1G Driveshaft out balance?

[Anfurnyy]

In August I took my car to the track and got some wheel hop and exploded the 2nd ujoint on the drive shaft.

Sent the back end of the 1st driveshaft segment spinning under the car blah blah.

I had a spare good 1st segment and swapped that and a new UJoint in knowing it would probably need balanced but went for a test drive and the car vibrates pretty horribly at around 35mph.
Only shop that does driveshaft balances here said I'd have to disassemble the whole thing and bring it in and they'll balance it piece by piece which takes a bunch of time and they quoted me " a couple hundred dollars" for a balance.

Decided to swap back in the original front segment with the new UJoint and it still vibrates badly around the same mph.

Put the car up in the air and stuck it in 2nd and let the wheels spin and peaked underneath maybe I see the first 2 segments possibly out of balance? I'm not really sure what to look for so asking for any insight. Maybe the shafts are bent?

Anything else to check?
It doesn't feel like a wheel out of balance, it feels much faster than wheel speed to me but maybe it could be?

VIDEO

 

[jdxnc]

You probably bent some portion of the shaft, I'd just find a complete used shaft and change it all, or for probably less than getting the oem rebalanced you could just replace the front section with a DSS aluminum shaft and use a good used rear section.

 

[Anfurnyy]

You probably bent some portion of the shaft, I'd just find a complete used shaft and change it all, or for probably less than getting the oem rebalanced you could just replace the front section with a DSS aluminum shaft and use a good used rear section.

After watching the video again it does look like the portion just in front of the 2nd ujoint that broke wobbles up and down a little bit. You're probably right.

I wish I could afford the DSS shaft but just bought a truck so stuff is a little tight. I might just swap completely over to this spare OEM driveshaft and hope that works.

 

[bastarddsm]

Check the yoke. If you broke part of the shaft good chance the yoke is twisted.

 

[Anfurnyy]

Check the yoke. If you broke part of the shaft good chance the yoke is twisted.

I'll check it thanks

 

[Anfurnyy]

Yoke is straight, output shaft splines are straight both with visual inspection. The yoke slides on the output easily, no hang ups or anything.

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Pretty sure the front 1/3 AND weld yoke that connects to the first 1/3 are bent.

Took it to drive shaft shop here and they can't balance a 3 piece. I even took it apart (unfortunately at the CV joint) and they said that they didn't have a spline small enough for the yoke and no joint small enough for the Weld Yoke.

So this shaft is screwed basically.

I do have a spare whole driveshaft I'm getting throw in.

 

[Anfurnyy]

Tried to install the spare driveshaft, but since i had removed the front 1/3 shaft without marking what side was what now im in a wild goose chase for the correct orientation.
I have the full entire spare driveshaft in, installed the front shaft and vibrated, rotated the shaft 180*, still vibrated, now ive flipped the shaft end over end, and it still vibrates starting around 50mph.

Only thing left is to now rotated it 180* again to see if somehow its out of phase with the rest of the 2 shafts, but comparing to how Jafro mentions his in his (rebuilding a drive shaft in 2023) video, it should be correct..

Does anyone have any pictures that reference the orientation of the Weld UJoints and the weights so i can verify what side is what?
This is before flipping the shaft end over end, and also rotating it 180* in the same move.

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im nearly 100% confident the last 2/3 of this spare shaft is good as i marked that before i brought it to the driveshaft shop but im unsure of the phasing of the front 1/3 shaft compared to the rear 2/3.

 

[Adam]

You can also run a dial indicator on it in different spots if you need help pin pointing where the specific spot is that's out