vibration at hwy speeds

[benualson]

1998 K1500 5.7L

Truck vibrates (not terrible but annoying) most noticeably at 60-75mph. I also notice it when I let off of the throttle to let it coast (again, at hwy speeds). Any Ideas?

It is not the front end as I had the whole front end replaced (not because of this issue).

 

[kennythewelder]

A vibration issue is almost always a tire balance issue, but the U-joints can cause this too.

 

[benualson]

A vibration issue is almost always a tire balance issue, but the U-joints can cause this too.

New tires. Wheels have been roadforce balanced

 

[michael hurd]

Driveshaft?

 

[wildncrazyguy]

1998 K1500 5.7L

Truck vibrates (not terrible but annoying) most noticeably at 60-75mph. I also notice it when I let off of the throttle to let it coast (again, at hwy speeds). Any Ideas?

I have the same truck and issue. I had new tires put on and then I noticed the issue. Had my tires road force balanced they called it, no change. I've been dealing with it and trying to find an answer, but hoping when I get new tires this Winter, it magically goes away. Probably not, but I'm hoping it was a tire issue out of round or something. Worst set of Michelins I've ever had... Drives great and no noticeable issues below about 60 or so. Most of my driving is around 50 on my way to work or the firehouse. Doesn't affect it at those speeds. For me 65-70 usually on the interstate. Seems to also go away if I get above to say 75 or more as well, but I don't like driving my truck above 70-75 really.

I guess I'm hoping for u-joints as my truck still has originals and I'm probably due, however, I don't notice any movement when checking them.

I'll be watching this thread in hopes someone stumbles upon something for you. Please do let us know the fix if you get it smoothed out. I'll update as well but will be a few months likely before I get my tires changed to know if that has any effect.

 

[House003]

I would definitely suspect a bad u joint

 

[sewlow]

Posted this info before. But, anyways...
I've chased this mysterious vibration in both my trucks. More so on the '98. With the '97, I've just learned to live with it.
I tried everything! Complete new brakes front to back, from the master down. 3 different sets of new tires. Road-force tire balancing. Different axles. Different wheels. New U-joints. 3 different driveshafts. A complete rear-end rebuild, including new gears.
Nothing helped!
During all this I found this out.
These trucks suffer from what's called 'beam walk'. The 2 frame rails after the cab resonate between each other @ certain speeds.
It's a design flaw & GM is aware of it. Their suggested cure? 500lbs of 'ballast'! WTF?
The only real cure is to box the frame rails from the rear cab mount to the last box mount. Boxing the middle crossmember is also recommended.

 

[shortchevy]

Posted this info before. But, anyways...
I've chased this mysterious vibration in both my trucks. More so on the '98. With the '97, I've just learned to live with it.
I tried everything! Complete new brakes front to back, from the master down. 3 different sets of new tires. Road-force tire balancing. Different axles. Different wheels. New U-joints. 3 different driveshafts. A complete rear-end rebuild, including new gears.
Nothing helped!
During all this I found this out.
These trucks suffer from what's called 'beam walk'. The 2 frame rails after the cab resonate between each other @ certain speeds.
It's a design flaw & GM is aware of it. Their suggested cure? 500lbs of 'ballast'! WTF?
The only real cure is to box the frame rails from the rear cab mount to the last box mount. Boxing the middle crossmember is also recommended.

Very interesting. This would explain why every 400 I have owned rides better with weight in the back, even when lowered. The nicest my 2500 ccsb has ever ridden was with an engine hoist and a sbc longblock in the bed... just over 500lbs.......

 

[1994GMCSierra]

Very interesting, i have a slight vibration too but again at 55-65ish mph. Ill try driving it around for a few miles with over 500lbs (of my mother-in-law) in the bed to see if it helps.

 

[StevensWMR]

My CCSB has highway vibration. And I keep a 500lb welding machine plus 400lbs of bottles and tools. Brand new tires that I’ve rotated and rebalanced. I have my gooseneck hitch welded to the frame rails so I can’t imagine they’re vibrating from resonance. Driveshaft shows no slack but to my knowledge u joints are factory. I want to say it feels like front end but unsure. Possibly front u joint or carrier bearing maybe?