Driveline Vibration(s) ?

[nwwheeler08]

So, Finally got the 87 Yj with the injected I6 swap, AX-15, NP231 and 8.8 rear w/ lsd. Dana 30 Front with an Aussie. Now the front had that adapter kit installed to lock it in full time. And for some reason it has some terrible vibrations when its in. Spicer U-joints look good. And its a Drivelines NW that looks straight. Any Ideas?

Also for the rear, its got an SYE kit with another Drivelines NW double caradine or whatever cv style. Now when under load theres a vibration. It feels like its coming from the driveline or tcase. I know the Rear diff isnt at the right angle but if it was a driveshaft issue, wouldnt it be all time not just under load?

I put the rig on a lift, started it and ran through first and second gears without the vibration.

Im going to take the rear shaft out and put in the front this weekend to see if the rear noise goes away.

Thanks Ahead of time for ideas Guys!

 

[slideshow86]

Now when under load theres a vibration. It feels like its coming from the driveline or tcase. I know the Rear diff isnt at the right angle but if it was a driveshaft issue, wouldnt it be all time not just under load?

I put the rig on a lift, started it and ran through first and second gears without the vibration.

I just got done going through a bunch of this.

The u joints will ALWAYS vibrate. It is REQUIRED to have good angles on both ends of the shaft. No matter what.

What I mean is this, Say you have a single (NON spicer/cardon/cv joint) u joint shaft on both ends. The top ujoint shakes with X amount of vibration, it takes matching the angle at the other end to absorb ALL of the vibration send from the other u joint. Its just the way it works, call it flaw of design. The ONLY way to not have a ujoint vibrat is have it work at zero working angle. You and I know, **** aint possible. So you just gotta match it as best possible.

Now, your dealing with a spicer,cardon or cv joint. It is designed to point the pinion (of rear or front diff) straight up at the transfer. Your spicer,cardon or cv joint will split the crazy angle up top in two.

The deviation of this is UNDER LOAD conditions. When under load with waggy springs you get axle wrap. this wrap changes pinion angle. Changing the angle makes the recieving ujoint no longer able to absorb the "sent" vibration. This is what "I" think your feeling.

Hope this helps, If you do a little searching there some REALLY good websites that really explain this and show pix. I just kinda summed it up.

If you can post a pic of both joints, im sure we could suggest some changes to achieve less vibes.

 

[Zoediak]

since you have not properly angled the rear axle after adding the SYE and CV joint, this will cause your vibrations..

take your rear axle yoke, angle it to point exactly at the output of the case, then rotate it down about 1*-1.5* and this will elimintate driveline vibrations for a cv jointed d-line...

oh.. and you want to do this with the springs loaded, meaning with the weight of the vehicle compressing the springs..... otherwise you will just be wasting your time thinking it was set up correctly.

generally what I do is replace my spring perches... bolt it together, place a jack under the pinion and raise it up to teh desired angle, tack the perches, remove and fully weld... but that is just me...

:awesomework:

 

[nwwheeler08]

yeah, im going to mess with the angle this weekend probably. I need to drop the tranny and t-case about an inch to get em away from the body. That should help.

Then its on to the front to figure out that whole mess.

Did take it out on a short little break in trip. had to do it in two wheel but it worked really well. Pretty impressed.

Thanks guys

 

[A1Fiddler]

Is the double-cardan new? I just had to track down the exact same problem and it ended up being that. Between the u-joints and the centering ball/spring mine was causing that issue under load.

 

[pokey]

since you have not properly angled the rear axle after adding the SYE and CV joint, this will cause your vibrations..

take your rear axle yoke, angle it to point exactly at the output of the case, then rotate it down about 1*-1.5* and this will elimintate driveline vibrations for a cv jointed d-line...

oh.. and you want to do this with the springs loaded, meaning with the weight of the vehicle compressing the springs..... otherwise you will just be wasting your time thinking it was set up correctly.

generally what I do is replace my spring perches... bolt it together, place a jack under the pinion and raise it up to teh desired angle, tack the perches, remove and fully weld... but that is just me...

:awesomework:

Yep all of this :awesomework:

 

[nwwheeler08]

yeah. im going to try to dig into all that this weekend. like i said i gotta drop the t-case and tranny down along with the skidplate thing about an inch. Its hitting a bit. So with that and hopefully some 4* shims on the springs it should pretty much take care of it. Im hoping the front is about the same issue. when i was taking a leaf out of the front i think i noticed the front pumpkin was tilted up a wee bit...So just down to tinkering with it.
Also have to get rid of the full time four wheel drive b.s. I Really like the Posi-lock system.