Truck is a 97 1500 4x4 with 5" Rough Country lift. I am having a fairly bad vibration only when in 4wd, so I am suspecting the front driveshaft is the culprit. Low speed when coasting and around 40km/h is when the vibes are worst. A list of things I've done so far are:

-Checked the CV at the transfer case, can't detect any play.

-Checked the U-joint at the diff and thought it had a wee bit of play, so I replaced it anyway as a cheap precaution; turns out it was just fine. Vibration remained the same.

-Tried checking if the shaft was out of balance per the service manual by using hose clamps on the shaft, rotating them 90 degrees and road testing. This only seemed to make vibes worse in any orientation.

-Played with the cam bolts on the lower control arms to angle the pinion up as much as I could to make driveline angles better. I would say this yielded me about a 1/8" of clearance on the front joint. Road testing I noticed a slight reduction in vibes, however still pretty prominent.

I also noticed I can move the driveshaft up and down at the slip-joint approx. 1mm total. I'm not sure if this is normal, it seems to be quite controversial on other forums. Is it possible that I don't have enough spline engagement in the slip joint (due to the lift) which causes this eccentric movement of the shaft during driving?

I know there are some guys here running around 7" (merc, Bartow), wondering if you guys have this issue or have lengthened shafts, etc.

I have a few crappy pics of my current driveline angles if it helps at all:





Any advice is appreciated.

 

I have never had a front end DS vibe, I installed the clocking ring to help with the front DS angle as I have plans to go bigger this spring. All DS are at stock length on my rig. 1mm movement is not much at all and I don't think that will cause your vibe. For some reason your DS angle looks much more than mine ever had.

 

Where are your snap rings?

I dont have a 5in lift but those angles are pretty extreme compared to other pix ive seen on this forum

 

Here are a couple of pix showing the front DS angle with the clocking/indexing ring installed.

 

They are the internal "C" style on the diff joint

I have to agree it's at a pretty awful angle. Much more up / down movement with droop on either joint and it will hit and I'd have to start clearancing. Here are some marginally better daytime pics on level ground:



Pinion angle (LCA's and DS are pretty much same angle). You can see I have the cam bolt adjustment maxed out:



Clearance at worst point at diff joint:



Clearance at forwardmost joint on CV at t-case:



Why is it so bad and what do you guys suggest? Adjustable control arms? Index ring? Would there be any other reason for the vibes besides this?

Thanks

 

Man that is close on the pinion end. You can only adjust so much with adjustable control arms have to keep in mind of front end alignment specs. So that leaves clocking ring or a Ford high pinion Dana. If you go with a clocking ring make darn sure it comes with a seal adapter you do need one. I got mine from North West Fab here in BC, Skyjacker and a few others make them. I also have a upgrade for the rear seal on the tranny side of things, changes it from a single lip seal to a double lip seal. I will find the part number and post it up.

 

I just went out and took a closer look at the double cardan. I took a pic of the clearance on the "good" side (last pic in my previous post). Clearance is paper thin on the other side. The driveshaft is on the top of the pic and the forwardmost U-joint in the double cardan below it:



Yeah...they're practically touching...Didn't see this at first, this is way worse than what I have at the pinion...looking closely it seems like they've just kissed each other a few times as well. I think I'm going to haul the shaft off and do some clearancing on both ends and go from there. Doubt this will cure any vibes but at least I'll have a bit more comfort room to work with when I do use 4x4 (rarely). This is primarily a pavement pounder after all.

Merc, with the indexing ring, did you have to mess with cutting the trans crossmember at all? How much are you clocked? After doing a bit of research the Skyjacker kit is looking like my best option. Seems to come with that seal adapter you were talking about, which I can only find sold separately by Skyjacker for $70. Also, apparently the index rings with multiple holes for adjustment are bad for leaks as its hard to seal against something with so many voids. Think I'll avoid that style...not the type of guy that likes to do jobs twice.

Is this my cheapest option for a resolution? I know custom driveshafts can get pricy so I think I want to avoid that. What about dropping the tcase and trans altogether?

 

No messing around with the crossmember or either DS, this is a true bolt in job. I would have to say it moved it down about 2-2.5 inches. It does put the front output ds flange close to the crossmember like 1/2-3/4" but I have yet to hear it hit and believe me I tried to make it hit. I was a little worried about all the holes in my clocking ring, one reason I dug up a double lip seal for the tranny (still looking for that number). The xcase already uses a double lip seal so no worries there. I also used black rvt on all the mating surfaces just because.

Not to sure what you mean by dropping the tranny and xcase together? I just pulled the xcase and did it that way.

Somewhere I have Sj part number for the full kit like all in one package I will start looking for that one as well. The kit I was thinking was IXR20K but stick to your route.

Edit: Wow I forgot just how expensive those SJ kit are ouch.

Some pix after the clocking ring was installed.










Double Lip seal for the tranny output shaft. This might not work for you as you are going twith the seal adapter.

 

Is this double lip seal a direct replacement for stock? Can it not be used with that adapter? Did you not use the adapter? If not, why?

I found this thread on pavementsucks, didn't quite understand how the adapter worked initially, but it looks like an extension piece that is tapped into the trans that spaces the seal out an amount equal to the thickness of the indexing ring. Is this correct?

http://www.pavementsucks.com/board/t...er-pics?page=2




I was referring to removing the tranny mount and cutting it / making a shorter one. I realize now that's a bad idea and it will not only affect my rear driveshaft angle, but will make the front one even worse.


Yeah it is pricy...if you could give me the scoop on this double lip seal I might go the cheaper route and buy the trans adapter (if required) separately and pick up a ring similar to yours with multiple adjustments. The skyjacker kit, like you said, is pricy and almost twice what you can piece it together for.

 

Just bumping this up again.

Realized my tranny mount is completely shot, which no doubt is furthering the vibration. The rubber isolator is completely debonded from the metal mount and I can lift the transfer case and tranny right up off the mount. The tcase shifter would often pop upward a good few inches on hard launches and when loading up with brakes held. It's pretty clear why now... Will be replacing ASAP.

Also hauled off the front DS to clearance it this weekend. Will report back with how it works out