Aluminum Driveshafts

[Bullitt]

I know that decreasing rotational weight from the drivetrain will free up wasted horsepower. Is there any downside to using an aluminum driveshaft on my big block Vette, though? I know that C5s and some F-bodies have them nowadays. I also know that a flywheel that is too light wouldn't be the optinum deal for the street and am wondering about the 'shaft. Thanks for any advice you can lend. --Bullitt

 

[SwaveDave]

Bullit,

Good question. Im interested in this myself as i have a 1970 BB with more than stock H.P./Torque. If you dont get a response, try DennysDriveshafts.com for the answer and let me know please.

Thanks, Dave.

 

[redmist]

FYI,
After discussions with a local driveshaft fabricator I've decided to go with a carbon fiber driveshaft but am sticking with the steel half shafts. According to him the half shafts are the ones that really take the abuse.

 

[SwaveDave]

INteresting going with Carbon Fiber on the Drive shaft. Keep us posted as to how it works for you.

Dave

 

[redmist]

Will do Dave.
I was a little skeptical at first but appartly they are standard issue on some new cars and trucks and drag racers also use them.
At least if it blows it shouldn't cause much damage.
I'm not sure it matters but the one I having made is about 16" shorter than a normal c-3 as I am installing an overdrive unit on the back of the M-21.

 

[Bullitt]

Weight

Does anyone know what a stock driveshaft off a Corvette weighs, anyway? I have a Turbo 400 underneath the car, right now. I'm not in the mood to pull it off, though. There's this place that sells used Nascar stuff, that has steel shafts and I'm wondering if they're lighter than mine. I figure if they can live on the track, they can handle the street. Aluminum shafts are running about $300 brand new, so what is that carbon fiber going to cost you, Redmist? And why did you choose carbon fiber over aluminum? I plan on pulling the shaft down to replace the u-joint in a month or so, but if I can gain some power by replacing it with something lighter, I will. --Bullitt

 

[redmist]

The advantages of carbon over aluminum are:
vibration dampening
spins up faster
won't wreck your car if it blows

Cost of course is a factor. They ain't cheap. Brand new they run about $500 to $800. My guy is making mine from a existing shaft he had for $200.

 

[sscam69]

Basically what you are trying to overcome is inertia which has to do with its mass. The lighter the shaft the less inertia the engine has to overcome. Think of inertia as the bodys(whatever it is) ability to resist acceleration or deceleration. It won't add power per say to your engine but the transfer of power form the tranny to the differential will be improved. You will notice that the car will respond a little better in acceleration and shifting.

my .02 cents

sscam69

 

[Bullitt]

I appreciate the input, but I'm aware of the light weight issue. I don't mean to sound ungrateful, though. What I'm trying to get at is this: Is there any disadvantage of running an aluminum driveshaft over the stock piece? Are there any wear concerns and do I continue to use steel U-joints? Thanks for any information that you can provide on these questions. --Bullitt

 

[sscam69]

Ok bullit to answer your question

No, not much wear concerns. Durability might come into question but that depends on who is making the shaft for you or where you are buying it from. How much your engine is outputing. As with any component you buy you just have to be sure its being made right.

You can have the aluminum shaft setup to be stronger than a steel shaft, question is how much do you want to pay for it! Another concern is connecting the u-joints to the shaft. I am not to sure how much the alluminum u end of the shaft can take or if you can weld a steel u piece to it for better durability. I am sure that you can only weld certain metals to aluminum but i am not to sure what you can weld to it, i dont have that information right now. In my opinion the weakest link in that whole setup would be the u-joints. Stay with the steel u joints.

i hope that helps instead of raising more questions or confuse you.

 

[Bullitt]

Thanks sscam69, for the additional information. I am also concerned about the u end strengths and how much it can endure. I'd like faster spool up so to speak, but not at the cost of becoming a catapulte in my car. I'll look into offerings by different companies to see what their advice is on this subject. I've been too busy lately, to run through the internet, but I should have some time today. I'll post what I find out. --Bullitt

 

[sscam69]

i am going to do the same for my shark. I am gathering information right now and i want to switch out the shafts (all 3) to aluminum or carbon fiber. The shafts are going to last you depending on how hard you push the car. If its just daily driving don't sweat it to much but if you are racing yeah you have to worry about the strenth of the shaft and that of the u-joints. I would be more worried about the ujoints than the shaft. I doesn't mean that nothing won't happen with the shaft but i would place my money on the joints. Let me know what you find. I am following chris's build up because he is doing some of the things i had in mind and its interesting to.

That silver shark with the chrome sidepipes looks killer!

 

[69MyWay]

I say just build more hsp to compensate for the weight!

Actually a good friend of mine has a 71 big block under restoration and he owns and drives a GT-1 racer. In fact, they did pretty good at the Rolex 24 in Daytona this year.

He is all into the weight savings. If he has his way, the 71 will come back to life as a carbon fiber, aluminum, and titanium monster. He has been looking into all of the possible options on weight reduction from his calipers to his interior options. He is a serious racer at heart and has a hard time making a compromise for comfort. In fact, he is the most hardcore race minded person I have ever met. He thinks any suspension travel is too much.

We don't argue, we just have a good time with difference of opinions. I am into the street duty with ocassional race fun. That means, I can justify lower strength, higher weight alternatives. The truth is, it is a street car above all, and will never be a race car. However, race technology is nice and helps make things go faster, longer, and stronger.

 

[sscam69]

I really enjoy street racing, I am an adrenaline junkie. I would actually like to go skydiving one of these days!

Anyways i want to reduce as much weight on the car within reason. I am going to by SSBC aluminum brakes, i have the composite spring already, remove the spare tire, aluminum shafts, remove air conditioning compressor and a few other mods to reduce weight. I hope to shed close to 200 lbs in the end. But i do enjoy the comfort as well so i am not going to strip the whole car. Again this is a cruising car not a daily driver so i can live with the mods.

I really got a kick of those gauges you mentioned Chris. I just got a copy of car craft (i think thats were i saw it) where there was a yellow drag vette with white gauges. I did some searching and i decided to put white with the neon green background for all the gauges and adding a boost gauge in place of the clock. I was trying to figure out what size gauge would fit in the stock pods.I think its 2 1/16" We did that mod for a 99 silverado (white gauge with green back at night) looked awesome. I hope within a year to have the mods in place.

sscam69

p.s. keep those pics and details coming, i am going to eventually going to do a body of restore of mine.

 

[Hib Halverson]

The only downside of an aluminum shaft on a C3 may be physical clearance. On the BBfH we use the later model (so-called HD) OE steel, driveshaft which I believe is a 2.5-in. shaft. Aluminum shafts are typically the next larger diameter. A 3-in shaft may present a problem in a C3.

Before I'd order an aluminum shaft I'd take some clearance measurement around your existing steel shaft.

Also, there's a great performance driveline manufacturer in Garden Grove California called Powertrain Industries, Inc. They specialize in custom-built, aluminum shafts for hi-po applications. The Ph. is: 714 893 4585. Ask for Jeff Helton.

 

[redmist]

Hib is right again as usual. I test fit the carbon fiber shaft and it rubs against the side of the tunnel.
I have banged out the tunnel enough already so I'm going back to steel.

 

[Bullitt]

Sorry to hear about that, Redmist. How bad is the rub? Are you talking about interference on the sides, on the top or all over the tunnel? I'm presently waiting to hear back from some companies on my emails, so I have nothing new to share. --Bullitt

 

[69MyWay]

I hope to shed close to 200 lbs in the end. But i do enjoy the comfort as well so i am not going to strip the whole car.

You would be surprised how heavy the rear and front bumper reinforcement is in that 79. This 79 clip I have laying around here is light as a feather until you try to lift the very rear section. It is almost like they put lead counter weights back there.

You could drop some serious weight by removing those and replacing your rubber bumpers with fiberglass copies. The rubber bumpers depend on the heavy under structure to keep them in shape. The fiberglass can stand on its own without any reinforcement underneath. Is that very safe? I guess that is up to you and the passengers that you make sign waivers before they ride with you.:cool

 

[Bullitt]

Some driveshaft info.

I did a search through the Internet and didn't find a whole lot on technical information. I don't think anyone will get back to me till next week or so. The best tech information I found was at:Dynotech Here's a quick run through of different materials.

• DOM Steel- Drawn over mandrel bent steel. High quality steel that Winston Cup racers use.
• 6061 T6 Aluminum- High quality, high performance replacement driveshaft for street use.
• MMC (Metal Matrix Composite Aluminum) - Light weight, high performance race shaft. 60% lighter than steel, 20% increase of speed and 40% increase in torque capability over 6061 T6 aluminum. The strongest aluminum available.

Both Dynotech and Denny's Driveshafts, balance and test their shafts. Both make custom shafts and stress the point that you must consider your intended use, like with everything else. The higher quality material you get will result in lighter weight, less vibration, free up horsepower and of course, lighten your wallet. I know where to get DOM shafts, but it may need to be modified for length. No one talks about the U strength, so if you buy a quality shaft it's really not an issue, I guess. There was mention about half-shaft strength and I know it's a concern with Corvette and AC Cobra owners. They take the most abuse when the driveline is hit with big power suddenly, i.e. spinning from a stop. :s Later generation Sharks got larger diameter shafts, but the u-joint stayed the same. Has anyone upgraded to the bigger half-shaft and experienced problems with high horsepower? I know I'll end up smokin' the rear skins ever so often, but I'm not into drag racing anymore. I'll keep you guys posted if I find out any new information. --Bullitt

 

[Ken]

Ya know? I've sorta been folowing this thread for a while but didn't really dwell on it because it was a "Shark" thing on the surface, and of course I don't have one of those.

Lately though I've been thinking that maybe I should pay closer attention and keep this in mind when re-assembling mine after the engine project gets underway. :cool

There's a lot of good stuff so far, keep the ideas coming folks!

_ken