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Rumble in 3rd member?

1099 Views 3 Replies 3 Participants Last post by  ogrebro, 
O
Had 411 gears put in my 9" rear end. I now have a noise, a rumble and vibration, not under power or completely off the gas pedal. The noise is in the neutral spot when not accelerating or decelerating. I don't remember having this noise before I changed the gears. I suppose there is a possibility that it is a u-joint or an out of balance drive line. I tend to think it is in the rear end, because the drive line and u-joints are new as of approx 3200 miles ago.

Any ideas on what and how to check this?

Many thanks!!!
Bill
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T
Having worked on Ford rear for many moons,usually if a "rumble" type noise means soimething is loose or has a crack in it making something move like a cracked carrier support cap.It could be possibly a pinion nut was not properly tighted down,caps,too much backlash or not enough.
A whine woulf indicate a bearing.Did the use the same bearings? Maybe they tighted the pinion down to tight.
That's a guideline,without bein there to hear it,could be anything Dude
Paisano
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cobalt327
ogrebro said:
Had 411 gears put in my 9" rear end. I now have a noise, a rumble and vibration, not under power or completely off the gas pedal. The noise is in the neutral spot when not accelerating or decelerating. I don't remember having this noise before I changed the gears. I suppose there is a possibility that it is a u-joint or an out of balance drive line. I tend to think it is in the rear end, because the drive line and u-joints are new as of approx 3200 miles ago.

Any ideas on what and how to check this?

Many thanks!!!
Bill
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The driving condition you are hearing the noise (the neutral spot when not accelerating or decelerating) is called "float". It sounds like a pinion bearing preload problem to me.

You can check the driveshaft phasing to be sure they didn't put it on wrong.
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O
Finally figured this out. My pinion angle was too severe about 6 degrees out. Put a 4 degree wedge to tip the pinion up. Still had the noise and rumble but only about 30% of original. Rear u joint was bad. Only about 2k miles but at the severe angle it apparently ate the thing. New u joint and it's nice and quiet.
Thanks for the help!!
Bill
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