S13 diff/trans shaking

[imdarkmatter]

I just finished swapping my ka24 into a shell. everything was assembled from scratch by me. installed is a j30 diff.
So upon completion of my s13 project, I drove it around for about 3 hours. it drove perfectly. just needed an alignment. suddenly, a loud clunk sounded like my diff exploded . now, when I drive above 15 mph, my shifter bounces up and down violently along with my whole car shaking. I have put it on jackstands an put it on first gear and it is smooth. I crawl underneath and find my diff bushings are shot. I replace with energy bushings. vibration is still present. it feels like the rear passenger coil over is smashing into my car repeatedly like it's bottoming out. any input would be great

[imdarkmatter]

bump for. crawling back under the s13 today

[PapaSmurf2k3]

Wow, almost sounds like a bad U-joint or missing bolt on the driveshaft or something.
After inspecting the driveshaft, I'd try removing the driveshaft from the diff and spinning the diff by hand to see if it feels funky. You could also spin the trans by hand via the driveshaft in neutral and check for the same thing.

Does it have the issue (when driving) whether its in gear or not?

[imdarkmatter]

Wow, almost sounds like a bad U-joint or missing bolt on the driveshaft or something.
After inspecting the driveshaft, I'd try removing the driveshaft from the diff and spinning the diff by hand to see if it feels funky. You could also spin the trans by hand via the driveshaft in neutral and check for the same thing.

Does it have the issue (when driving) whether its in gear or not?

thanks for the reply. I have spun everything over by hand perfectly. what makes me believe it is the diff is that when I reach the point of vibration ~15mph, I can push in my clutch and it stops. tomorrow I may crack the case off the diff and investigate the internals.
i just dont understand how everytging turns over by hand smoothly