simplysmn

what size tires are you running ?

Crossy's son

315/75r16

2 days before i put the lift on the 4x4 worked perfect, no shakes.

Now it's a death shake.

I think it's my pinion angle. Which makes me mad because skyjacker already has shims on the bottom of the springs, now i need to remove those shims which are part of the spring and install a different size shim?

i don't understand why i'm having this problem and noone with a 4" lift seems to have this issue .

ChrisLib

Did you check or go thru the double cardan joint? Sometimes the centering ball and/or the seat for it inside the joint become worn/broken or the spring looses its tension. see here
http://www.pavementsucks.com/tech-article-16.html

longshotranch

you should put the driveshaft spacer on at the trans case it will take some bind off the cardan joint

j-fox

This is what happened to a friends ford.
Big lift kit and he was told the stock front shaft was ok to use.
He crossed a speed bump in a parking lot and it extended far enough to bind up the Cardan--constant velocity-- joint on the front shaft.
It broke the Cardan joint and it wobbled like crazy. I found it when under it and had to remove it to show him how it works-- or didn't work right!
He had a new shaft made to fix it.

longshotranch

thats why they have a spacer to extend the shaft taking pressure off of the joint.
http://www.superlift.com/Catalog.asp?P=4310

Crossy's son

You guys must have no read my original post i just went through the double cardan and rebuild it all and clearenced the heck out of the moving parts so nothing binds.

yesterday i noticed it looks like the driveshaft slip yoke end has been hitting the front u-joint straps that attach the front driveshaft to the front axle yoke.

you can tell it's been hitting hard, it's taken alot of metal out of the straps on the yoke.

which points towards the pinion angle being the issue..........

Glen_63

Wondering if your ever reached an answer? It's the crap time of winter and after I put my shaft back in with the custom suspension 2" lift and refreshing it I have terrible vibrations. I'm going to try spacing it out from the tcase as soon as I buy some bolts.

oliver foster

I think Crossy's son had another post on this problem that had pictures of the front axles pinion angle, which looked bad.
I was thinking he wanted to install some leaf spring shims to rotate the driveshaft yoke upwards and improve the angle.
I have shims that came with both of the Skyjacker 6 inch lift kits that I bought over the years.
I know that SkyJacker will sell just the shims, as I needed a replacement on my old '72 Power Wagon after I cracked the original one.

cougar

I found that even a 1 1/2" lift on my 91 was enough to place the double cardan joint out of its operable range. I kept blowing the joint apart and couldn't figure out why. Turned out to be my overload shocks lifting the front just enough. Took them off and haven't had a problem sense.

Chrisreyn

I am NOT an expert at this, but just to throw a thought out there...

When I used to be into off-roading, I lifted quite a few CJ's...
It doesnt take much lift to create a drive line vibration due to pinion angle.
Generaly after lifting, you install larger tires, which increases torque induced axle wrap against the springs. This can cause a binding in the drive-line which isn't present when your NOT driving in 4WD..
If the transfer case and front diff are at too great a difference, you could be experiencing some torque induced binding in the driveline.

Like I said, I am not an expert on this by any means, but just an idea you may wanna look at.

totalloser

I suggest you read his post again and CHECK. With minimal angle, the u-joint phase is less of an issue, but when you have angle on them it gets BAD. And it might have been done by a shop or previous owner.

If this is the case, it can break ALL SORTS OF THINGS. Think motor mounts, differential carrier, broken transmission gears etc. I have seen all of these break due to improperly indexed driveshafts.

The results are too disastrous to not verify. And look closely because some driveshafts have an uneven spline count which allows it to be off by only half a spline. The rear on most of our trucks has an odd spline that prevents improper indexing, but not sure on the front shaft.

PS the proper solution to front driveline angle is to clock the transfer case.

Trebor

Does it vibrates with the hubs disengaged and only while in 4WD? If yes then take it for a short drive and let it vibrate. Then drag yourself under the truck and feel ALL of the components of the front driveline. The vibrating part will 90% of the time feel warmer than the rest of the mating parts. The high wear points are usually a u-joint in the CV joint followed by worn splines in the coupler slip joint. Also getting the CV joint bumped 180 degrees out of time can cause this but you said you marked EVERYTHING before you dismantled it.

totalloser

180 makes no difference at all. I'm guessing that's a typo. Uneven spline counts will prevent a true 180 off, and that is what is usually missed as it looks right unless you look closely. It gets worse and worse until you hit THE worst which is at 90 degrees off.

The yokes at each end of the shaft should be *perfectly* lined up.

One more detail a lot of folks don't realize: A U-joint is NOT capable of smooth transmission of force except when in a perfect line. As it misaligns the power is transmitted in stronger pulsations the steeper the angle gets. Even with pretty high angles the pulsations are mostly absorbed by suspension bushings, spring flex etc. I don't think this is the issue as this type of pulsation is minor when detected. Nowhere near the description here, but still worthy of note for someone with a minor vibration on their truck finding this thread.

Correction: 180 off will make no difference in *u-joint alignment*, but can screw up shaft balance badly. :P Oops. This vibration would be negligible at low speeds- undetectable probably until the driveline starts spinning fast. Like 40mph up usually.

mtdoragary

I know this is an old thread, but my unlifted 96's 4WD had been performing perfectly until today. And then when I used 4WD to get out of some slippery pasture, it shook violently when trying to drive down the road. Once I got it out of 4WD, the shaking went away. I looked underneath and saw nothing broken. WHAT could have caused THAT?