molding process.

Country of origin does not always guarantee good or bad.

About the best you can do is at least hopefully verify what basic rubber family parts are from

Ideally, items like CV boots, ball joint boots and tie rod boots "should" be Viton. But viton is expensive. The next best rubbers to use would be Buna-N or Neoprene. Both have less chemical resistance than viton but in different ways. Depending on the grease or oil you use you might get away with it and have decent lifespan.

Using these alternate rubber types is one of the ways that manufacturers are cheating out.

They might sell a complete axle assembly with cheaper Buna-N boots....and get away with it by putting in a specific petroleum based grease. But the day you clean those out to degrease them and use....maybe the wrong solvent or put in a synthetic grease of the wrong base....they crap out quick.

There are some manufacturers that are getting innovative and doing things like "co-molding"....where they take a lesser rubber like Neoprene and mold in a super thin (fo keep it flexible) inside layer of something like polyethylene which is very oil and grease resistant.

I have seen that on shock/strut boots and it's a damn fine method and lasts a long time. As long as viton. But sadly I have not seen that yet for CV boots.

Ray

[MarkWard]

Reminds me of an old joke. Punchline is “Good thing I didn’t step in it.”

[khughes]

[dieseltdi]

[dieseltdi]

[Xevin]

[Abscate]

Remember to gather more data by sniffing on alternate nostrils for better joint discrimination.

Safe travels
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🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🇺🇸 🍊 🍊 🍊

[raygreenwood]