Vibration

ness5575 · December 23, 2003

I have been having a vibration from under the truck - finally pinpointed when it happens. when the truck is under a slight load (for example from a dead stop up a slight incline, or from a dead stop when making a sharp turn), and i accelerate very lightly, at about 3 mph i get a real quick, loud vibration. doesnt do it on normal (harder) acceleration nor at higher speeds.

being that it only does it when moving, it is very hard to pinpoint what this might be. has anybody experienced anything similar??

RidesGuy · December 23, 2003

I have the same problem on a 2003 Sierra Z71. It seems it is only when it is cold out and moving at part throttle from a stop. It also does it when it decelerates slowly into first when coming to a stop. The primary area of vibration seems to be located near the passenger side. I have had no luck so far finding out what it is, I checked everything in the undercarriage.

Shaners · December 24, 2003

I've just started to get a vibration from a stop with a warm tranny. It's kind of like a chatter feeling.

If my tranny is less than 120* then it's OK but if it is higher then that then I get it the vibration.

It only occurs in my truck after I've gone at least 10 miles at 55 MPH or faster, and then come to a stop and after a second or so take off again...

Worktruck · December 24, 2003

Have been having similar experience with my 02 Sierra 4.8. Seems to have a "shudder" under very light acceleration when tranny is warm. Be interested to find out what it may be.

RidesGuy · December 24, 2003

I have been trying to stay away from the inevitable fact that it may be tranny related. All signs are starting to point that way however.

traxion · December 24, 2003

I know that you dont want it to be a tranny problem and I pray that it is not but, there may be a related problem with the torque converter not locking correctly. If it locks slightly then continues to disengage it will then continue to try to lock. That could be chatter (in and out in and out). If you accelerate firmly does it do the same thing? Maybe just a transmission oil change will help out. Just a thought.

bansell · February 1, 2004

Anyone figure out what is causing these problems yet?

HD2500 · February 1, 2004

I GOT THE SAME VIB HERE IS WHAT IS CAUSEING IT, THE DONUT GASKET THAT WENT IN BETWEEN THE EXHAUST AND WHER IT BOLT TO THE MANIFOLD WELL THEY DONE AWAY WITH IT , SO WHEN THAT HAPPEN THEY BOLT IT STRAIGHT TO THE MANIFOLD AND THE VIB COMES FROM THE FEED BACK OF THE EXHAUST.

bansell · February 1, 2004

I GOT THE SAME VIB HERE IS WHAT IS CAUSEING IT, THE DONUT GASKET THAT WENT IN BETWEEN THE EXHAUST AND WHER IT BOLT TO THE MANIFOLD WELL THEY DONE AWAY WITH IT , SO WHEN THAT HAPPEN THEY BOLT IT STRAIGHT TO THE MANIFOLD AND THE VIB COMES FROM THE FEED BACK OF THE EXHAUST.

So is there a fix for it?

booster · February 1, 2004

This could be the problem. Taken from the GM service website. There are quite a few similar posts here and will do some more research on it tonite.

Info - Buzz Noise or Vibration Felt in Floor or Throttle Pedal at Approximately 16 km/h (10 mph) or During 1-2 Upshift #03-07-30-032 - (07/22/2003)

Buzz Noise or Vibration Felt in Floor or Throttle Pedal at Approximately 16 km/h (10 mph) or During 1-2 Upshift

2003-2004 Chevrolet Silverado

2003-2004 GMC Sierra

Some customers may notice a buzz noise or feel a vibration in the floor or throttle pedal at speeds of approximately 16 km/h (10 mph). It may also be noticed during a 1-2 upshift.

This buzz or vibration may be a result of the supplemental brake assist (SBA) diagnostic test. (The SBA is mounted on the brake vacuum booster and creates vacuum for the brake booster in case of a vacuum loss or low vacuum to the brake booster.) The test occurs at 16 km/h (10 mph) after initial engine start-up. Normally, the test will not run again until the next engine start-up. Customers may believe that this is a transmission related noise as the 16 km/h (10 mph) diagnostic test may be very close to the 1-2 upshift speed under certain driving conditions.

This is a normal condition and no repair attempts should be made.

ness5575 · April 22, 2004

i started having some tranny problems (harsher shifting - checked fluid and it was an orangish brown color, despite being changed about 14k miles prior), so it took the truck in to the dealer yesterday (only have about 3k left on the 100k gmpp), turned out that i needed a new sun shield in the tranny.

since I got the truck back yesterday afternoon, my vibration (described earlier in thread) has disapeared!

Hotair · April 23, 2004

We had that Vibration or buzzing in the wife's 03 1500 Z71 Suburban. Apparently there is a service bulletin for that now. We just picked the car up for service and they put 2 straps around the muffler. So far so good.

az'03Silverado · April 23, 2004

I have the same thing in my '03 Silverado. It only does it at a certain rpm (around 900-1000) and sounds like a sympathetic vibration caused by the frequency produced by the engine at that rpm. From what everyone has said, it sounds like the sound is from the exhaust, which makes perfect sense. The brake booster test noise was a mystery, too. It sounds like a short squeak right before the first shift. Thanks for explaining that too, booster! I wasn't aware of that safety system.

Boogity3 · April 23, 2004

It could also be a worn pinion gear bearing in the transmission or worm gear teeth. This can happen a lot when you get on the gas a lot. Also, check your driveshaft for any dents. This could throw it out of round and add some vibration at various speeds.