Installing tubes in tires

[Captain Avgas]

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.

 

[cytoxin]

saw that as well, last year when i did mine

i just used the washer. deburred it and installed the washer alone with the bump piloted in the opening..... as they say YMMV

 

[Caveman]

Probably has nothing to do with it but you asked.

Any comments, any hardluck stories about tubes and valve stems.

Back in the Jurassic period, I used to race motocross. The harware you are talking about was used to keep the tire and tube from spinning on the rim and tearing the valve stem off of the tube when running low air pressure in the tires for better traction on certain soils. It would seem in my feeble mind that it might serve the same purpose on an aircraft if you had an air leak and low tire pressure upon landing. On the other hand it may just throw your tire / wheel assembly out of balance, so just consider this another data point from an over-the-hill racer. (And yes, the older I get, the faster I was).

 

[captainron]

Back in the Jurassic period, I used to race motocross. The harware you are talking about was used to keep the tire and tube from spinning on the rim and tearing the valve stem off of the tube when running low air pressure in the tires for better traction on certain soils. It would seem in my feeble mind that it might serve the same purpose on an aircraft if you had an air leak and low tire pressure upon landing. On the other hand it may just throw your tire / wheel assembly out of balance, so just consider this another data point from an over-the-hill racer. (And yes, the older I get, the faster I was).

Aaahh... for just a whiff of that blue exhaust smoke from a Bultaco.....