Fuel tank mounting

Bruce,

I found this picture of my Navigator without the tank.

I used the original tank mounting rubber and glued a piece of rubber hose behind it.

I guess I even used the NOC parts rubber for it. So the rubber is longer and the tank

sits better.

I guess this is not the correct rubber. The NOC shop sent me a piece of a rubber hose that fits over the spigot on the frame. Look for a rubber oil hose in the correct diameter an slip it over the spigot. You can also cut a bevel to the front  of thehose so the tank can be fitted easier. When I get to my workshop I can send you a better picture of the part. The rear tank support can be tilted a bit to accept the bolt. I had the same problem so I glued the old tank rubber to the NOC part to get it longer. I had no oil hose in a suitable diameter. My tank stays clear of the front styling panel.

Bruce, just to add to Ulrich's sage advice the NOC shop is offering the wrong rubber sleeve for the front tank mount, it is the wrong outer diameter and should have a much wider ineer diameter to fit over the spigot on the frame.  I tried all sorts of different diameter car rubber heater hose - none had the right combination of inner and outer diameter and the rubber was really too 'hard' to provide the best 'anti vibration' fit.    Eventually I found a spare silicone suspension bush which I think came from my Triumph Vitesse which with a little trimming with a Stanley knife fitted perfectly, provides sufficient cushioning and hasn't deteriorated in service for over a year now.   I also found that the tank isn't really happy unless you use the correct stepped bolt at the rear with the flat and stepped rubber washers all of which are available from the NOC shop - the rear mount sets the tank position which means the front frame spigot isn't all the way into the tank's front mount.   A previous owner had made up two hard rubber pads to cushion between the back of the tank and the frame tubes.  This held the tank too rigidly causing resonance and the stress on the flimsy rear bracket caused a hairline crack and a fuel leak that required specialist welding to repair.   Mounting it with the correct rubbers allows sufficient cushioning to relieve vibrations stresses on the mounts and ensures the correct clearance on the little headstock faring.   I hope that helps!  Nick         

The rubber grommet supplied by the NOC shop bears no resemblance to the original rubber sleave that was on my bike and on Ulrich's shown in his photo above.   The 1964 Norton Jubilee & Navigator Spares Part List shows the correct part on page 30, plate G, item G87.   It is a short length of rubber tube without the step on the NOC part and with a bigger internal and external diameter.   It is listed on page 22 under Petrol Tank as part no: 23408 petrol tank front fixing rubber.    I suggest you disregard the NOC supplied rubber grommet completely because in my experience it won't fit over the frame spigot and it's outside diameter is too small to be a proper fit into the tank mount - in sum it is completely the wrong part!   If you look at Ulrich's photo you will see that the original part, exactly the same as mine, a simple rubber sleeve which slips over the spigot and is the right diameter to be a snug fit in the petrol tank front mount.   It isn't designed to push all the way into the tank mount because that would position the tank to far forward, fouling the headstock and putting the rear mount 1" out as you found.   In the past the NOC shop provided what was just approx a 1 1/2" length of rubber hose - it wasn't really the right size but was much closer to the original than the current offering.   I hope that helps - I wasted hours over the last two years trying to fit both unsuccessfully hence the silicone suspension solution.   Good luck!

The NOC rubber didn't fit my Jubilee either.

I used some rubber fuel hose I had from another job and just cut it to length. Luckily, it was the right inner and outer diameter. I created a 'top hat' at the frame end using an even larger diameter hose slipped over the smaller one to protect the frame paint.

Dennis

Hi Bruce,

Another photo of a front mount. If you look at the front of the tank you will notice the hole for the rubber is closed and limits the amount the tank can be pushed forward.

I hope your fix works, but the original, as others have said, was pretty simple.

This works fine.

Peter

That is intriguing if rather baffling Bruce, I've had three Jubilees over the years and my current Navigator and they have all had identical petrol tank front mounts with exactly the same original rubber tube around the spigot that you can see in Ulrich's photos.   Your spigot looks idental and in the right place so I dont think there is a problem there.    None of my bikes have required an extension to the spigot or that rubber bush to be long enough to fit into the front petrol tank mount sufficiently to provide ample clearance between the front of the tank and the headstock shroud and to allow the rear mounting bolt to line up to secure the tank properly.   That matches what is shown in the 1964 spares book and is how the original tank mounting was designed.   

Finding the right diameter rubber bush / tube aside that only leaves the tank and the rear mounting bracket as possible problem areas.  You say the tank front mounting bracket isn't bent back, is there any sign of any repair work that might have moved its position?   What condition is the rear mount in?   It has a habit of cracking where it is welded onto the back of the tank and might have been badly repaired?   I presume there is no question over the location of the frame mounting point?   Perhaps a photo of the front and back of the tank showing the mounts and some measurements of the tank and the distance between the end of the spigot and the rear mounting point on the frame would help us check dimensions against our bikes which might help you find a solution?    

Nick             

Bruce

if you measure the distance between your rear mounting bolt hole and the front of the mounting bracket I’ll measure the tank I have on the shelf. As I recall the spigot doesn’t go far into the tank mounting.

dan

I agree Dan, I doubt if the spigot on my front mount goes into the tank mounting more than 1/2" or 3/4".   Push it in to the full extent and the tank fouls the headstock faring and the rear mount is about 1" too far forward for the bolt to line up.   Nick    

I just love that late Jubilee flamboyant red Bruce and the bike is looking fantastic so really frustrating when you hit this sort of problem.   Looking at your third picture the position of the tank with your mod and the rear mount secured looks perfect with the same sort of clearance I have on my Navigator at both ends.   Looking at the pictures of the tank the rear mount looks the same as mine so I don't think it can be that and the front mount looks normal and as you say it doesnt look bent or modified - baffling!  Lets hope Dan's spare tank measurements point you in the right direction.    If you want to check the position of the spigot to the centre of the rear frame mounting hole then I will take my seat and tank off and see if they are the same if that helps.  Nick  

Hi Bruce,

Here are three photos of tank with tape measure alongside. This tank has been fitted OK.

16 inches from front mount forward face to centre of rear mounting hole.

4 inches from the front mounting to front of tank - but see the photo to see how/where measured.

It seems your tank measures 15 1/2  ins instead of 16 ins. Hence as you suspected your front mount is 1/2 ins back and not engaging front mounting peg on frame.

Also one picture of front tank mount to help you spot the reason for the differences.

I may have to attach two pictures here and two on next message.

Peter

Bruce,

Next two photos.

Peter

Hi Bruce, just a thought, is there any chance your tank is a recently manufactured one from India?   They are frequently advertised on eBay and some of the discussions on the Commando and big twins forums suggest they are often inaccurately made and mounting points and badge holes don’t line up?   Not a very cheerful thought but it might explain the 1/2” difference Peter seems to have identified.   Nick

Sorry for the delay I was visiting grandkids at the weekend. My measurements are very similar to Peter’s, approx 4” at the front and an overall distance of 16.25 to the rear edge of the rear mounting. However the front mounting on the grey tank is 4” at one side and 4.25 on the other .... suggesting some manufacturing “tolerances”!  My guess is that you have a Friday afternoon tank!  it shouldn’t be difficult to extend the front tank mounting if required, it’s not part of the petrol holding part of the tank so welding, (or jb welding as it’s painted ) a tube extension should be easy enough, or extend the frame mounting by the same method, it would prob be more secure than a rubber extension? 

Brilliant solution and a very neat job Bruce, looking forward to seeing the finished bike - you are doing a cracking job from your photos!   Nick

At last Sunday´s ride I heard a rattling from the tank after a few miles. The front rubber came loose and the rattling was metal to metal at the front mounting. At home I checked the fitting of the tank to the stud and it was right on the front edge of the front mounting stud. My new solution is a bolt with hexagon head pushed into the mounting stud hole andcovered with heat shrinking tube to get some extra lenght of the front mounting.

I pushed a rubber piece on that bolt head which now reaches fully in the front tank mounting.

The tank now sits firmly on that rubber.

A Good solution Ulrich, how is the Navigator running since you replaced the pistons and retimed it?   Nick 

Nicholas, I took a ride last Sunday. The bike ran fine! Engine is (almost) oiltight.

I wanted to visit a friend some 15km away from my workshop and the bike cut out some 2km before my destination. No more electrical power anywhere! The glass fuse wire looked fine, of course I had no spare fuse with me. I also had no chance to measure battery power etc. Luckily my friend has a van so we loaded it up and he drove me back to the workshop. The glass fuse must have melted right under one of the metal ends. I changed my fuse holder for the car type plastic stick in fuses which are better available.

So it was a short ride and I noticed vibrations around 60mph. Will change the handlebar grips for sofert ones. Quite a difference to my Commando with isolsatics!

Really sorry to hear that Ulrich, I agree - those fuses are much better and not so prone to failing from vibration I find!   Any idea what blew the fuse?    If the vibes are that bad I would check all the engine mounting bolts and particularly the head steady - I find it takes them time to settle and need tightening after the first few runs.  Nick

No idea what was the cause.

Still running it in but I didn´t make many miles with all that breakdowns!

The vibes are not that bad . I am used to that smooth Commando- Isolastic ride!

And even more trouble:

The paint on the front mudguard cracked. The mudguard was chromed and the paint had no good surface to stick to. Will have it sandblasted with coarse grit and repainted. My painter told me so.