My driveway/parking area is on a little bit of an incline. When I'm backing my '76 Cutlass up into its parking spot I get a vibration that comes up through the floor. I only notice it when it's going up the incline though, and not when backing up on level ground. I also don't feel it when I'm going forward either. Is this in the u-joints, or do I have a deeper issue?

Thanks in advance.

 

Vibration "coming from the floor" and only in reverse sounds more like parts are touching the floor or body that should not be. Have you checked the motor and trans mounts?

 

No, I haven't. It wouldn't surprise me if they were worn out. It seems like everything is, haha. I was wanting to swap out the crossmember for a double hump one, so I can replace the trans mount at that point.

 

An easy u-joint check is to shift from N to D and N to R and listen for a clunk sound.

 

Check for places where the exhaust might be vibrating against the underside. When you put the car in reverse, the engine torques the other way, which can cause parts that normally clear to touch. When backing up an incline (as opposed to on the flat) you have to give it a little more gas, which torques the engine over just a little more. One thing to try is to jack up the rear, set the e-brake, and have someone shift from PARK to REVERSE and back. Look for movement in the exhaust system. Also look for broken motor or trans mounts, or worn bushings in the rear suspension that can also cause movement.

 

I bet your going to find the exhaust touching something. Either the engine or transmission mounts are rotten, or the exhaust hangers are worn allowing contact.

 

Or, the exhaust was routed with insufficient clearance in certain locations. I'd be lying if I said I'd never done that.

 

Thanks everyone for your responses.

I think the exhaust is probably the culprit. A previous owner cut off all of the original exhaust system and welded in a sketchy pipe and a glasspack that exited under the passenger side door. I was planning on replacing that over the winter anyway.