Performance & Modding Experts - ALU/Carbon Driveshafts - Whats the score?

[Dogbreath]

The polar moment of inertia of a propshaft is very low anyway, so the gains from swapping to a carbon version will be miniscule compared to a lighter flywheel.

Carbon is also not very resistant to damage from stone impacts etc. If the propshaft is exposed under the car (as most are) I wouldn't bother using one on a road car.

 

[Firestar_3x]

The polar moment of inertia of a propshaft is very low anyway, so the gains from swapping to a carbon version will be miniscule compared to a lighter flywheel.

Radius is less than a flywheel so it has less inertia due to the weight being closer to the axis so its easier to spin and slows down quicker anyways?

 

[Dogbreath]

Radius is less than a flywheel so it has less inertia due to the weight being closer to the axis so its easier to spin and slows down quicker anyways?

Basicly yes. The moment of inertia is directly proprotional to mass and proportional to the square of the radius, so slender tubes (e.g. driveshafts) have much lower moments than a flywheel.

 

[penski]

carbon - stronger, lighter, quieter as it absorbs harmonics better without the long term fatigue that can be associated with alu/steel.

It also burns up, cracks, shatters and is generally not something I'd want to use in a road car for critical components such as driveshafts, propshafts, wheels et cetera.

A lower rotational mass means you could see gains in whp upto 5% etc.

Cost a lot but id say these days its a very good product to use for getting the power down.

....Do you work for the company that makes them?

Assuming they're quite pricey - I'd want to see dyno proof of the atw gains because I'm struggling to see how it could reduce transmission losses.

Unless it's based on the quality of the CV joints et cetera? £30 of CF and uberpricey bearings and joints giving less transmission losses?

But that's irrelevant; calculated flywheel figures are useless anyway.

*n

 

[Zip]

I would say it wont give you any more BHP.

But it will give you more BHP per ton (probably not a whole lot but there will be little bit of an improvment)

 

[Gibbo]

Basicly yes. The moment of inertia is directly proprotional to mass and proportional to the square of the radius, so slender tubes (e.g. driveshafts) have much lower moments than a flywheel.

HI m8

Thanks for the explanation, fully understand what your saying and shall delete that from my list of possible upgrades.

 

[Wayn0r]

It also burns up, cracks, shatters and is generally not something I'd want to use in a road car for critical components such as driveshafts, propshafts, wheels et cetera.



....Do you work for the company that makes them?



Unless it's based on the quality of the CV joints et cetera? £30 of CF and uberpricey bearings and joints giving less transmission losses?

But that's irrelevant; calculated flywheel figures are useless anyway.

*n

not at all, my dad used to work for nissan so i asked him.

 

[penski]

not at all, my dad used to work for nissan so i asked him.

In what capacity?

*n

 

[Wayn0r]

30 years engineer. On the development team for the first skylines, senior engineer on the bathurst winning, and subsequently banned skyline. Then moved into rally with the Nissan (Previously Datsun) Violet, 240rs. i have pictures of the marlboro rally cars he built somewhere at home.

And he won the safari rally, monte carlo a few times as both driver and co driver.

Too much history to type, id have to dig out all his plates.

 

[penski]

30 years engineer. On the development team for the first skylines,

In '61? Crikey - that's going back a bit.

senior engineer on the bathurst winning, and subsequently banned skyline. Then moved into rally with the Nissan (Previously Datsun) Violet, 240rs.

Hang on...He went back in time...?

i have pictures of the marlboro rally cars he built somewhere at home.

Could you dig them out?

And he won the safari rally, monte carlo a few times as both driver and co driver.

See....Now that's interesting.

Nobody has won either rally in both seats.

In fact, the only team I can see winning both 'a few times' are the Shekhar Mehta/Mike Doughty team in, interestingly a Violet 160J in 79-82.

Now...Mike Doughty and Shekhar Mehta had damn good showings on the Safari.

But...Doughty never placed on the Monte Carlo.

Mehta came 14th in '84 though...

What's your dad's name? I seem to remember the Bathurst tech team being exclusively Japanese bar a couple of Australians and Kiwis who worked on the local and driver side of things.

*n

 

[Wayn0r]

Walter Ainsworth. (not much on google, i had a link to a Castrol website where there was a video about the old group b rally cars that got banned, 205 t16 etc, he was in that)

Im getting a train home later this afternoon so ill find the photos and the plates and post up some pictures.

I dont know the whole history of his career as, as stuborn as he is, he threw a lot of his memorabilia in the early nineties due to being "begrudged" at the whole scene, at which point he mechaniced for me and my 14 year motocross career.

he has the trophy from the safari rally aswell somewhere.

there is some pics of the skyline also at home somewhere however we have just moved house so finding it may take a short while :/

(edit> i dont know the exact dates, i just through out some stuff not in any particular order )

 

[penski]

Hmmm...John Morton/Walter Ainsworth in a Subaru RX Turbo were excluded on the '86 Lindisfarne Rally and had turbo failure on the first stage of the Quip Perfomance Centre Forest Stages in the same year. I'll dig out my British Rally Journals...

A couple of failed-placements on minor rounds of a mid-eighties national championship are certainly a far cry from "And he won the safari rally, monte carlo a few times as both driver and co driver."

*n

 

[Wayn0r]

haha yea, him and john where still pi***d, was a night rally and they had been drinking all day

Ill clarify the details later when i get home, i saw a monte carlo road book from the really aswell ill dig it out.