there are typicly 3 reasons why auto makers use a 2 piece shaft as opposed to a one piece. 1 angle whether it be pinion to tailshaft, or vertical i.e. not a straight shot from the tailshaft to the pinion. 2 length. or the 3rd a combonation of both.
as far as to "why" there is the "tube within the tube" or "rubber element" on driveshafts, it is primarily to deter vibration. a good fix but a pain in the ass to us driveshaft/machine shops that have to fix them 20 years later. :icon_bigg what happeneds is the rubber that is fitted in the tube just simply gets old and looses its ability to "stay put" in simple terms, and with us putting down some big power, it simply cannot maintain its phaze with the other tube yokes.
as far as there being a benefit going from a 2 piece to a 1 piece, depends on how you look at it and your reason for wanting one.
first thing people look at is the weight. 2 piece shafts have more parts, there for making them heavier. 2nd would be ease of maintaing a single piece. much easier to replace 2 joints rather than 3 sometimes 4 joints and a carrier bearing.
to the question "are there any set backs to going to a single piece shaft"...well, sometimes yes.
going to a single piece shaft can "sometimes" cause a harmonic resonating vibration "if" the shaft is ither built with insufficient diameter wall tubing and diameter tube. the longer the driveshaft, the more of a chance it will have to "hum" or harmonicly resonate and need to be very precise on how true or "straight" the shaft is and balanced.
one fix to this is to enlarge the diameter of the tube. another is to place a special piece of cardboard tube that is designed to go into driveshafts and help cut back on the "humm". i put these into all of my larger diameter aluminum shafts. there is also a maximum length that can be made out of steel due to the weight of a steel shaft while rotating will wanna make it "whip". and hence the introduction of aluminum shafts. but thats getting off subject, lol.
i think i babbled more than answered questions,:blah: if i can answer any questions just let me know.
