featherbed petrol tank rubbers

About security bolts. On Vincent it was fitted to twins, not to singles due to the torque difference between 998 and 499cc. Modern tyres has softer rubber than the ones originally fitted, so they usually don't need security bolts. Paint might make the rim prone to slip. If you plan to go off-road with low tyre pressure for better grip, security bolts is a good idea. I have the habit of not tighten the valve nut down to the rim, leaving one or two turns. Then I can see if the tyre has moved on the rim. As long as the valve goes straight it's Ok.

In short I've had no problems without security bolts in the last 50 years.

Mike

P.S. Sorry for my bad english

One reason for persisting with security bolts is that they prevent the tyre coming off the rim in event of a sudden blow out. Blowouts can occur with tyre creep quietly ripping the valve off the tube. There have been a couple of cases where a blowout has caused the rear tyre to come off the rim and jam against the swinging arm causing a lock up. It's not a common occurrence but it can happen. One of the reasons tubeless tyres are now common is that they are less prone to sudden deflation and they aren't bothered by tyre creep.

Modern low profile tyres just will not fit my 99. I am restricted to the older deep wall Avons. If security bolts were not beneficial when using these tyres then Norton would not have fitted them.

Even if the tyre stays on the rim it can be a quite nasty experience. Nowadays security bolts are fitted to speedway bikes, but back then we had the valve going out on the right side of the tyre. A puncture resulted in less traction so the bike broadsided more. When closing the throttle after the finish line the bike wobbled a lot as the centrifugal force on the tyre did not keep it on the rim in low speed. My main reason for not using them is that they are difficult to fit and the risk of them pinching the tube. As the kids has been quite good at changing tyres on their enduro bikes with security bolts, I might reconsider and let them do it.

Luckily most of my bikes has alloy rims that are serrated and works well without them.

Norton instruction book says: "if fitted" so it is up to you to decide.

At least in the early 50?s, security bolts were an option, not a standard fitting. My ?53 Dominator 88 did not have them, and, it was ridden to it?s limit, with no problems (teenagers are immortal!).

Re. tank rubbers: Early this year, I fitted a new (good quality Indian) tank, to my ?54 88. I bought new rubbers, from RGM, these were much thicker than 1/4" inch thick. I would suggest that, if you use the ones you have, cover them with foam pipe insulation.

Previously paul_standeven wrote:

Thanks for the comments on tyre security bolts. So it's up to me. I once had a rear blow-out at 70mph on my Super Rocket. The bike flapped about rather a lot, but the RoadRunner stayed on the rim

I have just fitted my new tank rubbers. I went to a plumbing supplies co, and bought a length of pipe insulation foam. It goes onto the frame top tubes in one length each side, and does raise the tank a little, as I wanted. The foam is visible gray below the tank, but as the tank is chromed, it's not too obvious. Because the foam is for hot water pipes, there's a good chance that it will cope with radiating engine heat. If not, I have spent a whole £2 and a few minutes on the experiment....

Another small mod I have made is a reflector for the underslung pilot lamp, from the aluminium cup for a mince pie.... The pilot is still a ridiculous item, but a bit brighter

Paul

Hi Paul,

If you decide to leave out the anchor bolt I would suggest plugging the hole from the inside with a smooth headed setscrew and a suitable dome head nut on the outside, suitably locktited, and not forgetting a new rim tape and wheel rebalance.

Dick