Long Term Problems with Driveline Vibrations

[Plannerman]

I recently lifted my Tacoma and have one very subtle driveline vibrations. I'm debating whether it's worth trying to correct the vibrations with shims and began wondering: if the vibrations aren't corrected, will I realize any sort of mechanical vulnerabilities as a result? If so, what would they be?

Thanks,
Matt

 

[enzo]

Check out Tacomaworld, there are tons of threads on this. East Coast Gear Supply has a replacement part for the front diff.

 

[1911]

Every u-joint that operates at an angle creates a vibration, it's just the physics of the u-joint. Trucks (and cars) are designed from the factory so that the u-joints on each end of the drive shaft(s) have equal but opposite working angles, which cancels the harmonic vibration. When you lift a truck, you change the working angles of the u-joints on each end of the drive shafts and if you change them enough, then the angles do not cancel each other and a vibration is introduced. The solution on a leaf-sprung axle is to shim the axle on the springs to change the pinion angle of the diff, which will change the working angles of both u-joints with respect to each other, i.e bring them back to equal-but-opposite angles. Here is a web page that explains it; there are many others if you google "drive shaft harmonics" or "u-joint working angles".

http://www.hotrodhotline.com/md/html/drive_shaft_harmonics.php

 

[Plannerman]

Thank you, guys. This website on drivelines and was particularly helpful. It looks like the answer is, yes, the vibration can be indicative of a situation that could cause premature wear.

Forgive me this if it is a silly question, but can you get similar vibrations
from changed angles of the front axles from lifting the front?

 

[1911]

... can you get similar vibrations
from changed angles of the front axles from lifting the front?

Technically yes, but it usually doesn't matter. On an IFS truck with (typically) CV joints instead of u-joints, it's a non-issue since CV joints don't suffer from the same angular problems as regular u-joints; that's why CV joints were invented. In fact, that is another way to solve your rear driveline vibration - replace one of the u-joints with a double-Cardan joint, which is a simple kind of CV joint.

Even with solid-front-axle trucks and leaf springs, it's usually not a problem simply because the front drive shaft is normally only engaged on the trail at slow speeds, so at trail speeds the vibration does not come into play and the extra wear is not an issue because it is infrequently used. The other issue with solid-axle, leaf-sprung front axles is that the steering caster is adjusted by rotating the axle, usually in a direction that makes the u-joint working angles worse! But obviously it is more important to have safe steering than it is to have perfect u-joint working angles on an axle that rarely sees highway use.

 

[downhill]

Thank you, guys. This website on drivelines and was particularly helpful. It looks like the answer is, yes, the vibration can be indicative of a situation that could cause premature wear.

Forgive me this if it is a silly question, but can you get similar vibrations
from changed angles of the front axles from lifting the front?[/QUOTE]

Yes you can. The problem comes at the bearing in the front diff that supports the axles. How much lift do you have in the front? Read this: http://www.tacomaworld.com/forum/2n...nt-differential-bearing-vibration-thread.html

The vibrations you have at the rear will vary with type of components you used to lift your truck. Well designed full leaf packs from the better suppliers rarely cause pinion angle problems. My driveline angles were brought back to perfect with just a small shim at the CB. In a 3 joint system like the Tacoma, two of the joints must operate at equal and opposing angles. The third must operate at zero since there is no additional joint to cancel it's oscillations. There is no way to correct your particular situation without measuring the angles and correcting the mis-matches. There is no magic fix.

 

[Plannerman]

Thanks, this Tacomaworld read was also interesting. Hearing that a vibration can cause long term issues, I'll look into shims. I'll start with the back because it seems the vibrations disappear when carrying a load, which seems to mean the the rear drive line is the culprit.


Sent via fat thumb

 

[Rutherfoto]

taco vibration

I have a 2007 Taco and have had driveline vibration since the first day I bought the truck. always on acceleration. I've installed an OME 3" lift, and still have the vibration...which in fact has gotten worse. I need to research this as well...

I had a vibration in my FJ40 which was corrected by shims...

 

[zidaro]

aside from driveshaft joint wear, the items i woild be most concerned with are trans. case output shaft/bearing/seal wear and pinion seal/bearing wear. Vibrating driveshafts blow seals first and then destroy the bearings behind them. Also, extreme case possibility of wearing a u or cv joint to failure and having a shaft lock your rear wheel at speed or come thru the cab. Not pretty either way.

bearing carrier drop is what you need to stop the mild/moderate shudder on acceleration.

www.streetacos.com may have something for you-

http://stores.streetacos.com/-strse-1/carrier-bearing-driveshaft-vibration/Detail.bok

 

[downhill]

bearing carrier drop is what you need to stop the mild/moderate shudder on acceleration.

www.streetacos.com may have something for you-

http://stores.streetacos.com/-strse-1/carrier-bearing-driveshaft-vibration/Detail.bok

Nobody knows that unless the driveline angles are measured. If the problem is at the pinion, then a CB drop will do nothing to correct it. It may likely make it worse. On acceleration the pinion is torqued up, so if it is already sitting too high that will cause a take off shudder. This is where 99.99999% of people go sideways trying to correct their vibrations. They start doing random things expecting a patent result. It doesn't work that way. They'll end up randomly trying things until either something works, or give up in frustration. There is no substitute for measuring your angles and correcting what is wrong.