| Author |
Message |
    
Randall smith
| | Posted on Friday, December 06, 2002 - 06:18 pm: | 
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Planning to tune the angles of my u-joints as the ultimate cure for vibrating driveshaft. Fairly certain that my u-joints are not properly lined up with the driveshafts and transfer case.
However I also suspect that the angles change when you acellerate or decellerate, and this has to be part of the tuning process. Unfortunately you can't observe this while driving.
Does anybody know:
When you accelerate does the pinion move up or down? How many degrees can it move?
Does the rear pinion move up or down when you accelerate?
I assume that the transfer case does not move during acceleration/decceleration. Does anything else on the truck move which may effect ujoint angles?
If you know for sure how driving down the road effects u-joint angles, I welcome your comments.
Randall |
Rob Davison (Pokerob)
| | Posted on Saturday, December 07, 2002 - 12:01 pm: |
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if you have the correct pinion angle on your lifted truck it should not have vibrations during acceleration , cruising speed or deceration. there is a working margin they design it knowing these things happen.
it's once you lift the truck that you start to drive around with it on the cusp of that design limit, eventually on accel or decel you will surpase the designed limitation and feel vibrations. do this enough and it will errode and unbalance and just plain wear out faster.
my point is you should try to achieve the pinion angle that it had when stock. how you do this is the tricky part but if you can get it back there. then all the math and concers have already been figured out.
rd |
muskyman
| | Posted on Saturday, December 07, 2002 - 01:51 pm: |
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Randall,
yes you are correct they do move
they rotate oposit the force of the tire
so under forwarde acceleration the rear pinion wants to rotate up and the front one wants to go down. vise versa for decelerations
in a linked coil spring vehicle the amount of rotation is considerable less then in say a leaf sprung vehicle.
spicer calls for less then 3* off under load. on a single cardin drifeshaft this number has to be diveded between both sides to 1.5*. anything more then that and you will start to feel vibration. when you get up near 4* the vibration really gets to be a broblem vibrating fasteners eating bearings and seal and wearing out u-joint at a very fast rate.
in addition to this is torque angle. this is the amount of planned shift in the axle from side to side when torque is applied. this load change also will slightly change the pinion angle and cause vibes. this is why when your panhard rod bushings and radius arm bushings are bad vibes will abound.
once you leave stock all these factors change, include into that worn bushings and its no wonder some people gets no vibes and some people get a huge problem with vibes.
get your self a $10 magnetic angle finder at the hardware store , start reading about drivlines and and different types of shafts and the reasons you use them and then lay under your truck and start measuring and understanding how it all works.
you have alot to learn before you even think about making changes
FWIW |
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