cor66vette

The drive is smooth from Zero to 50 in any gear. While cruising at 50 the car is still okay, then I get a slight rumble (vibration) when I accelerate, but not while maintaining speed. This rumble/no rumble continues at higher speeds, also. Any ideas? Thank you

DUB

All I can suggest is that all components of your driveline need to be inspected.

So...transmission mount, rear differential mounts and so on. Anything that will move when under a load (acceleration) and then lessen when you are sustaining a constant speed.

DUB

cor66vette

DUB

Thanks. Might there be anything specific I should concentrate on considering this happens at 50 mph and not at slower speeds?

I changed the 1/2 shaft u-joints but never got around to do the drive shaft u-joints. I'll do that and check everything else, also.

DUB

I have no idea on anything specific to look at. I would climb under the car and have to inspect it all...like what I had mentioned.

I do not know hat the 'smoking gun' is. Thinking about load and stresses that cause this...I am trying to picture in my mind what it might be.

Dodosmike

In addition to what Dub said:

Rear gear wear / slack?

Rotate the tires and see if the sound changes
R&R the drive shaft u joints, won't hurt.
Change diff fluid.

cor66vette

Okay, guys- thanks. I have a couple of things to try.

cor66vette

An easy fix, relatively speaking, to my rumble problem.

I've been planning to change out the drive shaft u-joints anyway, after I changed out the 1/2 shafts, so this gave me the motivation to get it done. I used the Spicer non-greaseable u-joints like I did on the 1/2 shafts. Forum member DUB had suggested them to me a while ago. Rumble gone - now it's smooth as.

Thanks for the comments and suggestions.

DUB

Glad that you found the problem and it is to your liking.

Those half shaft U-joints are pretty stout aren't they? Quite 'beefy'...if you know what I mean.

DUB

7T1vette

Get the car up to 60-70 mph, then put trans in Neutral and let the car coast at that speed. Is the vibration/rumble still there? If not, it is unlikely to be associated with the engine or transmission.

Possible items in driveline to consider, include (in order of likelihood):

Wheel balance

Old tires (getting 'lumpy')

Driveshaft and/or half-shaft balance

Dry/binding U-joint (note: if joint have grease fittings, give them some grease and test again)

{ OOPS! Apparently posted this after you found the problem... }