MINE IS A 97 extended cab 4.6 engine F-150 with tow package it has a steel driveline it is rusty but not much! you people with shiny drivelines? maybe FORD galvinized them to stop corrosion? galvinizing gives steel the long lasting shiny look of aluminum! but a simple magnet will tell you if its steel or aluminum?

 

I think I might paint mine. Maybe I'll use aluminum paint just to confuse those without a magnet in their pocket

 

I put my Palm Springs refrigerator magnet on my drive shaft and found it to be steel. (I guess California magnets attract steel???) I have a 1997 SC, 139" WB,4.6L, 4x4 ORP and trailering package. The diameter looks to be about 4" OD.

If you are easily bored, stop here!

I dusted off my old engineering books to look up the mechanical properties for both steel and aluminum. The specs are:

Weight:
Steel - .283 vs .100 lb/cu.in. for Alum.
steel is almost 3 times heavier

Tensile strength:
Steel - 65,000 vs 15,000 psi for Alum.
Steel about 4 times stronger in tensile

Shear strength:
Steel - 11.6 vs. 4.0 million psi for Alum.
Steel about 3 times stronger in shear

Shear strength is what you look for in a torsional (rotational) application like a drive shaft.

If I have not put you to sleep yet, you may return to the message board.

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Mine: '97F150,XLT,SC,4x4 ORP,4.6L,3.55LS,auto,6 CD,alarm,grill guard w/PICCA lights,dual exhaust.

Wife: '99Explorer Limited,pearl white/tan leather,4.0L,4:10LS,CD,sunroof,alarm

 

In conclusion:
A steel driveshaft of the same diameter as an aluminum drive shaft would be 33% stronger.

 

J-C, I want you to do my taxes.

Isn't 3 times, 300%?

Dewayne's calculations clearly indicate that the aluminum driveshafts will explode/disintegrate at speeds above 65 mph.

 

I reeeeealy like it!

Whats that? Huh? Do I hear Taps being played for you Aluminum guys!

 

Come on, this isn't any fun.

Isn't anybody gonna stick up for the Reynolds Wrap guys?

 

Raoul,
I figured that Ford would be making the Aluminum shafts solid - so they'd be stronger - thereby upping the weight and approaching the strength of steel.
Then I factored in the "Rust Factor" which would weaken the steel.
Since Aluminum doesn't rust, it would only be 25% weaker than steel.
What else did I miss???
I guess I'd better not paint mine with aluminum paint after all
Maybe you aluminum guys should paint yours ORANGE... LOL

 

I agree Raoul, If they don't want to play we will be forced to go onto something else. Maybe thats their plan. To let this die without a fight. I am dispointed in them.

(I'll bet my moma's *** they are rechecking J-C's calulations, gathering data and statistics just as fast as they can!)

 

Ramblings from another Engineer...
You are right the shear is the force that we are most concerned with here. Since the torque acting on a driveshaft is "surface loading" (that is to say the outer skin transmits the force while the center is hollow), the Aluminum will likely have a larger overall Dia. to lower the induced torque applied to the skin's Sq.in. The wall thickness may or may not be any thicker/thinner than the steel. The engineers can compensate for the lower shear strenght of the Aluminum by increasing the dia. and/or the wall thickness.
Making a solid driveshaft would be a deadly mistake! The rotational speeds are very high, and the part is only supported at the ends so... if the shafts had sufficient mass to bow (sag due to it's own inertia) the cetrifical force would force it to fly off the truck in an instant.
Ford as well as every other manufacturer buys specialty component parts such as driveshafts from companies like DANA. The Aluminum vs. Steel may just represent a different supplier. Engineering has likely spec'd steel peramiters as "XXX" and Alum as "YYY"
... the good news is the safety margin designed into these types of components would likely be in the 200-300% range so... if your steel shaft is rusty... don't worry. You only need to fear dents!
ok, so I'm long winded! I know already!
Bruce
ps. I wonder which one I have???

 

Ramblings from another Engineer...
You are right the shear is the force that we are most concerned with here. Since the torque acting on a driveshaft is "surface loading" (that is to say the outer skin transmits the force while the center is hollow), the Aluminum will likely have a larger overall Dia. to lower the induced torque applied to the skin's Sq.in. The wall thickness may or may not be any thicker/thinner than the steel. The engineers can compensate for the lower shear strenght of the Aluminum by increasing the dia. and/or the wall thickness.
Making a solid driveshaft would be a deadly mistake! The rotational speeds are very high, and the part is only supported at the ends so... if the shafts had sufficient mass to bow (sag due to it's own inertia) the cetrifical force would force it to fly off the truck in an instant.
Ford as well as every other manufacturer buys specialty component parts such as driveshafts from companies like DANA. The Aluminum vs. Steel may just represent a different supplier. Engineering has likely spec'd steel peramiters as "XXX" and Alum as "YYY"
... the good news is the safety margin designed into these types of components would likely be in the 200-300% range so... if your steel shaft is rusty... don't worry. You only need to fear dents!
ok, so I'm long winded! I know already!
Bruce
ps. I wonder which one I have???

 

Well you called it, cphilip. They bring in a heavy hitter to plead their case while purporting to be nuetral - "I wonder which one I have?" It was obvious to me Bruce is a lobbyist for the aluminum side trying to cloud the issue with facts.
(I just hate when they do that.)

Well, lets see them dispute this:

Was Superman the man of 'Aluminum'?

 

He he....(I sit here amused in my smugness)

 

Dewayne, I'm going to make a note that you're a good guy to have around.

 

OK, my theory...

For 2WD long wheelbase trucks, Ford would have to use a two-piece steel drive shaft to prevent the weight of the shaft from causing it to bow and eventually break. The cost of a two-piece shaft is probably more than that of a single aluminum shaft. I know it is cheaper to maintain- only one set of U-joints.

For short wheelbase and 4WD (where the transfer case is in the driveline) Ford utilizes shorter steel shafts of much smaller diameter. I suspect that these are the most economical (cheap) to produce.

So, I really can't believe you guys are bragging about your short skinny shafts.

Neal



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1997 4x4 Expedition- 4.6L, true dual exhaust w/glass-packs, K&N air filter, SuperChip, airbox mods, Edelbrock shocks, 285/75R16 BFG ATs, Optima "T-Bone" wheels, and Clarion In-dash CD player. Just added Smitty Bilt push bars and nerf bars!!

2000 4x2 F150 XLT Reg. Cab LWB- 5.4L, Tow Pkg, 3.55LS, CD player,Remote Keyless Entry, Sliding back glass, Special Appearance Pkg.

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