Severe wheel hop

[AKPacker]

I'm on my way home to Alaska with my M1079 and I'm getting some severe vertical wheel hop on the front axle to the point where it is undrivable above ~40mph. I've got about 1000 miles on brand new 14.00R20 tires with balance beads in them, there was some minor wheel hop since the start but I figured that was normal for large relatively unbalanced tires.

Within the past 50 miles it has become much more severe. I'm currently stuck in Spearfish North Dakota until I get this sorted out. It is Sunday so all the truck rpair shops are closed today. Does anyone have experience fixing wheel hop on their LMTV?

 

[Keith Knight]

Sound like a bad tire. See if you can identify the problem tire and replace it with your spare. If that doesn’t work take the other front tire off and put the other tire on. Most likely it’s only one tire. Could be the 3 piece run flat came apart causing it as well.

 

[GeneralDisorder]

Yeah - try swapping your spare to one of the front wheels and if that does nothing try it on the other side. I've never experienced anything like that on my same model truck. I have 20k miles on mine. Running MV/T's with '22 date codes. What date code are your new tires?

 

[Keith Knight]

He’s running new 14.00R20 tires, with 3 piece run flats up front. Not sure if his spare matches. Also not sure a 14.00R20 tire will fit in the spare area. Can’t imagine anything mechanical causing it but on civilian work vehicles I’ve experienced many tires causing that type of situation usually means a belt broke or the tread separating.

 

[Ronmar]

Yea I would say belt failure or tread sep, that or your run-flat came undone

its AWD, if you chock the rears and leave the park brake on, you can jack up one front at a time, start up, put it in D and rotate one wheel at a time to see if anything is out of round. You by yourself? You could set up you phone cam to video while you operate the truck, guard the brakes from the cab…

 

[AKPacker]

Thanks for the suggestions, tires have 2022 date codes, the spare matches. 14.00R20s fit in the spare location, they just stick out a bit further.

A mobile mechanic came and looked at it and he thought it was steering related, but wasn't able to help much beyond that. I'm more inclined to think it's a tire issue so I'm going to try swapping the spare with the right front wheel (I think that's the one causing the hop) as suggested.

 

[GeneralDisorder]

Steering related? I doubt that. Your truck has fewer miles on it than mine had when I purchased it. All the drag link and tie rod boots were shot but the joints were TIGHT. I cleaned them all out, packed with new grease, and installed Energy Suspension urethane boots. Downstream of the steering gearbox there's not much going on - just drag link and tie rods. If those are tight and the gearbox isn't falling off the frame I don't see how the steering could cause that. What an odd diagnosis.

 

[AKPacker]

Thanks, that was my thought as well. On the steering topic, are all these trucks "floaty" at speed? Mine is, at speeds above 60 it can get a bit floaty feeling, I assumed it has to do with the tall flexy sidewalls.

 

[GeneralDisorder]

Thanks, that was my thought as well. On the steering topic, are all these trucks "floaty" at speed? Mine is, at speeds above 60 it can get a bit floaty feeling, I assumed it has to do with the tall flexy sidewalls.

Negative. My truck is not "floaty". Even at 80 mph. I can let go of the wheel at freeway speed and the truck drives perfectly straight. Different tires of course....... no run flats in mine either.

 

[AKPacker]

Ok thanks, haha maybe I just chose the wrong tires, I thought I was doing good by going with brand new ones. I'll stick with MV/Ts next time.

 

[Ronmar]

What tire pressure are you running, that might effect “sponge”.

Did you check toe-in? Easy enough to do on these trucks.

 

[aw113sgte]

I think "floaty" is relative. These are straight axle trucks with large tires. They will be floaty compared to an IFS civilian truck. Mine is an A1R as well but 6x6. 60mph is no problem but it doesn't feel nearly as planted as my normal cars

 

[AKPacker]

I was running 85 psi cold. I did not check the toe in, I don't have calipers but I could use a tape measure to at least see if it is way off.

I assumed some "floatiness" was normal, these tires have a very rounded profile so only the center lugs make full contact with the pavement, that combined with a tall flexy sidewalls doesn't lend itself to tight steering.

 

[aw113sgte]

Another idea, jack up the front wheels and check for wheel bearing tightness. Eco hubs are held on by that single m5 screw in the split collar, if that comes loose the axle nut can back off. For the rear wheels you would need to turn off the park brakes or cage them (use those wheel chocks!)

 

[serpico760]

My thought is to check the rotational alignment of the beadlocker or run flat with the ctis valve on the rim. With the beadlocker ring to the ctis I know the alignment is critical otherwise you will be out of balance. I don't know was run flat but I would assume that would also be the case. Generally the heavy spot on the internal components inside the tire need to be rotated opposite to the ctis valve on the rim in my understanding.

 

[Keith Knight]

Let’s get back to basics is it wheel hop or death wobble? Wheel hop would indicate tire problems.
death wobble when the steering wheel goes crazy out of control is typically suspension, steering, etc.

 

[GeneralDisorder]

My thought is to check the rotational alignment of the beadlocker or run flat with the ctis valve on the rim. With the beadlocker ring to the ctis I know the alignment is critical otherwise you will be out of balance. I don't know was run flat but I would assume that would also be the case. Generally the heavy spot on the internal components inside the tire need to be rotated opposite to the ctis valve on the rim in my understanding.

The wheel valve and hose weighs 11.5 ounces. Additionally the TM work package for tire mounting make no mention of this alignment. Third - Goodyear says the tires don't require balancing. This has been consistent with my experience.

The beadlock hardware is probably 2 ounces at most (it's 4 tiny nuts and bolts, and two tiny bars), and there is a gap in the metal bead lock ring when it's assembled such that it would offset some of the tiny weight of the hardware.

Also I'm not seeing how the run-flat has any specific alignment. It appears to be symmetrical.

I'm not finding any evidence of this supposed bead lock / wheel valve alignment. I didn't pay this any attention when mounting my MV/T's (because again - not in the TM work package) and my truck is very smooth. Which I attribute to regular driving keeping the flat spots away.

 

[Ronmar]

Yea I think he used a 3 segment run-flat which would be symmetrical/balanced…

 

[serpico760]

The wheel valve and hose weighs 11.5 ounces. Additionally the TM work package for tire mounting make no mention of this alignment. Third - Goodyear says the tires don't require balancing. This has been consistent with my experience.

The beadlock hardware is probably 2 ounces at most (it's 4 tiny nuts and bolts, and two tiny bars), and there is a gap in the metal bead lock ring when it's assembled such that it would offset some of the tiny weight of the hardware.

Also I'm not seeing how the run-flat has any specific alignment. It appears to be symmetrical.

I'm not finding any evidence of this supposed bead lock / wheel valve alignment. I didn't pay this any attention when mounting my MV/T's (because again - not in the TM work package) and my truck is very smooth. Which I attribute to regular driving keeping the flat spots away.

Thanks for the info. Out of more good curiosity later I'm going to reread all that just to see if there is any mention. Also it doesn't hurt to review the information that I've likely started to forget!

 

[flyfishtrailer]

Did you discover the issue? I am curious to hear what it was. Hopefully something simple.