Vibration after "Lincoln Locked" D30

Since I plan to regear both front and rear and install Detroit rear/spool front, I went ahead and let my buddy weld my spider gears together in the front disconnect variety D30.

He had done this before and it looked like a good weld job was done (I watched). He had good luck with his welded front and rear for a couple years till he regeared/axle swap. He never mentioned any vibration problems with his welded axles.

So, after the weld was done, I only drove it home a short distance away. Next day, I get on the interstate and at 50mph to 75mph it started a driveline vibration really bad. The front axle was disconnected, of course.

What I am not certain of, was the vibration possibly caused by the welding of the front axle or did I more than likely bend my rear driveshaft at my last wheeling trip two days before I welded the gears?

Against the rules, I locked it in 4WD today and drove it about 1/2 mile on the street. It handled horribly. I have used 4WD on pavement before and it never was this hard to steer it, even on dry pavement. Could this be another prblem instead of the weld job?

I drive this XJ a lot, so I was hesitant on pulling the driveshafts out to isolate which axle the vibes were coming from. I was hoping it to be the rear.

Just looking for some reassurance and hoping the weld wont cause vibration

I dont think the welding the front itself caused the vibs...probably a worn out front drive shaft that you didnt notice before it started turning at highway speeds...check the splines for wear and the cv joint for wear...my wifes xj started that after we put the lockright in the front...

and it'll handle like poo in 4hi with at speed with the front locked.

you have a locked front in now. It wont turn.

Tally_XJ said:

Against the rules, I locked it in 4WD today and drove it about 1/2 mile on the street. It handled horribly. I have used 4WD on pavement before and it never was this hard to steer it, even on dry pavement. Could this be another prblem instead of the weld job?

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Well you've got a spool in the front now: what did you expect?

I drive this XJ a lot, so I was hesitant on pulling the driveshafts out to isolate which axle the vibes were coming from. I was hoping it to be the rear.

Just looking for some reassurance and hoping the weld wont cause vibration

Click to expand...

If you do end up pulling the front shafts to diagnose things do not drive on just the hubs!!! Make sure that you have stubs in them otherwise they will fall appart on you.

vibration =
now that its welded/spooled you dont have disconnect any more, the left front is going to spin the drive shaft even when the disco is open.

The only reason an open disco front end doesnt turn the DS is because the LF wheel will drive the spiders backwards and turn the discoed shaft instead of the DS, its less resistance.


Steering=
yes thats what a front locker will do, I have also heard something about "clocking" the axles so the ujoints are in the same phase, its supposed to make it easier to steer.
But dont worry about that since you have a disco and it will become unclocked everytime you open the front

I hope that made sense, its kinda a ramble but theres good info in there somewhere.
بوودرلي

yup probably need front shaft balanced or one out of a newer XJ that rotates all the time.

DOH!!

I forgot that the drive shaft now spins all the time with the spiders welded!!

I had it in my mind that the Transfer case controlled that. Well, guess I will pull the drive shaft and check the joints and balance.

Thanks for the answers!

If yer heep is lifted, the pinion angle may be outta whack...you wouldn't notice it before you welded the spiders because the shaft don't spin when disco'd.

i say pinion angle because now the drive saft spins all the time, unless you have lockout hubs

BUCKYXJ said:

yup probably need front shaft balanced or one out of a newer XJ that rotates all the time.

Click to expand...

x2
I had the exact same thing happen when I welded my D30...picked up at junkyard front drive shaft out of a non-disco xj and it solved the vibration problem for $11.50.

Out of curiosity. . . why would the two shafts be any different?

Is it because they (the manufacturer) knew the disco axle wouldnt be spinning the drive shaft constantly and didnt do as good a job balancing it?

Is it physically different/better?

Also, what is the reason I never got these vibes before. . . even when I DID have it locked in and was driving on the pavement? Lift is the same as always. . . I havent changed anything.

I dont think the shafts are different unless you have the older CV like CVboot and all shaft, or the newer double cardan shaft.

How about lift "s and year?

I think you should fire the welder he did a bad job! No mike for real your shaft has got to be outta balance. also are you sure your ratios are correct?

One more thing to consider...

I don't know how many miles you have put on it since it was welded, but from my experience, it can sometimes take a while for the ujoints to "adapt" to their new position/function.

For example: I would add an inch or two of lift and the driveline angles would change. I would have loud vibes at first, then after a few drives they would simmer down.

You might just try driving it for a while and see if it gets any better, depending on how bad it is to begin with I guess. Just don't be too hard on it if it is really rattling your teeth.

CrazyXJ said:

I think you should fire the welder he did a bad job! No mike for real your shaft has got to be outta balance. also are you sure your ratios are correct?

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Ok then Tim. . . . YOUR'E FIRED! (CrazyXJ is Tim, the one that welded me up).

I replaced all three joints in the front shaft today. . . vibration is gone! I will admit that the double cardan joint was a pain in the ass. I gotta look and see how it is actually SUPPOSED to be done. I have never done one before. I hate to think about the next time I do it again. . . . sheesh

Anyway, my heep is a 1989 XJ 2door with about 4 1/2" to 5" of lift (homebrew). JKS adjustable upper and lower CA's.

glad you got the vibs fixed. First thing I would've checked would be the slip yoke on the DS. Grab the yoke and see if you can wiggle it. If you can, the splines are worn and you need to replace the shaft.

Thanks Jason, I gotta tell ya that I grabbed and shook everything there was underneath the Jeep. Since I drive it to work almost everyday, I regularly have it lifted up and am checking and shaking things. I found NOTHING loose and nothing with any amount of play whatsoever. That is why I was at first so hesitant to replace the joints (even though I have heard squeaking coming from the front before).

There was just no sign that the joints were bad.

I think, after all of this has been done and discussed, that the whole problem was that the welded front spiders caused the driveshaft to spin at all times. Even though I had driven it at roadspeeds while in 4WD and front axle locked several times before, I may not have reached the 55 MPH speed that I did while on the interstate. That would have allowed me to miss the vibrations that I felt just after the "lincoln lock" was done.

However, vibes are now fixed and I learned something new: how to rebuild a double cardan joint. I could now do one in just about an hour I guess. This one took me three!

Lesson learned and am a bit wiser now!