QuestionHi I don't think this an alignment question and I hope you can help.
1999 GMC Suburban 2WD 1500. 130K miles
I took my truck in for brakes, serpentine belt,and smog check a couple of weeks ago. Pads were put on the front as well as rotors turned. Rear drums were replaced and the belt was changed. When the truck was returned to me I immeadiately noticed that it had a vibration when it reached speeds over 60mph. The mechanic stated that nothing he did could have caused that to happen. He suggested I had a "flat" spot on a tire. Took it to a tire and alignment shop put 4 new tires on, shocks in the front replaced and a good alignment. The car still shakes. I suggested to the mechanic that it might be the U joint or something with the drive train. He stated that it still shook when he put the vehicle in neutral and that proves it is not a U joint.
60mph truck is smooth 65mph and it bounces.
Any ideas or suggestions would be greatly appreciated
AnswerHi
ALL vibrations ON A VEHICLE are a reaction of a rotating
component.
A worn part MAY be a result of a vibration, but unless that part rotates, chances are it WILL NOT cause a vibration, under NORMAL circumstances. AN Imbalance in ANY rotating component will cause a vibration and will be felt, in the seat, steerring wheel the vibration will travel along the path of least resistance.
That being said and me being 100% GM Vibration certified let me ask you
1)Does it vibrate in nuetral? If so at what RPM does it start AND are you able to feel it?
2) At 65mph... are the RPM the same as it is when it is vibrating in neutral? Can you speed up to 70, put it in neutral let it coast down to 65... does it vibrate then at 65 but the engine at lower rpm (due to it being in neutral).
OK Also if it Vibrates in neutral, take the belt off, see if it still vibrates...
Is the A/C on?? Turn it off... does it still vibrate.
If it vibrates at same RPM both in neutral and at 65, and the belt was changed... and it did none of this beforhand..
suspect the belt OR a faulty tensioner/pulley.
I personally, going by what YOU say believe it is either this OR a rotor was misturned or mis replaced OR is excessive runoutand is hitting the pads at higher speeds due to the excessive runout.
If you answer these questions, I can help further OR
Take it to a GM dealership. Have them hook truck the the EVA (Electronic Vibration Analizer). If they know what they are doing, it should take no more than 1 hour to find your vibration and give you an estimate on repairs.
Also If you think it MAY be in the Tire/wheel assy's Find a shop with a Hunter GSP9700 at
http://www.gsp9700.com
in your area.
I hope this helps.
JUST ADVICE FROM EXPERIENCE
Good Luck
Pawl
