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January 30, 2004
Having just broke two propshafts on a test rig and having to do full
risk assesment on the items I can say that.....
If you completely dissasmble the propshaft then make sure you mark it
up and reassemble everything in the same orientation.
Most important is that two pins on the Hookes Joints at each end of
the shaft are exactly in the same plane. Because of the spline teeth
in the sliding part there is only one possible to way to assemble
this correctly. (possibly 180 degrees out, but only if the spline has
an even Nr of teeth, but not likely).
The Propshaft will have been assembled welded and balanced in the
correct orientation. Any deviation from this results in horrible
vibration and the angular operation of the Hookes joints just won't
work.
The weakest part of the propshaft assembly is the forging on the
yoke around the needle roller bearings. They generally fail here due
to improper installation, high constant operating angles (above 3
degrees) which results in heat and loss of lube at the bearings. This
is exacerbated and also the life considerably shortened by
transmitting excessive torque and speed.
The orientation of connecting to the diff is not important but again
if it hasn't caused a problem eg vibration then try and put it back
the same position it came off.
The angles between the bolt holes on the flange are 100 degrees and
80 degrees BTW. So it is only possible to attach them in two
positions 180 degrees apart.
The accepted safe life equation for general use is 5000 hours for
the prop assembly , but the makers do say that that this can be
exceeded by up to FIVE times !!!
I can give an account of how and why our props broke but it would
have to be offlist. Suffice to say it's for a new USA sports car
gearbox which can generate far higher torques than our LBCs.(1000Nm
or 738 lbf-ft)And the reason for breaking was not the the Torque or
speeed.
Alan
"Alan" < alan.east-jones@... > 28797
Posted on January 30, 2004 03:28 PM
Posted to category(s) Carburetor | Cylinder Head | Drive Train | Engine (external) | Engine (internal) | Lubrication System | Miscellaneous | Transmission | Tuning
