Front end wobble only at 30-35mph

[thompsoncustom]

Hey guys was wondering if anyone else has ran into this issue. My humvee is a 1097r with 6.5/4 speed and the front end seems to hop/wobble between 30-35mph but is perfect at all other speeds. Thought it might be my tires so I rebalanced them with weights twice and it didn't help, so I ended up fluid balancing them but the front end bobbing is still there but runs smooth as silk at 70mph on the interstate and all other speeds.

I did find there is a little play in the pitman arm but you can't feel the wobble in the wheel at all so I don't think that is it and couldn't find anything else loose or have any play like the axles but you can see the hood moving at the above problem speed.

 

[TOBASH]

Balance and alignment.

 

[thompsoncustom]

Balance and alignment.

Balance could still be a issue if one of the tires in messed up internally but I would image you would fell some vibration at highway speeds then.

Alignment is not something I have looked at and will definitely look at the alignment, would do it now if it wasn't raining.

 

[Mogman]

Is it "up and down" as in an out of round/balance tire or is it "side to side" felt mostly through the steering wheel?
Side to side would be more serious, careful inspection and replacement of any defective components would be the first thing, then a complete alignment.
You could also swap tires front to rear and see if it changes.

 

[LeftCoast32]

Swap the front wheels/tires with the back and see if the wobble/shake migrates.

 

[thompsoncustom]

Is it "up and down" as in an out of round/balance tire or is it "side to side" felt mostly through the steering wheel?
Side to side would be more serious, careful inspection and replacement of any defective components would be the first thing, then a complete alignment.
You could also swap tires front to rear and see if it changes.

Up and Down. Ya I've been thinking I need to swap them to see if it's the tires or not. It's nice out today so I might be able to get that done today.

 

[thompsoncustom]

well had time to swap tires front to back today but I've got stuff on it setup for the 4th of July parade in the morning so I'll have to test it after that.

 

[williamh]

Well the good thing that most parades only run at @2mph. I chased that same gremlin and ended up replacing all the tires and getting rid of the runflats. If I need runflats I’ll just foam fill the wheels on my way outta town.

 

[thompsoncustom]

was able to test swapping the tires front to back today, made no different the front end still bobs up and down. so can rule out the tires. didn't check alignment yet.

 

[williamh]

Alignment will not cause tire hopp. Out of balance / worn ball joints will but bad shocks will let the tires hopp and chopp the crap outta tires. If you push down on the corners of the truck ( not as easy as said as done) does it bounce ? Is there any oil on the shocks from the shafts ? You could pull them off and see if there’s any resistance going in and out.

 

[thompsoncustom]

Alignment will not cause tire hopp. Out of balance / worn ball joints will but bad shocks will let the tires hopp and chopp the crap outta tires. If you push down on the corners of the truck ( not as easy as said as done) does it bounce ? Is there any oil on the shocks from the shafts ? You could pull them off and see if there’s any resistance going in and out.

I could see it being a bad shock, it's a new problem so no chopped tires but I've already checked the ball joints.

most of the time pulling shocks is easy if the humvee is no different than I'll just pull them to check them out.

 

[thompsoncustom]

Alignment will not cause tire hopp. Out of balance / worn ball joints will but bad shocks will let the tires hopp and chopp the crap outta tires. If you push down on the corners of the truck ( not as easy as said as done) does it bounce ? Is there any oil on the shocks from the shafts ? You could pull them off and see if there’s any resistance going in and out.

pulled the drives side front shock today and with the shock out there is little resistance to fully compress the shock. extending the shock takes a lot more force and is what I would expect.