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Does anyone run a carbon prop?
alistairolsen - 24/5/11 at 02:25 PM

If so, was it significantly more expensive than a steel one?

cheers


Steve Hignett - 24/5/11 at 02:31 PM

about 1200 quid


blakep82 - 24/5/11 at 02:34 PM

^ yep, and for what? can't see its going to give any real benefit.

when i took bits off an old american van (1986 i think it was?) it has a plastic prop. don't think its carbon, but i would like to know what it is


r1_pete - 24/5/11 at 02:34 PM

some discussion on scoobynet Here


Mr Whippy - 24/5/11 at 02:35 PM

bargain not


scootz - 24/5/11 at 02:40 PM

The Mazda RX8 has a carbon prop.

I bought one from a scrappy ages ago to see if I could customise it, but all the carbon companies I spoke to said it was a non-starter.


Mr Whippy - 24/5/11 at 02:42 PM

quote:
Originally posted by scootz
The Mazda RX8 has a carbon prop.

I bought one from a scrappy ages ago to see if I could customise it, but all the carbon companies I spoke to said it was a non-starter.


probably bonded togeather so you'd destroy it trying to remove the ends

tbh most of the weight in a propshaft is in the joints and the sliding shaft, the tube is usually very thin walled

[Edited on 24/5/11 by Mr Whippy]


britishtrident - 24/5/11 at 02:58 PM

The Renault Espace 4x4 used a GPR propshaft I think is was really a technology demonstration exercise by Matra who designed built the Espace. Real advantage was it gave increased torsional elasticity.

From university istr GRP or Kevlar or a combination of the two would the choice for propshafts, production method is to take the two ends and join them by a former such as an alloy tube and rotate it between centres on a lathe like machine, the pre-wetted fibre fillament is wound round at pre-defined pitch ----- a bit like screw cutting on lathe but adding material, the next layer of fibre is then wound on in the opposite direction.


alistairolsen - 24/5/11 at 03:20 PM

Im not interested in the weight saving, more the way they fail, if and when.

I hadnt realised the cost was quite so high though!


nick205 - 24/5/11 at 03:21 PM

Other than the bragging rights and possible benefits on a serious race car I just fail to see the point over a steel one. As Whippy points out most of the weight is in the joints anyway. From an EoL recycling perspective a steel one makes more sense too.


nick205 - 24/5/11 at 03:23 PM

quote:
Originally posted by alistairolsen
Im not interested in the weight saving, more the way they fail, if and when.



I'd guess that they shatter or the bonded joints come apart.

Once broken I guess they might be safer than a steel prop in that the still rotating end would probably disintegrate in the tunnel rather than the major damage a broken steel one can inflict?


blakep82 - 24/5/11 at 03:28 PM

go to about 24 minutes into this
http://www.bbc.co.uk/iplayer/episode/b011dcb2/Richard_Hammonds_Engineering_Connections_Series_3_Formula_1/
it was on last week, will show you just about everything mentioned here (construction, approx cost etc)

it takes a lot more torque before it breaks, but it shatters rather than bending and twisting like steel.


alistairolsen - 24/5/11 at 03:29 PM

quote:
Originally posted by blakep82


it takes a lot more torque before it breaks, but it shatters rather than bending and twisting like steel.


exactly


Doctor Derek Doctors - 24/5/11 at 03:47 PM

This is the legacy of kids growing up playing Gran Tourismo..... a Carbon Fibre propshaft (400 credits if I remember) was a bargain upgrade for all cars.................... even if they were FWD and didn't have a prop!


r1_pete - 24/5/11 at 04:02 PM

It could create a market for transparrent tranny tunnels....


Steve Hignett - 24/5/11 at 04:12 PM

I should prob add to my price quote above, that the carbon prop manufacturer I know that sells them (exact price is £1163 IIRC), actually recommends that they are replaced every year too...

Well of course they bloody do!!!


iank - 24/5/11 at 04:30 PM

quote:
Originally posted by Steve Hignett
I should prob add to my price quote above, that the carbon prop manufacturer I know that sells them (exact price is £1163 IIRC), actually recommends that they are replaced every year too...

Well of course they bloody do!!!


Why did that comment remind me of this? http://www.youtube.com/watch?v=pBUzw-0ev_A


Neville Jones - 25/5/11 at 11:27 AM

I made a number of carbon prop shafts many moons ago. To do the job properly, you need to know the length between joints, and max torque, so that the fibres can be properly oriented.

Off the shelf jobs will have the fibres oriented at what is most convenient for the maker.

Another point to be aware of, is that the cfrp prop will be less compliant, springy, and will impart greater shock loads into the system, causing joint failure and possibly early gear failure. This was certainly the case on the car gears, and oddly enough, the grinder gears on racing yachts.

If using one, it should definitely be 'lifed', and same goes for everything it's attached to. The only way around this, is to use rubber donut type joints, but their weight then negates the use of the carbon. Another solution is to use the system where the tube is an inner and outer, with a flexible joining compound. But again, this negates the use of carbon to save weight.

Kevlar, and one or two other aramids and synthetics worked out to be the best compromise, but they showed to be very difficult to get the resins to adhere to.

Cheers,
Nev.


alistairolsen - 25/5/11 at 11:30 AM

quote:
Originally posted by Doctor Derek Doctors
This is the legacy of kids growing up playing Gran Tourismo..... a Carbon Fibre propshaft (400 credits if I remember) was a bargain upgrade for all cars.................... even if they were FWD and didn't have a prop!


With all due respect: No, it isn't


Doctor Derek Doctors - 25/5/11 at 12:40 PM

quote:
Originally posted by alistairolsen
quote:
Originally posted by Doctor Derek Doctors
This is the legacy of kids growing up playing Gran Tourismo..... a Carbon Fibre propshaft (400 credits if I remember) was a bargain upgrade for all cars.................... even if they were FWD and didn't have a prop!


With all due respect: No, it isn't


It was a joke, at the expense of Gran Turismo.

Calm down dear.