Crazy shake with no answers
07-12-2018, 07:09 PM
#1
Senior Member
Thread Starter
Crazy shake with no answers
2015 Lariat 3.5 eco
Rough country level, 1" blocks in rear
fuel wheels
fuel tires LT305/55/20
truck drives perfectly fine anywhere below 50mph. From 50-75 the truck shakes like crazy, it doesn't vibrate, it shakes. So much so that my passenger seat shakes about an inch either way, steering wheel shakes a little, but not as much as the rest of the truck. Just got wheels rebalanced today, checked driveshaft/u-joints and everything is checking out completely normal. Tires look perfect, only about 12k miles on them and no signs of uneven wear. Powerstop heavy duty truck/tow Pads and rotors have only been on for around 10k miles and there isn't any vibration/shake when braking. Anyone have any idea what I should check next?
Rough country level, 1" blocks in rear
fuel wheels
fuel tires LT305/55/20
truck drives perfectly fine anywhere below 50mph. From 50-75 the truck shakes like crazy, it doesn't vibrate, it shakes. So much so that my passenger seat shakes about an inch either way, steering wheel shakes a little, but not as much as the rest of the truck. Just got wheels rebalanced today, checked driveshaft/u-joints and everything is checking out completely normal. Tires look perfect, only about 12k miles on them and no signs of uneven wear. Powerstop heavy duty truck/tow Pads and rotors have only been on for around 10k miles and there isn't any vibration/shake when braking. Anyone have any idea what I should check next?
07-12-2018, 08:32 PM
#2
Junior Member
Probably not this but I'll throw it out there. Mine was doing something very similar, I'd give it throttle about that speed and the whole truck shook like crazy. I finally forced it harder and it threw a CEL at me and the dreaded wrench symbol but it wouldn't do it every time. Checked the saved code and it said 3rd cylinder misfire. They checked and found a cracked spark plug. I would've never thought that cause it felt like my front 4x4 drive system or something in the drivetrain. I've seen this issue in another thread the other day about spark plug issues. Search or check back a few days and you'll find it. Good luck.
07-12-2018, 08:35 PM
#3
Any end-play in the wheels? Lift it, rock the top and bottom in and out.
I have seen tires that looked absolutely perfect, would balance, and still had internal defects that would result in substantial shaking.
I have seen tires that looked absolutely perfect, would balance, and still had internal defects that would result in substantial shaking.
07-12-2018, 08:39 PM
#4
If it shakes on deceleration, then won't be plugs, but if it stops when decelerating, by all means check the plugs. It could be pinion angle causing it, put 1000# in the bed and see if it goes away or is diminished. Before they shimmed the rear axle the truck would shake at 80MPH. It would get vibrations decelerating, especially at 48 MPH.
07-12-2018, 09:41 PM
#5
Senior Member
Thread Starter
Probably not this but I'll throw it out there. Mine was doing something very similar, I'd give it throttle about that speed and the whole truck shook like crazy. I finally forced it harder and it threw a CEL at me and the dreaded wrench symbol but it wouldn't do it every time. Checked the saved code and it said 3rd cylinder misfire. They checked and found a cracked spark plug. I would've never thought that cause it felt like my front 4x4 drive system or something in the drivetrain. I've seen this issue in another thread the other day about spark plug issues. Search or check back a few days and you'll find it. Good luck.
07-12-2018, 09:44 PM
#6
Senior Member
Thread Starter
no play in the wheels at all. I'm trying to solve this from most obvious/least expensive options and working my way up but hoping it doesn't get to the point where I'd have to just get some new tires and see if that fixes the problem.
07-12-2018, 09:46 PM
#7
Senior Member
Thread Starter
If it shakes on deceleration, then won't be plugs, but if it stops when decelerating, by all means check the plugs. It could be pinion angle causing it, put 1000# in the bed and see if it goes away or is diminished. Before they shimmed the rear axle the truck would shake at 80MPH. It would get vibrations decelerating, especially at 48 MPH.
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07-12-2018, 09:48 PM
#8
Senior Member
Thread Starter
Weird part that I failed to mention in my original post is that after getting the front tires rebalanced today, the truck actually shook worse on the drive home. Makes me really wonder if it's just a bad tire or possibly a rim that is out of round?
07-12-2018, 10:51 PM
#9
Senior Member
Are you checking road force variation with the balance? I had a tire that balanced perfectly but the road force was 47 lbs. The max value for LT is 30 lbs. I will not accept a new tire above 15 lbs.
