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Splurged on a DSS driveshaft
- Thread starter BlitzVR4
- Start date
IncorpoRatedX
Well-known member
what a rip off, anyone really into 4x4's that looks at this thread will know what im talking about.
Yeah, I bought a Tom Woods expanding front U-joint driveshaft for my Jeep ZJ for less than $300...But, these are not a dime a dozen, either (for aftermarket). Heck, even the 'velle shaft is relatively cheap, including upgrading the pinion(s) to accept 1350 U-joints...However, an aftermarket shaft for the GTO would be just as much, I think...it too uses a multi piece.
It's like headers. I picked up 1 3/4" full, equal length for
It's like headers. I picked up 1 3/4" full, equal length for
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Dialcaliper
Well-known member
You've got it sort of backwards, but sort of not.
A piece made out of steel is significantly stiffer than the *same* piece made out of aluminum.
However it all depends on how you make the piece. The cross section can change everything, as can the application. *By weight*, aluminum and carbon steel have the same "stiffness", but the aluminum part has to be 3x as thick for the same weight, which causes problems in a driveshaft. The reason being, that stiffness and strength also relate to the diameter, not just the material strength - a steel driveshaft can concentrate all of its mass towards the outside resulting in a stiffer, stronger shaft (in torsion).
To make even more fun, the cross section makes a lot more difference in a twisting shaft than it does in bending (bending stiffness is a square of the radius, twisting stiffness is to the 4th power)
Flywheels are a completely different story - you can make a light flywheel from any material, but since aluminum conducts heat better and has twice the thermal capacity (so it runs cooler), it's a better choice for that reason alone, not because it's lighter or stronger.
In terms of strength to weight ratio, aluminum (6061 alloy used in driveshafts) is significantly better than carbon steel, but not as good as properly heat treated chromoly (also the advantage being, it doesn't need the same kind of heat treating post-machining).
In the end, the Aluminum driveshaft is not as strong or as stiff as a chromoly one of the same weight could be, but because it is more flexible in torsion, so it transfers less shock load to the rear axle. In a drag car where you are launching and straining the drivetrain a lot, but always under power, more flexible ends up being good. In a track car, where you are running on the edge of grip in all directions, and alternately straining the shaft in both directions repeatedly (engine braking under deceleration as well), stiffer is better, since it will be more predictable. Also, the steel has better fatigue resistance.
If that weren't enough, in driveshafts, a factor even more important that simple strength and stiffness is "critical speed", or the rotation speed at which the shaft will resonate and tear itself to pieces. This speed depends on diameter, stiffness, weight and
also tube length, which is why DSS did not make a one piece shaft. Ideally you want a lightweight, stiff, thin material with a short, large diameter shaft (Carbon fiber anyone?) for higher critical speed.
Quoting gtluke:
steel twists more than aluminum. aluminum has no flex, which is why your springs are always made out of steel.
the reason for the shaft is to reduce rotational weight. it works the same way as an aluminum flywheel. it also saves considerable weight off the car.
A piece made out of steel is significantly stiffer than the *same* piece made out of aluminum.
However it all depends on how you make the piece. The cross section can change everything, as can the application. *By weight*, aluminum and carbon steel have the same "stiffness", but the aluminum part has to be 3x as thick for the same weight, which causes problems in a driveshaft. The reason being, that stiffness and strength also relate to the diameter, not just the material strength - a steel driveshaft can concentrate all of its mass towards the outside resulting in a stiffer, stronger shaft (in torsion).
To make even more fun, the cross section makes a lot more difference in a twisting shaft than it does in bending (bending stiffness is a square of the radius, twisting stiffness is to the 4th power)
Flywheels are a completely different story - you can make a light flywheel from any material, but since aluminum conducts heat better and has twice the thermal capacity (so it runs cooler), it's a better choice for that reason alone, not because it's lighter or stronger.
In terms of strength to weight ratio, aluminum (6061 alloy used in driveshafts) is significantly better than carbon steel, but not as good as properly heat treated chromoly (also the advantage being, it doesn't need the same kind of heat treating post-machining).
In the end, the Aluminum driveshaft is not as strong or as stiff as a chromoly one of the same weight could be, but because it is more flexible in torsion, so it transfers less shock load to the rear axle. In a drag car where you are launching and straining the drivetrain a lot, but always under power, more flexible ends up being good. In a track car, where you are running on the edge of grip in all directions, and alternately straining the shaft in both directions repeatedly (engine braking under deceleration as well), stiffer is better, since it will be more predictable. Also, the steel has better fatigue resistance.
If that weren't enough, in driveshafts, a factor even more important that simple strength and stiffness is "critical speed", or the rotation speed at which the shaft will resonate and tear itself to pieces. This speed depends on diameter, stiffness, weight and
also tube length, which is why DSS did not make a one piece shaft. Ideally you want a lightweight, stiff, thin material with a short, large diameter shaft (Carbon fiber anyone?) for higher critical speed.
Quoting gtluke:
steel twists more than aluminum. aluminum has no flex, which is why your springs are always made out of steel.
the reason for the shaft is to reduce rotational weight. it works the same way as an aluminum flywheel. it also saves considerable weight off the car.
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turbowop
Well-known member
Brian 1
Luke 0
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Luke 0
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Brianawd
Well-known member
I believe with a drive shaft they are rated on Torsional spring rate in in-lbs per degree of twist. Carbon fiber is better than Aluminum and aluminum is better than steel.
The steel used in drive shafts is not the same as that of steel used in car springs.
The steel used in drive shafts is not the same as that of steel used in car springs.
pachood_1953
Well-known member
My buddy was in the same ball park with his stealth..Needed to rebuild the shaft, and he was having issues..
so he dropped something like 1200 dollars on a CF shaft (that didnt replace the whole thing).
It absolutely blew my mind. Thats what I paid for my gvr4.
so he dropped something like 1200 dollars on a CF shaft (that didnt replace the whole thing).
It absolutely blew my mind. Thats what I paid for my gvr4.
Dialcaliper
Well-known member
By the way, there are shafts made of both regular carbon steel (series 1045 usually), to which you are referring, and also of chromoly steel (4130), which is the same stuff many springs and sway-bars are made of. Chromoly shafts have a better critical speed are better than aluminum for the same diameter.
Critical speed followed by torque rating (strength) are the factors that determine shaft capability.
Quoting Brianawd:
I believe with a drive shaft they are rated on Torsional spring rate in in-lbs per degree of twist. Carbon fiber is better than Aluminum and aluminum is better than steel.
The steel used in drive shafts is not the same as that of steel used in car springs.
Critical speed followed by torque rating (strength) are the factors that determine shaft capability.
Quoting Brianawd:
I believe with a drive shaft they are rated on Torsional spring rate in in-lbs per degree of twist. Carbon fiber is better than Aluminum and aluminum is better than steel.
The steel used in drive shafts is not the same as that of steel used in car springs.
gtluke
Well-known member
Brian I'm pretty sure you are reversed. To absorb shock you want the most amount of spring, which would be moly steel. and the worst spring would be Carbon.
With bicycles some prefer using steel frame bikes because of their inherent shock absorbency, even though they are heavier. Aluminum beats you up more because it carries the shock through it more.
Aluminum doesn't really bend or spring, it just snaps.
With bicycles some prefer using steel frame bikes because of their inherent shock absorbency, even though they are heavier. Aluminum beats you up more because it carries the shock through it more.
Aluminum doesn't really bend or spring, it just snaps.
Brianawd
Well-known member
Quote:
Aluminum doesn't really bend or spring, it just snaps.
Then why do people use aluminum rods in there motors. aluminum rods transfer less shock to the rod bearing than a steel rod does..
Any way really does not matter. We are both right /ubbthreads/images/graemlins/grin.gif
Aluminum doesn't really bend or spring, it just snaps.
Then why do people use aluminum rods in there motors. aluminum rods transfer less shock to the rod bearing than a steel rod does..
Any way really does not matter. We are both right /ubbthreads/images/graemlins/grin.gif
But you cannot really compare an equal steel to aluminum to carbon fiber object, being each one needs to be 'tweaked' in some way (shape, composition, etc.) to give itself the best characteristic, with some negative aspect somewhere (cost, weight, feasibility, etc.). Apples to oranges to lemons; all look similar, but each has its own merits in different situations.
gtluke
Well-known member
that's a good point brian. i guess when it's a solid object like a rod it's softer.
now i have no idea.
now i have no idea.
turbowop
Well-known member
Brian 2
Luke 0
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Luke 0
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That would be silly...maybe the ricer version is like that, lol. Don't know if it's true or not, although would imagine they may use aluminum round stock as a mold template /ubbthreads/images/graemlins/confused.gif and it would be removed after curing; afterward, caps would be molded to the end.
It's a guess and don't have time to search for an answer.
It's a guess and don't have time to search for an answer.
Quoting Brianawd:
Quote:
Aluminum doesn't really bend or spring, it just snaps.
Then why do people use aluminum rods in there motors. aluminum rods transfer less shock to the rod bearing than a steel rod does..
Any way really does not matter. We are both right /ubbthreads/images/graemlins/grin.gif
I wouldn't use them in a street car. They break after a certain amount of time. I though that they were used for the weight savings. /ubbthreads/images/graemlins/dunno.gif
Quote:
Aluminum doesn't really bend or spring, it just snaps.
Then why do people use aluminum rods in there motors. aluminum rods transfer less shock to the rod bearing than a steel rod does..
Any way really does not matter. We are both right /ubbthreads/images/graemlins/grin.gif
I wouldn't use them in a street car. They break after a certain amount of time. I though that they were used for the weight savings. /ubbthreads/images/graemlins/dunno.gif
turbowop
Well-known member
/ubbthreads/images/graemlins/rofl.gif Oh man. Brian's aluminum rod schooling in 3...2...
Myles
Well-known member
^^^^^^
Mark always stirring the pot.
/ubbthreads/images/graemlins/rofl.gif
Mark always stirring the pot.
/ubbthreads/images/graemlins/rofl.gif
Brianawd
Well-known member
Quote:
I wouldn't use them in a street car. They break after a certain amount of time. I though that they were used for the weight savings.
In a street application, using the aluminum rod is a no brainer," BME President, Bill Miller recently said in an interview with an automotive magazine. "I don't know exactly how the myth that aluminum rods can't be used on the street got started, but I'll guess that early manufacturers of aluminum rods, back in the 60s and early-70s, weren't making them using the forging process we're using. With the material we've got and they way we manufacture the connecting rods, they'll live a couple hundred thousand miles on the street because a street application is, for the most part, low load. You gotta understand, our basic Aluminum Rod is made for 10,000 rpm and 800-hp. The design criteria for the connecting rod is way overkill for what it's gonna see on the street. We been running aluminum rods on the street for 20 years."
If you do a search on the net you will find 100s of thread where people are running aluminum rods on the street. I have not once read in any thread where some one running aluminum rods had one just snap and brake when driving down the road.
Do search next time. You may learn something
I wouldn't use them in a street car. They break after a certain amount of time. I though that they were used for the weight savings.
In a street application, using the aluminum rod is a no brainer," BME President, Bill Miller recently said in an interview with an automotive magazine. "I don't know exactly how the myth that aluminum rods can't be used on the street got started, but I'll guess that early manufacturers of aluminum rods, back in the 60s and early-70s, weren't making them using the forging process we're using. With the material we've got and they way we manufacture the connecting rods, they'll live a couple hundred thousand miles on the street because a street application is, for the most part, low load. You gotta understand, our basic Aluminum Rod is made for 10,000 rpm and 800-hp. The design criteria for the connecting rod is way overkill for what it's gonna see on the street. We been running aluminum rods on the street for 20 years."
If you do a search on the net you will find 100s of thread where people are running aluminum rods on the street. I have not once read in any thread where some one running aluminum rods had one just snap and brake when driving down the road.
Do search next time. You may learn something
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