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Driveline Vibes After SYE

Miller88

NAXJA Forum User
Location
Syracuse NY
I just had Rugged Ridge SYE installed on the XJ and am using a stock front driveshaft. Still having driveline vibes at indicated 60MPH and higher. Light throttle I'm fine, but if I am pulling a hill or using a good amount of throttle, it's bad to worse. If I drop to indicated 55MPH ... no problem at all.

My suspicion is I am getting a bit of axle wrap, pointing the pinion yoke up too far.

Some Info:
- Springs have 6 Degree Shim
- Pinion Yoke is pointed DIRECTLY at TCase yoke.
- Cardan joint is good (checked it & repacked)

Now, before I had the SYE, I had a 1'' drop and the axle was shimmed to 4 degrees (I stacked a 2 degree shim backwards on top of the 6) and I was ... okay.

After the SYE, I still had slight vibrations at above 65MPH, but nothing major. I got rid of the transfer case drop and shimmed back to 6 degrees. The DC joint is supposed to do all of the work.

My suspicion is that I am getting slight axle wrap at those speeds, causing the pinion to point up too far.

Any thoughts? I may drop the axle and put the -2 degree shims back in when I get a chance.

Thanks in advance!
 
first off... dont stack shims. i try not to even use them if possible.

i usually point my pinion slightly below strait at the case to account for pinion climb under power.

if your using a JY shaft, i would suspect that the slip shaft has slop. if thats not the case, it might be a good idea to take the shaft in and make sure its balanced... especially if youve replaced the Ujoints, you may have installed the double cardan joint out of phase from its original orientation.
 
I don't particularly like the idea of stacking them either, but it's what works until I can find a shim angle that works correct.

DS works fine in the front without vibration.

Not using shims is out of the question. I don't have the ability to cut the axle apart and point the pinion correctly and reweld. Of course, being leaf springs, no control arms to adjust either.
 
Everyone has the ability, but do you have the willpower?

I live in an apartment and can only do work when I borrow someone's driveway.

When I get a house with a detached garage ... I'm going to have lots of fun.

No, I don't have willpower. It's a good thing I don't have said house. I would be tearing into all sorts of things. Heh, if I had my own space to work, the XJ would be sitting on upgraded axles and have leaf springs in the front by now.
 
DS works fine in the front without vibration.

Not using shims is out of the question.
inspect the shaft. its free and easy.

and buy the right shim, dont stack them.

I live in an apartment and can only do work when I borrow someone's driveway.

When I get a house with a detached garage ... I'm going to have lots of fun.

No, I don't have willpower. It's a good thing I don't have said house. I would be tearing into all sorts of things. Heh, if I had my own space to work, the XJ would be sitting on upgraded axles and have leaf springs in the front by now.
i live in an apartment and go to school full time. i have a 1/4 mile of cord that i use to run 220 from my oven out to the driveway. it gets me a lot of looks... but it works.

you dont have the will, but its a good thing that you dont have a garage or itd be game on? i dont get it... make some friends in your local chapter, bribe them with beer. its how i got a lot of my work done.
 
242 Hack and Tap or a 231 with a full SYE? I've seen a bunch of hack and taps have vibrations, including my own.

231 Full SYE

you dont have the will, but its a good thing that you dont have a garage or itd be game on? i dont get it... make some friends in your local chapter, bribe them with beer. its how i got a lot of my work done.


That's how I lifted it twice and swapped out the front axle.
 
have leaf springs in the front by now.

:doh:



Have you tried getting the shaft balanced? Unless the are under load, aka driving in 4wd, you can get away with a lot more of an unbalanced shaft in the front.

And don't Stack shims.
 
:doh:



Have you tried getting the shaft balanced? Unless the are under load, aka driving in 4wd, you can get away with a lot more of an unbalanced shaft in the front.

And don't Stack shims.

The stacking of shims is only for testing purpoes.

Neither shaft has been balanced, but the shaft that is now in the back was in the front when I had to drive it as FWD for a few hundred miles after shearing off a bolt in the rear pinion yoke. It was fine transmitting power up to 75+.

Playing with shim angle is much cheaper than getting a driveshaft balanced. If playing with shim angle doesn't work, then I'll get the driveshaft balanced. Also a lot quicker to shim the rear end.
 
bad install.

how so? Its not that hard to install the h&t correctly. More importantly though, how would a bad install contribute to vibrations? Youre installing a splined receiver onto a splined shaft, it cant really be installed off center or lopsided. I dont doubt its bad install im just curious as to which part of the install would be the cause
 
any thoughts as to why this is?

The SYE output yoke has no bearing surrounding it to keep it straight. Unless the splines on the output yoke are incredibly tight (which few are), then you're relying on the bolt pressure to keep it centered and true. Mine was fine for a while, but eventually started to get worse and worse. The design of different kits and how well they were (or weren't) installed has an affect on this. Also, again because there is no bearing on the new yoke, the load on the output bearing is higher because of how far the angle and rotating mass are from the bearing.

Edit: even though there are splines, there is still about 0.025" of play, which is more than enough to cause vibes.
 
how so? Its not that hard to install the h&t correctly. More importantly though, how would a bad install contribute to vibrations? Youre installing a splined receiver onto a splined shaft, it cant really be installed off center or lopsided. I dont doubt its bad install im just curious as to which part of the install would be the cause

if you don't cut it straight, tap it straight, or get the length of the cut right it can vibrate.
 
Last night I bought some hockey pucks and hammered them into the front of the leaf pack. This did point my pinion down a bit. My other assumption was this would preload the springs and minimize the axle wrap.

Interestingly enough, it *did* help! I think the help was from the pinion pointing down a hair. I will shim to 4 degrees tonight and see what that does.

I didn't think an XJ would axle wrap without leaf blocks.

Yeah - the inherent issues of HNT SYE kits kept me from going that route.
 
Getting closer!

I can get on it hard until about indicated 60 on the speedometer before having problems.

I'm at 6-2 on the axle. I'll order a set of 3 degree shims and new U Bolts and make a day of it!
 
All fixed :)

I was taking measurements for a friend who is also building an XJ. I discovered that the front DS was completely maxed out.

Ended up buying part of a ZJ v8 shaft (it was missing centering yoke and one u-joint). Did a bit of mix and match between the too short shaft and all is well now!
 
Well, that didn't last long.

I got about 300 miles out of it and then started to have bad vibrations again. Pull the rear shaft and it's fine. I will be dropping the ZJ shaft off to be rebuilt and balanced.

If that does'nt fix it, I'm going to sell it or bring it to the scrap yard. It's a shame - 120,000 miles, solid frame and floors, runs great ... but can't get rid of driveline vibrations.
 
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