Just fixed driveline vibration!!!For free!

No it didn't, vibration frequency changed with with acceleration & deceleration though. Still a happy camper short of the takeoff shudder!

 

I tried the 180 turn on the CB, take off shudder got a little worse, would love to get a fix for this. I probably notice more because I'm really looking for it now.

 

It happens on all vehicles with a drive shaft if the angles are wrong.

If you have a 2 piece shaft with single U joints on either end (stock shaft)... your pinion/axle should be parallel to your transmission output.

If you have a solid one piece drive shaft (double cardan), your pinion/axle should be pointed directly at the drive shaft. The front two U joints will split the angle equally if your rear U joint is at 0 degrees.

This is drive shaft angles 101.

If you have a lift you should know and check your drive shaft angle. If you are going to have to have one angle off have your rear axle housing 1 degree off as it will torque up under acceleration.

Get your angles straight. Get your drive shaft balanced. Dont have too much lift/angle for your drive shaft. You wont have any vibrations.

 

Well like I said earlier in the posts the high speed shakes were fixed except for the low speed shudder. So last night I rolled her into the garage and installed the 3/8" carrier drop spacers that I had on the already flipped carrier. Now all my angles looked good, I took it for a drive and only a slight hint of vibration at take off. I can barely notice it and believe me I now notice every possible vibration! All the angles look good so I don't believe there is a need for any more tweeking. Hope this can help a few people.

 

Good work!

 

I would like to confirm the OP's diagnosis and cure. I did the same thing, and its smooth and vibe free. I also took some post fix pics. Assuming transfer case output shaft is 0.0 then front u-joint is 3.2 degrees, middle u joint is 3.3 degrees for a total deflection of 6.5 degrees. Rear joint is 0.5 degrees with the shims.

i also had a friend of mine put the truck on a rack and we noticed that the low speed shudder is coming from the front u-joint and the high speed vibes are coming from the rear most u-joint. This is opposite of what I had expected.

Here is a simple HowTo on how to take the measurements.


before you take any measurements print out this sheet and use it to keep track of the numbers






1. measure the transfer case output angle here ( Make sure it is clean) and set the measuring device to 0.0



2. next measure the front most shaft angle here (again make sure its clean and you are not on on a weight or a sticker)



3. measure the rear shaft ( on the large section, again no stickers or weights)




4. keep the device on the rear shaft and re zero it.

5. measure the rear diff input angle here (make sure that you are just above the ridge that runs through the middle of that face) Be sure its clean and rust free



6. now look at the picture that you filled out and decide what you need to do.

I would start with the diff angle. If your angle is greater that 3.0 then I would go with a axle shim. This will close this angle, but wont do anything to the rest of the mess.

Now look at the rear shaft measurement . this is your total deflection that you have to deal with and since I don't know of any practical way to change the transfer case output angle, we just need to split the difference through the middle joint. If the first joint angle is greater than half the second measurement the the carrier bearing needs to go up, but if its less than half then it needs to go down.

adjust carrier bearing as needed.

Flip upside down if you need to go up and shim to get as close to equal as you can.

thanks again to HVACBMAC for the leg work

 

I am digging all of this and actually have an appointment this next week for the dealership to break everything down. My question is simple:

What is actually VIBRATING? Is it the u-joints, transfer case, pinion bearing, carrier bearing, etc?

 

No prob. Erll! I used to work on heavy equip. and trucks. On the big boys bad vibes take things out in the drivetrain. With the POS bearing isolator on our trucks any unbalance or out of time u-joints get the shaft whipping, and with the trucks being light we can definitely feel it. Pass on the driveline 101 to others, I sure will. Enjoy the ride!!!

 

By the way ERll, nice write up!

 

Interesting

 

The drive shaft .

 

When a U joint allows one shaft to spin off the other's input the second shaft will speed up and slow down as it rotates relative to the sttepness of the angle from 0. You need another U joint to canel out that effect by doing the opposite in time at the same angle. On a one piece double cardan shaft it happens automatically at the double U joint/CV. Then the shaft going into pinion must have its U joint a 0 degrees or it has the same effect.

On a 2 piece shaft there are single u joints on either end. They must have the same and opposite angles to cancel out the speeding up and slowing down effect. ANY time you have differing angles or a U joint that are not operating at 0 degrees you get the speeding up and slowing down effect felt as vibration.

 

sub'd for future mod

 

Very interesting read.....where can I purchase one of these angle degree finders?

Thx

 

Ok i am lost

 

Wixey WR300 Digital Angle Gauge

http://www.amazon.com/gp/product/B001PTGBRQ

 

Our shaft has 3 U joints. One at the transmission output, one at the carrier bearing, one at the axle/pinion. One has to be at 0 degrees beacause there is an odd number of U joints

Techically its two different drive shafts. It must have one U joint at zero degrees. The other two must be equal and opposite. Thats it... how hard is it to understand?

It does not matter if the zero angle is at the pinion, the intermdiate position, or the transmission... so long as the other two Ujoint angles are equal and opposite resulting in parallel inputs.











Rules:

1. U joints cause the driven shaft to speed up and slow down in a predictable and mathmetical way... while its not the same, think of when you turn that bottle jack and it wont go around smoothly and the crank has slow and fast points. The further a U joint is off 0 degrees (straight) the more the driven shaft slows and speeds up as it spins. The average will be the same RPM as the input speed.

2. You must have a joint slowing while one shaft is speeding up and speeding up while one shaft is slowing or you will get vibes.

3. If you dont have a U joint to put at an equal and opposite angle as a cancellation force it must be at zero so there is not slowing and speeding up as it rotates.

Those 3 rules govern drive shaft angles. It solves any drive shaft angle issue. Its like a math problem where A+B+C=0 where two of the numbers are the same but one is positive and one negative. Those are the dirve shaft angles. If A = 2 then B must equal -2 and C must equal 0.

I hope that explains it.

You change pinion angle with shims.

You can use the carrier bearing drop or flip to alter angle there.

Dont have any angle over 3 degrees.

 

Harbor Freight has one for around 20 dollars and fits on top of the yokes well.

 

So If you Flip the CB and use the CB spacer's. Do you have to use the rear shims to get angle correct?
What if you dont use the shims. will the angle then be worse then before?

 

it really depends on how your angles look now. As long as you have one at zero and the other two are equal and oppisite then no /minimal vibes. The big problem is that when you lift it changes the rear shaft angle in regards to the carrier bearing. If you make the first two angles equal and don't change the rear pinion then you will probably get some high speed vibes. the take off vibes are probablydue to the front shaft u-joints not being equal . As was said before you can have any one of the joints at 0.0 as long as the others are equal.

Check your output from your transfer case and then the front shaft and if that is 0.0 then you just need to get the differential angle to match the middle joint angle.

hope this helps