"Death Wobble" cause

[KPolman]

2/15/2004



Regarding Dana 60 4wd front end “death wobble. ”

I’m surprised Chrysler engineers haven’t figured this out.



Assuming the wheels are balanced and aligned properly, I would look for an out of tolerance badly worn axel housing and steering knuckle. The way to check this is to jack the front wheel off the ground by the housing, not the knuckle. Have someone jump on the hub. If the wheel drops, the housing and steering knuckle have too much clearance.



That large spring above the teflon taper bushing is what holds the lower Timken kingpin bearing in engagement when the front end is unloaded by a bump. When the housing is worn and the wheel is unloaded by a bump or warped rotor bounce, the spring compresses and allows the lower taper roller bearing to come out of engagement with the kingpin causing a severe side play condition. You can check this by removing the four spring cover bolts to release the spring tension. If the wheel flops around you have too much axel housing clearance and an expensive housing replacement repair.



When the wear becomes excessive the spring can’t keep the kingpin engaged in a bump and the oscillations increase the wear rapidly until the “death wobble” becomes extremely dangerous. I found that after a quarter million miles the knuckle on the left side had an eighth inch of vertical play. The right side was O. K. So what did I do to eliminate the play? I eliminated the springs.



Having a machine shop, I turned a couple of 5/8" thick steel cups to go over the teflon bushings. I drilled and tapped the spring housings through the grease fitting holes for 1/2"-20 bolts. The stamped housing will need a nut spot welded on the inside. The cast housing has enough thickness for the threads. I then relocated the zerks off to the side and drilled an eighth inch hole in the steel cup to allow the upper kingpin to get grease. That solved the “death wobble” problem for good.



Mopar may not approve of my redesign but it does work and it is a`simple thing to put a wrench on the bolt every grease job to make sure the cups have no clearance. I haven’t noticed any wear to take up over the last 10,000 miles because there is virtually no load on the cup. The only load on the bolt and cup is when the front wheels are off the ground and my truck won’t “pop a wheelie. ” Not yet anyway.



If anyone wants a drawing of the steel cup modification send me a SASE or fax number.



Ken’s Machine Shop

general delivery

Silver Peak, Nevada 89047

775-937-2244

 

[jlast]

While this is a chrysler product we drive the axle is dana also.



And while the problem is not new nor are the parts, as this same axle been used since the 70's.



While weak springs, broken springs, and such are possible while age, amount of use and abuse are all factors in the specific problem you are addressing.



While after 250,000 miles i do believe somewhere along the line there needed to be axle maintainance in which these springs should be looked at and replaced along with bearings and such. Plenty of service out of these pieces.



Chrysler biggest problem started when they gave these axle specs to dana. Chrysler had these axles built with less then 3 degrees of caster, and compared with GM 6 - 8 degrees on basically same axle. the less degree of caster only multiplys any problems in the front axle, front suspension, and why 1st gens have huge problems when springs start to sag they loose neg caster.



While i do like your design I also would suggest just change the worn springs, place a couple of washers in the spring pockets to increase load on spring (not ideal). I do like your design on the no constant load on the bearing, or possibility to set a load on the bearing.



Any of this are you able to email? pics, etc...



also i am sending you a Question on a design i have.