Wheel hop

[jimm1009]

When I rescued my truck a while back it had all the axle shafts installed along with the front drive flanges installed just as Uncle Sam likes it.
I notice on the way home on the smooth interstate when I creeped up on 51 or 52 MPH the front end wobbled kind of like the old Willys CJ2A jeeps did (death wobble).
I thought that the right front time was going bad or just not balanced because it was scalloped and wobbled. If you force it faster then the whole front end starts to wobble and when you back it down to 48 or 49 and then back up to 50 and stay there then life is good.
The problem stayed the same after tire swapping. I next put the former right tire on the left front for troubleshooting and the problem actually got a little worse. The wobble came in around 48 MPH but the road was not as smooth either.
I have taken the right front hub off and replaced both outer races and the inner roller bearing due to water marking and the very early stages of metal breaking down.
The outer roller bearing was examined under a 15 power glass several times and kept in service. The right front spindle looked realy good and no wear was found in the diamter.
Everything was put back and torqued as per the TMs.
I am going to pull the left front hub / drum this weekend and inspect the brakes, the bearings, and of course repack them too.
Don't know what else to look for at this time except to check the tie rods and shake both wheels while they are both on jack stands. I will check steering box for wear as installed.
2nd thing that I noticed is what I think that you guys were calling wheel hop from drive line bind. Both rear axles still coupled together and all axles shafts still installed. Driving down a rougher paved highway today and the back end seemed to be hopping a little.
Is this driveline bind or is this possibly tire(s) out of ballance. One inner tire on forward axle is at 50% life while the others are at 75% or better with 1 at 90% life remaining.
All tires are 9:00 x 20 NDCC tread pattern on OEM wheels. All lug nuts on front are torqued and all outer lugnuts on rear are torqued. Have not removed outer wheels to torque inner nuts to date. Everything is at 350 ft lbs. per TM
Jim
>>>>>> Any input from the seasoned deuce mechanics would be most welcomed.

 

[DanMartin]

Air shift or Sprag transfer case? If it's a sprag case, it may not be disengaging correctly. You are starting out in 1st, right?

Also check the tires again, you may have one trying to come apart on you. Look for bulges or blisters.

 

[reuben]

out of balence tires do that for me, done a lot of driving an old chevy dump truck with 9 x 20's and certain tires seem to slip a bit sideways easily on the split rims.

 

[Recovry4x4]

Jim, try bumping up that front tire pressure to 60. You have scallops? Prolly need to check toe and start shopping for front shocks, they can do weird things to the front of a deuce.

 

[Bill W]

Scalloping on the outside corners of the tread?
Could be time for a set of new shocks ( as mentioned)

 

[jimm1009]

The scalloping is on the outside (outboard) corner of the tire on right side only.
I have not checked the shocks other than I know they are not leaking fluid.
Will have to pull them off to inspect.
Do have the sprag transfer case. I'll pull the front driveshaft for quick troubleshooting
check.
I'll go in baby steps;
Tires to 60 PSI first & test drive.
Front drive shaft next & test drive.
Shock check third.
I assume from everyone's comments so far that driving without front shocks will serve no purpose in troubleshooting so there is not a fix for this EXCEPT to install new ones and go from there.
In the mean time, I still need to do the L/H front bearing servicing and inspect the brakes.
I have a squeal that I suspect is the wheel cylinder dust cover being bent up as was the one on the right side. No damage to the right drum so I was lucky there.
Jim again

 

[FormerNewMVGuy]

My truck was showing the same front end signs as yours, The tow was way off, I corrected the tow in, and now it runs along as smooth as silk

 

[jimm1009]

Scott,
Which way was your tow-in out? Too much or too little. I think you are on to something there. It could be tierods but I've not put it up in the air to check this (weekend project).
I've heard tires shops say the this causes the scalloping on cars and small trucks too.
Did you do this check and adjustment per the TM or a different procedure?
As a side note. I have only driven this truck a total of less than 200 miles so far. I assume that this scalloped tire has been there for a while but it could be a tire that they threw on there just before they turnd the truck in for disposal. The left front tire is almost new so only the shadow knows for sure.
Thanks,
Jim

 

[ironhorsethegeneral]

sounds like alignment problem. too much tow end if on outer side. shocks do not cause this kind of problem. they just cause tires to go out of round and the truck will bounce a lot. remember front tires need rotating just like cars. good luck!!

 

[FormerNewMVGuy]

It was towed in a full 1 -1/4 inch to far, which was scalloping the outside of the tire on the right side. I jacked the truck up so i could spin each tire, as i spun the tire i made a center mark on it with a paintstick marker. I then let the truck back down on the ground, measured the front side then the back and adjusted it until it was towed in about 1/8th of an inch.

 

[tiger422]

Tie rod ends will do this they should have very little to no play.

 

[jimm1009]

Well I took 1.5 baby steps tonight.
I clearly need to remember that big truck tires do not hold pressure like smaller radial tires.
After 20 days or so the front tires were down to 40 PSI. I put them both up to 60 PSI and removed the scalloped tire and put the other nearly new tire on the r/h front corner.
One inner dual was down to 25 PSI and the others were down between 35 and 40 PSI.
Put all the rear tires at 52 PSI with new truck gage.
Drove truck up semi-smooth two lane highway and the wobble was still there at 49 to 50 MPH. This wobble is more than a tire out of balance because the tires in the front have had 3 different ones mounted in various configurations.
I'm going to check the torque on the front u-bolts and raise it up in the front to check camber tomorrow night. If nothing is found then I will do the l/h front wheel bearing and drive it then. I will next take the front driveshaft off for one final drive before posting again. I don't want to take too much space on this valuable forum but I sure will need some advice if nothing turns up too.
Jim

 

[cranetruck]

The deuce tires should hold pressure as well as any tire, mine show hardly any drop after a year...
I have found that the front tires need to be closely matched as to wear, mfg and pressure to run smooth (given alignment to spec, of course). If all your tires are worn, I would suggest that you get at least two new ones for the front.
Some of the scalloping is caused by the rear axles being coupled without an interaxle differential, which will cause the truck to want to go straight (resist turning) and increases the turning circle also. For highway driving free up the rear axles. Singles will help also.
You should be able to find more on this with a search on this site.

 

[Bill W]

I'm still betting its the shocks but you may also want to check the spring bushings for slop

 

[cbvet]

FWIW-
I replaced one of the Michelin 1400-20s on the front of the 5 ton with a Goodyear.
Got an annoying shimmy about 40 mph. Replaced the other front with a Goodyear & the shimmy is gone.
Eric
CBVET

 

[jimm1009]

Taking notes as I read. All great ideas...thanks bunches fellow MVers.

Jim

 

[TacticalTruck]

purpose in troubleshooting so there is not a fix for this EXCEPT to install new ones and go from there.

You could remove the shocks and manually push them in and out to see if there is any dampening resistance left in them.
Jeff

 

[BEASTMASTER]

RE: Re: Wheel hop

i drove a mack that did that. the bushings in the front spring hanger were oblonged.replaced said bushings and drove like new.