Signs of a bad harmonic balancer?

[IHaveAMustang]

So recently I have noticed when driving around in the 66' it's a lot more "shaky". Like it's causing my whole car to shake with a resonance that is causing vibration noises and my gear shifter is wiggling back and forth.

I know it's not driveshaft or wheel balancing because I can shift to neutral when coasting 50-60 and the whole car smooths out.

Also, when just sitting in neutral and stopped, I can rev the engine and the whole car shakes.

When restoring the coupe, it came with a 302 block that I think we determined was out of a 84' LTD, but never really confirmed it. We first went with the 28oz harmonic balancer, but it seemed to vibrate more than my brothers 66' 289. So we put the 50 oz and it seemed to do well. But lately it just seems awful.

Is this a sign it's going bad? It was rebuilt 2007/2008 so its over 12 years old.

Are there any other causes for vibration under engine rev/power but not in neutral?

It has a Tremec T-5 out of a 93 GT

[jw33]

If it is a stock style balancer the rubber part could be shot and may be falling apart moving around too much. Checked the motor mounts yet? What flywheel is in it?

[cool cat]

When my balancer went bad, i was able to pull the rubber part from the metal part it used to be bonded to. I don't know how it didn't get launched through the hood, radiator or somewhere else.

[IHaveAMustang]

If it is a stock style balancer the rubber part could be shot and may be falling apart moving around too much. Checked the motor mounts yet? What flywheel is in it?

Motor mounts are good from what I can tell, no obvious cracking and motor doesn't move under RPM

I have no idea what flywheel is in it. I believe it was whatever came stock with the T-5, we literally did nothing but install the transmission as everything felt tight/good. In theory, it should be the 50oz.

My dad and I restored this car over a decade ago back when I knew nothing about engines/transmissions and so I didn't document anything like a moron. It may require unbolting the trans and see if I can find any markings or engravings.

I'm going to pull the fan and get a hold of the balancer and see if there is any play in it. Im hoping that is what it is.

[cool cat]

if it isn't the balancer, something else might be loose. While you're under the car, grab the driveshaft, see how much play there is while it is in park,.

[Big A]

Look for beer bottles in the trash can and/or a sudden increase in the use of perfumes, air fresheners, and gum.

[IHaveAMustang]

if it isn't the balancer, something else might be loose. While you're under the car, grab the driveshaft, see how much play there is while it is in park,.

Will do - it's a newer custom made aluminum drive shaft that we made just for the T-5, and it was pricey, so hope it's not the issue

Look for beer bottles in the trash can and/or a sudden increase in the use of perfumes, air fresheners, and gum.

Uhhh? You're going to have to explain that one to me.

[mardyn]

Has it always had the vibration problem or is it a recent occurrence?

It's pretty easy to differentiate between the 28oz and 50 oz flywheels as the weight are generally on the front (engine) side... but if flywheel is wrong, the vibration would be there from the start.

mardyn

[IHaveAMustang]

I've noticed it more and more over the past year. It has always vibrated (as old cars do) but it just seems super shaky now. I'm beginning to think now that my balancer is dying/dead.

[garycrist]

I had a vibration problem that drove me nuts.
It even seemed like a miss a speed and under load.
The bolts from the tranny to engine were loose!
Easy to check.

[IHaveAMustang]

I had a vibration problem that drove me nuts.
It even seemed like a miss a speed and under load.
The bolts from the tranny to engine were loose!
Easy to check.

I'll take a look as well. We didn't have the hardware to bolt the trans to the engine (previous owner lost them) so we got Grade 8 bolts and put them on there. I didn't loctite them, so maybe they've worked themselves out over the past 12 years.