Turbo6guy

Can anyone plrase tell me why, on a 2002 QCSB, a 3 inch lift will cause me such a headache? Lift the truck, now I've got a vibration. Take the front shaft out, its gone. I ground down the joint where it could be touching, 3 times, no dice. Had it spun, it is in perfect balance, and is perfectly straight. Skyjacker says 3 inches should not be enough to throw thing out of whack. The guy that spun it measured the angle with a formula for that and said its at like 15 degrees. Does anyone have any suggestions?
I've also been told about an indexing ring that twists the transfer case down so the angle isnt so bad, anyone have to use one of these things? Snows coming soon, need the truck to plow. Any advice will be appreciated.

phox_mulder

Very good question.

I have that vibe with my 4.5" lift, along with a popping while turning in 4x4 (offroad of course)

According to Skyjacker, it shouldn't be there.

Know of many trucks with the same lift that don't have the vibe.
Know of a couple trucks that got a high angle driveshaft, and it didn't fix it.
One guy has the indexing ring along with the high angle shaft, and still has the vibe.

Skyjacker includes the indexing ring with their 7" lift.

From what I've read, it's a lot of work for something that might not fix it.

Anyone finds a solution, please post.
I didn't buy a 4x4 only to worry if it will be there when I want it.


phox

nitrousn

the vibration fix is in the pinion angle. i have a digital electronic angle finder. i am sure if you measure the front driveshaft angles you will find out that is where the problem lies. if the casters are able to be adjusted in the right direction you might be able to correct the angle. if not you will need to replace the upper arms to that of an adjustable type. one other item to check is the slip spline on the driveshaft. if its out to far which i doubt it could be loose and allowing some shaft whip. most likely the pinion angle correction will cure the vibration.

CTD NUT

The problem with lifting a CV equipped vehicle is that the u joint at the opposite end of the driveshaft was intended to run at 0 degrees. ANY u joint running at an angle needs to have another u joint in the shaft running at the opposite but equal angle to cancel out any potential harmonic vibrations. When this is not possible a CV is used. The CV is designed to allow the two u joints it contains to run at the exact same angle to eliminate vibrations. The catch is that the third u joint at the other end of the shaft CANNOT have ANY angle because there is no other u joint to cancel out the vibration. For high angle situations where a single u joint on each end of the shaft won't accomdate the angle, a custom shaft with a CV at each end is what is used. However, I agree with nitrousn - a pinion angle change may be all that is required to alleviate the angle of the u joint. You are however changing the caster when you do this.

Trucks that don't have an axle disconnect will have the problem compounded because the front shaft is always spinning so it may appear worse in some trucks and not others.

Just my .02

Turbo6guy

Well guys I appreciate all the input. I talked to NTW today about the indexing ring and the guy said it is only for a 5 inch lift and it wont work. I called Skyjacker and he said he's never heard of this problem with a 3 inch lift. My last truck was a twin to this one but with a 360. My father bought the truck so I'm going to try his driveshaft. If that doesnt work I'm up the creek. So we'll see. I'll keep you posted. Thanks again. Eric

nitrousn

one other possibility is bad u - joints. not loose type bad. the joints may have some worn spots because of age and miles and the rollers quit rotating in the cap and cross journal. this may not of been serious at the original ride height. now you have lifted it and the joints are running at different angles. with the change in angles it may of forced the rollers and causing a bind in the joint. this possibly could cause your vibration. it is just one more place to pay attention to.

BigBlue

I don't have a vib in the front end on my Skjacker lift. I've got a pop while turning that is driving me stark raving mad (phox, that sleeve thing was tight).

KATOOM

Yes, Its you pinion angle causing all your problems. I have typed this a many of times now but here goes again. For whatever reason DC changed the specs for the front axle on the '02's WITHOUT the vacumm axle disconnect. I'm assuming you dont have this, right? Anyway, they pushed the axle foward 2" and rotated the pinion downward, causing more pinion angle. And removed the vacumm axle disconnect system. Now the front driveshaft not only spins ALL the time but the u-joints are running at higher pinion angles. Why? Dont know. Maybe some sort of alignment correction. But this is the reason many with the '02's (with the solid axle housing) feel a vibration around 65+ mph in stock form. Adding a lift can only make it worse unless you change the arms correcting the pinion angle. But I dont know what this will do to your caster angles. And CTD NUT is right, the angle at the pumpkin should be set a 0* (or as close to) since there is a CV at the transfercase.

stimpe

Im having an issue like this also. My front shaft angle is definitely off, mechanic says theres too much pressure on the ujoint and they wear out every 2000km , and he said the only option is to drop the transfer case to put the front shaft at the stock angle, does this sound right? And how hard is it to change the pinion angle

KATOOM

Dropping the transfer case will only exaggerate the double cardan joint angle and only might release the pinion joint a little. Robbing Peter to pay Paul. Not to mention it will change the engine angle which will affect all that its connected to, including the radiator fan. Not worth the effort in my opinion. You can rotate the pumpkin but because you're talking about a front axle you then involve alignment issues like camber and caster. The "proper" way to fix this is to have the knuckles cut and re-welded, restoring the alignment specs when the axle is rotated.

stimpe

What knuckle are you saying to cut? And i have the solid front axle, can it still be rotated easily to realign?

KATOOM

The knuckles are the outer part of the axle housing that allows the tires to turn. Where the ball joints are. At the end of the axle tubes, there is a large Y that sits sideways and the axle u-joints sit inside the knuckles. And I was already referring to a solid axle. Think of it this way..... When you tilt the axle to raise the pinion angle then the knuckles will also rotate. When the knuckles rotate you alter all the alignment specs and the only way to regain them properly (depending on how much you rotate the axle housing) is to remove the knuckles and have them welded back on in the correct position. This is why most lifted solid axle trucks have funky front driveshaft angle. Because its to expensive and time consuming to have the knuckles moved so they can properly rotate the pinion angle.

stimpe

thanks alot for the explanation it makes sense to me now. will talk to the mechanic and update in a bit