Closed driveshaft benefits?

steve-cook

steve-cook

Member
Just as a thought I was wondering if anyone had any comments about why Henery went with the closed driveshaft over open?

What are the benefits/Shortfalls

Just personal curiosity as I am getting ready to pull a transmission out of a 38 ford for the first time, ow yea does anyone have any pointers before I start.
 
i was able to get my rear end out in 45 min, i had to jack up the trans, for the bell to clear the floor, this was in a 36 pickup
 
steve-cook said:
Just as a thought I was wondering if anyone had any comments about why Henery went with the closed driveshaft over open?

What are the benefits/Shortfalls
Click to expand...


Ford was devoted to the single, transverse leaf spring suspension. Some might say because Henry was noted for being thrifty (one spring cheaper than two), others may differ. Whatever the reason, in order to control rotation of the rear axle on it's axis a rigid control device was needed. He favored the central mounting of the spring for the "better" wheel travel on the poor roads (moreso early century than later) of the day.
 
Also, with common 4-spring type setups the heavy part of all springs is on the axle...the extra unsprung weight is serious on a light car. The tube and the front radius rod allowed full control of axle without binding or torque effects from braking.
 
Another "advantage" of the closed drive shaft is only ONE universal. I'm pretty sure that the engine and transmission pretty much line up with the drive shaft and the universal only comes into play with deviations from the normal standard loaded height, such as more stuff in the back of the car or hitting a bump or whatever... Also, at the time, the pre-lubricated, sealed U joint didn't exist, and putting the universal "inside" made things somewhat easier.
 
Sounds reasonable, Pete, but I am also thinking Fords were noted for the flexibility of their frames. I do know that coupling rotating systems together is close to an
exact science in some venues. Millwrights must be close to perfect making the alignments, even when using a flexible coupling, lest they have unnecessary vibration and put undo wear on bushings or bearings? comments? In other words, even a few thousandths nonalignment can be a catastrophe. Not to whip it to death, but it is also amazing how a small lead weight can erase the unbalance of
a tire.
 
perrysmith said:
Sounds reasonable, Pete, but I am also thinking Fords were noted for the flexibility of their frames. I do know that coupling rotating systems together is close to an
exact science in some venues. Millwrights must be close to perfect making the alignments, even when using a flexible coupling, lest they have unnecessary vibration and put undo wear on bushings or bearings? comments? In other words, even a few thousandths nonalignment can be a catastrophe. Not to whip it to death, but it is also amazing how a small lead weight can erase the unbalance of
a tire.
Click to expand...

I do know that a single U joint, at an angle with a constant speed at one end will give an oscillating speed at the other end. For that reason, an open driveshaft with two U joints must have them timed properly so that the oscillation put out by the first is cancelled by the second AND that the angles of both joints should be the same. That's why I suggested that the entire drive line is lined up under "NORMAL" conditions. Seeing the old movies of Model T's in the ruts or going down steep embankments with their frames all twisted up can be tolerated for periods of time. Also, the vibration is much more than linearly related to speed. Start going real fast and THEN misaligned out of balance stuff can go real bad real fast!
 
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