stupid drive shaft. whats better steal or alumn
- Thread starter Orangeracer
- Start date
OT: Anyone going to be in Vegas that has a Shaftmasters aluminum(or steel) driveshaft installed? I'm REALLY curious to see if they are much quiter than my unknown brand driveshaft, which makes a hollow clunk sound when engaging.
I'll answer for him.
Yes it raises the critical speed, and he runs a custom 2 piece. With the speeds these cars can attain, it's a smart move to run a 2-piece (like toyota did)
Yes it raises the critical speed, and he runs a custom 2 piece. With the speeds these cars can attain, it's a smart move to run a 2-piece (like toyota did)
IJ.;1134816 said:
I do not beleive the original poster asked about how big of a difference there is between aluminum and steel. He asked for the best solution given his current situtation. I think most people would agree a one-off aluminum shaft is comparable in price to a steel shaft. If we want we can go into complicated math about chemistry and physics about this. I am a mechanical engineering student so lets get into that.
SySt;1135535 said:
i was once an engineering student who thought I knew everything....
then I hit the real world and learned how little I knew.
SySt;1135535 said:
OK... then tell me why Toyota spent the money on a 2-piece drive shaft that was probably more than twice the cost of a 1-piece?
Poodles;1135709 said:
it just might be for the same reason I bought a new carrier bearing from toyota instead of going for a one piece shaft....
its known as NVH...not something you want in a luxury gt car. (or any car for that matter)
So does the 2 peace stock hurt driving or power transfer at all.. i think i am going to do a 2jz in the near future.
HommerSimpson;1135735 said:
HP is not the issue...DS critical speed, angle to the differential, balance, and torque are the issues.
Orangeracer;1135776 said:
if you're looking for a driveshaft, i have an 11 pound aluminum one made by shaftmasters for $325 shipped
I'm going to throw something out concerning 1 piece drive shafts...the vehicle speeds you would have to reach before the DS hits critical speed RPM are ridiculous...well above the threshold of what the engine/tranny combos are capable of.
Using this calculator...I came up with:
http://www.supramania.com/images/doward/Calculator.xls
Inputs:
Aluminum 6061, 0.125" thickness
Tube length: 39 inches
Diff Ratio: 3.91
275/35x18 rear tires
Output:
Critical Speed: 12,480 rpm
1/2 Critical Speed: 6,240 rpm
Torsional Yield: 1990 ft/lbs.
The torque this DS can handle is 4 times what you would see on a 500 HP car. On my A340E, the max MPH that can be obtained at 7000 RPM is 195 MPH. That is equivalent to a DS critical speed of 10,000 RPM...20% below the calculated critical speed of this drive shaft where failure would occur. 1/2 critical speed is where you have to pay attention to harmonic vibration...this occurs on my car at 120 MPH. DS balance and internal dampening (my Shaftmaster DS used HD foam) is extremely important at this point. Harmonics can set up a stress failure of the shaft over time if it's allowed to happen...my aluminum 1 piece has ZERO vibration at 120 MPH (1/2 critical speed). I can tell little difference between this DS and the 2 piece stock DS in terms of NVH across the RPM range and the highest speeds I've sustained.
Unfortunately, Arizona is not in Germany...hitting the highway doing 120-150 for any prolonged period of time would result in a criminal speeding and/or reckless driving charge. A track car may warrant different consideration depending on the sustained speeds.
Take this for what you will...I'm going to stick with my aluminum DS
Using this calculator...I came up with:
http://www.supramania.com/images/doward/Calculator.xls
Inputs:
Aluminum 6061, 0.125" thickness
Tube length: 39 inches
Diff Ratio: 3.91
275/35x18 rear tires
Output:
Critical Speed: 12,480 rpm
1/2 Critical Speed: 6,240 rpm
Torsional Yield: 1990 ft/lbs.
The torque this DS can handle is 4 times what you would see on a 500 HP car. On my A340E, the max MPH that can be obtained at 7000 RPM is 195 MPH. That is equivalent to a DS critical speed of 10,000 RPM...20% below the calculated critical speed of this drive shaft where failure would occur. 1/2 critical speed is where you have to pay attention to harmonic vibration...this occurs on my car at 120 MPH. DS balance and internal dampening (my Shaftmaster DS used HD foam) is extremely important at this point. Harmonics can set up a stress failure of the shaft over time if it's allowed to happen...my aluminum 1 piece has ZERO vibration at 120 MPH (1/2 critical speed). I can tell little difference between this DS and the 2 piece stock DS in terms of NVH across the RPM range and the highest speeds I've sustained.
Unfortunately, Arizona is not in Germany...hitting the highway doing 120-150 for any prolonged period of time would result in a criminal speeding and/or reckless driving charge. A track car may warrant different consideration depending on the sustained speeds.
Take this for what you will...I'm going to stick with my aluminum DS
John: Worst case scenario was 4.3 diff and a .68 5th in the Tremec with an engine that would pull 8300 in 5th.
I'm not saying a one piece WILL fail just that they can under these circumstances and get a bit tired of people that don't understand the issue shit canning the 2 piece because they're too tight to pay for a bearing.
I'm not saying a one piece WILL fail just that they can under these circumstances and get a bit tired of people that don't understand the issue shit canning the 2 piece because they're too tight to pay for a bearing.
if you're concerned with the 1 piece failing, install some saftey loops for added piece of mind.
Exactly Ian...each situation, tranny/differential/tire configuration, and use of the car is unique. If you go with a one piece, it absolutely must be balanced perfectly...the shop that makes it better be good. Safety loops are a very good idea. The problem with the stock two piece is the dual tube, bonded rear section...if it's twisted up, the shaft is no longer in phase and can cause torsional issues during power transfer. The two piece design is not as dependent on balance and affords a greater safety margin for sure, but the speeds we're talking about is well above 150 MPH on stock tranny/differential components. Not too many folks sustain these kind of speeds on a regular (or if ever) basis.
Material wise, steel is not necessarily "stronger", it has a higher modulus of elasticity allowing flex to the torque applied. The cost is the greater tube weight...3 times what you get with aluminum. Critical speed increases to 12,788 RPM using a steel tube...not a huge benefit when you consider the NVH aspects of using steel. Saying aluminum is limited to xxx HP is completely wrong.
The decision to go 1 or 2 piece needs to be thought through...just giving the OP the tools to do this.
Material wise, steel is not necessarily "stronger", it has a higher modulus of elasticity allowing flex to the torque applied. The cost is the greater tube weight...3 times what you get with aluminum. Critical speed increases to 12,788 RPM using a steel tube...not a huge benefit when you consider the NVH aspects of using steel. Saying aluminum is limited to xxx HP is completely wrong.
The decision to go 1 or 2 piece needs to be thought through...just giving the OP the tools to do this.