Aluminium vrs steel driveshaft

[Matthew Jeschke]

My 2001 Tahoe setup has a steel driveshaft. I've been curious why GM / Chevy switched to Aluminium. I'd think they'd break easier? I see claims they make better gas mileage but wouldn't that be EXTREMELY minimal. Like a 1/10 of a MPG maybe? They are lighter but all the mass is near the center anyways so it takes very little torque to spin no?

Reason it's on my mind is... There's several laying at the junkyard I could swap onto my truck. Wondering if I should grab one and try it

 

[exp500]

The aluminum D/s is generally a larger dia. and wall thickness. Second issue is any rotating aluminum WILL fail. Thought that was in Engineering 101. BTW ever see aluminum D/S on Class 8 trucks? Think cheap reliable.

 

[Matthew Jeschke]

Yeah, makes since. I'd think the steel driveshaft would be superior, especially cause is smaller diameter possibly of negating potential advantage of aluminium which is a bigger diameter (moment of inertia). I was surprised when I started working on these trucks and a few others to see aluminium driveshafts. I'd think maybe on a sports car but even then, as you mentioned, I'd think soft metal would just rip w/ enough torque. Kind of wondered if my thinking was wrong but you seem to confirm it.

Also the steel driveshaft on these GMT800 trucks is really light to begin with. I mean how much performance could an even lighter (if that) driveshaft provide. Makes no sense.

 

[strutaeng]

Interesting. OP, do you know when they went to aluminum? Could be related be cost of raw materials when vehicles being manufactured. Otherwise, it was probably just to reduce weight? My 06 Suburban 2500 2wd is aluminum. I've got a similar project 04 suburban, but 4x4. I don't remember if that one is steel or aluminum.

The 06 Suburban driveshaft is larger diameter. Also, it's single piece. Obviously, steel is much stronger than aluminum (about a factor of 3 iirc) so to keep the torsional strength equal (relatively speaking), the outer diameter of the aluminum version needs to be greater than the steel version - but not 3 times greater because stresses are not a linear function of diameter.

My 99 Silverado ECSB 2wd and my K3500 CCLB are both steel driveshafts and 2 piece.

And I want to say our 2020 Express 3500 passenger van is also aluminum and single piece? I will check later (it's raining here) and will edit if necessary to avoid giving out wrong information.

So I don't see an issue swapping to an aluminum version so long as it's the same wheelbase and donor vehicle matches gvwr.

 

[Matthew Jeschke]

@strutaeng interesting! You're one smart guy. Are you a mechanical engineer? I studied computer engineering back in the day so know enough to be dangerous with the machinal load stress stuff.

I was just mainly curious about the Aluminium as I could probably get one for peanuts. Internet search lends one to think it's for performance / efficiency reasons... However, cost of materials makes more since in my mind.

After this post, I think I'll stick with my steel driveshaft. My truck primarily exists off road, not sure I want to chance the aluminium, especially if it gets dented. I also built it up with HD components & modified a 6.0L for it.

 

[strutaeng]

@strutaeng interesting! You're one smart guy. Are you a mechanical engineer? I studied computer engineering back in the day so know enough to be dangerous with the machinal load stress stuff.

I was just mainly curious about the Aluminium as I could probably get one for peanuts. Internet search lends one to think it's for performance / efficiency reasons... However, cost of materials makes more since in my mind.

After this post, I think I'll stick with my steel driveshaft. My truck primarily exists off road, not sure I want to chance the aluminium, especially if it gets dented. I also built it up with HD components & modified a 6.0L for it.

Me, smart?! Nah, I'm average.

I'm a civil (structural) engineer, just understand these concepts from statics/dynamics and strength of materials classes (which mechanical/aerospace majors also take).

Yeah, for your use, steel is probably a better option. Interestingly, I had asked my buddy that has an 06 Duramax 2500HD CCSB 4x4 and he also said his is a single piece aluminum.

Nice! Sounds like you have a sweet rig!

Cheers!

 

[Matthew Jeschke]

Thanks @strutaeng The GMT800 chassis is really fun to work on. I bought a C5 years ago but haven't touched it. Nightmare to work on. Needed something to tinker with!

Civil Engineering sounds about right. It was just that fellow engineer radar haha. Civil is really cool especially because we had more girls in the statics and dynamics classes haha. I only got the intro ones but you guys actually use math! Super cool. Computer engineering was some electrical stuff but once I got in real world all they wanted was programming *ug* I quit.

 

[Trey Hardy]

My 2001 Tahoe setup has a steel driveshaft. I've been curious why GM / Chevy switched to Aluminium. I'd think they'd break easier? I see claims they make better gas mileage but wouldn't that be EXTREMELY minimal. Like a 1/10 of a MPG maybe? They are lighter but all the mass is near the center anyways so it takes very little torque to spin no?

Reason it's on my mind is... There's several laying at the junkyard I could swap onto my truck. Wondering if I should grab one and try it

Just my 2c you would need to be making some serious Hp to snap one of those aluminum driveshafts I wouldn’t worry about it that much personally the aluminum is pretty strong for what it is and I’ve seen some of my buddy’s beat the immortal dog shit out of their trucks raising hell and mudding and they always would break a u joint or break the rear differential I’ve never seen them break a driveshaft and I’ve seen them do some pretty crazy shit

 

[Matthew Jeschke]

Oh cool, that's good to know. My father's truck has one, F150 w/ coyote motor. Pretty sweet engine, but I've not had a chance to take it for a joy ride

That said in the 90's he bought a GMT400 Silverado and then a Suburban. I was in my teens then and new driver! We had a couple OBS ones but I was just a little tike then. Um those GMT400's were, indestructible, don't ask me how I know. Those things were so tough, that well it sold me on one as an adult