Vibration.... BAD!!!! 454??????????

[Patriot]

Hey fellas, I picked up my 78 2WD Suburban today and the truck is all original and I am only the second owner. The truck has a 454/400 combo and when I took down the highway bringing it home just an hour ago it had a terrible vibration. I vibrates from about 25-30 and up. I know the 454 is extenally balanced and was wondering if it could be someone put the wrong flywheel in it. The motor doesn't vibrate when in park and reved up. It is the original motor tranny combo. Could it be a driveshaft?? I am going to dig into it more tomorrow. Any hellp or ideas would be great guys. Thanks alot.


Patriot

[83burban]

If it were the motor it would vibrate at any speed. I would check drive shaft first, then maybe motor mounts and trans mounts. Also see if a wheel is grabbing - aka - check the brakes

[baclay9]

Wheel weights?

[71swb4x4]

It could be a host of things, but start with the easiest first. Since it is speed related and not RPM related you can rule out the motor.

Mud/snow packed in a wheel can make for a nasty vibration.

A broken belt in a tire can also cause vibration.

[hitcher]

when you say you picked it up i assume you just bought it from the previous owner ? . cant he shed some light on why its acting like that , surely it was like that before you bought it .

[nbpro]

Originally Posted by 71swb4x4

It could be a host of things, but start with the easiest first. Since it is speed related and not RPM related you can rule out the motor.

Mud/snow packed in a wheel can make for a nasty vibration.

A broken belt in a tire can also cause vibration.

^^ x2

[Patriot]

Originally Posted by hitcher

when you say you picked it up i assume you just bought it from the previous owner ? . cant he shed some light on why its acting like that , surely it was like that before you bought it .

He said it was perfect. It makes a vibration like I said when it is moving but when you let off the gas it goes away??? I am stumped. It is wierd. I can run it around the Black Hills up and down the Hills and it vibrates going up and not so much down due to coasting. Under load it vibrates but coasting...NOTHING????? I had a vibration on a 4X4 truck many years ago and I found it to be the flywheel.

HELP FELLAS!!!!!

[hitcher]

i was going to say a loose engine mount but that would probably be vibrating all the time , worth just checking though . i remember riding back with a friend who just bought a truck and thats what happened to him

[Irish's_79_Step]

my little s10 had some what of a similar problem. vibrating under load. turned out to be bad universals. just a shot in the dark.

[hitcher]

its worth just getting under the truck and checking everything that could come loose . transmission , mounts , u joints like irish 79 just said . also anything to do with the steering

[Patriot]

Originally Posted by Irish's_79_Step

my little s10 had some what of a similar problem. vibrating under load. turned out to be bad universals. just a shot in the dark.

Can you feel this buy checking the driveshaft for movement???

Did replacing them fix the vibration??

[Irish's_79_Step]

its my work truck so i just took it to a shop. but i do know replacing them took my vibration out.

[Patriot]

Originally Posted by hitcher

its worth just getting under the truck and checking everything that could come loose . transmission , mounts , u joints like irish 79 just said . also anything to do with the steering

Hey hitcher, on a side note, when I was stationed at Ft. Sill I got to visit Lawton OK. Nice town. I LOVE Oklahoma. If it wasn't for being chased by Brown Recluse I would move there. We have Black Widows here but there aren't aggressive like your crazy spiders there. I never saw an Armadillo until I was there. Those little suckers would walk with us during ruck marches and sleep with us in the field. Neat little tanks they are.

[hitcher]

Originally Posted by Patriot

Hey hitcher, on a side note, when I was stationed at Ft. Sill I got to visit Lawton OK. Nice town. I LOVE Oklahoma. If it wasn't for being chased by Brown Recluse I would move there. We have Black Widows here but there aren't aggressive like your crazy spiders there. I never saw an Armadillo until I was there. Those little suckers would walk with us during ruck marches and sleep with us in the field. Neat little tanks they are.

yeah you have to be real careful when doing stuff in the yard or digging through junk yards . ive had brown recluses , black widows , scorpions and snakes out at my place . just lifting a piece of wood up you take your life in your hands haha

[Patriot]

Originally Posted by hitcher

yeah you have to be real careful when doing stuff in the yard or digging through junk yards . ive had brown recluses , black widows , scorpions and snakes out at my place . just lifting a piece of wood up you take your life in your hands haha

NO KIDDING!!! I witnessed the Brown Recluse bites on Soldiers there and it sent a few guys out of the Army. The bite is just plain NASTY!!!!!

[pig rig]

U joints

[tucsonjwt]

This can be dangerous. I would not drive this truck without having someone check it out - not a good condition for guesswork. Most alignment shops will diagnose your truck for minimal cost or free - check for ads like "21 point free insepction" to get some professional advice. This is better than guessing and throwing money at it. It is possible that you could have something like a bad ball joint which could snap and cause an accident (it happened to me). I would rule out the steering and suspension issues first (these are the most dangerous) then move on to the drivetrain (Ujoints, center carrier, etc.)

[71swb4x4]

You can put the back on jackstands and slowly bring it up to speed to see if the vibration is in the steering. It it still vibrates, you know it isn't steering related. If it doesn't vibrate that doesn't mean that it is the steering, but it can at least eleminate teh steering if it does vibrate. Of course do this in an open area and make sure the front is clear, so if you fall off the jackstands you don't run through your garage or run your kid over.

I would check the tires and u-joints first. They are parts that most commonly fail IMO.

[pig rig]

well he said it vibrates under a load but it dosnt vibrate at idel so with those two statements that rules out engine, trans, tire and wheels

so whats the rotating mass that transfers power?

[Clyde65]

I would check the ujoints asap, next it could be a flywheel or torque converter.

[Telecasterjoey]

Yup probably U joints

[sandorjoben]

I had the same problem a couple months ago, noise/vibration/clunking over a certain speed and also a small clunk when initially put into gear. Change the universal joints. On mine the needle bearings in two of the bearing cups on my rear-most U-joint were blown to small frags or were non-existant. An easy and inexpensive fix. Check them first and then look for other problems from there. If the 'burban you bought sat for any period they(U-Joints) probably just dried out from lack of use/lubrication.

Dave

[thepenguin99]

If it doesn't vibrate in park my money is on driveshaft. Either bent or u-joints.

[jchav62]

I vote u-joints/carrier bearing.

[Patriot]

I will be checking on it tomorrow. Will put it on jack stands to check for the vibration. I reved it up today and not noise or vibration. I didn't have time today but tomorrow I will look into it further.