HARD KNOCK, EXTREME VIBRATION AT HIGHWAY SPEEDS

  • Tiny
  • Calguard11a
  • 1999 Mazda b4000
  • 108,000 miles

I have a 1999 Mazda B4000 4X4. I was driving home on the freeway he other day and there was a loud knock and a violent vibration came through the truck. I got off the freeway and stopped, so did the vibration. I got back on the freeway and when I got up to speed it happened again. When I drive in 4WD Hi on the freeway or 2WD under 45 I don't seem to have problems. Any help would be appreciated

Saturday, December 10th, 2011 AT 8:00 PM

4 Answers

  • Tiny
  • rivermikerat
  • Expert
  • 6,118 posts

Check the U-joints and driveshaft yokes for play.

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Saturday, December 10th, 2011 AT 8:01 PM
  • Tiny
  • Calguard11a
  • Member

I'm sure I can google that. Is it safe to drive at sub-freeway speeds?

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Saturday, December 10th, 2011 AT 8:06 PM
  • Tiny
  • rivermikerat
  • Expert
  • 6,118 posts

Raise the vehicle and shake the driveshafts. They shouldn't move (up and down/side to side) more than 1/8 of an inch at the yokes. Fronts are actually CV joints (constant velocity) See first image. I'm unable to find any images for the rear driveshaft.

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Saturday, December 10th, 2011 AT 8:18 PM
  • Tiny
  • rivermikerat
  • Expert
  • 6,118 posts

I wouldn't drive it too long. You can do more damage, even at sub-freeway speeds.

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Saturday, December 10th, 2011 AT 8:19 PM

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