[punkin]

Hello all,

My 68 firebird project continues to drag out but hopefully it will be worth it in the end.

New motor in hand, 4L80e on the way and a 9" rear in the works. Obviously a lot of changes and a new drive shaft will eventually be required. I'm very interested in a carbon fiber unit. I did do a quick search of the forums and all I found so far were some rather older exchanges so I do apologize if this has been discussed at great length already.

In my search, it appears QA1 has a great deal of confidence in their product being suitable for high-performance applications as well as street use. Also according the info offered by QA1, other than cost, not a lot of drawbacks. Some considerations include clearance and heat. No X or h-pipe planned so other than making sure I can get full suspension travel and draining my savings even further, this looks like a good choice.

Anyone with any real world experience with carbon fiber drive shaft used on the street? My application again is for 68 firebird.

Thanks in advance for taking the time to read this posting. Have a great day.

[turbo69bird]

Man I’d be real worried on the street something would come up and whack that thing leave you stranded . I’ve thought about it too but sounds too fragile
For me with all the warnings

[4zpeed]

Originally Posted by turbo69bird

Man I’d be real worried on the street something would come up and whack that thing leave you stranded . I’ve thought about it too but sounds too fragile
For me with all the warnings

Good point if one is building for the street, consider a loop?

No shaft failures myself so far but always something to consider.

Here is a thread with what might be some relative insight and info.

https://forums.maxperformanceinc.com...d.php?t=848617



Frank

[JLMounce]

You've got a high performance build going on. If it's in your budget, I'd run it.

The street issue typically comes up because the carbon shafts won't bend or dent, they just disintegrate if they have a catastrophic event. Modern sports car and muscle car enthusiasts including the Supra guys, 3000 GT's Mustang, Camaro's etc. all have large contingents of people daily driving cars on the street with carbon fiber driveshafts.

In the end if something happens that is going to destroy that shaft and leave you stranded, the same would have happened to a steel or aluminum shaft. As with all driveshafts, hitting something rigid hard enough is going to irreparably damage it and you're not going far, or anywhere at that point. Case in point there are warnings all over factory steel driveshafts on modern cars stating if it's dropped, it needs replaced.

Additionally, many of the carbon drive shafts on the market, like from ACPT are actually a thin-wall aluminum core, strengthened with use of a composite wrap.

Common road debris that wouldn't otherwise damage your vehicle, is not going to damage a carbon driveshaft. If something fluke happened like a piece of angle iron getting wedged into the shaft were to occur, again, it's taking out the steel/aluminum unit as well.

[Mike Davis]

I run a PST Carbon Fiber in my 66. It has held up to almost 775HP for about 4 years now. I mostly race the car but do drive it on the street a good bit. I would have no problem running one on a street car. They are slot safer than any steel or aluminum shaft.

[punkin]

Fantastic input all. Thank you.

As for the safety loop(s) I do have one but I do plan for a far more beefy solution that will be integrated with the new drive shaft cross-member. I've also seen some interesting solutions for a second loop as part of the rear housing. Once everything is assembled I'll need to have a long look at suspension travel before committing to this solution.

A number of years back I did have a steel drive shaft attempt to exit the car. Beat the dickens out of the underside. After seeing what is possible, I'm really avoidant to the aluminum solution. I would far rather the drive shaft disintegrate than experience that all over again.

Again, thanks to you all.

[GOAT8U2]

Heat = Kills Carbon Shafts

I was gonna buy one and had PST and other online threads suggest that is not worth the risk. It was made pretty clear that heat is the enemy of these shafts, any exhaust pipe that's nearby puts the shaft at risk.

I had a friend break his with low miles on it, many Mopar guys were having the same issue in their street cars. While I don't technically have one, I was ready to buy it and was suggested by the company to not put it in my street car GTO.

[Bob with the 66]

Originally Posted by GOAT8U2

Heat = Kills Carbon Shafts

I was gonna buy one and had PST and other online threads suggest that is not worth the risk. It was made pretty clear that heat is the enemy of these shafts, any exhaust pipe that's nearby puts the shaft at risk.

I had a friend break his with low miles on it, many Mopar guys were having the same issue in their street cars. While I don't technically have one, I was ready to buy it and was suggested by the company to not put it in my street car GTO.

X2,
I was told by a well known drive shaft manufacturer to keep C.F. shafts on the track and not on the street. Just a small nick could shorten it's life span and for MY build Aluminum was fine.

[Chief of the 60's]

LOL!

They make high-end cars out of CF but we should run and hide from a CF driveshaft. LMAO

My take is not about durability, its about budget. The car is not a Top Sportsman car or a Pro-Mod therefore a CF driveshaft is just a waste of money to impress the uneducated at some car show.

[Sirrotica]

Upon reading, the effects of heat on the CF, it says the sustained heat over 200 degrees will have an effect on the resin in the CF, and start weakening it.

On a street car it probably wouldn't be a stretch to have the temps reach over 200 degrees. I also read that some of the high end cars that use CF on the street have heat shields to protect the CF resin from exhaust heat, FWIW.

[Chief of the 60's]

They make CF brakes and wheels as well, FWIW.

[Sirrotica]

It's not the CF that fails, it's the resin used to bond the aluminum ends to the tube that fails. I have no idea of what resin is used on wheels or brakes, but I'm sure it's no the same resin.

I just read up on the failure criteria and reported what I read, I didn't engineer the parts. Don't shoot the messenger...........

I had a friend that raced late model stock cars that bought some CF wheels for it, and they also failed in use. A big investment that didn't pay off in increased performance, or longevity. He never bought any more of them.

There are also hybrid driveshafts that are an aluminum tube core that are wrapped with CF for reinforcement, so just looking at one someone couldn't tell if it had a aluminum core, or not.

Upon researching CF wheels, the early ones had failures due to heating. They then made changes to the resin and other components to keep the wheels from overheating, and ultimate failure.

[RocktimusPryme]

I dont have a hard take on if you should or shouldnt use it. If OEMs are using it now in production HP street cars I would say fire away I guess. But reading this I feel like there is some misconception about the pros/cons of carbon fiber.

I worked for an Aircraft company that used carbon fiber hulls.

CF is incredibly strong structurally. We did a demonstration when I was in A&P school where we made a carbon wing section and an aluminum wing section then ran the both over with a truck. The carbon held up better.

What CF is NOT good at is handling small area impact. To give an example, most of us have been on an aluminum fuselage airliner. Most of us have flown through clouds. No problem. On the flip side, with the carbon fuselage UAVs I worked on, if you fly through clouds, the plane would come back down and look like it had caught the chicken pox during flight. Many clouds have small traces of hail in them. Those small ice impacts played hell with the fuselage.

Same thing with dropping a screwdriver. Drop a tool on a metal panel and maybe you get a dent. Do it on carbon and you probably get a hole. Anyone who worked on the planes I did for any length of time got that merit badge at least once.

How often does road debris fly up and hit the driveshaft? No idea. But a small rock impact could cause a weakpoint that an alloy driveshaft probably wouldnt notice that could lead to failure.

If nothing else I would think a CF driveshaft would require much more diligent inspection for mechanical damage.

[punkin]

I thank you. It surely feels a bit risky. QA1 is very confident of their product and thus far in my conversations with them the biggest immediate concern they seem to have is with heat. The person I spoke with described their product being used in off-road and dirt track applications but, one never really know if you're being "sold" on something. I have a bit of time...I'll continue to solicit comments and I'll keep doing some poking around on other forums.

[Dragncar]

I have been kicking around a CF drive shaft for awhile now. I just race my car so I do not think heat would be a issue.
But the damage I have seen from broken steel driveshafts can be horrific. Just about ruins the car in some cases .
I like the idea of the whole thing going "poof" if the worst happens.
Trying to fix major undercarriage/floorboard damage on these old 60s would be a major pain.
Its not like we can go down to the corner junkyard for donor cars anymore.

[Formulajones]

Originally Posted by punkin

I thank you. It surely feels a bit risky. QA1 is very confident of their product and thus far in my conversations with them the biggest immediate concern they seem to have is with heat. The person I spoke with described their product being used in off-road and dirt track applications but, one never really know if you're being "sold" on something. I have a bit of time...I'll continue to solicit comments and I'll keep doing some poking around on other forums.

I would tend to think absolutely not on that comment because the driveline shop I deal with in town won't even build an aluminum shaft for the offroad desert racing trucks around here (let alone a carbon fiber), and he provides his service to hundreds of people running in various classes in the South West here.

His reasoning is that even aluminum doesn't like being hit with an obstruction, they will fold up like a prezel, so he builds "Steel only" for those applications.

With that said, and knowing he has a stellar driveline reputation out here spanning over 40 years, as well as in his own desert racing class, I just don't see a carbon fiber shaft even being considered for an application like that. As Rock said, they are structurally strong but they can't tolerate a small area impact at all. And in an off road situation it WILL get hit with debris.

[ta man]

For the OP I would suggest going with a CM shaft..all CM inputs and yokes and call it done.

[punkin]

That does present the fewest unkowns. Tried and true.

[Will]

Originally Posted by RocktimusPryme

...
What CF is NOT good at is handling small area impact. ....

How often does road debris fly up and hit the driveshaft? No idea. But a small rock impact could cause a weakpoint that an alloy driveshaft probably wouldnt notice that could lead to failure.

If nothing else I would think a CF driveshaft would require much more diligent inspection for mechanical damage.

This for me rules out CF in a street application.

I remember when I tried CF fishing poles. I loved the feel and the action I got from them but any little scratch or nick and the darned things shattered right at that point. Nothing like hooking a lunker and having your pole snap off as you're fighting it. The second time that happened the line got dragged across the broken section of pole and it cut the line. Nice big fish swam off with my lure and about 30' of line dragging behind it. Have NEVER broken a fiberglass/carbon composite pole which are almost as good.

After that I did some reading and discovered how notch/nick-sensitive CF is. Seems like a terrible idea for a highly stressed rotating member on the underside of a street car. I'll stick with aluminum or steel.