Anyone have any ideas about an abrupt vibration in a 1997 Ford F150 4X4 with a 4.6 L, when you take your foot off the gas at highway speed. The vibration starts right away and lasts for about a second then goes away...<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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Not sure what it could be, but it has just started doing this, so my guess is that I need to fix something...<o></o>

 

Check the U-joints in the drive shaft. Good luck!

 

Thanks, but do you mean check, or just replace?

I ask because I'm not sure how to check...

 

Disconnect the drive shaft from the rear axle. Check for smoothness in the flexing of the rear joint. Pull the drive shaft out of the transmission and do the same at the front universal. If the joints are not smooth then replace them. Good luck!

 

Thanks John, I'll give it a try.

 

Keep us informed as to what you find. My 01 does the same thing. My unjoints on the rear drive shaft were replaced about 6 months ago, but maybe I got a bad one.

 

if you can feel it in the steering wheel, check the tie rods on the front end, and the idler arm bolted to the frame under the radiator. loose bushing inside the arm will show up under deceleration.

 

Remember to mark the shafts in relation to the tranny and differential, they need to go back in the same way to maintain balance.

 

Sorry for the delay, but here is the results after changing my u-joints. First off, the bolts attaching the drive shaft to rear end were much tighter than expected. Broke a ratchet drive.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
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After replacing both u-joints on the rear drive shaft (rear u-joint badly worn) the vibration on deceleration has been eliminated.<o></o>
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Thanks for the advice and help, once again it was greatly appreciated.<o></o>
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Happy Holidays<o></o>

 

Happy New Year to all

 

My truck did the same thing when the driveshaft u-joints were bad. If you were doing 60 mph or more, it would shake on deceleration.
When we pulled the driveshaft, we found that the u-joints werent moving smoothly and upon removal of the u-joints, we found that the seal had failed, which allowed water to get at the needle bearings and they pretty much rusted out.
I bought a set of greasable u-joints at AutoZone for $20 and so far, so good. You will need a pain adaptor for your grease gun in order to grease the joints, but at least that way you know the u-joints have fresh grease in them and that you are doing all you can to protect them from moisture.
I cant complain, the original set of u-joints lasted over 150,000 miles. I think thats pretty good considering the harsh Wisconsin winters my truck has to endure.

 

Other ideas for a cause of a vibration. When going 70+ and take your foot of the gas, I get a vibration, but not through the steering wheel. It continues if I put the truck in coast in neutral or even shut it off and coast.

The front u joint on the rear axle was stiffer in one way compared to the other, so I replaced that u-joint and changed the transfer case fluid while I was under the truck. The other u-joint appeared fine (not really that old). I was careful to mark and matcht he parts back up so that they are in the same position as before.

Other thoughts on what might be causing this?

 

Thought maybe the vibration might be tires. Took them to the tire shop where they were purchased and had them balanced and rotated. I never do that as often as I should, especially since they do it free of charge if you have bought any tires from them in the past.

Seems to have helped a small amount, but did not resolve the vibration.

What is the best way to check the tie rod ends? The vibrations isn't felt through the steering wheel, but I might as well check that.

Is there a way to check the balancing on the drive shaft? What about taking it off and reinstalling 180 degress for the original orientation and check? Would that cause more potential damage than possible insight into the vibration?

Thanks