Very bad vibration at 20 MPH even when coasting with the engine off

CHEVROLET S-10
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PZPTTR
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2001 S-10, automatic 4 cylinder, 70,000 miles, 2 wheel drive, extended cab. Truck has a very bad vibration at 20 MPH, hardly noticeable at other speeds, all 3 u-joints have been replaced (one was bad), drive shafts were checked for balance and were okay. vibration exists even if engine is turned off and coasting. two different garages have failed to find problem. transmission shop says it is not transmission, engine or torque converter related.
Nov 9, 2007 at 11:25 AM
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CHEVY22
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this is a tough problem. there were a lot of trucks with the same problem right from the factory but sounds like this wasn't. a few questions; is the truck lowered?stock wheels and tires? was the carrier bearing replaced when the u joints were done?

Jim
Nov 10, 2007 at 9:06 AM
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KASEKENNY
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This is a two piece drive shaft and it has what is called a double cardan joint. They require lubrication from a specialized lubrication tool. Basically it is a smaller nipple and requires lubrication or it will fail and cause the vibration that you are feeling. This is common on any truck with these double cardan joints because most shops don''t have the tool so they just skip it.

I attached a TSB that talks in more detail about this. I understand that you replaced u joints but this is most likely the cause.

Please reach out with questions and we can go from there. Thanks
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Mar 26, 2020 at 5:18 PM
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