Captain Avgas
Well Known Member
I noticed that the inner tubes (for the mains) that came with my RV7A finish kit had 2 nuts and a washer on the stem (the nose tube did not).
Neither Vans plans nor instructions have anything to say about these components so I went to the archives. Everyone seemed to be saying throw them all out...but I was suspicious of the advice so I went to Vans. And they said don't use them...so I didn't.
However on installation of the tubes in the tires I found that the metal stem of the tube does not want to centre in the hole formed by the two half rims coming together....it's fully to one side. I didn't like that so I tried all things humanly possible to get them centred (both side were exactly the same and offset in the same direction). But no...when inflated the stem definitely does not want to centre in that hole. In eyeing the tubes it looks to me that the stem is probably not vulcanised in the true centre of the tube. This is not an alignment problem 'around the tube' (that would be easy to fix) rather it's an alignment problem across the tube.
Now it seems to me that the purpose of the nuts and washers as provided on the tubes is to force the tube stem to be centred in that rim hole and I am now wondering whether Vans are giving good advice by telling builders to throw them out.
What have other done. Have people not used them as I did and found the stem to be slightly offset. You actually need a small mirror to see the offset so many might not have noticed it.
On the other hand have some people used these components and had good success.
Any comments, any hardluck stories about tubes and valve stems.
Neither Vans plans nor instructions have anything to say about these components so I went to the archives. Everyone seemed to be saying throw them all out...but I was suspicious of the advice so I went to Vans. And they said don't use them...so I didn't.
However on installation of the tubes in the tires I found that the metal stem of the tube does not want to centre in the hole formed by the two half rims coming together....it's fully to one side. I didn't like that so I tried all things humanly possible to get them centred (both side were exactly the same and offset in the same direction). But no...when inflated the stem definitely does not want to centre in that hole. In eyeing the tubes it looks to me that the stem is probably not vulcanised in the true centre of the tube. This is not an alignment problem 'around the tube' (that would be easy to fix) rather it's an alignment problem across the tube.
Now it seems to me that the purpose of the nuts and washers as provided on the tubes is to force the tube stem to be centred in that rim hole and I am now wondering whether Vans are giving good advice by telling builders to throw them out.
What have other done. Have people not used them as I did and found the stem to be slightly offset. You actually need a small mirror to see the offset so many might not have noticed it.
On the other hand have some people used these components and had good success.
Any comments, any hardluck stories about tubes and valve stems.