Whole truck shimmy

[whistlingdeuce]

My father and I recently got a 1971 M818 5ton tractor from Gov. Liq. For the most part the truck is great. But at around 45 or 50 the truck gets a horrible shake to it. the shake is side to side and doesn't transfer into the steering wheel. I checked some things and found that the passenger side power steering arm was loose in the joints. I tightened them up but the truck still shimmys going down the road at around 50. I followed inmy car with dad driving the truck but I can't see anything that looks out of whack. There is no obvious damage to any rim or tire. Anyone have any ideas?? Thanks in advance for any and all info.

 

[wheelspin]

check all your rear tires. a flat tire on the rear wont look low because it has friends to lean on. i lost a inside tire on my way home with my truck. the tube tore in half and bunched up in one side and threw the balance off badly.

 

[beaubeau]

What you have is a typical Hop from most Twin axel trucks. Older trucks with Walking beam suspensions, especially. I have driven many Commercial trucks that do the same thing. Especially at speeds about 45mph to 52 mph. I assume it is the lack of Perfect Ballancing of not just tires but the complete running gear. Worst vehicles are TRK.Trac. {m818} No weight over rear axles. Some improve when tires warm up . Good luck, Phil

 

[NDT]

My M135 did that for about 300 miles until one day KABLAM the right front tire blew to smithereens. It was side to side vibration too, it would rattle the windshield stay braces. My vote: tread separation.

 

[vj]

try switching front wheels to the rear, get the best looks out side wheels that on the rear, and put on the front. vj

 

[Srjeeper]

Check that all the lug nuts (inner & outter) are tight. These tires will 'flat spot' from sitting, so sometimes the farther ya drive the smoother it gets. Also check air pressures and that all the driveshafts are tight and in time with eachother.

Be safe and good luck.........

 

[BEASTMASTER]

my 5 ton did that and i found the front tires to be real low. put them up to 65 lds and the shake went away.