Vibration

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Dec 16, 2004 | 08:11 PM

mohavi

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From: Tucson

Vibration

I had recently put in a used rear end in my truck. It was working just fine the only thing is that it was low on oil. I went ahead pu somein and everythig was cool for a couple of days. the only thing i know was that it came out of a 70 f-100 which just got out of wreck actually the thing flip over a couple times. 3:73 gears the problem is when i reach at 2000 rpms the whole cab vibrates and when it passes that rpm range it stops. my old rear end use to knock everyt tire revolution so i got rid of it quick thinking just replace it with another. both seals leak and so im thinking i just screwed my self over and should of fixed it the first rear end in the begining. is it my rear end thats the problem or is it something bigger? sorry for the long story

Dec 17, 2004 | 03:17 PM

ivanribic

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From: Spokane, WA

Check your u-joints first. A worn u-joint will cause a vibration like this and it will generally happen right about the same speed every time. Generally the vibration feels worse if you're accelerating. I just had to replace a u-joint yesterday . . . I had a nasty vibration that felt like the truck was coming apart from 15-20MPH and then it smoothed out after that.

Dec 17, 2004 | 08:46 PM

mohavi

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From: Tucson

how do i know if the u-joints are bad?

Dec 17, 2004 | 10:22 PM

hdgapeach

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From: Franklin, GA

Get under the truck and grab the shaft by hand near the joints. If you can move the shaft up or down/left or right, the joint is shot. Re-post with what results you find.

Dec 18, 2004 | 01:28 AM

ivanribic

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From: Spokane, WA

Also try rotating the driveshaft and watch the u-joint. If you rotate the driveshaft back and forth there should be no play in the joint. If you notice any then you've got a problem. If the joint is on its way out you can usually hear it clunking if you move it back and forth or shift it side to side like Peach said.

Dec 20, 2004 | 11:42 AM

mohavi

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From: Tucson

well its too late for me to check them cause i usually do all my maintenance on the weekends. i forgot that i had to work and guess what happened. the driveshaft fell out while i was driving! i was lucky cause i was turning in to a street and it made the most horrible noise ever. so it was the u-joints so i have already picked some up and i found out that i also needed the ceter support because it was cracked all over the rubber. so my thinking is that if that support was cushioning that vibration that it already gives out that was cause the u joints to go bad. correct me if im wrong i really dont know that much about drivetrains but that my guess

Dec 20, 2004 | 12:22 PM

ivanribic

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From: Spokane, WA

There can be a number of things that make U-joints go bad. Lack of lubrication, extreme angles, out of balance shafts, regular wear and tear . . . you name it. It sounds like you're talking about a pillow block on your driveshaft that's worn out. Long trucks like Supercabs and Crewcabs had these to support the extra long rear shafts. Do you have 2 seperate sections to your rear driveshaft? If that rubber cushion starts to wear it'll also cause vibration and could put extra stress on the joints. I don't imagine it costs too much to replace it though.