Funny vibration at take off...HELP!!!!

[goober34]

I have a 74 L-48 4 speed. At take off, I have to get it over about 1500 RPMs before letting off of the clutch. Otherwise, I get a funny vibration which rattles the entire car until I get it up to about 12-1500 RPMs. It also does this if you let the RPMs drop without taking it out of gear...in other words...like a rolling stop without the clutch depressed.
I have been told that it could be my clutch, but it kinda feels like the rear end. I am pretty good at troubleshooting an engine...but i am no drivetrain expert. Anyone please help. I have read the other threads about a loud noise at take off, and I wouldn't say it is a "clunk", but more of a vibration. It kinda feels like when you try and take off in third gear in a standard tranny...that is the closest thing I can describe it to.
Would greatly appreciate your help. To see progress on my Vette and my buddies 190 Superbird clone, visit and join http://autos.groups.yahoo.com/group/Restorationdummies/

 

[Jack]

Clutch ... maybe flywheel also needs resurfacing.
A broken/weak motor or trans mount can act up like this also.
JACK:gap

 

[waterboy1976]

Goober.....I am having the same problem with my 73....I also get a vibration when I shift from 4 to 3 and 3 to 2 when coming to a stop light. Everything in my driveline is new. Flywheel is resurfaced, new clutch etc. Does this make sense : If the clutch it adjusted to far out ie: when the pedal is depressed, when you engage the clutch (let pedal out) if it is adjusted out too far will it start to grab, which causes a vibration, and then once the pedal is let out more the clutch grabs the flywheel better and the vibration goes away? Does that make sense? I am fighting the same problem....What kind of clutch did you install?

 

[JohnZ]

That's also a classic symptom of deteriorated diff nose mounting bracket-to-frame crossmember bushings - causes noise/vibration under accel/decel/braking, lets the rear universal rise up, can even interfere with the tunnel/floor pan. See it frequently, as few folks ever check that area or even know the bushings are there.

 

[waterboy1976]

all my mounts and bushings are new......................