Bushings or U-joint

[opus10583]

Hi,

My new toy, 1978 Spider, exhibits a sharp knock in the rear under spirited acceleration. I've read that could indicate worn upper link bushings, obviously it could be the rear u-joint as well: Can anyone here tell me how to differentiate between the two?

The previous owner rebuilt the drive shaft but didn't replace the rear U-joint spider, and I'm betting all the suspension rubber in the car is factory "fresh".

Thanks,
Mark

[azruss]

is the knock rpm or tire speed related, or constant.

[opus10583]

is the knock rpm or tire speed related, or constant.

Hi,

None of the above: A sharp knock on the reapplication of torque while briskly motoring.

Thanks!

[v6spider]

applie parking brake and grab the driveshaft with the car in neutral and see how much rotational pay is in the driveshaft. If you can feel it klunking with more that a 1/4" of rotational play then it could be the rear end.. if you can shake the driveline and get side to side play it could be u-joint do the side to side check at both the front and rear of the driveshaft... hope this helps these are the methods I used to determine those issues...

cheers!
Rob

[opus10583]

It was the trailing arm bushings. Replaced them all, the knock is gone.