Steel or aluminum driveshaft??
06-04-2008, 03:48 AM
#1
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Steel or aluminum driveshaft??
I am in the market for a new driveshaft and would like to know peoples thoughts on steel vs. aluminum. Of course you all have probably read by now my experience on the dyno last week and the driveshaft snapping in 3 pieces. The stock one was only an 1/8 inch thick to our surprise, so we were thinking somewhere in the neighborhood of a 1/4 inch thick aluminum shaft and stronger U-joints?? Thanks!
06-04-2008, 05:39 AM
#2
Aluminum is no good for trucks putting down alot of power at high speeds. Because aluminum is lightweight it's length can be much longer than a steel DS, this is great for CC's and big SUV's which have longer wheel bases and in general aren't built to go 150mph. Steel DS have a tendency to sag the longer they become due to their increased weight. But because of a aluminum DS additional length it's diameter has to grow proportionally in order to maintain it's strength. And because of its wider diameter it's rotational mass is moved further from the center axis which means the lower it's critical speed becomes before she breaks. You can strengthen and balance a Aluminum DS but the issue still remains, and you therefore cannot spin it faster than a comparable steel one.
Also the longer you make it the heavier it's gonna become, and in order to keep the weight down they are hollow. Being hollow creates another issue, since the walls are so thin it leaves the DS vulnerable to direct side impacts and any significant damage will unbalance the DS and she will wobble herself to death. A small ball peen hammer can easily damage an aluminum DS enough to reach that point so imagine what kind of damage a stray rock or a flying tire weight or in some cases (mine included) a cross member can do.
Third drawback is it's length. The longer you make it the more it's vertical travel will become and the more clearance you will need from frame and crossmembers. I encountered that problem and my stock DS was hitting my stock cross member when flexing and rubbing itself down and eventually would have broken in two.
Pro's of Aluminum:
Lightweight
Can be much longer than similar steel ones
good for high torque applications
Con's of Aluminum:
Break easy at high rotational speeds
Wide diameter
Not as durable to abuse as steel
Hollow
Hope this helps!
Also the longer you make it the heavier it's gonna become, and in order to keep the weight down they are hollow. Being hollow creates another issue, since the walls are so thin it leaves the DS vulnerable to direct side impacts and any significant damage will unbalance the DS and she will wobble herself to death. A small ball peen hammer can easily damage an aluminum DS enough to reach that point so imagine what kind of damage a stray rock or a flying tire weight or in some cases (mine included) a cross member can do.
Third drawback is it's length. The longer you make it the more it's vertical travel will become and the more clearance you will need from frame and crossmembers. I encountered that problem and my stock DS was hitting my stock cross member when flexing and rubbing itself down and eventually would have broken in two.
Pro's of Aluminum:
Lightweight
Can be much longer than similar steel ones
good for high torque applications
Con's of Aluminum:
Break easy at high rotational speeds
Wide diameter
Not as durable to abuse as steel
Hollow
Hope this helps!
06-04-2008, 07:14 AM
#3
Aluminum is no good for trucks putting down alot of power at high speeds. Because aluminum is lightweight it's length can be much longer than a steel DS, this is great for CC's and big SUV's which have longer wheel bases and in general aren't built to go 150mph. Steel DS have a tendency to sag the longer they become due to their increased weight. But because of a aluminum DS additional length it's diameter has to grow proportionally in order to maintain it's strength. And because of its wider diameter it's rotational mass is moved further from the center axis which means the lower it's critical speed becomes before she breaks. You can strengthen and balance a Aluminum DS but the issue still remains, and you therefore cannot spin it faster than a comparable steel one.
Also the longer you make it the heavier it's gonna become, and in order to keep the weight down they are hollow. Being hollow creates another issue, since the walls are so thin it leaves the DS vulnerable to direct side impacts and any significant damage will unbalance the DS and she will wobble herself to death. A small ball peen hammer can easily damage an aluminum DS enough to reach that point so imagine what kind of damage a stray rock or a flying tire weight or in some cases (mine included) a cross member can do.
Third drawback is it's length. The longer you make it the more it's vertical travel will become and the more clearance you will need from frame and crossmembers. I encountered that problem and my stock DS was hitting my stock cross member when flexing and rubbing itself down and eventually would have broken in two.
Pro's of Aluminum:
Lightweight
Can be much longer than similar steel ones
good for high torque applications
Con's of Aluminum:
Break easy at high rotational speeds
Wide diameter
Not as durable to abuse as steel
Hollow
Hope this helps
Also the longer you make it the heavier it's gonna become, and in order to keep the weight down they are hollow. Being hollow creates another issue, since the walls are so thin it leaves the DS vulnerable to direct side impacts and any significant damage will unbalance the DS and she will wobble herself to death. A small ball peen hammer can easily damage an aluminum DS enough to reach that point so imagine what kind of damage a stray rock or a flying tire weight or in some cases (mine included) a cross member can do.
Third drawback is it's length. The longer you make it the more it's vertical travel will become and the more clearance you will need from frame and crossmembers. I encountered that problem and my stock DS was hitting my stock cross member when flexing and rubbing itself down and eventually would have broken in two.
Pro's of Aluminum:
Lightweight
Can be much longer than similar steel ones
good for high torque applications
Con's of Aluminum:
Break easy at high rotational speeds
Wide diameter
Not as durable to abuse as steel
Hollow
Hope this helps
Not to thread jack but way did you go with ur DS? reason being I'll be looking for a replacement myself when I get back I dont trust the stock one nomore...
06-04-2008, 08:13 AM
#6
Staging Lane
I'm going with a 2 piece steel ds, I'm just making a bracket for the center bearing. When I asked the engineer what the max hp would be for the ally shaft, he did some calc's and came back with 465 bhp. the steel one's he's building for me calc out at 1200bhp.
06-04-2008, 10:00 AM
#7
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i've been there done that, broke a stock steel driveshaft and a "heavy duty steel" locally built driveshaft. had it with breaking tranny's and driveshafts so i called Denny's and he told me the only thing that would work in my app is Aluminum or Carbon Fiber, but he didnt sell those
Aluminum was 500
Carbon was 1000
i got a Denny's aluminum and it hasent failed me yet even blasts up to 140 or so, what is really a piece of mind is i get zero vibrations at any speeds during WOT
Aluminum was 500
Carbon was 1000
i got a Denny's aluminum and it hasent failed me yet even blasts up to 140 or so, what is really a piece of mind is i get zero vibrations at any speeds during WOT
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06-04-2008, 11:47 AM
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465 seems hellaciously low considering the stockers are good for much more than that.
https://www.performancetrucks.net/fo...ted+driveshaft
https://www.performancetrucks.net/fo...ted+driveshaft
06-04-2008, 12:35 PM
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Thanks for all your help guys. I decided to go with a one piece aluminum driveshaft that will be custom built for my app. I also got lucky and found a case and tail for my 4l60e tranny for total cost of 120 w/shipping. Now i just need to figure out how I want the exhast done, finish the tuning we started and hope that everything works out. I am hoping for around 500rwt and about 385-400rwhp. I think i will be done for now, since I will forking aver another 3 or 4 grand.