Engine Vibration

[Logan Robb]

To my knowledge, engine, transmission, and drive shaft are original to the car. 

I am worried I am falling down the rabbit hole of vibrations. 

Some tests I’ve done recently:

Going down flat and level good blacktop about 65/70, fairly noticeable vibration. Shift to N, vibration is significantly lessened. 

When revving engine in P or N, there is fairly noticeable vibration. 

Where should I start first? I know the rear portion of the drive shaft is often to blame and I am worried that is the case in my situation. But that seems like a hefty job I am unsure I can complete myself.

Ive also seen mention several times of the harmonic balancer. Again, not sure that’s something I can complete myself. 
I am not opposed to have work done on those two areas, but finding someone in my area (Bloomington IL) to do the work is going to be a hurdle. 

So, what are your thoughts on the issue?

1964 Fleetwood

Thanks! 

Logan

[Logan Robb]

As always, I appreciate your experience! 

I think getting as many new rubber parts as I can seems like a good place to start. 

Having the engine and trans out are in my 5 year plan, so any internals will wait until then, but engine mounts and trans mounts seem like a fairly reasonable repair to see how that would fix the issue. 

Are there any good ways to diag perhaps the rear portion of the drive shaft or maybe the center support bearing? Those also seem like reasonable repairs. 

At the end of the day-the vibration is really not that dramatic. I feel a bit like Clovis, I’m sure my passengers would not notice the vibration, but I do HAHA and my ADHD is running rampant. And I am chasing things that aren’t a severe issue. realistically, the vibrations only start to get worse at 75/80+ which I NEVER run that fast regularly. Putting around at 45-65 is like a dream and that seems good enough for me. 

[Logan Robb]

I absolutely plan on keeping my car for the remainder of my life. But safety and driveability come first at this moment in my life. 

If I had endless resources, I’d have the car fixed up in no time! But I’m only 25, so I think I’m doing alright with it for now! 

[Logan Robb]

No need to speed in a Cadillac! You'll always get to where you're going. Just avoid the Highways....

[Logan Robb]

Putting an update in here primarily for me-

I did more road testing (really just joy riding around after work) tonight, and while I do feel like perhaps there is some drive train vibration, I really feel like the vibration is coming from the 4 corners. I have new ball joints coming and new front shocks as well. then a trip to the tire shop so they can install those new parts and get a good road force balance on all 4 tires. After that, we will see where we are. I think an alignment is in order as well. 

A few questions I'll pose to the thread-

Should tired be balanced w caps on or off? Ill make sure to have the shop put the weights on the inside as to not interfere with the caps. 

Any special needs for doing an alignment? Or fairly straight forward-something that any tire shop should be able to handle?

Thanks!

Logan

[Logan Robb]

I see very few cars from the 60s around here at car shows! Last summer, I was almost always the only Cadillac. If I wasn’t, there was only one other, usually newer. 

Love my 64!