Vibration at Highway Speeds
 

I have a 1998 4.3 Blazer. 2 Door 4x3. I have a very hard vibration when I get it to about 65-70. But I can only feel when I have my foot on the throttle or have the cruise control on. The second I let off the gas, it stops. I have check the tire balance and alignment and that is not it.

RE: Vibration at Highway Speeds
 

Hmm, when I reach high 70's and beyond my blazer starts to shake which I would consider normal for any "older" vehicle I guess. When I ride in my firends 98 chevy 1500 at 70 mph the thing shakes also. But its weird how yours only shakes when you press on the gas. I would say its a tranny issue...output shaft?

RE: Vibration at Highway Speeds
 

Where do you feel the vibration, in the floor, seat or steering wheel? Does it go away if you go 75?

RE: Vibration at Highway Speeds
 

Sounds like the start of universal joint problems. I'd give a thorough check of all of the joints on the rear driveshaft.

RE: Vibration at Highway Speeds
 

This is not the same problem as yours, because it would not go away when you let your foot off the gas - however just a quick tip: Two days ago we got an ice storm and the ice was heavy enough on one side of the wheels to create a vibration at highway speed. You can get the same thing from snow build-up. The next day, the ice had melted and everything back to normal. Just gets you worried for awhile.

I don't think there should be vibration at highway speeds just because it's an older vehicle. I've also had it from a broken belt in the tire, which won't show in a static balance but will in a dynamic balance. It takes very little weight shift to create a problem.

Doug