Need addvice on a new drive shaft

[murphy41]

This.

I don't know why everyone thinks their truck is special that a normal local drive shaft shop cant do it. Just tell them what you do with the truck and they will know more about it then you will. Its their job.

I agree with Lee here. When I did my manual to auto conversion I needed mine lengthened. I took it down to the local drive shaft shop that has done race car stuff for 20 years. Told the lady that owns/runs the shop what I needed, and what I was doing with the truck. And instead of lengthening the original shaft. She build me a completely new drive shaft using .120 tubing, and all new end yokes. With new joints. Think it cost me $210 to have it built. I also asked her if the added weight would affect the truck and if aluminum would be better. And she said in all honesty, With the torque the diesels make I don't think it'll be a substantial notice. And if I wanted reliability, the .120 steel one was the way to go.

I see the OP got a drive shaft. But info is always good for future search results.

 

[Supershafts]

In all fairness, Jim (f6jbob) is about as hard on a driveline as anybody. Not to say that he abuses it, but he's launching with slicks in a 2wd truck. He's got his sh!t together with that truck and it flat hooks.

I used to love watching him launch his old truck and was amazed at how hard he would come out of the hole and not worry about driving it home (sometimes >15hrs from home). The way that truck short tracks gives him plenty of time on the big end to work his magic and boot many a racer off the ladder in the 12.0 class. His trophy shelf looks like the awards table at a national event. LOL

OP, good luck with your new parts.

Here's the thing though, it's a 2x truck which is lighter than a 4x truck, so having made shafts in the 1 pc conversion since the 90's as a alternative for the stub slip when they wore out, and performance and racing use and my own testing which no one in there right mind would ever do, it does raise the question how he did.
Thing is length and diameter are important to shaft design for the power, weight and speed, for any vehicle not just trucks or cars, even boats everything is important to how the shaft is made.
Having dodge trucks in the high 11's on 4" shafts, having the SRT's and diesels in the 300hp to 900hp even a few over that, but that area can equate to 700 and 1900 ft lbs.
None have failed.
That's just trucks since the 90's, forget the cars and boats

I didn't actually lengthen my original shaft. I replaced the tube with a longer tube from a dodge pu. I just thought I should clarify that. I reused both ends from my shaft.

Looking at the pics from what i can see it looks like it was a 4.5" tube, as best i can make out, it does look appear to be a factory style used in ford, what is the wall dimension ? is it .083/5, .065. .090 or .110 ?, the weld yokes appear to be 1410 visteon, it's hard to see as im not holding it in my hands but i am curious.
As i have 4" shafts which are exceeding 12's, and that shaft seems short and not in the 70" to 90" area
Measure that wall dimension and the diameter and overall length.
When it broke also, odd that it twisted and broke the weld.


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I agree with Lee here. When I did my manual to auto conversion I needed mine lengthened. I took it down to the local drive shaft shop that has done race car stuff for 20 years. Told the lady that owns/runs the shop what I needed, and what I was doing with the truck. And instead of lengthening the original shaft. She build me a completely new drive shaft using .120 tubing, and all new end yokes. With new joints. Think it cost me $210 to have it built. I also asked her if the added weight would affect the truck and if aluminum would be better. And she said in all honesty, With the torque the diesels make I don't think it'll be a substantial notice. And if I wanted reliability, the .120 steel one was the way to go.

I see the OP got a drive shaft. But info is always good for future search results.

How can you have a new AL shaft built and the tube costs just under 200 and thats for 3.5" ?

Unless they're using some extruded tube which is not that same as 6061 alcoa tube which is not extruded and also straightened to within .0005

If you really paid 210 it wasn't new parts or its not the right stuff and i'd be nervous with that.
I couldn't build a stl shaft for 210 unless i used all the china parts like others do.
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[Supershafts]

if aluminum would be better. And she said in all honesty, With the torque the diesels make I don't think it'll be a substantial notice. And if I wanted reliability, the .120 steel one was the way to go.

wow really missed that part....

So she made you give up increased acceleration and about 1 to 2 mpg depending which shaft configuration your truck came with.

Diesel or not, weight in the driveline is just as important, to performance and mileage.
It's why some of the heavy trucks go to CF stuff, thats all for the sole primary purpose of mileage.

 

[murphy41]

It wasn't aluminum. And they sold the parts to me at cost because they had ordered them in for someone else and they backed out and had been sitting on the parts for awhile. I also should have clarified that the $210 was for the carrier back piece. As I didn't have the upper piece built at the time. I apologize on not clarifying. I had the upper piece built later on.

 

[murphy41]

wow really missed that part....

So she made you give up increased acceleration and about 1 to 2 mpg depending which shaft configuration your truck came with.

Diesel or not, weight in the driveline is just as important, to performance and mileage.
It's why some of the heavy trucks go to CF stuff, thats all for the sole primary purpose of mileage.

Mileage was the last thing I was concerned about.

 

[f6jbob]

It never broke any welds. It twisted it in half. Thats all. The front half came out of the tranny and left the truck. I had to unbolt the back from the rear end. This all happened as I launched from the starting line.

 

[Supershafts]

Mileage was the last thing I was concerned about.

Were you concerned about performance ??? because you lost that too.

I don't see why you would only do the rear half, and then doing a 2 piece and making it heavier is hurting you more than helping.

In a 2 piece configuration you are technically running two shafts that are balanced as a assembly, but they each hold a specific power and speed rating, so the benefit of a 2 piece is like what mercedes and bmw do, run lighter shafts and the least diameter they can, yet having all the power and economy they can get.
Depending what you're making you wouldn't need more than a 3.5" 2 piece in .083 wall, and increasing that a mear .010 would add more power capability, yet still be lighter which will give you better perf and mileage than having that 4" .120 wall.

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[Supershafts]

It never broke any welds. It twisted it in half. Thats all. The front half came out of the tranny and left the truck. I had to unbolt the back from the rear end. This all happened as I launched from the starting line.

What were the specifics of that shaft ?

length __. Diameter __. Wall dimension .___

Then your trans, hp, weight

 

[Supershafts]

So seems you had a .065 shaft, get back to me on the diameter, either way though its at best going to be 4.5", but i think it's gonna be 4" and 4" or 4.5" at .065 isn't a performance shaft, that is a mpg shaft.

Had you had the shaft built and used even the .083 over the .125 you never would have had that happen.

The difference between .065 wall and .083 wall in torque capacity is nearly 1000 ft lbs, whether it's 4" or 4.5".
So having the .065 tube with 4" and you have a issue to deal with at 3600ft lbs, whereas the .083 tube moves it up to 4700, the .125 moves it up further to 6600 area.

It's quick math figures, but that's the areas of torque you're in with the shaft.

The shop you used never should have put that shaft together for what you were doing and the performance you had.


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[Hurley]

So seems you had a .065 shaft, get back to me on the diameter, either way though its at best going to be 4.5", but i think it's gonna be 4" and 4" or 4.5" at .065 isn't a performance shaft, that is a mpg shaft.

Had you had the shaft built and used even the .083 over the .125 you never would have had that happen.

The difference between .065 wall and .083 wall in torque capacity is nearly 1000 ft lbs, whether it's 4" or 4.5".
So having the .065 tube with 4" and you have a issue to deal with at 3600ft lbs, whereas the .083 tube moves it up to 4700, the .125 moves it up further to 6600 area.

It's quick math figures, but that's the areas of torque you're in with the shaft.

The shop you used never should have put that shaft together for what you were doing and the performance you had.

While you're at it, and for discussion's sake, can you explain the difference in energy required to spin either of the two shafts that makes up the difference in fuel economy?

 

[f6jbob]

So seems you had a .065 shaft, get back to me on the diameter, either way though its at best going to be 4.5", but i think it's gonna be 4" and 4" or 4.5" at .065 isn't a performance shaft, that is a mpg shaft.

Had you had the shaft built and used even the .083 over the .125 you never would have had that happen.

The difference between .065 wall and .083 wall in torque capacity is nearly 1000 ft lbs, whether it's 4" or 4.5".
So having the .065 tube with 4" and you have a issue to deal with at 3600ft lbs, whereas the .083 tube moves it up to 4700, the .125 moves it up further to 6600 area.

It's quick math figures, but that's the areas of torque you're in with the shaft.

The shop you used never should have put that shaft together for what you were doing and the performance you had.


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I gave you the diameter when I gave you wall thickness.
4.5 inches. I'm just giving my experience with an aluminum shaft. Obviously I screwed up not going to a thicker shaft. Penny cheap and dollar foolish on my part.*bdh*

 

[Supershafts]

I gave you the diameter when I gave you wall thickness.
4.5 inches. I'm just giving my experience with an aluminum shaft. Obviously I screwed up not going to a thicker shaft. Penny cheap and dollar foolish on my part.*bdh*

The only reason i commented was because of this mistake*, and the mistake on that shop for not making the right call on the tube used.

*So I lengthened the aluminum shaft. Bad move on my part. I went with 4" steel. I don't remember wall thickness but more than stock.

Now your experience doesn't/didn't make AL the problem, your experience was with someone not all that experienced at there craft.

.l

 

[Supershafts]

While you're at it, and for discussion's sake, can you explain the difference in energy required to spin either of the two shafts that makes up the difference in fuel economy?

The best way to and easiest way to describe driveline gains is by comparing it to carrying weight.

So if we remove a pound in the driveline it is equal to 15 to 20 lbs of carrying weight, mostly cars will get the 20 lb effect while trucks and light trucks get the 15 lb effect.
So when you go from a 2pc assembly of/in the 60 lb area and go to a 25/27lb shaft it is equal to and feels like you lost 500 lbs.
That loss takes less energy to start and accelerate, and the benefit to easier pulling, and quicker performance also gains in mpg because you aren't using more energy to turn heavier weight.

Same holds true with flywheels, harmonic balancers and internal trans parts, on the inside of the motor it's grams instead of pounds.
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[kevinsmachine]

I can do any kind of shaft u need