This is a demonstration of driveshaft working  angles for u-joints. On the table here I have a  

four-wheel drive drive line set up with the rear  differential rear two-piece propeller shaft some  

manufacturers call it a drive shaft some call  it a propeller shaft of a transfer case and our  

front propeller shaft and our front differential  well all u-joints have a maximum working angle  

that they are to operate at and unequal working  angles can cause vibrations so the purpose of  

this demonstration is to show you how to first  measure u-joint working angles and then how to  

adjust the working angles just a little bit  of theory the u-joints will accelerate and  

decelerate twice per revolution as the propeller  shaft rotates and as one accelerates we want the  

other one to be decelerating its its companion  u-joint so on the rear propeller shaft here  

there are two u-joints that work together  to cancel out each other's accelerations and  

decelerations and the way that you measure the  working angle of u-joint is to somehow measure  

the angle of the pinion gear itself and so right  here on our rear differential of a 2007 tundra we  

have a pinion flange right here and this flat  side of the pinion flange is where you can put  

an incline ometer there are digital versions that  you can get for smartphones a lot of them are free  

and we're just going to measure the angle of  that flange right there while it's on the truck  

with the suspension fully loaded obviously here  on the bench we don't have the suspension fully  

loaded or even here but we are just going through  the process of showing you how to measure u-joint  

working angles so the working I'm sorry so the  angle of this front of the flange on the front  

of the pinion gear on the rear axle is 2.8  degrees and then we have another in Phenom  

etre that we put here on there the rear piece of  the two-piece propeller shaft and it's measuring  

an angle of 1.9 degrees so the working angle of  this u-joint is the difference between those two  

angles so you take the larger one the 2.8 and  you subtract the smaller one the 1.8 and we get  

a 1.0 degree working angle of this u-joint now  in order for that u-joint to properly cancel  

out the accelerations and decelerations of this  other u-joint the one here in the middle by the  

center support bearing the working angle of this  u-joint also needs to be one degree or very very  

close to it in other words we want the working  angles to be equal on the center u-joint and on  

the rear u-joint and whether you've got a lift  kit on your truck or your vehicle is lowered  

the closer you can get those two angles to being  equal the better off you're going to be well to  

get to measure this working angle to calculate  that working working angle we're going to take  

the angle of this rear propeller shaft which if  you recall is 1.8 degrees and then we'll measure  

the angle of the front portion of this two-piece  propeller shaft and it is 4.6 degrees well once  

again we're going to subtract the smaller from the  larger so we have 1.9 degrees of the rear piece  

of the two-piece propeller shaft we're going  to subtract that from 4.6 so that would be two  

point seven degrees is the working angle of this  Center you joined now remember I said to cancel  

out vibrations the best you can we want to have  the center u-joint and the rear u-joint working  

angles be the same well we had one degree of the  working angle back there and 2.7 degree working  

angle here that's not close enough they need to be  within half a degree typically is the maximum spec  

and preferably they need to be identical well  to fix that we're going to have to change the  

position of the center support bearing up or down  or at the rear differential on the leaf springs we  

would have to put shims a wedge type shim to point  the pinion nose up or down farther so that that  

angle would become more equal so we'll play with  out here in just a minute the other thing about  

a two-piece rear driveshaft is that the front  u-joint does not have a companion u-joint to  

cancel out its accelerations and decelerations  and so that means that the angle of this front  

joint the working angle needs to be almost zero  and so if we look it has an angle coming out of  

the transmission transfer case three point nine  degrees and that's measured right on the flange  

itself and the front piece of the two-piece  prop shaft is four point six two so we are  

0.7 degrees different between those two so as we  have a 0.7 degree working angle of this front you  

joined well the specification typically in the  book is around half a degree on this particular  

vehicle it allows for clear up there 0.8 nine  degrees plus or minus one degree with for the  

Toyota specifications so technically that front  u-joint is within specification because we have  

a 0.7 degree working angle which once again is  just the difference between the the angle of the  

output shaft of the transfer case and the front  propeller shaft now one thing about the output  

shaft of the transfer case and that front piece  of the two-piece rear propeller shaft is that the  

angle of this input shaft from the transmission  through the center line of the transfer case as  

a matter of fact through the whole center line of  the transmission and the engine crankshaft all of  

those should be lined up with each other including  the front piece of this two-piece propeller shaft  

if we had a three-piece propeller shaft it should  also be lined up so what I want you to do is think  

of the front piece of a multiple piece propeller  shaft as simply being an extension of the output  

shaft of the transfer case or the transmission  it should be as straight as possible typically  

we don't want a zero Degree working angle because  the u-joint won't move and have any lubrication  

there but half a degree or less is the typical  specification and then the rearward piece back  

here that moves up and down with the suspension it  has the companion joints that work to cancel each  

other's accelerations and decelerations out so  for working angles once again all we do is to the  

difference between the angles on each side of the  u-joint so the rear pinion angle is measured at  

the flange and then the propeller shaft angle the  difference between those two is the working angle  

of the rear joint the center joint it's working  angle is just simply the difference between the  

angle of the rear propeller shaft and the front  propeller shaft and then that front joint the odd  

joint it's working angle is simply the difference  between the output shaft speed their output shaft  

of the transfer case or transmission and the front  piece of the front drive shaft and that's it's  

working angle so the way to correct any of those  angles is we can shim the transmission or transfer  

case mount typically up we typically can't take  it down the center support bearing it's bolted up  

to the flange that are mounting that amounts to  so we could put shims under it to bring it down  

and then the pinion once again can be lifted up or  down you can buy shims in half degree increments  

that go on leaf springs under the u-bolts to  tilt the pinion gear up or down to help correct  

improper u-joint working angles so once you get  those working angles equal on this rear propeller  

shaft you should not have a vibration at least a  second-order propeller shaft speed vibration and  

I will have more videos on vibration diagnosis  but if you're working angles are wrong or your  

u-joints are bad you will typically end up with  two shakes or two vibrations per revolution of  

the propeller shaft and balancing tires balancing  drive shafts propeller shafts won't do anything  

you can you can replace the parts and it still  won't fix it these angles must be correct and  

you must be able to measure them and correct them  with shims or body modifications to get rid of  

the vibration this has been a demonstration  of how to measure u-joint working angles on  

a multiple piece rear driveshaft or propeller  shaft it would work the same for a single piece  

propeller shaft single piece front propeller  shaft or multiple piece rear propeller shaft