Paintwork & Decal Questions

[Octane]

Hey guys,

My Mk 1 has been restored/repainted by the previous owner, and all of the original decals have been placed on over the top coat of colour.
One of the flanges on the tank has developed a crack, so I'm going to reweld this and then have the tank professionally repainted with NOS decals shortly, and I have some questions with regards to the original methods used by the factory.

Are the decals placed over the top of the final coat of colour? Or placed on under a clear top coat?
(Also, is this the case for all of the decals on the bike?)

The 'Made In Italy' decal on mine is slightly askew, and I'm not sure if this was done on purpose after the last repaint to look original or if it was just clumsy on the painters behalf. Should this be straight and aligned perfectly to the filler cap?

Is the yellow pinstriping around the silver patch on the side of the tank brush painted on? or airbrushed?

Does anyone happen to know the colour code for the Mk1 red/silver/yellow? Otherwise I'll have my painter colour match whats already there before blasting.

Thanks!

[nalimugmug]

Hi,

These colours cross matched from an original Mach 1 which had been in covered storage for 30 years.

Silver-Mercedes- DB744.70F

Red- BS539

Yellow- One shot lettering enamel. 191L-Imitation Gold- applied using stencil tape and a fine artists brush

Finesse Striping Stencil Tape- F10

I used these on my Mach 1, just perfect in my opinion.

I placed the decals on top of the clearcoat and left them as that.

Cheers

[Octane]

Thanks very much for the reply! Very informative and exactly the info I was after!

[nalimugmug]

Your welcome.

Ill mail you some pics if you let me have your email address.

[DewCatTea-Bob]

By: Octane...
" One of the flanges on the tank has developed a crack, so I'm going to reweld this "

____ That cracking is a common-problem with the fuel-tanks of many Duke-models. _ The cracks form about anywhere between the weld (to the main tank-body) and the hole for the mounting-bolt -(8mm / 1.0mm-thread), but usually closer to that hole.
Simply welding the crack is not a repair which will permanently solve the issue.
__ You should fashion a plate of steel (to fairly match the shape of the tank-ear/flange) and have it welded-on over the original (on the inner-side, so as to back-up the mounting-flange so that it [or they, if you have both sides done], can then better withstand the stress of engine-vibration).
At the very least, you should add 1.5" - 5/16ths" fender-washers with the mounting-bolts.


" Are the decals placed over the top of the final coat of colour? Or placed on under a clear top coat? "

____ As I recall,, there originally was no (obvious) top-coat of clear, so the decals were laid directly on top of the factory-paint.


" The 'Made In Italy' decal on mine is slightly askew, and I'm not sure if this was done on purpose after the last repaint to look original or if it was just clumsy on the painters behalf. Should this be straight and aligned perfectly to the filler cap? "

____ While a rare instance may have been ever so slightly crooked, most were quite straight enough.


Duke-Cheers,
-Bob

[Octane]

Thanks bob for the clarification.

The outside side of the flange cracked all the way through and broke the spot welds holding it to the inside plate which broke away from the tank.
Once I'd ground the paint off, it appeared to have been repaired before as there was evidence of brazing around the bolt hole.


I just re-brazed up where it had cracked, and put a few stronger spot welds between the 2 plates. Looks to have come up allright. I should have it painted again within the month, although unfortunately not in time for this years concours

[double diamond]

Brazing the existing crack will ensure recurrence of this failure before long. Brazing is the worst possible repair for sheet metal because the crack in the base metal is still there, it's just been covered up. Just a matter of time before vibration takes it's toll and the crack reappears. The only hope for failures like these is careful prep and TIG welding. The reinforcing plates are probably an improvement but they tend to just direct the root cause of the failure (i.e. vibration) elswhere, leading to a crack at a different location. The only lasting solution is to rubber mount the tank (not just rubber washers between the tank and frame) but then the mounting doesn't look original. Matt

[DewCatTea-Bob]

" The outside side of the flange cracked all the way through and broke the spot welds holding it to the inside plate which broke away from the tank. "

____ I've seen some flange-ear mounting-tabs cracked-up quite badly but I don't recall ever seeing such extensive destruction.
Everyone needs to keep an eye on those mounting-ears if ya ride ya'r Duke much, especially in colder weather.


" it appeared to have been repaired before as there was evidence of brazing around the bolt hole. "

____ I'm not at all surprised, cuz as I had mentioned, that cracking-issue is a very common-problem.


" I just re-brazed up where it had cracked, and put a few stronger spot welds between the 2 plates. "

____ I would not expect that repair-job to last too/very long however. _ You really need to do something to make it capable of withstanding the stress it's forced to endure.
If you don't add extra pieces of sheet-steel to those ears, then you should consider modifying the mounting-method to accept a rubber & bush setup similar to that which is employed by the wide-case fuel-tanks.
Just before Ducati came-out with their w-c.tank mounting-method (by 1968), in 1967 they had devised a different rubber-mount setup which worked with the flat n-c.style mounting/flange-ears (without the added cylinder-sleeves modded to the w-c.tank-ears). _ That rubber-mounting method should've been employed by Ducati several years sooner, as it seemed to solve the cracking-problem well enough, (although I never had much experience with it cuz it was a very rare employed feature [which Ducati apparently had pretty-much copied from other Italian-made fuel-tanks] ).
Hopefully somebody here has such a fuel-tank mounting-setup which they can post a picture of, for the rest of us to see & check-out.
(This particular topic-issue has been fairly well covered before, in the past here.)


Hopeful-Cheers,
-Bob

UPDATE/add-on... I now see that dd/Matt has posted while I was working on my-own post here, and I pretty-much agree with all he has intended to convey in his post !
Now that he & I have confirmed that your nice work will likely not last for long, you should more fully understand that some additional modification should be done, before you refinish your planned paint-work.

[Octane]

Thanks again for the advice guys.
Firstly, I should mention that I'm a fitter/machinist/welder by trade, and have some experience with brazing in the past incl repairing 60's F1/F2/FJ race car chassis'.
I did try to tig weld the crack at first, but the tig wire metal wouldn't take to the existing brazing and I didn't want to risk grinding off too much of the original metal to remove the brazing.
You can see that there is already a strengthening tab on the inside of the 2 mounting flanges (have a look at the back tab in the first picture) When the outside tab cracked near the bolt hole, the inside tab remained in 1 piece. I've added must stronger spot welds hold that inside tab onto the outside tab better, and then braized up the crack on the outside tab, so for it to break off again, it would have to crack the brazing, AND break all of the new spot welds.
I do appreciate your input though, and I'll look into a rubber mounting option for it, even if it is just an electrical style rubber grommet to remove some of the vibration. I'd like to keep the bike as original looking as possible.

[DewCatTea-Bob]

" I should mention that I'm a fitter/machinist/welder by trade, and have some experience with brazing in the past incl repairing 60's F1/F2/FJ race car chassis'. "

____ Okay, I'll bet then that YOUR repair-work will LAST longer, but still, without further attention of some sort, certainly colder-weather riding will eventually cause some cracking to reoccur SOMEwhere near the same area.


" You can see that there is already a strengthening tab on the inside of the 2 mounting flanges
When the outside tab cracked near the bolt hole, the inside tab remained in 1 piece. "

____ Usually, BOTH the ear-mount AND it's back-up tab crack-up together in pretty-much the same cracking-line.


" I've added must stronger spot welds hold that inside tab onto the outside tab better, and then braized up the crack on the outside tab, so for it to break off again, it would have to crack the brazing, AND break all of the new spot welds. "

____ That type of destruction (experienced by your previously repaired mounting-ears) is not the regular/usual cracking-destruction which commonly occurs (to stock tanks).
So what I predict will happen next-time, is that both layers of metal will become cracked together-as-one, (just as usual),
(that is, if you take no further prevention-steps).


" I'll look into a rubber mounting option for it, even if it is just an electrical style
rubber grommet
to remove some of the vibration. "

____ The type of rubber-grommet you're considering is very-much the same as Ducati once briefly employed (before the type of rubber-mounting they remained-with for most pre-1971 w-c.tanks. _ The main-difference is that the hole was only about 10mm so that it would fit tightly over a bushing (that had a 8mm inner-diameter),
resulting in a somewhat similar rubber-mounting as that employed by the w-c mounting-system, (although not as good).


" I'd like to keep the bike as original looking as possible. "

____ Well (I'm afraid), if you really want to "keep" it that way, then you shouldn't ride/run it too-much !


Hopeful-cheers,
-Bob