Race chassis

[richban]

then a fire breathing 300 twin.....

Well I had a fire breathing 300 twin only 5 weeks ago. One broken back and a rather broken bike later I think the 50 / 90 are more my speed for a while.

[Yow Ling]

Some sheet metal chassis that Jan Thiel made in the 70's , I think they are sheet steel but dont hold me to it.
Multiple world champion bikes "Jamathi" 50cc , dressed up as Bultaco in this link

http://www.elsberg-tuning.dk/bultaco.html

[husaberg]

Some sheet metal chassis that Jan Thiel made in the 70's , I think they are sheet steel but dont hold me to it.
Multiple world champion bikes "Jamathi" 50cc , dressed up as Bultaco in this link

http://www.elsberg-tuning.dk/bultaco.html

Ribbed for stiffness rather than pleasure

http://www.jamathi.nl/
http://www.elsberg-tuning.dk/jamathi.html

[husaberg]

[Grumph]

Looks like an internal brace, lazy "Z" shape spot welded through the sides.

Early frames welded using fluxed rod, nice....and I bet that welder still has a bad back.
Lesson there - raise the workpiece, or sit down.

[jasonu]

Ribbed for stiffness rather than pleasure

http://www.jamathi.nl/
http://www.elsberg-tuning.dk/jamathi.html

That makes a lot of the Buckets out there look rather over engineered...

[Frits Overmars]

When designing the monocoque structure of the Ossa, Eduard Giro, with his formal back ground in aviation, specified magnesium alloy sheets not available in Spain, but was denied an application for their import from another country... Not to be deterred, he arranged the “clandestine import” of the material on the backs of mules using a smugglers route over the mountains from France... Frits, perhaps you might be able to confirm or dispel the reality of this tale, and might I be able to detect some small influence from the Ossa concept in your own creations?

I can't confirm nor deny the realiy of that smuggler tale but I can definitely confirm the Ossa influence in my own monocoque racer.

Some sheet metal chassis that Jan Thiel made in the 70's , I think they are sheet steel but dont hold me to it.

Yes, the first Jamathi monocoques were steel sheet. Below are two pics of the first one, the 1972 model (the same year that I built my 500 monocoque, without Jan and me knowing about each others plans). The third picture shows the 1977 Bultaco, one of my all-time favorites. Because of the peculiar colour there were rumours about its frame being titanium. In reality it was stainless steel, sandblasted to take the shine off, so the buckling after welding was less noticeable .

[husaberg]

That makes a lot of the Buckets out there look rather over engineered...

Maybe but tire tech and suspension has moved on heaps since the 70's. Not to mention the riders are likely a little bit heavier.

http://www.carbonfibretube.co.nz/ind...on_Tube_Prices
http://www.hexcel.com/Products/Honeycomb/
http://www.cgcomposites.com.au/Aerospace.html
http://www.nzcomposites.com/Products...Materials.html

The latest composites can be bent and shaped and glued with aradite products
Where is JasonU.

[Grumph]

Maybe but tire tech and suspension has moved on heaps since the 70's. Not to mention the riders are likely a little bit heavier.

Ignition coils have got a lot smaller too...

But the best tuning trick is still to put a skinny kid on it.

And to follow Frits comment about blasting the stainless monocoque - never paint a frame silver unless the welding is absolutely flawless.
Silver will show everything up in horrible detail. Dull nickel is actually quite a bit better if you must have silver.

[jasonu]

The latest composites can be bent and shaped and glued with aradite products
Where is JasonU.

Lancair uses huge amounts of Hysol 2 pot glue to bond the carbon parts.

[husaberg]

Lancair uses huge amounts of Hysol 2 pot glue to bond the carbon parts.

Do they use a modern equivalent of the old Ciba Geigi M board ie honeycomb sheaved with aluminium?
Like this stuff.
http://www.pantah.eu/bilder_racing/s...ah_div_095.jpg

Ignition coils have got a lot smaller too...

But the best tuning trick is still to put a skinny kid on it.

And to follow Frits comment about blasting the stainless monocoque - never paint a frame silver unless the welding is absolutely flawless.
Silver will show everything up in horrible detail. Dull nickel is actually quite a bit better if you must have silver.

Gloss finishes much like lycra is not so great at hiding inperfections.
Pits, ugly rough welds and uneven finish far to much like a facet on a gemstone.

i love nickel especially when it ages into a sort of verdigris patina.

[Grumph]

i love nickel especially when it ages into a sort of verdigris patina.

Don't see a lot of that over here on the dry side of the hill.....

[jasonu]

Do they use a modern equivalent of the old Ciba Geigi M board ie honeycomb sheaved with aluminium?
Like this stuff.
http://www.pantah.eu/bilder_racing/s...ah_div_095.jpg



Gloss finishes much like lycra is not so great at hiding inperfections.
Pits, ugly rough welds and uneven finish far to much like a facet on a gemstone.

i love nickel especially when it ages into a sort of verdigris patina.

Mostly CF. They had other thickening materials that (I think) is made from kevlar. Basically it was 2 thin sheets sandwiching a corrugated sheet. They bonded it to the CF parts where thickness and additional stiffness was required. TBH I kept away from that part of the production process, fucking hate anything to do with the dust and slivers the composite materials created.

[Grumph]

Mostly CF. They had other thickening materials that (I think) is made from kevlar. Basically it was 2 thin sheets sandwiching a corrugated sheet. They bonded it to the CF parts where thickness and additional stiffness was required. TBH I kept away from that part of the production process, fucking hate anything to do with the dust and slivers the composite materials created.

For the short time I worked for John Britten, my small lathe was left on the premises. I'd come in mornings and it would be covered in black shit. At that point there were a lot of bits being made from what was basically fiberglass filler mixed with chopped CF. It actually machined quite easily - although a bit hard on cutting tips - but the bloody dust...evil stuff.
I was quite happy to let the tribe of night time volounteers breath it rather than me. I'd simply grab John's vacuum cleaner and do the lathe area before I did anything else.
Edit - just remembered that in the book, there's mention that much later on they used power files to shape CF parts. They didn't last long as the CF dust either stuffed the electrics or wore the gear drives.

[jasonu]

For the short time I worked for John Britten, my small lathe was left on the premises. I'd come in mornings and it would be covered in black shit. At that point there were a lot of bits being made from what was basically fiberglass filler mixed with chopped CF. It actually machined quite easily - although a bit hard on cutting tips - but the bloody dust...evil stuff.
I was quite happy to let the tribe of night time volounteers breath it rather than me. I'd simply grab John's vacuum cleaner and do the lathe area before I did anything else.
Edit - just remembered that in the book, there's mention that much later on they used power files to shape CF parts. They didn't last long as the CF dust either stuffed the electrics or wore the gear drives.

Yep. Once that crap gets into your clothes you may as well burn them, ya just can't get rid of its itchyness. It's worse than fiberglass.