Bad vibrations (Part 2!)

Have you thought maybe putting on one of those camera's at different part of the car to see what is happening. Or get your buddy to follow you and maybe he can see something.was the car ever in a wreck. Are rear spring bushings o.k. and not stuffing around when you get to that speed. You may have done all this and I haven't read it but to me it sounds right rear diff problem.

I have something really easy for you to try. Disconnect the PVC hose and plug it so you don’t have a vacuum leak and see if it smooths out while sitting still. Probably won’t change anything but I have had PVC valves cause surging.

The motor idles and runs smooth. Gutless as a sick pig, but smooth.

The rear spring bushings were replaced when the springs were.

So far I've had people follow me to check it while I'm driving, and everyone says the rear end is solid and straight going down the road.

Back again with more wasted time and money.

Took the car on my vacation. 3.5hrs one way. Not a fun experience at all (driving wise).

Got it home. Checked over the whole front end. I don't know why, maybe I felt like looking at dirty slimy undercarriage parts. Anyways, I didn't find anything. I decided for shots and giggles to turn up my torsion bars a bit, as a friend of mine said that while following me on the road that the car appeared to lean a bit. Took the car for a short drive after that. No change.

Shook both front wheels. To my surprise, they wiggled. The drums wiggled. The wheels bearings were loose. Removed and inspected the bearings, repacked them and reinstalled them. Retorqued them too. Wiggled the wheels again, no more jiggly wheels! Took it for a drive...

Now, it's a bit better. Fixed? No. Better? Sure why not.

It still vibrates at 70. Actually, it vibrates at pretty much every speed above 55. It smoothes out after awhile, but there's still a shudder felt in the car at pretty much all times.

Brought it home. Ran the car through the RPM ranges in park. Hmm. There's a shudder at ALL rpms now. Pulled the motor mounts. Found the PS one to be loose, and both to be pretty aged. For $20, I replaced them. Took it for a drive, and they didn't improve anything. It still shudders at all RPMs. Vibration on the road is still the same.

Unsure as to what's causing the motoro shudder. It used to only do it at high idle (1300-1500rpms). Now it does it all the time. I can run the throttle up by hand and keep a hand on my air cleaner and feel it vibrate all around. My guess is it's gotta be either an internal motor issue or the exhaust is too restricted (though it's stock with a glass pack on it...).

Kinda looks to me like a compression and leak down test is in order to check this things health. I've looked high and low for vacuum leaks, and have not found any. The carb is a reman Carter BBD that I checked over myself for accuracy since we all know how good reman carbs can be.

This thing is such a dog though that finding out it's got a dead lung or a misfire won't surprise me. Stomp your foot to the floor from a standstill and it does...nothing. Really it just grunts. It struggles to spin it's tires on gravel. The only time it feels even remotely peppy is when it downshifts, and even then it's pretty fleeting and it dogs again once it gets back into third gear.

Talking to a colleague today about a shop truck he used to drive. He said the truck developed vibrations like you've been describing. Turned out to be the torque converter.

I hope it isn't. Don't have time to pull the motor/trans. Also don't have the money to guess at a TC right now either.

You don’t need to pull the engine to take out the converter to check it.

If your not going to pull the trans and have checked everything else out, then I’m at my end to be able to help.

The trans is last thing that you really haven’t looked at, and if the converter is out of balance, know matter what you do, it’s gonna vibrate.

Check rearbrake drums.They may be out of round
or weight my be missing.
Have the rears balanced on car the old fashioned way.on the car if you can find an old type balancer
that clamps on the wheel.
Mayfind your problem that way.

I just don't understand how we can make it 13 pages in to a post about a driveline vibration and the rear end still hasn't been cracked open and looked at. Am I missing something? I'm not trying to be snarky, but there are generally 3 big sources of vibration (engine, trans, and rear end) and the one just keeps getting ignored.

We recently had a 6 roll rollover at the drag strip at 145 mph-ish (thankfully no one hurts God bless roll cages), but the telling feature was the driver said he felt a vibration in the rear.

That sparked everyone to look at their issues- if you feel something it may be something.

I have recently seen a car with a slight rear vibration at speed, which looks to be rear lugs bottoming out the studs. They USED to work fine, but gradually over time it seems to have “squished” the alum rims. Shaved 30 thou off the nuts and it seems to have worked. Not my car. So even if the wheel nuts seem tight, maybe there is a slight gap? That’s a fairly easy and cheap check.

That’s a good call!