74 850 oil tank

New to the Norton world, restoring a 1974 850. At point of removing the oil tank, still working on getting it off the lower mount but when it's out is there recommendations on rework needed ? I know CNW offers a rebuild that sounds pretty good. Any other items to take care of.
Thanks JW

I do a similar mode to CNW, I grind the lower mount off and then get a plate welded over the area, paint and then stick a hard rubber buffer on there so its back up the the same height as the mount. I then drill the front and back rubber buffer holes out from 1/4 to 5/16 on the tank and the frame. I fit the large rubber buffers with 8mm or 5/16" studs at the top front and rear and let the bottom rest on the bottom frame mount. No more worrying about the lower mount insert fracturing and allowing all the oil to escape, had it happen twice but it cannot happen again.

Welded bottom and the rubber buffer used at top mounts (studs may need shortening)



Rubber buffer (later cut into 3 to fit)



Rubber buffer from side, approx 8mm thick

In the 41 years I've owned my 74 850, the oil tank has broken at the rear tab probably 5 times. I've welded, epoxied, brazed, etc and it lasts for a while but ultimately breaks again. The one on the bike now is broken, and I have the tank wedged in place with foam rubber and black tape. It'll get me by for this season, but come winter this tank is going to CNW to be dealt with once and for all.

Nice work @kommando. I think I'll go this route when I get it out. Amazing to think that the design was off that much given the failures reported.

kommando said:

I do a similar mode to CNW, I grind the lower mount off and then get a plate welded over the area, paint and then stick a hard rubber buffer on there so its back up the the same height as the mount. I then drill the front and back rubber buffer holes out from 1/4 to 5/16 on the tank and the frame. I fit the large rubber buffers with 8mm or 5/16" studs at the top front and rear and let the bottom rest on the bottom frame mount. No more worrying about the lower mount insert fracturing and allowing all the oil to escape, had it happen twice but it cannot happen again.

Welded bottom and the rubber buffer used at top mounts (studs may need shortening)

Click to expand...

Would the muffler mount buffers work for this?

maybe I don't get it but I removed the bottom oil tank bolt some 20 years ago and stuck thick foam pad under it

yes the top two rubber snubber securing things do break over time due to vibrating stress I suppose but they are cheap enough to replace

I think that using exhaust rubber mounts would not be such a good idea because they are too firm.
If the smaller soft ones give up the ghost, so what? Install new ones. Cheap and easy.
It is just like the exhaust mounts, they really are at best a fudge , a bodge. But keep an eye on them
and renew as needed.
All british bikes in the Commando and below price level should be inspected like an airplane, that is,
regularly.

I had the tank crack where the top strap was braised/welded to the tank. It had the bottom rubber and bolt installed. I had it re-welded and then went through the horrible experience of reinstalling the bottom bolt and rubber spacer. That took the better part of a day. Fortunately for me that bolt vibrated out and disappeared along with the rubber spacer. Well, then I ran the bike for 11,000 miles until I discovered that the top rear isolating rubber was disintegrating. So I replaced it with a new one . So, now what I should worry about ? To be sure, I will never again attempt to install the bottom mounting bolt.

lazyeye6 said:

I had the tank crack where the top strap was braised/welded to the tank. It had the bottom rubber and bolt installed. I had it re-welded and then went through the horrible experience of reinstalling the bottom bolt and rubber spacer. That took the better part of a day. Fortunately for me that bolt vibrated out and disappeared along with the rubber spacer. Well, then I ran the bike for 11,000 miles until I discovered that the top rear isolating rubber was disintegrating. So I replaced it with a new one . So, now what I should worry about ? To be sure, I will never again attempt to install the bottom mounting bolt.

Click to expand...

I ran mine for 20 years like that. Went through a nl bunch of the rubber mounts.

Forgot to mention: If it hasn't already been done, ditch that whole chain oiler business (plate numbers 24 through 36)and seal up the stub from the tank.
Put all those parts in a safe place and sell them for a fortune to a restorer type. In forty years, I mean.

Lots to do just on the oil tank then ! Will post a pic

I took the bottom bolt out and screwed a stud in and sat it back down on a grommet (I think), no thread on the end of the stud so it just sits there and the top mounts hold it in