MkIII Oil Tank

Status
Not open for further replies.
W

wjrich

Joined
Oct 7, 2012
Messages
202
Country flag
Giving the bike a pre-ride check today an noticed a disturbing amount of movement in the side cover- oil tank side. Pulled the seat, removed the side cover and saw a couple of things that don't look good, although I'm not sure on 1 of them as I never paid attention to it before.
First is the front tank mount- picture below-

MkIII Oil Tank


At first it almost looked as if it was designed this way, and couldn't really confirm looking at the parts manual. Seems to me this should be connected, but can't tell from the parts pic.
MkIII Oil Tank

Second is the rear tank mount- hard to see in the picture, but it's sheared off at the tank.
MkIII Oil Tank

Obviously a fix is in order here before the tank snaps at the bottom mount. Any suggestions? My first thought is to send it off to CNW with a check...
Can I get to the bottom mount without major disassembly of other parts?
 
Not really, it's quite a bit of labour ,but must be done. See if they have a straight exchange thing to help speed it all up ?
 
not a big deal, no need to take off the oil tank and send it out

just order the two rubber snubbers that are fractured from Old Britts or whomever and replace them

and then forget about it, the very bottom oil tank bolt does not necessarily cause a fracture there,
however if you have some free time this winter then remove the oil lines when you are doing your annual oil change and wiggle the tank out of there, most fiddly is the bottom fastener

when I pulled my tank out I did not weld a plate over that bolt hole, just left it be and glued a thick piece
of rubber on the bottom of the tank to rest on it, been fine for some 30 years
 
1up3down said:
not a big deal, no need to take off the oil tank and send it out

just order the two rubber snubbers that are fractured from Old Britts or whomever and replace them

and then forget about it

Thanks 1up.
Here's what I don't understand- on both mounts, part #2 (06-0636) looks to be rubber in the center with threads sticking out both ends- I can see that being a quick replacement as the original front has sheared completely.

Bigger problem is the rear mount. The tab attached to the tank is still held to the frame with part #2 and the associated nuts and washers but has separated/broken off from the tank. Not sure I can get around not having that reattached.

MkIII Oil Tank
Click to expand...
 
once you get wiggle around and get the bottom fastener and the oil lines in the rear of tank off, you should be able to wiggle it out of there ok

then, I would just take it to someone who can fashion a securing back bracket and weld it on

since you would then have it with a welder, might as well have him weld a little plate over the bottom hole
and stick some thicker foam down there to provide some support, although many don't do anything down there and let it just suspend by the top two rubber fasteners with no ill effects
 
The bottom bolt should not be done up too tight as it can cause the tank to crack. Some recommend beefing it up by welding a plate to it
Mine was put back on a rubber pad and the bolt done up with locktite until it contacted the base - not overtightened but just enough to hold it
It's a bit experimental but so far so good
 
I've repaired 3 oil tanks now - all broke the rear mount.
It isn't a huge drama to get a replacement bracket fabricated, but I would absolutely NOT weld - the tanks are a brazed-up assembly.

I've also brazed on bottom doubler plates to prevent stress fractures around the bottom spigot. Over time the grommet which it bolts to loses flexibility, and should be replaced periodically. Some people replace the bolt with a plain spigot, which I'll be doing on my Proddy racer build

MkIII Oil Tank


Note that the intact original is tacked on both sides, but not across the top where they fatigue fracture.
I braze them all the way round, introducing a fillet where the stresses are concentrated - this one's a bit messy, but it's solid, and looks just great painted, hidden under the side panel and photographed from 20 feet away :oops:

MkIII Oil Tank


MkIII Oil Tank


Finally, the mod required to accommodate the PR seat

MkIII Oil Tank


Maybe I should be offering a service exchange on these :wink:
 
Andy's mods are very similar to the ones I do. I just did up 3 tanks yesterday. I also reinforce the front mount and remove the chain oiler spigot.

A complete tank with mods, gloss black powdercoat and new HD iso rubbers is $125 plus shipping with your old tank in exchange.

Outright $200 plus shipping.

I'll take some photos this morning and get them posted.
 
That last photo catches it perfectly - a good fillet of braze to minimise the stress concentration. Shame Norton never bothered...

Another aspect is when installing the tank make sure the oil lines don't put additional stress on the mounts, and keep the battery well clear of it
 
It seems most of the fixes are things that would only have taken a few minutes. But when you start adding them up, it turns into hours. And hours add $$$ to the final product. At least we are still able to repair the parts and use them.
 
Mcmaster-Carr sells heavy duty rubber bushings that last longer than the AN bits.
 
My repair was indeed braised not welded - apology for the misleading term
The rear rubber mount does not seem up to the task it was intended for
it was broken when I got the bike and could easily be sheared again while doing it up if not careful
If the two threaded ends of the rubber mount were fixed inside either end of a spring it would provide a more robust assembly and still provide flexibility
I thought about doing this if it fails again provided the spring allowed enough movement
It seems feasible but there may be a reason it was not done this way?
 
Jed said:
My repair was indeed braised not welded - apology for the misleading term
The rear rubber mount does not seem up to the task it was intended for
it was broken when I got the bike and could easily be sheared again while doing it up if not careful
If the two threaded ends of the rubber mount were fixed inside either end of a spring it would provide a more robust assembly and still provide flexibility
I thought about doing this if it fails again provided the spring allowed enough movement
It seems feasible but there may be a reason it was not done this way?
Click to expand...

It's certainly one of the weaker points of the design, but broadly speaking it's fit for purpose. If it was an aircraft the rubbers would be thrown away every 5 years irrespective of condition, and at that I guess there would be a vastly reduced likelihood of failure. You just have to pray the replacements haven't been sitting on a shelf for 10 years!

Also bear in mind the *correct* (i.e. not necessarily the *best*) silentbloc bushes have hex abutments, so they can be restrained (kept neutral) when tightening up; it rather looks like the PO didn't bother - one of yours has spiralled into oblivion, and any rubber under stress will inevitably shear very rapidly

My T140 has an oil-bearing frame. Does this make it a better bike? :roll: :wink:
 
Put the refurbished oil tank (nice job by bwolfie on the tank) on yesterday and it is leaking from the banjo bolt. I've got both washers, hoses nice and snug, but leaking which it never did before. Do I just need to tighten the crap out of it?
 
If the washers are copper and you have used the old washers they will have work hardened, so if they are not too squashed and deformed, try annealing them to get the softness back. If that fails get new ones. If they are fibre, always use new ones.

Hope this helps

CB
 
All is well with the newly refurbished oil tank installed, and actually my problem with the high beam dash indicator being on all the time fixed itself- after hitting the same bump in the road that caused it to light up in the first place.
Had a great ride yesterday, and when I stopped for gas I realized that the entire left rear portion of the bike was convered in oil to include the tire sidewall. I am assuming that my oil tank vent hose- which vents to the atmosphere as I don't have the stock air cleaner assembly on the bike- puked out all the oil. I did an oil and filter change when installing the oil tank adding 3 quarts of oil as per the manual. I'm getting the sense that I overfilled, hence the puking out of the vent hose. Could anything else be causing that much discharge from the vent hose?
 
Status
Not open for further replies.

Similar threads

C
MKIII Primary Oil
Replies
19
Views
820
Torontonian
Torontonian
Tornado
Oil Tank Cap Seal
Replies
8
Views
621
Onder
Onder
10drum
Oil tank vent options
2
Replies
30
Views
1,596
marshg246
marshg246
Richard Tool
Wideline oil tank studs purpose ?
Replies
2
Views
203
Richard Tool
Richard Tool
Marian
Enots Oil tank cap leaking
Replies
16
Views
1,208
Fast Eddie
Fast Eddie
Back
Top