Drive shaft- alum vs moly vs carbon vs price ?

[FUNFER2]

I've only used steel, so I'm curious about the others. I looked up a few carbon fiber users on the internet. Some lov'em other say there's not much weight savings to made a difference, they cost much more and damage more easily than even aluminum. (really)?

Carbon fiber just looks and sounds cool. lol....

(maybe ain't worth a crap, I don't know)

Or, with as short as the shaft is in our Cobra's, don't matter anyhow pa.

What do you have and why ?

[Dirty Harry]

I wanted my driveshaft shortened a little more and took it to a driveshaft specialty shop. I told them I wanted it re-balanced after shortening. They said that they would, but said that a shaft that short really wouldn't require it. Apparently, it's the 4-footers that develop harmonic vibrations and such. For cost and durability, I don't think you can beat steel for a 13 incher. I've had my car for 25 years and no one's ever seen my nicely painted driveshaft but me.

[twobjshelbys]

No need to get exotic and spend a gazillion dollars. What driving conditions are you going after that will exceed the capabilities of what the standard is? CSX3170 probably drives his car harder than anyone here. Don't get any more than what he has.

[mdross1]

When I had my shaft built it was with a thicker wall tubing, knowing the car would be drag raced using slicks. Given that these cars are not that heavy even power shifting doubt there would ever be shaft problems.

[Tommy]

There are guys who spend an extra $10,000 just to have an extra 150 HP on their dyno sheet that they will never effectively use. So if the goal is bragging rights, go for the most expensive one. But if the goal is performance, I suggest most buy a steel or aluminum drive shaft and spend the money saved by not buying a carbon fiber shaft on other, more effective performance enhancements (e.g., driving school). ... I agree with those who said the drive shaft on most Cobra replicas is too short for its construction to make much difference.

[Dwight]

I load tested a stock steel Mustang shaft for 13 yrs and 42,000 miles in a Lone Star. Never broke it.

I vote to go with stock steel unit in a street car. I think mine was about 19" long. And when I had it balanced I told the guy to make sure is was good to 150 MPH. I wanted smooth.

Ditto what Tommy said

Spend your money on something like good tires.

Dwight

[Morris]

The secret is not the driveshaft.......it's using the larger Spicer 1350 u-joint at both ends....especially since it's a few inches away from your body.....

[1795]

Originally Posted by Morris

The secret is not the driveshaft.......it's using the larger Spicer 1350 u-joint at both ends....especially since it's a few inches away from your body.....

Was waiting to hear your input on this one Morris. Wanted to have mine set up right.

Jim

[Morris]

Originally Posted by 1795

Was waiting to hear your input on this one Morris. Wanted to have mine set up right.

Jim

Jim

You might have to change the Yoke on the Pinion nose cause most Dana 44's have a Yoke for a Spicier 1310 U-Joint... and they are fine for the street where they don't tax the drive line.... but racing .... is a different story.

You can buy a yoke for the transmission any size you want. stay with good quality products.

[patrickt]

Originally Posted by Morris

Jim

You might have to change the Yoke on the Pinion nose cause most Dana 44's have a Yoke for a Spicier 1310 U-Joint... and they are fine for the street where they don't tax the drive line.... but racing .... is a different story.

You can buy a yoke for the transmission any size you want. stay with good quality products.

This is kind of interesting. The theory at ERA, when they were building my car, was that for a predominantly street driven build, they wanted a Spicer 1330 Series on the front of the driveshaft, and a 1310 Series on the back of the driveshaft. Their theory was that if something locks up badly, and one of the u-joints is definitely going to go, then they wanted to control which one did, and they wanted the rear to be the one that went. Of course there's a driveshaft hoop and, their theory is they wanted the driveshaft flopping around only until you threw the clutch in, not until you came to a stop. Over the last decade, I've heard smart engineers endorse that theory and other ones call it stupid. So, pick your poison, I guess....

[Morris]

Originally Posted by patrickt

This is kind of interesting. The theory at ERA, when they were building my car, was that for a predominantly street driven build, they wanted a Spicer 1330 Series on the front of the driveshaft, and a 1310 Series on the back of the driveshaft. Their theory was that if something locks up badly, and one of the u-joints is definitely going to go, then they wanted to control which one did, and they wanted the rear to be the one that went. Of course there's a driveshaft hoop and, their theory is they wanted the driveshaft flopping around only until you threw the clutch in, not until you came to a stop. Over the last decade, I've heard smart engineers endorse that theory and other ones call it stupid. So, pick your poison, I guess....

In all of our Race Cars and all of the Trans Am Cars I drove and maintained over the last 30 years .... we use a Spicer 1350 U-joint and have never had a failure......

Do you think there is a reason for using the best products you can use ......

Lose a race or DNF in a Race and you'll understand why you never error on the side of Questionable products.... Always go with the Quality and Safety products. Especially when it's in the car next to your legs and butt.

[patrickt]

Agreed. Do you see any sense in having one u-joint intentionally larger, or smaller, than the other u-joint with the intention of controlling which one goes in the event that something happens that forces the occurrence of one of them having to go? Or was that just a case of an engineer over-thinking the equation....

[Morris]

Here's the difference..... you make the choice....



and this is a Mark Williams Trans Yoke

[patrickt]

Right, but if one of the u-joints has to go -- do you care which one it is? And you can't say "I'm going to build those u-joints so big that neither one will ever go." You have to pick one, or the other, or say it doesn't matter.

[Morris]

Originally Posted by patrickt

Agreed. Do you see any sense in having one u-joint intentionally larger, or smaller, than the other u-joint with the intention of controlling which one goes in the event that something happens that forces the occurrence of one of them having to go? Or was that just a case of an engineer over-thinking the equation....

Patrick

Engineers always try to figure out smaller ways to to do things and that's there profession...... but Experience has overcome many engineering idea's....

So I believe we should listen to them then use our experience to make a intelligent decision on the side of Speed and Safety.

But when you are spinning a Drive Shaft at 7500 rpm's next to your body.... well that ends the question....

And I don't want a driveshaft failing on the rear or front on my car for one second.... the drive shaft can do a lot of damage in 2-3 seconds that it's going crazy.......you may not be able to put the clutch in at that point........that is just not smart....

That's like walking up to a Tiger and slapping him in the face and saying "now you got 2-3 seconds to go like mad".....

[patrickt]

Nobody wants any u-joints failing any where, any time. But, if the little race fairy said to you "Morris, one of your driveshaft u-joints is going to fail. I'm not going to tell you when or how it's going to fail, but I'm going to let you pick whether it's the front or the back one." What would you tell the race fairy?

[Morris]

Originally Posted by patrickt

Nobody wants any u-joints failing any where, any time. But, if the little race fairy said to you "Morris, one of your driveshaft u-joints is going to fail. I'm not going to tell you when or how it's going to fail, but I'm going to let you pick whether it's the front or the back one." What would you tell the race fairy?

Patrick

I'd tell the Race Fairy to go Kiss a Rattle Snake and tell me how it feels....

I might then tape a photo of my car's front end on their mirror.... so they see what it looks like ..... cause all they are going to see is my Rear end in the Race....

Then tell her that there are other Competitors out there that need her advise...Please feel free to talk to them......

[patrickt]

Well the race fairy says you're no fun. I'll try it this way then, from a purely theoretical standpoint, do you see any difference, in any regard, from a failure of the front u-joint versus a failure of the rear u-joint? Or do you view the failure of either as being, essentially, an identical occurrence?

[FUNFER2]

Patrick, that actually makes a lot of sense.
Thank you.

[scottj]

When we were running ball spline transmissions a carbon fiber driveshaft was the only type we used. In the Cobra I'm running 1350's on an 8" steel driveshaft.