Chassis Cracks and Broken Brackets

[Marc.com]

Suzuki achieved such low weights on their RH/RN works bikes with liberal use of titanium nuts/bolts and fixtures and lightweight magnesium castings. The frames were made from wafer thin chro-mo and were regularly replaced. Pipes often lasted only one moto.               

and sometimes the frames didn't even last a whole moto 

[Lozza]

FIA is for cars the FIM is for bikes Ti is far from being banned it just isn't used as wisely as thought,as there are better materials. It is banned in the UK from being used for axles, spindles and brake caliper bolts. 
Ti work harden??? Commercialy Pure(CP) Ti has so much spring back it's frustrating and labourious to form into any shape other than a circle. Tube takes a lots of force to produce even slight bend arcs without specialised equipment.

Every nut and bolt,
Spokes,
Spoke nipples,
Rim locks,
Rims,
chain sprockets,
gear shift lever,
Brake lever,
Handle bars,
Hand levers,
Throttle body,
Fork springs,
Shock spring,
Fork dampener rod,
Bash plate,
Air box,
Seat base,
Fuel tank,
Footpegs,
Exhaust pipe including header and muffler,
Exhaust springs,
Engine valves,
Intake manifold,
Axles,
Front number plate,
Cable guides,
Flywheel,
Drive chain,
Chain guard,
Front and rear brake backing plates,
Front and rear brake stays,
Triple clamps,
Front and rear hubs,
Piston,
Clutch basket,

except for exhausts, engine valves, fork and shock springs Ti isn't the ideal choice of material for any of those components especialy chains, flywheels and pistons. Aluminium and Magnesium alloys will have less mass and better strength to weight ratios. Ti is 4.5g/cc Al is 2.8g/cc Steel 7.8g/cc and Mg 1.74g/cc. Makes the decision pretty  easy.

[mx250]

Every nut and bolt,
Spokes,
Spoke nipples,
Rim locks,
Rims,
chain sprockets,
gear shift lever,
Brake lever,
Handle bars,
Hand levers,
Throttle body,
Fork springs,
Shock spring,
Fork dampener rod,
Bash plate,
Air box,
Seat base,
Fuel tank,
Footpegs,
Exhaust pipe including header and muffler,
Exhaust springs,
Engine valves,
Intake manifold,
Axles,
Front number plate,
Cable guides,
Flywheel,
Drive chain,
Chain guard,
Front and rear brake backing plates,
Front and rear brake stays,
Triple clamps,
Front and rear hubs,
Piston,
Clutch basket,

What's that a list of Lozza, the things that can, the things that can't or the thing that are made of Ti?

[monaro308]

I remember asking someone why dont they use titanium in the wings of jets and planes,being lighter and stronger that aluminium.
Answer was that titanium gets weaker and more brittle in cold/freezing temps than aluminium,which is more flexible.
Thats what i was told anyway 

[vmx42]

FIA is for cars the FIM is for bikes Ti is far from being banned it just isn't used as wisely as thought,as there are better materials. It is banned in the UK from being used for axles, spindles and brake caliper bolts. 
Ti work harden??? Commercialy Pure(CP) Ti has so much spring back it's frustrating and labourious to form into any shape other than a circle. Tube takes a lots of force to produce even slight bend arcs without specialised equipment.

Every nut and bolt,
Spokes,
Spoke nipples,
Rim locks,
Rims,
chain sprockets,
gear shift lever,
Brake lever,
Handle bars,
Hand levers,
Throttle body,
Fork springs,
Shock spring,
Fork dampener rod,
Bash plate,
Air box,
Seat base,
Fuel tank,
Footpegs,
Exhaust pipe including header and muffler,
Exhaust springs,
Engine valves,
Intake manifold,
Axles,
Front number plate,
Cable guides,
Flywheel,
Drive chain,
Chain guard,
Front and rear brake backing plates,
Front and rear brake stays,
Triple clamps,
Front and rear hubs,
Piston,
Clutch basket,

except for exhausts, engine valves, fork and shock springs Ti isn't the ideal choice of material for any of those components especialy chains, flywheels and pistons. Aluminium and Magnesium alloys will have less mass and better strength to weight ratios. Ti is 4.5g/cc Al is 2.8g/cc Steel 7.8g/cc and Mg 1.74g/cc. Makes the decision pretty  easy.

Just because you can, doesn't mean you should 

[Ji Gantor]

At no stage did I say all of those parts would be better made in Ti.
This is just a list of components at can be made from Ti that will not breach the FIM rules.

The skin of the new airbus is made from a composite of aluminium and fibre glass.
If that was suggested some time ago people would have said No Way.

Double back flips and forward flips in FMX Again a few years ago most would have said No Way.

The earth is flat.

An MX bike with the exhaust at the rear and the fuel at the front, Come On.

Try and keep an open mind.
Without dreams nothing goes forward.

So using Ti nuts and bolts is a waste of time, very interesting
I will make some phone calls today and see if I can buy some magnesium nuts and bolts

Ji

[Lozza]

Graeme, that was just a list of components Ji thought might be worthwhile making from Ti. Basicaly unless very high temps (or making a spring)are involved Aluminium is a better choice, Mg bolts don't exist as Mg isn't a ideal material for bolts, Al , Ti, CrMo or steel are best for any load bearing application.  Monaro Ti is NOT lighter than aluminium it's lighter than steel and twice the mass of aluminium and about 10 times the cost.Pure Ti is a very resilient material Ti is very difficult to cast in intricate shapes(golf clubs aside) unlike other materials
There will be a good reason why something like a Ti chain has never been used before, even in 'money is no object' racing like MotoGP a Ti chain has never been used.Ti nuts and bolts are lighter than steel but not as light as 7075 or 2027 Al bolts and nuts.
I might save 2.5kgs from using Ti bolts in a bike cost say $1000, but the juice isn't worth the squeezing.As the overall power to weight ratio doesn't change that much.
Bike 100kgs with 20HP has 0.2kg/HP power to weight ratio.
97.5kg bike with 20 HP has 0.205 kg/HP power to weight ratio

100kg bike  with 21HP has 0.21 kg/HP power to weight ratio.
That can be done for far cheaper than a wheelbarrow full of Ti.

[Ji Gantor]

Density                                   Yield Strength               Mod of Elastity         Strength -Weight  Ratio   Stiffness to Weight Ratio
CrMo 4130    7833 kg/m3            620MPa                        210GPa                   0.079                                0.268
Ti Grade 5     4428 kg/m3           827MPa                        107GPa                    0.186                               0.0241
Al 6061 T6     2707 kg/m3           275MPa                        67GPa                     0.1015                              0.0247

I have compiled the above chart.
All three materials have about the same stiffness to weight but Titanium wins the race when it comes to strength to weight ratio.
Ji

[Ji Gantor]

Lozza, as usual, is correct.
Things like a chain would not be worth while doing unless you combine other materials or change the design. Pistons are made from titanium as Ti has a very low thermal expansion.
Carbon fibre is even better than all these materials when used in the right location.

Can you imagine having titanium tyres.
But you could use titanium as the reinforcing for the tyre.
Two different ways of looking at the same problem.

Ji

[mx250]

Graeme, that was just a list of components Ji thought might be worthwhile making from Ti.

Ah eh, I wasn't paying attention was I.

I think weight saving is an interesting subject especially for MX. It doesn't just effect acceleration (power to weight), but also braking, steering/handling and suspension performance. I think it is well worth the effort and the money (within reason ) - and chase the ponies (but I would rather have a light weight bike with moderate power rather than a perky, powerful overweight pig ).

Concentrating on unsprung weight would always be a priority. I'm particularly curios about Ti spokes and nipples. It not hard to imagine taking a kilo of both wheels (for no loss of strength?). I once read of a Henry prepared road Duke that had them. The works Hercules of the '70's also used them.

[Ji Gantor]

And sheding a kilo of unsprung spinning weight is worth 2 kilos of unsprung weight, like in the case of titanium reinforcing in the tyres, spokes and nipples.

Do you think the F1 designers sit around saying "Just because we can doesn't mean we should"
With that attitude they would not be around for very long.
Take Rossi's engineer he is always thinking of ways to get more speed from the bike.

Ji

[Ji Gantor]

Bike 100kgs with 20HP has 0.2kg/HP power to weight ratio.

Shouldn't this be 0.2hp/kg which is power to weight ratio.

Ji

[Ji Gantor]

Hi Walter,
In my case if you have seen my racing videos I think the most weight on the bike is sitting on the seat.

I am doing a comparison right now so I will let you know soon.

Ji

[VMX247]

Intermission .....
Have just received a 1968 magazine on the Sprite/AE and its saying; A point that struck us was the workmanship.All welds are heliarc............What a heliarc 
thanks --resume transmission--

[Ji Gantor]

Lets take a look at a very simple part that can be replaced by Ti.
The front brake stay on a 1977 Maico.
From the factory it was made from aluminium and weighs 82g.
The stay has a typical cross sectional area of 0.000108 square meters and is 250mm long.
To check weight we multiply the cross sectional area by the length by the density of aluminium.
0.000108x0.25x2700 = 0.0729kg or 73g
The stay has a cable connector and alignment spacer so this would be close to its actual weight of 82g.
This stay is in tension when the brakes are applied so the cross sectional area at the weakest section is at the connecting bolt.
The area is 0.00006 square meters.
To reverse engineer this component we apply the following.
area x tensile strength = force
Aluminum 6061 T6 yield strength 275mpa permissible strength for axel tension = Fy 0.6 = 165mpa
0.00006 x 165 = 0.0099kn

To produce the same load carrying capacity using Ti grade 5 yield strength 827MPa or Fy 0.6 = 496MPa
area = 0.0099/496 = 0.0000199 square meters

If we apply this to the typical cross sectional area but this time using bending moment instead of tension we find the following.
The original cross sectional area could be reduced to one third of the original size.

0.000108/3= 0.000036 square meters.

Now to do the calculations to determine the weight of this product in Ti
0.22x0.000036x4428= 0.035kg or 35g
0.03x0.0000199x4428= 0.0026kg or 2.6g
Plus the extra weight for the cable connector and spacer 14.7g

Total Ti weight = 52.3g
Weight saving = 29.7g

That is a weight saving of 36% of unsprung weight.

These calculations should not be used until checked by a registered engineer.
These calculations have been supplied for demonstration purposes.

Ji