Author Topic: 73 SFC replica for sale  (Read 2705 times)

Offline helicopterjim

  • Hero Member
  • *****
  • Posts: 1736
  • No shit, there I was - and the crack was 90!
Re: 73 SFC replica for sale
« Reply #15 on: October 29, 2019, 03:18 »
I was under the impression they were originally cadmium plated.  With time, the plating does discolour a bit, I'd expect zinc to become a lot darker.

piet

Zinc ...... cadmium is a goldish  colour 
74 SFC
72 SF
74 3C
75 3C
79 (81) Formula Mirage 1200
Various Ducati's, Guzzi's, Puch's ... a BSA Sloper and maybe even an R90
I don't have a 1977 Honda XL 175 but I do have a Chang Jiang CJ750 with a sidecar.

Chilliwack, British Columbia

Offline Paul Marx

  • Hero Member
  • *****
  • Posts: 4516
    • Les motos de Paul
Re: 73 SFC replica for sale
« Reply #16 on: October 29, 2019, 06:53 »
Zinc ...... cadmium is a goldish  colour

Well, yes and no.
Cadmium would seem to age quite nicely.

My SFC has received cadmium.
It did seem very latin pimp on the photos I got and can't find but on the later photos appears quite correct.

Paul

Online sfcpiet

  • Administrator
  • Hero Member
  • *****
  • Posts: 7962
  • NRW, Germany
Re: 73 SFC replica for sale
« Reply #17 on: October 29, 2019, 06:54 »
I used to think Galing a frame would be great long-lasting protection but after getting my dirtbike box trailer hot dip galled it went from an easy one-hand lift and push to a full-blown backbreaker. It's insanely heavy now, but definitely no rust in the last 20 years it been in my back yard. Odd choices for a lightweight race bike.

Vince,

Galvanising/electro-plating is a completely different process to hot dipping.  Galvanising uses electricity to deposit a microscopic thin layer of metal on something, hot dipping is essentially painting with molten metal.

Reckon the plating on the SFC frames would have been lighter than primer and paint.  Moot point though, considering what those frames weighed in the first place...

piet
180s feel quick, 120s are...      If it ain't broke, fix it till it is.

"A motorcycle is a bicycle with a pandemonium attachment and is designed for the especial use of mechanical geniuses, daredevils and lunatics"  Georg Fitch 1916

Offline Vince

  • Hero Member
  • *****
  • Posts: 8287
Re: 73 SFC replica for sale
« Reply #18 on: October 29, 2019, 07:14 »
Good to learn new stuff, thanks mate.

Offline Lav the impala

  • Sr. Member
  • ****
  • Posts: 398
Re: 73 SFC replica for sale
« Reply #19 on: October 29, 2019, 07:56 »
Vince,

Galvanising/electro-plating is a completely different process to hot dipping.  Galvanising uses electricity to deposit a microscopic thin layer of metal on something, hot dipping is essentially painting with molten metal.

Reckon the plating on the SFC frames would have been lighter than primer and paint.  Moot point though, considering what those frames weighed in the first place...

piet

Galvanization or galvanizing is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which the parts are submerged in a bath of molten zinc.

Electroplating is the process of plating one metal onto another by hydrolysis, most commonly for decorative purposes or to prevent corrosion of a metal. There are also specific types of electroplating such as zinc plating, copper plating, silver plating, and chromium plating

Offline Paul Marx

  • Hero Member
  • *****
  • Posts: 4516
    • Les motos de Paul
Re: 73 SFC replica for sale
« Reply #20 on: October 29, 2019, 08:17 »
Bob Heath used to race his G50 with an unpainted frame to gain a few grams.
Apparently quite a common practice in the days when bikes didn't churn out hundreds of HP.

Paul

Offline Piranha Brother 2

  • Hero Member
  • *****
  • Posts: 2098
  • It was once a 1973 750 SF1
Re: 73 SFC replica for sale
« Reply #21 on: October 29, 2019, 12:28 »
Bob Heath used to race his G50 with an unpainted frame to gain a few grams.
Apparently quite a common practice in the days when bikes didn't churn out hundreds of HP.

Paul

I trust he also took strong laxatives the morning of the race, shaved every hair from his body, removed his false teeth (which he had fitted to allow him to remove them on race day), didn't drink any fluids and slept in a sauna for three days prior to help rid himself of unwanted grams of body fluid ... sheesh! FFS!
What ... leave it standard??!!

Offline Tippie

  • Hero Member
  • *****
  • Posts: 2355
Re: 73 SFC replica for sale
« Reply #22 on: October 29, 2019, 13:01 »
Virtually all of the Rob Norths and copy/replicas racing here have unpainted frames.
SF2 17483 (race)
SF2 17424 (road)
An Australian living near Oslo in Norway

Offline Shamrock

  • Hero Member
  • *****
  • Posts: 909
Re: 73 SFC replica for sale
« Reply #23 on: October 29, 2019, 13:54 »
Its orange for crying out loud. I dont understand what all the bickering is about.  ;D

Offline CLEMTOG

  • Hero Member
  • *****
  • Posts: 4522
Re: 73 SFC replica for sale
« Reply #24 on: October 29, 2019, 14:04 »
when I mechanicked for sidecar race teams, almost all of them were  bare metal chassis, this was (mainly and the big point) so that inspection of all areas, for cracks and defects could continually be looked at. It was my idea (when Tony Bateup was building a new chassis for Brian Houghton and the Bevan imp) that a pilot hole was drilled internally at all tube joints, to connect the innerds of them all together, then a 1/4 BSP boss was welded on near the headstock to carry a pressure gauge with another boss and a Schrader valve at the rear, the idea? simply pressurise the whole tube chassis to around 20PSI, and if a crack occurs the pressure drops. This seemed like a good idea but it didn't tell you if a brazed on bracket outside of the tube formations had cracked, or even broken off, as in the case of the rear brake pedal at the IOM in 1975? ! it dropped into the streamlining, fortunately and Brian still won the Southern 100, mainly because he was so far ahead that he was already hard to beat, there was a lot of front wheel lockups though, as the pedal linked all three wheels, and the handlebar lever and calliper was really only for scrutineering, which stipulated separate brake systems.
Then they had riveted/glued aluminium chassis, such as Seymaz, LCR etc and then carbon fibre. sometimes made by Arrows cars.
CLEM

Offline Paul Marx

  • Hero Member
  • *****
  • Posts: 4516
    • Les motos de Paul
Re: 73 SFC replica for sale
« Reply #25 on: October 29, 2019, 16:39 »
I trust he also took strong laxatives the morning of the race, shaved every hair from his body, removed his false teeth (which he had fitted to allow him to remove them on race day), didn't drink any fluids and slept in a sauna for three days prior to help rid himself of unwanted grams of body fluid ... sheesh! FFS!

Every little bit helps when you're hustling a 45 HP machine around the Isle of Man.

Paul

Online laverdas

  • Hero Member
  • *****
  • Posts: 722
Re: 73 SFC replica for sale
« Reply #26 on: October 29, 2019, 18:38 »
For what it's worth i think cadnium plating is banned in the UK.
 Bentley motors (local car plant) had to remove and dispose of all cadnium plated parts from there stores due to the toxic nature.
Regards Andy

Online MarnixSFC

  • Hero Member
  • *****
  • Posts: 1482
    • Int. Laverda 750 SFC Owners Registry
Re: 73 SFC replica for sale
« Reply #27 on: October 29, 2019, 19:06 »
When you ask people in Breganze there is no consensus about the frame finish, but I had several unrestored frames in hands and took one to my local plater, who did a check and said it definitely was zinc plating. A friend who wanted to try cadmium plating managed to get an aerospace company to do a frame. The result wasnt as expected and the frame is now painted silver..

I too think that they plated the frames because cracks can be quickly be detected. Drum brake SFCs often suffered cracks, supposedly because they were they were raced in endurance races to the limit, and beyond.

Marnix
International Laverda 750 SFC Owners Registry

Offline helicopterjim

  • Hero Member
  • *****
  • Posts: 1736
  • No shit, there I was - and the crack was 90!
Re: 73 SFC replica for sale
« Reply #28 on: October 29, 2019, 22:16 »
For what it's worth i think cadnium plating is banned in the UK.
 Bentley motors (local car plant) had to remove and dispose of all cadnium plated parts from there stores due to the toxic nature.
Regards Andy

Cadmium wouldn't be totally banned ........ 90% of the hardware on aircraft is cad plated and so far there is no viable replacement. Cadmium has a major advantage in that consistent and smooth torquing is achieved as well as superior corrosion resistance. No other plating can offer both at this time.

Jim
74 SFC
72 SF
74 3C
75 3C
79 (81) Formula Mirage 1200
Various Ducati's, Guzzi's, Puch's ... a BSA Sloper and maybe even an R90
I don't have a 1977 Honda XL 175 but I do have a Chang Jiang CJ750 with a sidecar.

Chilliwack, British Columbia

Offline Dellortoman

  • Hero Member
  • *****
  • Posts: 12478
  • My wolf mate 6/5/1996 - 3/1/2011
Re: 73 SFC replica for sale
« Reply #29 on: October 30, 2019, 02:47 »
I used to think Galing a frame would be great long-lasting protection but after getting my dirtbike box trailer hot dip galled it went from an easy one-hand lift and push to a full-blown backbreaker. It's insanely heavy now, but definitely no rust in the last 20 years it been in my back yard. Odd choices for a lightweight race bike.

G'day Vince,

Hot dip gal shouldn't have added a significant amount of weight. It's only a thin coating. Are there any tubular parts to the trailer chassis, such as RHS or round tube? If so, one or more of them may have filled with zinc and not drained when the thing was lifted out of the dipping tank.

I enquired about getting my bike trailer galvanised many years ago, and they said all tubular parts had to have pressure relief holes drilled in them. The explanation at the time was that the molten zinc is very hot and any sealed spaces with air in them could build up a high pressure inside. They didn't want any explosions due to gas pressure build up. However, that meant molten zinc could get in, and there's no guarantee that it'll all drain out when they lift it out of the tank. Maybe if you drill a few drain holes and get it re-dipped it'll come back lighter.

In the end I decided to paint the trailer rather than getting it galvanised. Much cheaper and easier. It's still hanging together after 40 years.
Location: Tasmania, Approx 4253S 14723E