Vibrations after SYE install

[ogreshooter]

OK, here is the scoop.

1990 YJ, PORC SYE, Exploder driveshaft (1992 front d-shaft). 4" RE springs, SUA. (ShOuld be everything pertinent)

Now, I installed the SYE this weekend, got the d-shaft, had my local driveline guy rebuild, shorten, balance the shaft. I installed it.

Now, when I drive down the road I have some vibrations. I get them upon acceleration through 3-5th gear. I do not have the t-case drop in, and it was removed so the proper length could be established. I also have a weird sound when I let off the gas in fifth gear, it is a growling kind of sound that was not present on friday just before I started in on the SYE.

What in the hell happened?? I cut 1.25 inches of the sift rail, maybe a bit more, but not much if at all. I needed to do that so the tail house could go on. I started at 1", but needed a bit more. Did I cut off too much, and is this my problem?? :confused:

Let me know what the guru's of the board have to say. And hopefully it is something other than "you're fawked :flipoff2: "

[Trailer Guy]

I think the pinion angle is off. What type of angle do you have on the pinion? I think most YJ's with SYE kits need about 15 to 18 degrees on the pinion.

[ogreshooter]

OK, and if that is not there, then what do I do? More shim?

I did notice that my transfer case and tranny are as far back on the skid plate as possible. Do you think moving that forward would help?

Just looking for advice. I am not putting that stupid t-case drop back in at all.

Thanks!

Ogre

[Trailer Guy]

OK, and if that is not there, then what do I do? More shim?

I did notice that my transfer case and tranny are as far back on the skid plate as possible. Do you think moving that forward would help?

Just looking for advice. I am not putting that stupid t-case drop back in at all.

Thanks!

Ogre
Forget about where the trans and t-case mounts to the skid, I don't think that has anything to do with it. I wouldn't run the t-case drop kit either, that would be crazy. When I did my first SOA (7 years ago) I had the same exact issue. The place I bought the parts from (won't mention names of course) told me to place the pinion at the angle to match the t-case. This would have been true without the SYE, but I was installing their SYE kit and they knew it. Now when I setup a rear pinion, and using a CV rear shaft, I point the pinion directly at the output shaft on the t-case, then lower it about 3 degrees, to take up for axle wrap. I don't get any vibration issues on anyones rigs, and I've never had a complaint. When talking about setting up proper driveline angles, I should probably talk to Jess @ High Angle. He has always helped when I needed it, and never steered me wrong.

[ogreshooter]

OK, fixed the rear vibes, next question. I have vibes on the hwy in 4wd, and the 4wd does not come out. I can shift out of it, but something is binding and not letting loose.
Any ideas?

[butch6924]

Here's an idea, don't drive on the highway in 4wd. It's not meant to go over 55 mph. The vibes are probably from an unbalanced front DS. YJ front DS's aren't balanced because they're not designed to be truning that fast.

[ogreshooter]

I was only going 45 mph, and I had it balanced so that I could drive on snowy roads. There should not be any problem with that. I will check it out though.

[ogreshooter]

Well, I disconnected the vacuum and took out the front d-shaft. Thunking and vibrations are gone.

Troubleshooting steps from here? any suggestions??

[xtusseryx]

Here's an idea, don't drive on the highway in 4wd. It's not meant to go over 55 mph. The vibes are probably from an unbalanced front DS. YJ front DS's aren't balanced because they're not designed to be truning that fast.
Funny, my front YJ driveshaft was balanced from the factory.

[butch6924]

Funny, my front YJ driveshaft was balanced from the factory.

I'm hearing a lot of people saying that. I don't really know why some are and some aren't. I guess it's not so much of a rule as I thought.

Well, I disconnected the vacuum and took out the front d-shaft. Thunking and vibrations are gone.

Troubleshooting steps from here? any suggestions??

I is your front DS balanced? Check to see if there's a balancing weight welded to the outside of the tube to know. That would be my next step.

BTW, sorry if I came off like a d!ck in my previous post. I just re read it, must have been in a pissy mood when I posted that.

[ogreshooter]

Oh well, life goes on. I am a dick from time to time. I am having it re-checked this morning (Front d-shaft). Then I am going to hook the vacuum back up and see if the clunking comes back without the d-shaft. If so, looks like waggy axles are closer in the future than I thought....