Random vibration help

[stroker2]

Well its the truck in sig. I out of the clue had a vibration start up today. Driving down the street at 40mph and a vibration starts up. Not a harsh one but definitely noticeable. There is also a vibration sound to it. I pull off on a side street immediately and get down to ~25mph and the vibration suddenly stops and i get out and check u-joints and all are tight. I check that carrier bearing and the bearing itself is tight but the rubber around the bearing lets the driveshaft move about an inch upward or so but with resistance.


I have narrowed it down to between 30 and 45 mph that it does this as thats all the faster i drove. Had it to 65 once but it never vibrated when i took it to that speed. It seems if i hit a slight bump in the street it starts vibrating and will quit if i slow down or sometime will randomly quit on its own. I dont believe that its engine or tranny related because i can kick it into neutral and idle down the road as it does its vibrating but it doesnt change anything. Rpms or any select gear doesnt seem to matter. Any ideas?

Thanks!

 

[littleredstroker]

Sounds like a u joint. They may be tight, so were mine. I've replaced them 4 times in the last three years, evey single one of them started vibrating at 40 and went to 60 then went away. Give it a few weeks and it will start vibrating all the time and will clunk when you put it in gear. Bet you all the $$ in my wallet. ( bout 3 $)

autocorrected by taptalk

 

[stroker2]

I just dont understand the random on and off vibration while still maintaining the same speed

 

[stroker2]

Update, i commuted about 4 mi this morning and a couple instances of vibration arose but nothing big. They went away fairly quickly. Had about a 5 mi commute this afternoon and not a single instance of vibration :shrug:

 

[littleredstroker]

Depending on the amount of tq it will cause different things. Most often vibration happens when there is no strain on the joints. Get to speed and start feathering the throttle . I bet you can get it to vibrate

autocorrected by taptalk

 

[stroker2]

Depending on the amount of tq it will cause different things. Most often vibration happens when there is no strain on the joints. Get to speed and start feathering the throttle . I bet you can get it to vibrate

autocorrected by taptalk

I appreciate the help so far! Thank you! It didnt seem like torque depended on it to me. Compression braking wouldnt make any difference while it vibrated and giving throttle wouldnt change anything either. I mean its not like i cranked up the chip and put all 850lbs of torque through the drive train but i built up 5 psi and that didnt change anything.

Also, i just checked the lug nuts for fun and all are tight. Sway bar bolts are all tight and i just put brand new bushings in both front and rear sway bars and end links

 

[littleredstroker]

It's hard to be good with words here but I will try. If tq is applied on accel you won't notice it as much, or if tq is applied on decel when the engine is slowing you down you also won't feel it as much. But there is a certain amount of pedal where there is no tq in either direction and its " floating" for lack of a better word. That's where you will feel the vibration At its worst.

Get to 30 mph, let off to slow down the hit the throttle hard , listen for a clunk or see if you can feel it. On mine it took about a week or two of driving before I started to notice the clunk.

autocorrected by taptalk

 

[littleredstroker]

It could also be the carrier bearing . I would bet its one of the two but I'm pretty sure its u joints. Are all the rubber seals in place ?

autocorrected by taptalk

 

[stroker2]

I understand what you are explaining with the torque and i have tried all that and didnt notice a difference. I didnt check the rubber seals around the u-joints yet but the rubber "bushing" or whatever you want to call it around the carrier bearing is fairly worn and letting the driveline move around about an inch. I have tried to get it to clunk but cant. I have a manual tranny so i do what i can to make it clunk. Dont notice any clunks during shifts or anything

 

[stroker2]

Yet another update, my exhaust tip was touching the body of the truck (doubt thats the issue since i could put torque on the engine twisting the exhaust into or away from the body and the vibration would quit if i slowed down enough) so i fixed that and decided to put my hubs in and drive around like that. I drove my same route for my commute today (4 mi there, 4 mi back) and got zero vibrations :shrug:

 

[stroker2]

Well i went down the interstate 30mi and no vibration but it did seem like something was making a little extra noise underneath somewhere. Also, cruise control works only half the time. Hit a bump and cruise kicks off and take a bit to be able to get it come on again...not sure the problem there or if its related to the vibration or something

 

[littleredstroker]

I wonder if it is the carrier. I would guess the cruise is in related. Have you ever replaced carrier/ u joints?

autocorrected by taptalk

 

[stroker2]

I bought the truck at 138k and its now just about to turn 160k and i have never done anything as far as u-joints or carrier bearing or anything related. My receipts and records from the previous owner dont show anything about u-joints or carrier bearings. Wouldn't surprise me if one or more was going out but its weird to me that its a random vibration and my cruise is now acting funny

 

[stroker2]

This is the only thing loose that i can find but im pretty sure its been that way for a while so i dont know why it would cause a random vibration but who knows. Otherwise everything seems to be as tight as a nun on sunday


Carrier bearing rubber, between the cross member and the rubber above the drive line

 

[me2]

Otherwise everything seems to be as tight as a nun on sunday

 

[kadeninabnitt]

how about leaf spring bushings? mine had a simmilar deal turned out one of my spring bushings was just a sleave inside a sleave no rubber. changed it out no more issues so far.

 

[stroker2]

Im not sure. I have yet to experience the vibration since i mentioned earlier in the thread that i havent heard the vibration. Not sure what the deal is.

 

[stroker2]

Well the vibration quit for a while (1.5-2 months). Thought it was the carrier bearing buushing so i shimmed that to see if that helped. Went on a 400 mile on way trip a week ago and come back and make it 300 miles and it starts vibrating at almost all speeds now. Hit a bump and it start vibrating and making a sound from the front end. Hit another bump just right and it quits. Manual hubs are out and everything so the only thing that should be turning very quickly are the hubs. If i come to a stop as its vibrating, it sounds like something in the front end is a little rough. Im starting to think its wheel bearings as i did the front brakes 10k ago with quality parts. I have a little brake dust on the front left wheel too. Just doesnt make sense as to why it happens when i hit a bump and why it quit for a while.

 

[DSTRYER]

my truck is doing the same thing!

 

[BlueScab]

Had the same noise with mine. 45 mph it would start shaking the truck. Checked it over saturday and the bolts were very loose where the drive shaft bolts to the rear end. Just an idea, good luck with getting it figured out.