LMM: Drive shaft wall thickness question

[Frankin_truck]

I finally got to make my first pull on the weekend with my new set up. Well long story short my stock lmm aluminum drive shaft did not like 940hp going through it lol. So looks like I need a stronger shaft and I am leaning toward steel 4" shaft. To do that I have to change to 1480 ujoints (lmm have 1485 .010" narrower) where I am having a hard time deciding is what size tube do should I go with? Options are .083" or .095" wall (all 4" O.D)that's the biggest I can get 1480 4" weld on yokes. I can get .130" wall 4" O.D tube that I could machine the end of it to accept the .095" weld on yoke or am I going way over kill???? That do some most truck 2.5 2.6 trucks run for a drive shaft??

 

[THEFERMANATOR]

If your truck came with an aluminum shaft, then a steel shaft is not going to work. Going up to a larger diamter steel is going to greatly increase your rotating mass, and is also going to run into critical speed issues much sooner. So unless this is a dedicated puller, stick with an aluminum shaft. Go to .125 4 1/2" aluminum shaft, and call it a day.

 

[duramaxzak]

I run a 5"X.125" aluminum shaft with 1485 joints on my puller.

http://www.driveshaftspecialist.com/Truckhtml/Chevy-GMC.html

 

[Frankin_truck]

The stock aluminum shaft is 5". I wish I could get a heavy duty aluminum faster but I am limited where I live. I see most ext. short box trucks run a 3.5" steel tube they can't be much shorter then a ccsb wheel base? I haven't done the math but the critical speed issue I wouldn't think would be far off if the ecsb runs a 3.5" tube if I jump up to a 4" tube should be close?

 

[Frankin_truck]

Duramaxzak have you ever had front shaft issues?

 

[messejme]

I think he is saying that the increased mass of the steel shaft's characteristics cause problems on drive trains that came with aluminum shafts.

 

[duramaxzak]

Duramaxzak have you ever had front shaft issues?

No, I run a stock front shaft with solid u-joints (non greasable)

 

[Yellow Jacket]

4" X .095" is plenty of steel driveshaft, that's all we've ever run and still run in our 3.0 truck. And that is what I ran in my 948rwhp twins truck also...

For street duty, the 5"-6" aluminum is the way to go...

 

[mike diesel]

Hmm still running my factory aluminum shaft in my truck. 1000whp. I should probably get my hoops put on.

 

[Frankin_truck]

4" X .095" is plenty of steel driveshaft, that's all we've ever run and still run in our 3.0 truck. And that is what I ran in my 948rwhp twins truck also...

For street duty, the 5"-6" aluminum is the way to go...

did you run your truck with the twins on the street? I really want to have it up and running to this friday for a pull so maybe i will look into getting a aluminum 5"-6" for street use, i order a 4" .095" wall steel one see how it works. Do you run a billet yoke? or waste of money?

 

[moparkxracer]

This is what I'm running,

 

[duramaxzak]

I run this yoke from DHD.

http://dirtyhookerdiesel.com/i-1490...1480-american-axle-mfg-aam-11-5-rear-end.html

 

[moparkxracer]

Are you running that on the street? I'm interested in getting one but not ute on getting rid of the stock one with the rubber vibration absorber

I run this yoke from DHD.

http://dirtyhookerdiesel.com/i-1490...1480-american-axle-mfg-aam-11-5-rear-end.html

 

[duramaxzak]

Are you running that on the street? I'm interested in getting one but not ute on getting rid of the stock one with the rubber vibration absorber

No, track only since I installed it.

 

[Frankin_truck]

This is what I'm running,

That is one piece of art lol

 

[moparkxracer]

It really is!! Shame to have it under the truck. The u joints look tinny but they are 1480.

 

[Frankin_truck]

Hmm still running my factory aluminum shaft in my truck. 1000whp. I should probably get my hoops put on.

Depends what you do with your truck lol. My stock aluminum shaft hung together for lots of high hp pulls on the dyno on thrusday and then broke on saturday at the track on my first pull with the built motor lol. Cant win sometimes

 

[Yellow Jacket]

Hmm still running my factory aluminum shaft in my truck. 1000whp. I should probably get my hoops put on.

I dumped and had lots of street use on stocker, when I went back to long road use I used to go back to stocker until I got my current billet aluminum...

Sled pulling stocker gave up first hook, drag racing and street got nothing on sled pulling as far as being hard on driveline parts IMO...

I never had a billet yoke, but I just bought one for a customer, definitely a sexy piece... And I broke 2 yokes in one summer, I just didn't have $600+ for the billet one...

 

[duramaxdiesel]

When I snapped my aluminum shaft on my CCSB LMM I asked the shop if I could have a steel shaft made like the one on my ECSB. He said no. Something about it blowing up after a certain RPM or speed. Never understood that.


Nick

 

[Yellow Jacket]

When I snapped my aluminum shaft on my CCSB LMM I asked the shop if I could have a steel shaft made like the one on my ECSB. He said no. Something about it blowing up after a certain RPM or speed. Never understood that.


Nick

I never really understood either, but with steel, I would get a resonance more than a vibration at 70+.... But I tuned a c4500 with a rollback on it, one driveshaft was lengthened to 80+ inches... During the road test the driveshaft twisted out from under the truck at 85mph and pogostuck the pavement, pretty scary deal from the cab and seeing parts bouncing down the highway in the rearview mirror...