Vibration at 70mph+

[SL87Chevy]

Hey all,

87 Silverado all stock. It vibrates alot once I hit 70mph and above. It does fine at lower speeds. What would cause this problem or is this normal for these trucks? What should I look for or what needs replacement?

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[CSFJ]

When was the last time you looked the tires over? Are they still in balance? Have any belts shifted to cause them to go out of round? (on close inspection, do any of the tread blocks look to be higher on one side than the other?) Do they show any signs of dry rot or weather checking in the tread valleys or on the side wall?

 

[Charlie]

Tires (condition/balance), wheel bearings, u-joints.

 

[CSFJ]

Wheel bearings would be more constant, and manifest at lower speed. U joints would typically show up under load or coast situation.

 

[SL87Chevy]

Thanks! I've only had it since March so I'll check the balance first. Tires are in good condition.

 

[MrMarty51]

Whats the hurry 87, keep it under 70 and it`ll be good.
Welcome to the forum.

 

[rpcraft]

If you have had the tires and wheels and u-joints checked already try flipping the driveshaft 180 degrees to the yoke on the rear axle and see if it changes anything. One other thing to do is check the front rotors and see if they have any crud up in the vent holes on the rotor, and likewise weight he rear drums and verify they are close to the same weight (and if you can find someone to check their balance they may be an issue as well. One other option is they might be out of round and that applies to the front brake rotors as well. They might be warped from excessive braking.

 

[Merlin3e9]

Did this problem get better? Ever figure out what the vibration was? My 87 R10 vibrates from 60-65. Had the tires rotated and balanced, but it didn't go away. Tire shop thinks the tires have flat spots from sitting. I'm disappointed because the tires still have a lot of tread left.

 

[Matt69olds]

Is the vibration there in park, with the engine turning at the speed it would be at 70? If so, you can rule out driveline issues. You could try “reclocking” the converter in the flex plate. There are 3 possible positions, maybe a different one would help. Is the vibration there at steady speeds? Does it go away, or get worse depending on throttle position and engine load? Make sure the exhaust isn’t touching something,and trans mount is in good condition.

 

[eskimomann209]

Did this problem get better? Ever figure out what the vibration was? My 87 R10 vibrates from 60-65. Had the tires rotated and balanced, but it didn't go away. Tire shop thinks the tires have flat spots from sitting. I'm disappointed because the tires still have a lot of tread left.

Usually the flat spots can be seen when they try and balance the tires
Tire shop if they handled the tires,
should know (not think ) if they are flat

 

[73c20jim]

If you have a flat spot, you can have the tires trued back round.