Just fixed driveline vibration!!!For free!

I don't know what you have read, but I'm not surprised the pinion is off in that direction. I am surprised it's that much, but now your numbers make sense. This whole thing really makes me curious as to why these differences occur. You'll see a bunch of trucks with numbers very similar, and then a flyer like this. Weird. It's still all fixable but a bigger PITA because of the axle shim.

 

You are right in a sense. You can get a momentary shudder just from the axle wrap that is not a true vibration. A takeoff vibration usually lasts as long as you stay on the gas accelerating. That's the difference. The vibration happens when the pinion is too high to begin with, and then gets twisted higher till the Ujoint starts to sing. It's a combination of mismatched pinion angle and axle wrap. The pinion doesn't drop back down until the power comes off and the vehicle speed stabilizes. A momentary stutter at take off is probably just the springs tweaking. This problem is a lot worse on the 4.0 because of the higher torque.

 

just 2.5" billy 5100s (set at 0.85) all around and 2" AAl

 

if my pinion angle is so wrong would that be something that Toyota would fix under warranty or will they just say my lift did it?

 

No idea about that. The lift may have caused it. People should ask when they buy a lift whether it is designed to maintain proper pinion angles. Pretty much nobody thinks of that. All-Pro says theirs does and mine was perfect.

 

I think I should have gone with a better rear lift, the toytec 2"AAL tilted the Pinion up alittle, making about 1.6* off from the TC... But with just lowering the CB about 3/8's it has made my take off shutter almost gone. Its tolerable and Im done messing with it.

 

Maybe this will help some of you.

http://www.pirate4x4.com/tech/billavista/PDFs/Federal_Mogul_how_to_measure_driveshaft angles.pdf

 

I've been trying to figure out what my angles will look like after I fix the rear diff problem with a shim. It looks like shimming the rear diff will increase my rear shaft angle further. So once that is done it will require a large CB drop in which will increase the TC shaft angle. It's already at 3.5 degrees and going higher frowned upon, am I right?

here's a BEFORE and AFTER (presumed) pic:



EDIT: all measurements were done from zero-ing the angle finder on the TC

 

That supports my theory of putting in a shim backwards to create a little more pinion angle. I need 2-3 degrees more pinion angle to match and cancel the TC angle.

 

OK , on my phone , the values above in the diagram are not mine .

If you read left to right on the above diagram my angles are

0 , 3.9 , 3.3 , up .65

What / where do I shim ?

I have a vibration at 40 mph that is similar to an unbalanced tire , but it is not tires

 

Your first and second shafts are within 1* of eachother which is good, and I'm assuming you zeroed your phone once it was placed on the TC and then got the rest of the angles. In this case, you should get a .5 degree shim from Summit Racing and you'll be within .15 of perfect.

 

I actually used a digital inclometer for the angles , and yes , zeroed on the TC , the rest of the angles are relative to that .

 

my post totally got hijacked by a cell phone post!

BTW I noticed that a lot of people on the thread are getting rid of there vibes but not with the recommended measurements. I recall someone posting that even if you don't have the vibes, you could still be doing harm to your vehicle.

 

Then what I'm saying should be correct, it's simple math...you want the TC and the Pinion to be "equal but opposite." Visualize what a shim will do, it's going to tilt your rear axle forward a certain # of degrees when placed "fat end towards the rear." That being said, you need .65* of "tilt" in-order-to get things parrallel. Badger has done all the work, given all the advice, now all we have to do is go measure and $hit and figure it out. Understanding what needs to happen conceptually is much easier in my mind that looking at #'s and figure out what's going on. You need a 2 shafts nearly the same, within a degree or so, and you need your TC and your Pinion to be "equal but opposit" or darn close.

 

Yeah that wasn't my post. My pic was used but numbers changed. Here's mine:

 

With the shim in " fat end to the rear " it will tip the pinion up more making it worse , no ?

My pinion is tipped up .65 already

 

yeah that's the way I see it

 

Sorry misspoke, reverse the direction! Point is you understand what needs to be done, so fix it!

 

Well maybe now , sorry for asking questions in this thread I guess ?

 

Quote OZ:
If you read left to right on the above diagram my angles are

0 , 3.9 , 3.3 , up .65

What / where do I shim ?

I have a vibration at 40 mph that is similar to an unbalanced tire , but it is not tires

Oz, Have you shimmed your CB? How much lift do you have? I'm asking because it's unusual for the second shaft to have an angle less than the first. That's especially true since your first angle is just 3.9. Let's make sure we have correct numbers first. That seems to be the biggest challenge.