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featherbed petrol tank rubbers

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featherbed petrol tank rubbers

Posted by paul_standeven at December 06. 2017

I'm after a few tech advice ideas for my 1955 Model 88 Dominator

I have some NOS petrol tank rubbbers.  They are about 3" long, go half way round the top tubes, and are 1/4" thick.  They are very hard....  There's a flat plate above the voltage regulator, mounted on the front of the tool tray.  The back of my petrol tank rests on this, causing vibration.   I'm thinking of alternative tank mounting rubber.  What about pipe insulation foam?  Or perhaps just sticking some softer rubber to the underside of the tank?

My wheels have security bolts, making tyre fitting a real hassle.  My rims are Dunlop steel, with the wheel wells painted to prevent corrosion.  Does anyone have problems if they simply remove the security bolts?

Paulo

Re: featherbed petrol tank rubbers

Posted by Mikael Ridderstad at December 06. 2017

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

Re: featherbed petrol tank rubbers

Posted by Gordon Johnston at December 07. 2017

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.

Re: featherbed petrol tank rubbers

Posted by robert_tuck at December 07. 2017

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.

Re: featherbed petrol tank rubbers

Posted by Mikael Ridderstad at December 07. 2017

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.

Re: featherbed petrol tank rubbers

Posted by John Shorter at December 07. 2017

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: featherbed petrol tank rubbers

Posted by John Shorter at December 07. 2017

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.

Re: featherbed petrol tank rubbers

Posted by paul_standeven at Friday 16:28

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

Re: featherbed petrol tank rubbers

Posted by paul_standeven at Friday 16:31

Are you referring to Avon RoadRiders?  I have TT100s on the bike at present, and they are a tight fit.  I had to correct offset wheel rims before they could go in.  So are the RoadRiders even tighter?  Will they go into my 88?

Paul

 

Previously robert_tuck wrote:

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.

Re: featherbed petrol tank rubbers

Posted by richard_hudson1 at Friday 21:11

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

Re: featherbed petrol tank rubbers

Posted by paul_standeven at Saturday 00:49

Hello Richard,

I had that in mind if I deleted the security bolts, I would plug the hole.  Who knows, there might be a commercially-made device on sale

When I fitted the TT100s, the front wheel had a bad out-of-balance condition.  I experimented with balance weights, and settled on a 3/4" AF socket on the valve stem. Smootheness achieved!

Paul

 

Previously richard_hudson1 wrote:


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

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