Carbon Fiber...Driveshaft?

[treesnake]

Has anybody seen one of these before?

I've got this one for a Gen 3 and have a few questions for the racers on here before installation:

-What effect would an ultra-light CF driveshaft have?(obviously weight..)
-Would it be similar to an alum. flywheel?
-Inertia?

Thanks

 

[dave6666]

Has anybody seen one of these before?

I've got this one for a Gen 3 and have a few questions for the racers on here before installation:

-What effect would an ultra-light CF driveshaft have?(obviously weight..)
-Would it be similar to an alum. flywheel?
-Inertia?

Thanks

I've seen one on ebay before. Did you snag it?

You are probably on track with the thought that it is similar to the effect of a lighter flywheel as it is less mass to get rotating during acceleration.

 

[mjorgensen Woodhouse]

Depending on the price it is cool, but the diameter is too small to have much affect on rotating mass like the flywheel and the stock one is not all that heavy.

 

[Newport Viper]

Talk to these guys Precision Shaft Technologies, Carbon Fiber Driveshafts and Racing Shafts

 

[02 Graphite GTS]

Treesnake,
Do you know who makes it?
Does it by chance have the letters "ACPT" on the aluminum ends?

 

[Shandon]

The smaller center of gravity even over the length would limit the improvments. The lighter the driveline gets (just like flywheels) is good for HP numbers but if things get too light it can make drivability hard (around town). Light driveline can be great on the track but ***** in stop go traffic. Very, Very cool part!! Probably biggest benefit would be from overall car being lighter and a little quicker rev on the track. Just too darn cool though!! Keep us posted on your experience if you put it on.

 

[Kai SRT10]

I have one on my car. (Precision shaft technologies.)

One of the benefits (other than being lighter and stronger) is that it is safer. If a regular driveshaft breaks, it can rip through the underside of your car, or "polevault" off the street.

A carbon fiber shaft, if it breaks, will come apart and disintigrate rather than tearing a hole in your underside.

 

[RTTTTed]

So the weight difference would be 2#? Stock is aluminium and doesn't weigh much. CF shafts are popular in cars like the Stealth R/T TT as the stock shafts (3 piece) have 'smeshed' Ujoints and a bad U-joint requires a new driveshaft. Those 3 pc shafts are really heavy as well as being long and requiring 2 steady bearings.

Ted

 

[bluesrt]

Has anybody seen one of these before?

I've got this one for a Gen 3 and have a few questions for the racers on here before installation:

-What effect would an ultra-light CF driveshaft have?(obviously weight..)
-Would it be similar to an alum. flywheel?
-Inertia?

Thanks

tree/quit jackin with everybody,you know thats not cf,cause i made those-its just dark high strenth packaging tape wraped around your original shafts!

 

[treesnake]

Depending on the price it is cool, but the diameter is too small to have much affect on rotating mass like the flywheel and the stock one is not all that heavy.

It was a gift.

I've seen one on ebay before. Did you snag it?

No, it's not from Ebay

Treesnake,
Do you know who makes it?
Does it by chance have the letters "ACPT" on the aluminum ends?

I will check but I believe it does

The smaller center of gravity even over the length would limit the improvments. The lighter the driveline gets (just like flywheels) is good for HP numbers but if things get too light it can make drivability hard (around town). Light driveline can be great on the track but ***** in stop go traffic. Very, Very cool part!! Probably biggest benefit would be from overall car being lighter and a little quicker rev on the track. Just too darn cool though!! Keep us posted on your experience if you put it on.

Pretty much what I was thinking. Too bad I'm really not into "BLING"...

tree/quit jackin with everybody,you know thats not cf,cause i made those-its just dark high strenth packaging tape wraped around your original shafts!

SSHHHHHHHHH.....

Thank you for the answers. I knew some people on here would know...

The car will be on a lift so I will be able to see it.

Guess I will need to find CF skid plates to match....

It never ends...

 

[Cop Magnet]

Very funny.

However, I disagree with some posts. The effect would be (if real) closer to lightweight wheels than lightweight flywheel. Would not affect driveability at all. Doesn't spin with the engine so would not cause bogging down on clutch release like a lightweight flywheel could. I agree without a higher radius, the effect might be negligible. Still, it is lightweight rotational mass and would reduce inertia in theory.

 

[pteam]

Would carbon fiber really be stronger than the aluminum oem one?

 

[GTS-R 001]

I checked into this a few months ago with a leading carbon drive shaft producer and the way they computed it, the diameter and amount of CF needed to handle the torque of the stock viper (modified viper would require more) teh weight savings was negligible,

As Kai pointed out the safety features are the only mitigating factor otherwise it is a waste of money

 

[Martin]

Would carbon fiber really be stronger than the aluminum oem one?

Here's something near and dear to my heart (I used to be an Aero/Astro Engineer, and we worked with CF composites all the time). The beauty in CF composites is you can orient the strands in such a way to be strongest where it needs to be - and designed so that it's possible to make the part much stronger than an equal weight aluminum or other alloy piece, or make it much lighter than a standard piece of the same strength. For a driveshaft, the carbon strands are oriented at approximately 45 degrees from the longitudinal axis - which makes them the most effective against torque. In most aircraft applications, the torque is almost always in one direction (oriented with the thrust axis) so you can make the shaft strongest for that case and orient most of the carbon fiber to support that load - and minimize weight a LOT. For a car, fibers need to be oriented about equally in both directions (about 60% for the forward direction, about 40% for the reverse direction), so you lose out on the biggest benefits of the composite structure, but it's still going to be lighter than a similar strength metal shaft.

 

[bluesrt]

Here's something near and dear to my heart (I used to be an Aero/Astro Engineer, and we worked with CF composites all the time). The beauty in CF composites is you can orient the strands in such a way to be strongest where it needs to be - and designed so that it's possible to make the part much stronger than an equal weight aluminum or other alloy piece, or make it much lighter than a standard piece of the same strength. For a driveshaft, the carbon strands are oriented at approximately 45 degrees from the longitudinal axis - which makes them the most effective against torque. In most aircraft applications, the torque is almost always in one direction (oriented with the thrust axis) so you can make the shaft strongest for that case and orient most of the carbon fiber to support that load - and minimize weight a LOT. For a car, fibers need to be oriented about equally in both directions (about 60% for the forward direction, about 40% for the reverse direction), so you lose out on the biggest benefits of the composite structure, but it's still going to be lighter than a similar strength metal shaft.

smartin up with martinremember the martin gas station logo.

 

[Martin]

smartin up with martinremember the martin gas station logo.

Funny you should mention that - my girlfriend has always given me the compliment that I could be a natural resource. Instead, unbeknownst to me, I just continue to contribute to global warming as I sleep at night...

 

[2000_Black_RT10]

Here's something near and dear to my heart (I used to be an Aero/Astro Engineer, and we worked with CF composites all the time). The beauty in CF composites is you can orient the strands in such a way to be strongest where it needs to be - and designed so that it's possible to make the part much stronger than an equal weight aluminum or other alloy piece, or make it much lighter than a standard piece of the same strength. For a driveshaft, the carbon strands are oriented at approximately 45 degrees from the longitudinal axis - which makes them the most effective against torque. In most aircraft applications, the torque is almost always in one direction (oriented with the thrust axis) so you can make the shaft strongest for that case and orient most of the carbon fiber to support that load - and minimize weight a LOT. For a car, fibers need to be oriented about equally in both directions (about 60% for the forward direction, about 40% for the reverse direction), so you lose out on the biggest benefits of the composite structure, but it's still going to be lighter than a similar strength metal shaft.

Good reply Martin. I think we tag teamed on this subject before regarding composites. I don't think there is a great advantage in weight in that particular driveshaft assembly. The ends are aluminum, and the overlapping bond would need to be around 25 mm, meaning that the aluminum ends would contain more material because the aluminum ends need to extend into the carbon tube by 25 mm minumum for a proper bonding surface whereas in an aluminum welded assembly, probably only 1/4" overlap into the tube, then welded. In this case, the weakest point would most likely be the bond joint to the aluminum. The aluminum ends don't look like they are coated, anodized etc.. whereas aluminum on carbon promotes galvanic corrosion. Another disadvantage to this assembly, which appears to be straight cut tube of carbon, is that the bond is smeared when the parts are assembled for bonding (no taper), and there's no clamping pressure for the bond, which is not ideal for a good bonded joint. These are assumptions, just sharing some composite design insight..
Regards,
Mike

 

[02 Graphite GTS]

OK, I have to be careful here.
If they are in fact made by ACPT, then I can tell you that they are very well engineered and that the aluminum ends are bonded into the end of the CF about 1.5". They have done extensive testing and have put them on 1000 hp cars.

My company does a lot of work balancing a variety of parts for them.
While we do balance their driveshafts, we are not balancing all of them. They will only send them out for balance if their customer puts that requirement on them. Almost all the driveshafts for the Japanese cars and Corvettes are required to be balanced and we do those. The rest do not.

Treesnake, If you put them on and notice vibration coming from the rear end, I HIGHLY recommend that you have them balanced. While they are relatively light and the diameters are relatively small, the process in which they are made make it very difficult to control rotational center of mass. It would not surprise me one bit if they are found to be considerably out of balance.

PM me if you would like any more info or want to have them balanced.

 

[Makara]

The smaller center of gravity even over the length would limit the improvments. The lighter the driveline gets (just like flywheels) is good for HP numbers but if things get too light it can make drivability hard (around town). Light driveline can be great on the track but ***** in stop go traffic. Very, Very cool part!! Probably biggest benefit would be from overall car being lighter and a little quicker rev on the track. Just too darn cool though!! Keep us posted on your experience if you put it on.

Smaller center of gravity? The center of gravity, regardless the of size of an object, is just a point.

 

[Shandon]

Smaller center of gravity? The center of gravity, regardless the of size of an object, is just a point.

Correct
Sorry for the poor wording just trying to keep it in quick "car guy" terms. I believe everyone gets the point of what I was saying without re-hashing high school physics. The rotational mass is closer to the center of gravity in this application to put it in more correct terms.

 

[treesnake]

Here's something near and dear to my heart (I used to be an Aero/Astro Engineer, and we worked with CF composites all the time). The beauty in CF composites is you can orient the strands in such a way to be strongest where it needs to be - and designed so that it's possible to make the part much stronger than an equal weight aluminum or other alloy piece, or make it much lighter than a standard piece of the same strength. For a driveshaft, the carbon strands are oriented at approximately 45 degrees from the longitudinal axis - which makes them the most effective against torque. In most aircraft applications, the torque is almost always in one direction (oriented with the thrust axis) so you can make the shaft strongest for that case and orient most of the carbon fiber to support that load - and minimize weight a LOT. For a car, fibers need to be oriented about equally in both directions (about 60% for the forward direction, about 40% for the reverse direction), so you lose out on the biggest benefits of the composite structure, but it's still going to be lighter than a similar strength metal shaft.

Good reply Martin. I think we tag teamed on this subject before regarding composites. I don't think there is a great advantage in weight in that particular driveshaft assembly. The ends are aluminum, and the overlapping bond would need to be around 25 mm, meaning that the aluminum ends would contain more material because the aluminum ends need to extend into the carbon tube by 25 mm minumum for a proper bonding surface whereas in an aluminum welded assembly, probably only 1/4" overlap into the tube, then welded. In this case, the weakest point would most likely be the bond joint to the aluminum. The aluminum ends don't look like they are coated, anodized etc.. whereas aluminum on carbon promotes galvanic corrosion. Another disadvantage to this assembly, which appears to be straight cut tube of carbon, is that the bond is smeared when the parts are assembled for bonding (no taper), and there's no clamping pressure for the bond, which is not ideal for a good bonded joint. These are assumptions, just sharing some composite design insight..
Regards,
Mike

That's exactly what I was going to say.....

 

[treesnake]

OK, I have to be careful here.
If they are in fact made by ACPT, then I can tell you that they are very well engineered and that the aluminum ends are bonded into the end of the CF about 1.5". They have done extensive testing and have put them on 1000 hp cars.

My company does a lot of work balancing a variety of parts for them.
While we do balance their driveshafts, we are not balancing all of them. They will only send them out for balance if their customer puts that requirement on them. Almost all the driveshafts for the Japanese cars and Corvettes are required to be balanced and we do those. The rest do not.

Treesnake, If you put them on and notice vibration coming from the rear end, I HIGHLY recommend that you have them balanced. While they are relatively light and the diameters are relatively small, the process in which they are made make it very difficult to control rotational center of mass. It would not surprise me one bit if they are found to be considerably out of balance.

PM me if you would like any more info or want to have them balanced.

The alum. u-joint end has a "PST" inscribed into it?.

I was definitely going to get it balanced when/if I install it. I will need to know the HP rating before I do.

Thanks for the answers....

 

[Tom F&L GoR]

I think saying it has a low polar moment of inertia is better.

For you CF experts, if you orient the fibers in the direction to produce mostly tension, what happens under compression? For example, a driveshaft built up for torque in one rotational direction would twist and break if not designed to provide enough "engine braking" on lifting throttle? Does that mean these driveshafts should be installed only in one direction?

 

[2000_Black_RT10]

I think saying it has a low polar moment of inertia is better.

For you CF experts, if you orient the fibers in the direction to produce mostly tension, what happens under compression? For example, a driveshaft built up for torque in one rotational direction would twist and break if not designed to provide enough "engine braking" on lifting throttle? Does that mean these driveshafts should be installed only in one direction?

Since this is one of those things I do for a living.. Typically you see carbon fiber fabric which is weaved criss-crossed. Such as 2x2, that means the weave is under 2 then over 2 (think of a knitting a thread going under 2 then over 2 threads). You can also get different angles of criss-crossing, 45 deg, 90 deg etc.. There's 4x4, that's over 4 then under 4. Then there's uni, which is unidirectional, all the strands go in the same direction. So if the driveshaft was comprised of unidirectional for one torsional direction, then yes, you would not get the same stiffness in the opposite direction. If the fabric is criss-crossed equally, such as in 2x2 or 4x4, then you would get the same stiffness in either clockwise or counterclockwise direction. There are also different thicknesses of carbon weaves. Unidirectional provides the best finish because it is not weaved, yet a criss-cross pattern looks cool (4x4 being more dramatic), but provides a rough initial finish (think of trying to paint a knitted sweater) and you need to build up clearcoat to attain a smooth finish. Another point, is that the bond to the aluminum pieces as I suspected, is 1.5 inches which means more aluminum which adds weight in relation to carbon, and the bond is only to the inner ply of carbon fiber. A better design would be a tongue and groove design, a groove in the aluminum ends that the tube would seat into. Looking at the pictures, it appears they used unidirectional material cut 1 approximately inch wide strips and criss-crossed the strips to make a tube (like a cardboard toilet paper tube) which would provide a good result for either torsional direction of rotation (disregarding the bonding inside only surface disadvantages). It may also be off-the-shelf carbon fibre tubing that is available from several carbon fibre suppliers. Yet, if the current design provides enough strength, that's all you need. This is just some more design insight..
Regards,
Mike

 

[Newport Viper]

The alum. u-joint end has a "PST" inscribed into it?.


I was definitely going to get it balanced when/if I install it. I will need to know the HP rating before I do.

Thanks for the answers....

http://www.pstds.com/ click here......

 

[Chuck 98 RT/10]

So how much does this thing weigh?

 

[steve911]

I will have the same concerns about corrosion. Bare aluminum or even anodized aluminum and CF do not play well together. Even in neutral atmospheres, corrosion occurs at an alarming rate and the worst part of it is that the major contact area between the two materials is not visible and therefore not inspectable.

Another thing I would like to know is what type of adhesive is used to bond the two pieces together.

Steve A.

 

[2000_Black_RT10]

Knowing you have knowledge Steve since we chatted before.. Good points and I'd probably assume a cold bond, DP expoxy, 460 or.. and depending on the adhesives we tested the results can vary quite a bit regarding bond strength as you would know too. Other option they could have taken would be a layer of glass on the inside to discourage galvanic corrosion.
Regards,
Mike

 

[Newport Viper]

Got a response from PST.....

There are some very interesting and accurate posts in this thread. We did build this shaft several years ago, the length is so short that the weight savings is small at best.
As far as balance they are balanced at time of assembly with the joints and slip yoke in place. Our bonding procedure is proprietary however all of the concerns expressed in the thread have been addressed. Our shafts are SFI certified to withstand over 2800 ft/lbs of torque, and are used in may Pro-Mod applications over 2500 HP. PST is the largest producer of custom carbon fiber drive shafts in the world. If there any further comments or questions I can be reached at 888-575-7888 or Precision Shaft Technologies, Carbon Fiber Driveshafts and Racing Shafts

Mark Veldhuis,

PST Inc.

 

[treesnake]

Thanks "Newport Viper" and all the other answers. As usual, got answers to my Viper questions here on the VCA Forums...