Vibration after gear installation
 

I've just put a new 3.55 gear in my car. When i go at 85 mph i feel a little vibration and i push the clutch or put the car in neutral ,it vibrate very bad. I've check the u joint, wheel bearing, the mark on my driveshaft ,everything is O.k. My wheels are balanced. The car was running great 2 days ago with my old gear.

Try removing the axle damper (the big weight looking thing near the front of the center section on the diff), they're tuned to different gear ratios.

Either try rotating the drive shaft 180 degrees, and if that doesn't take care of it an Aluminuim one usually does.

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Thanks to Miracle max and 93cobra but it will still vibrate.Does everyone had this problem? Is it normal or what? Do i have to live with this problem? It shack VERY BAD at 100mph +

I HAD THE SAME PROBLEM UNTIL I WENT TO AN ALUMINUM DRIVESHAFT. HOWEVER IF THE VIBRATION COMES IN WAVES(VIBRATION INCREASES AND DECREASES) IT COULD BE YOUR HARMONIC BALANCER. BELIEVE IT OR NOT YOU CAN TWIST THE OEM DRIVESHAFT. TO CHECK THE DAMPNER: START YOUR CAR AND POINT A FLASHLIGHT ON THE DAMPNER. IF IT IS GOING OUT IT WILL WOBBLE LIKE A BENT BICYCLE RIM. WORKS BETTER TO DO THIS WHEN IT'S DARK OUT SO YOU CAN SEE IT MOVE BETTER. IF IT IS THE PROBLEM, DON'T WAIT TOO LONG TO CHANGE IT. IT WILL COME APART. THE DAMPNER IS A TWO PIECE DESIGN. ALSO EXCESSIVE HARMONICS CAN BREAK DOWN YOUR MOTOR.

Re: Vibration after gear installation
 

rotating my stock shaft 180* helped a ton when I had 3.73's put in, prob put shaft on in wrong position to start with, took weight off of housing, but my aluminum shaft made it smooth as stock.

Re: Vibration after gear installation
 

Any time you change to a 3.55+ gear, you should have your driveshaft precision balanced. The guy who did my gear install said it should go hand-in-hnd with a gear change. It took my vibration away - cost was $50.

Re: Vibration after gear installation
 

Your problem is in the pinion bearing preload. You didn't crush the sleeve to the proper running torque on the bearings. When you decel, the pinion is sucked deeper in the mesh and unloads the rear pinion bearing. Time to take it back apart again.

Re: Vibration after gear installation
 

I quit using crush sleves on the pinion long ago for this reason. A spacer kit is made to replace the crush sleve.

I recomend http://www.fortesparts.com/ for the part if you don't have a source.

Re: Vibration after gear installation
 

You guys may have just solved a problem I have been chasing for ever! I have had the same problem ever since I bought a 4.10 third member for my eight inch about 8 years ago. I have tried everything and never been able to find it.....now I just gotta find someone to help me :)

I love this board.
Ryan

Re: Vibration after gear installation
 

good thread.... I need to look into that spacer, I re-used my crush sleeve, so far everything's fine....but I have something wrong with a carrier bearing, since i hear a whine only whine when i make right hand turns, Things arent caddilac smooth in my car at over 105+ mph with 3.90 grs, but having the aluminum d/s helps alot, problems can be in the u-joints as well.