Freerider15

Wow, lots of incorrect information in here.

Given that there is a slip shaft of that DS, the assumption can be made he is running an SYE and CV.

As such, he does NOT want parallel angles. Ideal is ~2° down from alignment.

Your driveline angle in that picture should give you very little if any vibration. It could come down some, but it's not bad.

Logic states your gears were not setup properly.

Freerider15

I would disagree on exposed splines. If that were the case, many many rigs and well built buggies would have problems at speed. You'd be surprised how little of the DS needs to be engaged for it to work fine.

Yes, more spline engagement means greater strength, but that's not the issue at hand.

5-Speed

I was just stating that it was 100% my issue. I had vibes, then I had Adams make me a longer shaft and no more vibes. Nothing else changed.

There is also the difference between right and wrong. Even if there are no vibes but you only have 1/2" of spline engagement, thats just wrong. Adams states that there is a certain amount of the spline that needs to be engaged for a reason.

And trust me, I have seen many "well built buggies" with tons of issues. Just cause one person thinks its right and seems to work, doesnt really mean it is. We have $300k off road vehicles that come through the shop daily and I guarantee you I can find multiple issues with every single one. Anything from bracing in the wrong spot to suspension geometry that works but is very wrong.

Freerider15

If you have 1/2" of spline engagement, of course that isn't really going to work.

But even 2" of engagement on a 7" slip shaft shouldn't cause issues (vibration wise).

The bigger issue I've found, is either too much (or more often too little) spline "dip" (the blue stuff on the splines). If there wasn't enough on to begin, or if it's become worn it will cause all sorts of fun things.

Depends on the builder and their quality. Hell, all one has to do is go to SEMA and walk about big gay truck land to see the hacktacular fab that hundreds of thousands of dollars gets you.

Now, stuff rolling out of places like Jimmys4x4, Campbell Enterprises, Trent Fab, etc...I'd have a harder time believing (but they very well might not build their own shafts).

Hell, I know guys (and soon to be one) that run non-cv drivelines (like most buggies) that have all sorts of "supposed to vibe like hell" setups...that barely give them a peep.

Due to the before and after the OP mentioned, I'd still point to gears due to:

1.) Improper break in
2.) Backlash too tight or too lose
3.) Other various things installed with gear installs (I've known of carrier bearings that though were perfect in the box), caused issues when actually run)

70hemicuda

Oh boy .Lots of information going on here. Okay so I know that for my sye and style driveshaft you want the pinion pointing at the tcase, but I also know you want it 3 degrees or less lower than the driveline to account for axle wrap. That picture I took it looks dead on, almost a tad higher on the pinion side but maybe I'm looking at it to hard. The vibes I get now are from day one of getting my Jeep back after gears. The driveshaft did help, but only a tad. I'm still going to take the shims out to see if possibly the pinion is too high. After that it's going back to the shop that did the work. I only got probably 1200 miles on the gears

ClydesdaleKevin

I get a pulsing vibration from my 98 once I hit around 40-50mph. I still haven't figured out what is causing it yet. It fades out around 65mph, but I rarely drive that fast. I'll keep an eye on this thread to see if you figure it out, and see if it applies to mine.

Kev

Jmet8

70hemicuda

So havent had a lot of time to really dig into this but i got some things done. shims from the rear removed so now i have my pinon 2 degrees below the driveshaft. It helped but not all the way. The front pinion was way out of wack, my degree finder was messed up. Got a nice digital one and now its within 2 degrees. castor at about 5 to 5.5 degrees. it helped with the vibes at around 50. Now its the same vibration from 50 on. Before it was heavier at certain speeds. I am using wheel spacers (I know, not great but i like my wheels too much) I thought maybe because they are cheaper ones they were bad so now i am running spidertrax. No change. I noticed that the vibes are heavier on acceleration and when i let off the gas they subside greatly. I also have noticed my transfer case output shafts have some play in the them up and down so its probably time for a rebuild. I am also running a hack n tap sye and have read some threads where people expierence vibrations from those. So next step is a full sye and transfer case rebuild. This was coming up soon anyway as my jeep has almost 200 thousand, but hopefully this will solve my issue.

70hemicuda

Been a while since I've been able to do much. Bought a Comanche so that's been my priority and just kinda been ignoring the vibes. Rebuilt tcase helped a bit but still there. Rebalanced tires and still there. Well today I drove with the front driveshaft in only and low and behold no vibes at all. also think I an hearing a whirring noise from the back end but I could be over sensitive now to noises. Gonna call the guy up and try to bring it in for a rear end check. I bought a full case lsd (I'm over the locker in the rear for DD) and a full rebuild kit just to have when it goes in as I can't afford the jeep to be down for long. If it does end up being say the pinion bearing, I can reuse the gears right?

Rlmx

Installed an SYE and Tom Woods double cardan drive shaft. Vibes at 45+ MPH for me. So frustrating.

Tried a 7* (as a result of some poor measuring) shim, a 1 inch t-case drop, a 4* shim, and a 3*.

Pulled the rear drive shaft. Smooth as silk.

Installed the front drive shaft to the rear. Same bad vibes.

Still befuddled.

Re-geared from 3.55 to 4.10. Same bad vibes. (This wasn't an attempt at a solution. Was just part of the plan.)

For an Adams (or any) double cardan shaft, engineers recommend that the angle of the shaft is to be within 1/2 degree of the pinion, NOT 90 degrees.

Many practitioners recommend that the shaft be 1 or 2 degrees below the pinion angle.

Did all that, only to learn that the pinion angle isn't my problem. But no certain what it is.

The next step here is to have a mechanic run the jeep to 45 mph on a lift.

Found that my transmission mount is cracked. This isn't likely to be the problem. But will correct, hope, and pray.

Please let us know if you find a solution.

jim9006

Since I didn't see it mentioned, I'll add another point of interest. Have you checked your motor mounts? They do sag out and/or break which can change angles all the way back to your transfer case. Just say'n