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94 Silverado Road Vibration


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94silverado
Novice

Nov 1, 2010, 11:54 AM

Post #1 of 13 (2838 views)
94 Silverado Road Vibration Sign In

I have a 94 Chevy Silverado 1500 Extended cab, 5.7L with 180K miles. I just replaced the u-joints. Now the whole truck vibrates when I reach 25 mph, lessening after I reach 40 mph. I'm thinking it may be the center mount bearing. Any ideas?


(This post was edited by 94silverado on Nov 1, 2010, 12:17 PM)


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 1, 2010, 3:40 PM

Post #2 of 13 (2822 views)
Re: 94 Silverado Road Vibration Sign In

If this just started after replacing the u-joints, then I would bet there is a problem with the installation. One of the needles may have fallen to the bottom of the cup preventing it from seating all the way and causing the joint to be off center.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



94silverado
Novice

Nov 2, 2010, 2:28 PM

Post #3 of 13 (2813 views)
Re: 94 Silverado Road Vibration Sign In

Thanks for the advice. There's one cap that seemed a little stubborn so I think I'm just going to take the joint apart and check. You're the only one of all the people I've talked to that seems to make sense.


94silverado
Novice

Nov 2, 2010, 2:29 PM

Post #4 of 13 (2812 views)
Re: 94 Silverado Road Vibration Sign In

Thanks for the advice. There's one cap that seemed a little stubborn so I think I'm just going to take the joint apart and check. You're the only one of all the people I've talked to that seems to make sense.


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Nov 2, 2010, 2:39 PM

Post #5 of 13 (2808 views)
Re: 94 Silverado Road Vibration Sign In

You'll probably find a needle bearing in the bottom of the cup.



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



94silverado
Novice

Nov 20, 2010, 2:28 AM

Post #6 of 13 (2783 views)
Re: 94 Silverado Road Vibration Sign In

I reinspected all the cups and bearings and reinstalled the u-joints. I have less vibration now but I think there's still some vibration coming from the rear end and I think may be because I didn't install the cups properly in the straps. I left the clips on the cups and tightened down the straps so that the clips butt up against the inside edge of the straps. I guess I could take the clips off and push the cups outward so the cups are flush with the outside edge of the straps. I just don't remember how close the cups were to the outside edge of the straps.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 23, 2010, 9:20 PM

Post #7 of 13 (2767 views)
Re: 94 Silverado Road Vibration Sign In

? Straps? You mean U-bolts I think. If U-joint is installed properly pressed into driveshaft it should fit snugly in place in the yoke of the rear end then you tighten the U-bolts.

I didn't think this had a "center bearing?"

T



94silverado
Novice

Nov 24, 2010, 9:07 AM

Post #8 of 13 (2756 views)
Re: 94 Silverado Road Vibration Sign In

? Straps? You mean U-bolts I think. If U-joint is installed properly pressed into driveshaft it should fit snugly in place in the yoke of the rear end then you tighten the U-bolts.

I didn't think this had a "center bearing?"


You're right, they are U-bolts. It does have a center bearing I suppose because it's an extended cab. When I pressed the u-joint into the yoke I put the clips on the cups so that the cups would be centered and wouldn't fall out when driving.




Tom Greenleaf
Ultimate Carjunky / Moderator
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Nov 24, 2010, 10:36 AM

Post #9 of 13 (2754 views)
Re: 94 Silverado Road Vibration Sign In

OK - if driveshaft is now know installed properly then a center bearing could cause vibrations. Been a while since GM did that on many vehicles - mostly the truck/Suburban types.

As said - been a while and replaced a few now so long ago all I recall is those are not so DIY friendly and if struggling with a plain U-joint it may not be for you.

Pretty sure when those fail you can get and usually BOTH a vibration AND a noise. Is mounted such that it can move just pushing on shaft on purpose and the mounting must be right too,

T



94silverado
Novice

Nov 25, 2010, 1:01 AM

Post #10 of 13 (2744 views)
Re: 94 Silverado Road Vibration Sign In

I guess I'll get it looked at. Maybe there's someone I can find who can convert it to a one-piece driveshaft.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 25, 2010, 2:47 AM

Post #11 of 13 (2741 views)
Re: 94 Silverado Road Vibration Sign In

Been out of biz for a while and still mess with some. Not sure if a single shaft will be available or not but do ask. They used to self "rebuilt" whole drive shafts (exchange yours) that would be balanced and ready for a quick installation.

If you pounded out the old U-Joint it may have damaged the shaft! Arggh. You can tap with hammers but should press old one out thoughtfully not to damage shaft. If it's off balance or bent it won't ever be right. Same with install of a U-Joint - pressed in not hammered in.

It's funky. Some vehicles never need a U-Joint and some will get a second one. I've seen them be perfect at 250K from new and others eat them for some reason. Replacements should have or usually have a grease fitting. Need a special needle thing to poke into it to grease. They shouldn't need greasing every oil change but just once in a long while.

The mounting for center bearings is flexible and the rubber may be an issue. I'm near sure you have to take that apart there to replace the mount so back to not so DIY friendly.

No matter what the cause it needs to be fixed. The vibration isn't helping the rear end nor the output shaft of the transmission,

Good luck with the fix,

T



94silverado
Novice

Nov 25, 2010, 2:28 PM

Post #12 of 13 (2731 views)
Re: 94 Silverado Road Vibration Sign In

Yeah, I think you may have the right answer in that it may be out of balance. I did use a hammer on the driveshaft to free up the u-joints. I guess what I could do is go to a junk yard and reinstall the u-joints, this time a bit more gently.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 25, 2010, 4:21 PM

Post #13 of 13 (2726 views)
Re: 94 Silverado Road Vibration Sign In

You can and I do hammer the old one out but you need to know just where the forces are going. New ones should not be hammer in. A love tap is fine but not the sledge hammer. It gets them in but at the risk of messing up the job,

T







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