Driveshaft Balance 93 GMC Sierra extended cab 4x4

[masher41]

Got a weird high frequency vib at 65mph +. Rear of truck off ground on jackstands - def in rear. Looking at u joints and driveshaft. U joints have no obvious problems. Does this pic of driveshaft balance weights look normal?? Looks like it's been worked on before.

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[masher41]

Update: took to driveshaft shop today, guy there says this is normal procedure for DS balancing weights, had him replace both u joints and balance DS assembly. Will know whether this resolved the shake at 65mph+ in next day or so. He did say that the u joints looked like aftermarkets due to grease fitting, however whomever changed them could have reassembled out of phase on slip yoke end resulting in shake. If this doesnt solve the prob, seriously considering buying the NVH app to help diagnose further.

 

[RichLo]

Glad you took it to a pro for balancing.

I'm sure you already had your rear tires re-balanced also? Sometimes wheel weight fall off or a tire has tread separation.

 

[masher41]

Glad you took it to a pro for balancing.

I'm sure you already had your rear tires re-balanced also? Sometimes wheel weight fall off or a tire has tread separation.

Yes, I have 4 new tires, mounted and balanced before trip to driveshaft guy. Trying not to fall in the black hole of chasing vibration, but we'll see how it goes.

 

[GoToGuy]

New tires, most likely not, but swap front to rear just to eliminate the possibly. New tire with defect could always slip thru.

 

[packer0440]

Maybe I'm not seeing this right, but it almost looks like that driveshaft has had a section added on to it? If that's the case hopefully they welded it on perfectly straight. Also is this a 2 piece driveshaft?

 

[454cid]

Maybe I'm not seeing this right, but it almost looks like that driveshaft has had a section added on to it? If that's the case hopefully they welded it on perfectly straight. Also is this a 2 piece driveshaft?

I think it's one of the driveshafts that has a carbon fiber sheath over it. My dad's old 1990 4.3L GMC had one of those. They were a Dana product, I believe. The epoxied balance weight looks weird to me, Though.

 

[Erik the Awful]

If it still vibrates, the old trick is to put a hose clamp around the driveshaft and move it around 1/4 of the way at a time to see where the vibration is better or worse.

 

[masher41]

I think it's one of the driveshafts that has a carbon fiber sheath over it. My dad's old 1990 4.3L GMC had one of those. They were a Dana product, I believe. The epoxied balance weight looks weird to me, Though.

Correct, 1 PC with black wrap.

 

[masher41]

New tires, most likely not, but swap front to rear just to eliminate the possibly. New tire with defect could always slip thru.

Tried back to front tire swap, feels the same. Should have driveshaft back and in by Wed/Thurs.