tank rubbers

Lorenzo · Apr 14, 2014

I am fitting a steel tank on my commando roadster and I am wondering if anyone can show how to fit the rubbers:
I mean the thick and thin rubber on the frame and the oring rubbers on the front studs
a picture may help..

I already used the thick on the back (on the side of the seat) and the thin on the front
furthermore I used four oring rubbers per each stud before meeting the frame and then another rubber oring and metal washer just after the frame
with this setting, my feeling is that the tank is quite high on the back..
what if I am fitting both a thick rubber both on the back and the rear and perhaps use more rubber washers?

any suggestion and comment? anyone doing some experimentation on the different configurations which may come out?
thank you!

Hobot · Apr 14, 2014

On Roadster tank I seem happyiest with 5 thick rubber washers glued under tank with metal washer under em on mount and one rubber washer under the mount clamped by wide thin washer to nip down just enough to stay and not crush out rubber dampening. I let rear of tank rest on tunnel pad to slightly compress down by strap or just leave strap off.

Lorenzo · Apr 14, 2014

what is the setting of the tunnel pads? are you using two thick rubbers, or one thick and one thin?

hobot said:
On Roadster tank I seem happyiest with 5 thick rubber washers glued under tank with metal washer under em on mount and one rubber washer under the mount clamped by wide thin washer to nip down just enough to stay and not crush out rubber dampening. I let rear of tank rest on tunnel pad to slightly compress down by strap or just leave strap off.

Hobot · Apr 14, 2014

My tanks had enough factory hardened tunnel cushion left to fully support rear of tank on it so didn't need or use rubber spacers on the strap, just metal spacers or washers to get decent tank clamp down stabilzation but not as strongly as the front main load carriers. A Commando is a thinking man's motorcycle so must fudge efficient tunnel cushion with some robust forgiveness of mounts. Too solid fatigue beats tanks. Can't really get too loose as long as don't rattle looser. Main force on rear of tank is riders knees in a panic state or off road zings. Regular drops and crashes don't seem to strain rear of tank much nor touch the paint, till bars bend peg fracture level the forgiveness factor comes into play.

L.A.B. · Apr 14, 2014

Lorenzo said:
a picture may help.

The height of the tank at the rear is basically goverened by the number and thickness of the rubber washers, also the profile of the curved 061321 Roadster tank retaining strap (with foam rubber strip) and not by the foam pad which becomes compressed as the two rear mounting nuts are tightened. Late Roadsters had two 060622 "exhaust mount" rubbers at the rear instead of separate studs and rubber washers.

http://www.nortonmotors.de/ANIL/Norton% ... 30&Part=11

DogT · Apr 14, 2014

As Les says, the grommets under the studs at the front of the tank are dependent on how thick the spacer is between the main tube and the tank, and the tank dimensions. If your old spacers are worn out, I used a set of Zorries (flip flops) and cut them up to fit as spacers between the frame tube and tank and glued them to the tank, like the original spacers. Then I determined how much space was needed to fill up between the tank studs and the wings., I cut out round pieces of the same zorries for the round spacers. Then I ditched the old nylocks which are a pain in the ass to put on and take off and under the wing, I used the large washers, then a standard nut then the reflector bracket and then another nut as a lock nut. Now I can take the tank off by just loosening the bottom nut and rolling everything else off by hand. Seems I take the tank off a lot.

I also made a 1/4" AL bracket under the wings as an additional support since one of mine broke off and I had it welded back on.

Dave
69S

Lorenzo · Apr 14, 2014

I understand that the rubber washers going on the front studs are those that set up the height and not the pads going in the frame tunnel
it seems to me that originally those rubber washers were four on the top of the frame wings and one going just below with the metal washer (so 4+1)

I tried to add one more rubber washer to lift the tank up slightly to the front, but it seems to me that the studs may contain exactly only 4+1 rubber washers..
any thought?

DogT · Apr 14, 2014

You really don't want the wings to take the weight of the tank, you want the center tube to do that. The wings should just keep the tank from falling off. Otherwise like mine, they'll break off.

I think originally I had 3 spacers above the wings and one below, but that all changed when I put the new spacers (flip flops) between the tank and the frame tube.

I notice now when I take the tank off, the new flip flop spacers glued to the tank have taken a shape to mold to the center tube. I think you just have to work with it to find out what works when installing new spacers, at least that was my experience and it cost me $50 or so and a trip to the welder to fix it. It seems fine now.

Dave
69S

Lorenzo · Apr 15, 2014

if the center tube frame should take the weight of the tank, what if I am using the thick rubber also on the front? (usually the thick should go only on the rear, while the thin should go on the front) I wish this may also help in raising the tank a bit more on the front..
any comment/suggestion on this?

DogT said:
You really don't want the wings to take the weight of the tank, you want the center tube to do that. The wings should just keep the tank from falling off. Otherwise like mine, they'll break off.

I think originally I had 3 spacers above the wings and one below, but that all changed when I put the new spacers (flip flops) between the tank and the frame tube.

I notice now when I take the tank off, the new flip flop spacers glued to the tank have taken a shape to mold to the center tube. I think you just have to work with it to find out what works when installing new spacers, at least that was my experience and it cost me $50 or so and a trip to the welder to fix it. It seems fine now.

Dave
69S

DogT · Apr 15, 2014

I'm not sure about the thick and thin washers for the tube. Mine were disintegrated, so I just made it work. Seems I put 2 layers of flip flops at the front of the tank and one at the rear. It made for less space from the tank to the wings where the studs and the old 3 hard donuts were, but that didn't bother me, I just got rid of those hard ones on the studs and used another piece of flip flop and I only use one of those. And it doesn't' put any stress on the wings. It just holds the tank in place so it doesn't rattle about.

Now if you've gone out and bought new replacement spacers for the tank on the tube, I'd put it on without the donuts on the studs and see where it is as far as spacing goes and just barely fill up that tank to wing space with the donuts on the studs. You can certainly put one below the wing too, I just didn't think it was necessary and took up more space that I needed on the studs for 2 nuts.

I like the flip flops because they seem the right consistency between soft and hard and they don't disintegrate. I tried tube insulation and that was too soft plus they compressed and inner tube was too hard and impossible to glue or build up.

Lorenzo · Apr 15, 2014

Thank you DogT
what is interesting to me is that you used a thicker 'flipper' cushion spacer on the front and a thinner on the back of the frame central tube
Norton Spare Parts Book says to use the thicker on the rear and the thinner on the front, but it doesn't look right to me
are you speaking about a metal or a fiberglass tank?

DogT said:
I'm not sure about the thick and thin washers for the tube. Mine were disintegrated, so I just made it work. Seems I put 2 layers of flip flops at the front of the tank and one at the rear. It made for less space from the tank to the wings where the studs and the old 3 hard donuts were, but that didn't bother me, I just got rid of those hard ones on the studs and used another piece of flip flop and I only use one of those. And it doesn't' put any stress on the wings. It just holds the tank in place so it doesn't rattle about.

Now if you've gone out and bought new replacement spacers for the tank on the tube, I'd put it on without the donuts on the studs and see where it is as far as spacing goes and just barely fill up that tank to wing space with the donuts on the studs. You can certainly put one below the wing too, I just didn't think it was necessary and took up more space that I needed on the studs for 2 nuts.

I like the flip flops because they seem the right consistency between soft and hard and they don't disintegrate. I tried tube insulation and that was too soft plus they compressed and inner tube was too hard and impossible to glue or build up.

B+Bogus · Apr 15, 2014

My roadster setup has 3 rubber pads above and one below at the front, and a generic 'tank mount' moulded rubber (as seen on all the world's TZs) taped to the frame spine close to the rear of the tank. The tank is clamped to this with a steel strap bolted across the rear mounts direct to the tank. The strap has a rubber pad bonded to it which fits between the strap and the underside of the frame spine - underneath the moulded pad.

It's too late in the day to get photos, but the tank sits like this...

DogT · Apr 15, 2014

I have a Fiberglass with the buttons on the rear for the rubber band to hold the rear. That may be all the difference in the world, I really don't know, I've not had another tank or bike to compare. All I can speak to is what I have. I have a neighbor with a 71/72 and a metal tank I think. I really should go look at it and if I could play with it that would be interesting. I have the early fork stops and worry about getting a new tank because of the swing of the front end. I also use a mirror under the left bar and it's preciously close to the tank when at full tilt.

L.A.B. · Apr 15, 2014

DogT said:
You really don't want the wings to take the weight of the tank, you want the center tube to do that. The wings should just keep the tank from falling off. Otherwise like mine, they'll break off.

However, later models had a different coil bracket that bolted to the underside of both tank mounting "wings" (same as your extra piece of alloy plate does) so wing bracket fracture doesn't seem to be a common problem on later ('71-on?) Commandos.

tank rubbers

Lorenzo

Hobot

Lorenzo

Hobot

L.A.B.

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DogT

Lorenzo

DogT

Lorenzo

DogT

Lorenzo

B+Bogus

DogT

L.A.B.

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