Vibration

[athawk11]

At about 30 MPH, I have an intermittent vibration.  I'm waiting on the new U-joints from Walcks.  When I replaced them on my truck, I learned it was critical to mark the position of the dual shafts and to reassemble exactly how I found them.   I didn't know this rule when I took the Willys down to the frame, so I cleaned up the shafts, replaced seals Installed 1 new u-joint out of 4 and put it all back together.  I think this may be the source of my vibration.

Does this rule apply to an old Willys too?  Is there something else I should look for if this doesn't solve the vibration?

Tim

[Gunslinger]

Hey Tim,
Thats a good place to start, the two universals on each shaft have to be lined up as close to each other as possible or it will vibrate.  It cold also be that one of the u joints is starting to go out.  Once they start its pretty amazing how fast they get nasty.
Todd

[RussellL]

What speed is your vibration? �Is it real fast like the drive shaft? Or is it much slower? �At 30 mph you are right in the speed where many jeep owners experience the phenomenon known as Death Wobble, or front end shimmy. �It is a much slower, maybe 5 pulses per second, and more violent vibration that jerks the steering wheel back and forth and starts very abruptly. �A driveshaft vibration will be much faster. �Maybe 10 times faster and will start softly and build up as speed increases.

[rocketeer]

They should line up like this:



Larry

[athawk11]

I must have been more careful with these than I thought.  The alignment (per Rocketeers photo) looks dead on.  The length is a 1/16th" long on the rear shaft. Not sure what would cause that.  

Russel, it's definately the super fast vibration.  I haven't experienced the 'death wobble'.  I hope I never do.  From what I have read, it sounds terrifying.

I should get the U-joints today.  I'll get them installed and let you know the result.

Thanks all.

Tim

[Carls_jeep]

I would like to add to the yoke alignment issue. If a yoke won't line up then rotate it 180 deg and try again. Depending on the spline count the yoke may only line up at one certain spot. Close enough is not good enough in most cases.

[bretto]

To add what Carl said.  They may only line up one way.  At least they did on mine.  Mine are keyed in a way that that there is a wide spline one side.  Cant go together any other way.
Brett

[Chasm]

Tim:

I play with newer Jeeps too and a common cause of vibes that you describe has to do with changes in the suspension height. I am just throwing this out there because I don't know if you have lifted the suspension with bigger springs or shackles. Increased drive-line angles due to a suspension height increase can cause vibes from the U-joints. The quick fix on newer Jeeps is to lower the transfer case, with spacers, to return the drive line to the original angles.

Good luck in getting the vibration sorted out!

[athawk11]

Chasm, �No new shackles or springs. �And no additional lift. �Just new shocks on the front. �I guess I just started at what I know. �It felt like the vibration on my daily driver. �When I got to 35 MPH and 68 MPH, My old Tundra vibrated. �

On the Jeep, I replaced one u-joint that was clearly shot. �I just can't remember what position the new one is in.  I also can't remember how it felt when I first got the Willys. It may have vibrated then.  At the time, I was more concerned about how I was going to get it stopped, as the brakes were horrible.  The Crankshaft pulley was also bent, so the engine shook around a little.  (I also had a broken motor mount, so the radiator fan would clang against the shroud.  I'm guessing I'm not alone.  Everyone probably has crazy stories about the condition of their New...Old Willys.
 ï¿½
The post by Carl now has me a little worried. �I did pull the Yoke and replaced the seal. �(Axle is a DANA 41.)
I pulled it out, cleaned and inspected it, (small groove where it makes contact with the seal), installed the new seal, added Permatex 2 to the splines, slipped the yoke right back in and bolted it down. �Per Bretto and Carl, I just can't remember if there was one way in...2 ways in...hmmm. �It just slipped right back in. �Maybe I got lucky. �Bretto, Does your M38 have the 41 or 44 rear end? Or...?

Tim

[Gunslinger]

Just a thought, have you balanced the tires?  Un balanced tires can make a huge difference and feel like a bigger problem than it is,

[rocketeer]

No Permatex. The splines get greased with regular lubricating grease so they can smoothly move back and forth as the suspension goes up and down when you're driving.

Larry

[Carls_jeep]

Tim, that's not the yoke I was talking about. The yoke I was referring to is the yokes on the drive line, the sliding part that comes off the drive shaft.

You don't have to orient the yoke on the axle pinion.

[johnnybravo]

OTHER SUSPECTS:
 ï¿½-Splines in yoke and Splines on input stub shaft, after installed, wiggle test drive line
 ï¿½-Another U joint, maybe one cup is dry, wiggle test
 ï¿½-Bent Drive line, inspect on work bench
 ï¿½-Output yoke on axle and/or transfer, wiggle test

[athawk11]

Thanks Carl.  I thought you were talking about the yoke that inserts into the differential that the driveshaft is attached to.  I think Rocketeer was following your line of thought.  I'm the only dork in the room today.  Rocketeer, I did not put Permatex in the drive shaft splines.  You must have read that and thought I'd lost my mind.

My rear drive shaft will not come completely apart. It slides in and out smoothly and is fitted with a zerk , but there is a small cup welded to the shaft that stops the shaft from sliding completely apart.  Is this common?  Do I have an aftermarket shaft?

I got the new u-joints and installed them last night.  It's not a severe vibration, but it's still the same.  I am begining to wonder if it's the new NDCC tires.  Is it possible that this tire tread just runs more rough than the radials I took off?  I just have nothing to compare it to.

Johny,  thanks for the list of vabration sources. I did check the items you mentioned.  Overall the driveline is tight and well lubricated.  If one of you could stop by and take it for a drive, I sure would appreciate it.  Coming to Colorado anytime soon?  

[Carls_jeep]

The cover your referring to at the spline should screw off. I guess it's tack welded because the threads are buggered.