Galloping truck

showcrop

Well-known Member
I went to town to pick up a few things including some six inch drain pipe and some water softener salt. On the way back I felt a little low rate vibration from the rear. As I crested a hill and let off the gas it got a whole lot worse. I thought for sure the drive shaft was about to fall out. The truck is an '06 F-350 with diesel 4WD, and I had 7 10 foot lengths of 6 inch drainage pipe, and two forty lb. bags of salt in the back. The truck has 92,000 on it and had a new rear brake caliper put on it Monday. I have had plenty of instances of harmonic rear tire bounce driving an empty tandem dual truck, and it seemed like that at first but then it got a whole lot worse. This afternoon after removing the pipe and salt I put it in my shop and got it up in the air and I could find nothing. U-joints tight, both shafts, tires wheels tight, new caliper tight. I even ran it some checking for any movement or out of round. I took it back out over the same stretch of road and now it is as smooth as could be. Any ideas?
 
Loose yoke,broke belt in tire,front axle shaft universal joint going bad,even something that is tight just needing greasing can do that. I would try greasing it first.
 
(quoted from post at 10:12:36 08/07/21) Loose yoke,broke belt in tire,front axle shaft universal joint going bad,even something that is tight just needing greasing can do that. I would try greasing it first.


As I posted in my OP I already checked for all that and a test after removing the pipe was as smooth as normal. One thing that I didn't mention is that the drain pipe is flexible. It doesn't seem possible that 40 lbs of pipe flexing together could move the truck but that is all I have. Thanks.
 
I had a Dodge Ram 2500 that did something similar with nothing in the bed. I was driving 70 mph on an interstate and went over a bridge expansion joint. Started bouncing so bad that I thought the truck might flip over! All the dirt and dried mud from the undercarriage broke loose and as I slammed the brakes I looked in the rear view and saw a cloud of dust so big that it stopped three lanes of traffic with some of the vehicles pulling onto the shoulders. Looked like a bomb went off. I limped home under 40 mph. Couldn't find anything that was loose. After a few days of slow driving, I crept the speed back up and it happened again at another expansion joint. After searching the web for solutions, discovered the steering stabilizer bar had a crack that could only be seen by prying with a large prybar while on the rack. Replaced it and truck was fine.
 
Seized slip yoke or wore out slip yoke ? I had a one ton that
had a horrible driveline shudder at times had the driveline
balanced again and new yokes put on and it fixed it . My new
dodge with 340,000 miles on did something similar to what
yours did the other day I had a ten thousand pound baler on
the hitch and the only thing I could figure is it must have made
the driveline angles just right or something because it hasnt
ever been back
 
="showcrop"](reply to post at 17:30:20 08/07/21)

Maybe with the flex pipe (the black corrugated sewer type) held down by the salt towards the front, the vacuum flowing over the tail end was lifting the flex pipes.
And causing them to flap up and down creating what felt like the vibration??
 
Just because they are tight doesnt mean they are good one
could be seized or about ready to to seize. also had a tire
getting ready to explode do it before
 


It looks like it was the steering stabilizer. A few days later it turned into "panic stop" death wobble. So it was easy to diagnose the stabilizer. The Fire Dept. utility truck recently started to display the same early symptoms as mine, which included a little minor vibration of the steering wheel and the same galloping though not as pronounced when descending a hill.
 
A steering stabilizer will not fix death wobble under any circumstances. Two things cause wobble, loose track bar joints and too much toe in. For some reason Ford likes to spec a lot of toe in 1/4-3/8. Theres not a straight axle ever built that likes that much toe in. In the dealership I first check for any loose parts and cut the toe back to 1/16 in. After going round and round with Hotline having me replace just about everything and taking caster down to almost 0, the toe is what fixes them every time. Taking caster away takes away stability at highway speeds.
Bottom line is replace any loose parts, then do a proper alignment.
 
Well I have not owned a Ford since 98 and have not worked on any since like 2000, BUT i would crawl under it and check and see if the pinion shaft will move up and down and side to side . Learned early on that the CRUSH space on the 10 and quarter rears will collapse Been there done that . My 88 ended up EATING a ring and pinion . They will crush when your forcing a load in rev. as i found out i was backing my truck and trailer with a tractor on it up a farm lane in low range 4 wheel drive . While backing the force is on the ft. bearing and crush spacer . I have worked on a lot of rear ends in my life time and none were such a PITA as the 10 1/4 Sterling to set up . Ya need a special shim driver to drive the side shims in to preload the side bearings , the crush spacer is a cheat way to load the pinion bearing to get your 28 to 32 inch pound of rolling preload at the factory . I did away with the crush spacer and had a bunch of solid spacers made in .001 inkerments in thickness . since to do this i could not install the ft. seal so i shot for a 30 inch pound rolling preload and it took me five trys with spacer changes to hit my mark . LOTS of shell we say colorful words were spoken during this rebuild . While i was working on my truck one of the neighbor farmers came over and said he wondered if that is why his ft seal was leaking on his 89 so we checked and yup his pinion was also loose so when i was done with mine we shimmed his solid and he told one of his friends and we did that one and another and another and so it started , i passed on my findings to a friend that was a ford tech and how it was done and Walley started doing that on all he found . The guy that made the spacers was going thru a LOT of stress proof stock . He would take the stock and first bore the hole then turn the outside then put a radius the cut it to length as the starter shim then make the next one .001 smaller . Oh yea you start this by taking a new crush spacer and installing it and then putting the yoke on and a new nut and tighten it to the torque load to get it to start to crush then ya keep on crushing till ya get to the say 29-30 in. lbs rolling . Don't worry about not having the new seal in . Once you have reached the rolling preload that i all back apart remove the yooke the ft. bearing and the crush spacer . They will spring back a little but start you solid spacer thickness from there and make them smaller . For ease of this now you do not need a new lock nut use the old one and torque it down each time to around 450 Ft. Lbs. while checking rolling preload . Once you have made it then now you need a NEW NUT install your new seal put the yoke on and the new nut and pull it down to spec.s
 
(quoted from post at 14:09:11 09/18/21) A steering stabilizer will not fix death wobble under any circumstances. Two things cause wobble, loose track bar joints and too much toe in. For some reason Ford likes to spec a lot of toe in 1/4-3/8. Theres not a straight axle ever built that likes that much toe in. In the dealership I first check for any loose parts and cut the toe back to 1/16 in. After going round and round with Hotline having me replace just about everything and taking caster down to almost 0, the toe is what fixes them every time. Taking caster away takes away stability at highway speeds.
Bottom line is replace any loose parts, then do a proper alignment.


Sorry to burst you bubble Brian. It has been five weeks now.
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top