picture of my exploded flywheel

[gstallons]

You just can't screw down aluminium. The whole idea is ill for a long lasting street bike. Sooner or later it comes loose when the Alu has crept away, then the wheel starts moving and now it's only a question of rather short time until it fails.

Hubert

 

 

Please explain your statement.. "You can't just screw down aluminum" .....

[luhbo]

You see it everywhere on your engine, so far it's ok, but not for such a high stress connection as on the flywheel. The steel one is fixed with 12.9 screws, the corresponding torque and glue for security. It's the nature of aluminium to creep away under such loads. That's also the reason you don't find it very often in electrics/electronics for bus bars and other elements that have to be screwed down. The connections will come loose.

Next thing is the Young modulus. It's one third of the steel one. As the flywheels have very similar dimensions you could estimate the deformations under load to be 3x the ones of a steel wheel.

For a flywheel I think it's quite an edgy solution.

Hubert

[Lucky Phil]

You see it everywhere on your engine, so far it's ok, but not for such a high stress connection as on the flywheel. The steel one is fixed with 12.9 screws, the corresponding torque and glue for security. It's the nature of aluminium to creep away under such loads. That's also the reason you don't find it very often in electrics/electronics for bus bars and other elements that have to be screwed down. The connections will come loose.

Next thing is the Young modulus. It's one third of the steel one. As the flywheels have very similar dimensions you could estimate the deformations under load to be 3x the ones of a steel wheel.

For a flywheel I think it's quite an edgy solution.

Hubert

Cant agree with this,there are literally thousands of engineering examples of alloy components under stress held together with bolted joints that last many many years.The concept that a well engineered aluminium alloy component will undoubtedly deform over time and lead to the fastener losing tension and then failure is just wrong.

The aviation industry would be in serious trouble if this was the case.

Ciao

[Skeeve]

...The concept that a well engineered aluminium alloy component will undoubtedly deform over time and lead to the fastener losing tension and then failure is just wrong.

[emphasis added]

 

Clearly an invalid assumption in re: the Guzzi "racing" flywheel.

 

BTW, you misspelled "aluminum."

 

The irony being that as Pete Roper has pointed out, the heavier flywheels are much more useful to a daily rider and don't put the strain on the rest of the components as the superlight alloy flywheel does...

 

Ride on!

[Lucky Phil]

...The concept that a well engineered aluminium alloy component will undoubtedly deform over time and lead to the fastener losing tension and then failure is just wrong.

[emphasis added]

 

Clearly an invalid assumption in re: the Guzzi "racing" flywheel.

 

BTW, you misspelled "aluminum."

 

The irony being that as Pete Roper has pointed out, the heavier flywheels are much more useful to a daily rider and don't put the strain on the rest of the components as the superlight alloy flywheel does...

 

Ride on!

I was speaking in generalities,but having said that I dont know that the genuine RAM flywheel has the issues that the std Guzzi one does.

Peter is entitled to his opinion on the merits of aluminium flywheels,but after many years of riding Ducati's of all persuasions with much less engine rotating mass I have my own views.

When I fit my RAM unit I don't expect to be able to necessarily ride the bike the same way as with the heavy unit and if that means I have to ride it a gear lower and keep the revs higher then thats fine by me.That's how I want it to feel and respond.

Dont see clutch or final drive spline wear being an issue if the bike is ridden with some sense of awareness.

Dont know where you learned to spell but where I come from its ALUMINIUM as I originally posted,but feel free to check the spelling/grammar and correct if required if it makes you feel better.

Ciao

[Skeeve]

Dont know where you learned to spell but where I come from its ALUMINIUM as I originally posted,but feel free to check the spelling/grammar and correct if required if it makes you feel better.

Ciao

 

Ah Phil, you missed the joke: we 'Murricans spell & speak it funny... No matter.

As for the suitability of aluminum as the material for Guzzi flywheels, we can agree to disagree. My point was that there is marginal need to even go there, since one can machine the steel flywheels down to the point where they are close to the aluminum ones in wt., but manifestly stronger to the point that one does not need to be waiting for them to explode. And the Guzzi donk does like more flywheel mass than an inline four...

 

Your point that the use of aluminum in airplanes argues that they should be safe for use in flywheels is not pertinent either, simply because the use of aluminum in airplane frames/skin is a vastly different application. You don't see aluminum being used for flywheels in aircraft motors, nor do you see ground vehicles subjected to the extremely cautious & diligent maintenance schedules one must adhere to in aircraft. I'm just sayin' there's a logical discontinuity in your argument. Even if you do spell aluminum funny! ;D

[Lucky Phil]

Dont know where you learned to spell but where I come from its ALUMINIUM as I originally posted,but feel free to check the spelling/grammar and correct if required if it makes you feel better.

Ciao

 

Ah Phil, you missed the joke: we 'Murricans spell & speak it funny... No matter.

As for the suitability of aluminum as the material for Guzzi flywheels, we can agree to disagree. My point was that there is marginal need to even go there, since one can machine the steel flywheels down to the point where they are close to the aluminum ones in wt., but manifestly stronger to the point that one does not need to be waiting for them to explode. And the Guzzi donk does like more flywheel mass than an inline four...

 

Your point that the use of aluminum in airplanes argues that they should be safe for use in flywheels is not pertinent either, simply because the use of aluminum in airplane frames/skin is a vastly different application. You don't see aluminum being used for flywheels in aircraft motors, nor do you see ground vehicles subjected to the extremely cautious & diligent maintenance schedules one must adhere to in aircraft. I'm just sayin' there's a logical discontinuity in your argument. Even if you do spell aluminum funny! ;D

Ok,copy the spelling thing.

I guess we will differ on the flywheel issue,but as I pointed out the RAM units seem to be fine unlike some of the original Guzzi single plate units which apparently DIDN'T use the RAM flywheel.

The RAM flywheel and clutch assembly weigh some 2kg less than the already lightest big twin (V11 Sport)dual plate clutch.Removing another 2kg off the V11 clutch would be rather challenging I would imagine.

With ref to aviation,I wasn't considering aluminium skin structures but other aero applications.The concept that Aluminium compresses under bolted up load and therefor fails as a general statement needed to be challenged.

Ciao

[luhbo]

...

With ref to aviation,I wasn't considering aluminium skin structures but other aero applications.The concept that Aluminium compresses under bolted up load and therefor fails as a general statement needed to be challenged.

Ciao

 

I don't see a real need to challenge my statement. Aluminium has this tricky behaviour, even the expensive alloys are not free of it. The Young-modulus and the resulting 3x bigger deformations are a fact, too. If you don't follow very special design rules or even avoid the material completely for certain applications it will give you problems. Now I don't see where the design of the steel wheel and the light alu one differs.

Using such a bodgey flywheel for racing purposes may be something different, very similar to aviation if you like. But then you should keep the same maintenance intervalls as they have them for racing - or for aeroplanes. I at least wouldn't want to open my bike every 2.500 km just to check whether things are still fine, the more as 'being fine' is not clearly defined. Will you then change it as soon as the smallest crack is visible or only after the first small parts have come free?

 

Hubert

[Lucky Phil]

...

With ref to aviation,I wasn't considering aluminium skin structures but other aero applications.The concept that Aluminium compresses under bolted up load and therefor fails as a general statement needed to be challenged.

Ciao

 

I don't see a real need to challenge my statement. Aluminium has this tricky behaviour, even the expensive alloys are not free of it. The Young-modulus and the resulting 3x bigger deformations are a fact, too. If you don't follow very special design rules or even avoid the material completely for certain applications it will give you problems. Now I don't see where the design of the steel wheel and the light alu one differs.

Using such a bodgey flywheel for racing purposes may be something different, very similar to aviation if you like. But then you should keep the same maintenance intervalls as they have them for racing - or for aeroplanes. I at least wouldn't want to open my bike every 2.500 km just to check whether things are still fine, the more as 'being fine' is not clearly defined. Will you then change it as soon as the smallest crack is visible or only after the first small parts have come free?

 

Hubert

It needs to be challenged the same as the statement "a bodgey flywheel" needs to be as its a sweeping generalisation.Depending on the original design and application some things can be copied straight from steel to high grade aluminium.

If we were to take your post a face value then we should all still have cylinder heads made from cast iron because the aluminium ones will compress under the load of the cylinder studs clamping them to the cases.

Also what makes you think the RAM clutch unit is purely for racing?I would suggest the vast majority sold are running around on the street.

There is also evidence to suggest the failures that have occured are with the "original fit" Guzzi units which used RAM clutch components but didnt use the RAM flywheel.

Ciao