Bad vibrations (Part 2!)

[threewood]

I have had the inspection cover off the trans and I rotated the torque converter by hand to check for weights. I do not see any areas on it that look like any weights have fallen off. The flexplate appears to be okay as well. I stuck a thin mirror up there and a light to check it out and I don't see any cracks.

I believe the motor is extrnally balanced.

1964 Poly 318 should be a steel crank = internally balanced. Do you have a picture of the harmonic balancer? Thinner one is for internal, thicker one for external.

 

[Dave145]

I don't have a shot of the balancer currently. It is rather small and thin walled. Stock motor and trans.

Never noticed a vibration in park or with the car not moving before. Only have really looked/felt for it now. As I stated, it's a pretty certain rpm range where this exact vibration is felt, but now a different vibration is felt at lower RPMs.

Plugs, wires, cap, rotor, distributor, ignition box all new. Carb rebuilt last week. Motor seems to run just fine. Also as I said, all weights on the torque converter are present and the flexplate visually looks alright.

 

[5.7 hemi]

At this point, I say tank that boat anchor/trans and toss in a big block/4 speed. No more of this constantly changing vibration that you and everyone else on this forum can’t figure out.

 

[67440chrg]

I cant offer any advice that hadnt been thrown out already. Good luck I am interested to hear what it is.

 

[Dave145]

Here is a shot of the balancer

 

[oldkimmer]

U say u checked the diff angle at .5 degree, is that up or down? What is it tranny angle? Up or down or 0.u need at least 3 degrees difference between them Kim. Example: if the trans is down 1 degree ur diff needs to be down 4 degrees. Or if tranny is up 1 degree ur diff needs to be down 3 degrees

 

[oldkimmer]

Have u ever checked to see how much play is in the rear transmission tail shaft bushing? Should be nil to just noticable anymore than that it needs replacing. Kim

 

[Dave145]

I've checked the bushing plenty of times. Pinion angle is not the problem here.

The car has different vibrations throughout the room range at this point.

Do I know why they changed? Nope not at all.
Have I experienced them in this car before? Also, nope.

I'll pull down the inspection cover on the trans again and check to make sure all the weights are present in the torque converter next.

The balancer is fine. I checked the timing marks at TDC and everything lines up. I can't imagine the balancer rubber being bad and leaving the timing marks in the correct positions.

 

[khryslerkid]

I'll pull down the inspection cover on the trans again and check to make sure all the weights are present in the torque converter next.

Cast crank motors need the weight on the converter. Steel crank motors do not use a weight on the converter. In your pic of the dampner, it looks like a Steel Crank..

I don't recall what engine you're working with there. What's the history on the engine and trans, any work ever been done, trans or engine replaced?

 

[Dave145]

The engine is the stock poly 318. To my knowledge it's never been apart. All the bolts on it look undisturbed, so that backs up my theory a bit...

The only upgrades to it so far have been the motorcraft 2100 carb swap to replace the worn out Stromberg, and electronic ignition. The carb is turned right according to the plugs, as all the plugs are a very nice red/tan color. It pulls roughly 16" of vacuum at idle. Timing is set to 12°, stock spec is 10°, but it has a bit more pep at 12. Advancing/retarding the timing has zero effect on how it runs. The heat riser valve in the exhaust is rusted in place, but I was able to get it open with a vice grips on the shaft.

The trans is the 727 and is also untouched and original.

 

[ckessel]

Any word on the road force balancing on your tires/wheels? I remember from my previous job, on two separate vehicles with repro tires and stock steel wheels, they both shook bad at highway speeds even though they balanced on the Bean machine. The Bean unit did not have the road force feature like whats on the Hunter. You could get into the settings and it would show you the dynamic runouts of the tire and wheel and if it could be helped by repositioning the tire on the wheel. On both of those vehicles the wheels were not round or straight and the tires had out of round issues. Since the vehicle owners supplied the tires, they had to deal with their suppliers of the tires and get better wheels. They both decided to live with the shake. You can balance out issues on the machine but once it gets on the car, with the ground force on them, its shake city. I can't remember on your long list of checks, did you swap tires/wheels with someone whose units don't shake?

 

[Dave145]

I have not had them roadforce as it would be useless against this issue being that the vibration from the motor/trans is appearing even with the car sitting still.

 

[ckessel]

Missed that part. Will keep watching for updates and hope you slay it.

 

[Dave145]

I checked the converter tonight. No weights on the ring gear portion of it. Someone told me they welded weights to the side of the converter that goes into the trans. I have no idea.

I removed all the belts to see how it ran without the accessories. No change.

Between 1300-1600rpms there's a slight shudder while running. As I said a few posts back, it's more of an oscillation than anything else. I can visually watch the front of the motor start to shake, then watch it move backwards through the car.

At 2000rpms it mostly smoothes out, but still very very slightly shudders.

At 2500rpms sometimes I can feel the pounding vibration beginning, other times it's still and feels solid and fine.y guess is as good as yours here.

These numbers and feelings are with the car in PARK. Being that it isn't moving, that kind of rules out the driveline behind the torque converter and the wheels/tires and such.

At this point I fear it's coming down to pulling the motor and/or the trans and putting either a motor or a torque converter in it.

Here's a point I figure is worth asking. The exhaust on this thing is as large as my garden hose. 1.5" downpipes, then a single 2" pipe backwards. I feel this is too small, even for a 99% stock motor. Could there be too much back pressure causing this "thumping" sensation? The car launches decently for what it is, but has a pretty gutless mid-range.

 

[Dave145]

Well I'm unfortunately back again. I decided to put new tires on the car. Brand new MasterCraft Avenger GTs sized 215/70r14. The look great and ride nice...

But the vibration is still here. The best part is that now it seems to start at 65mph.

I guess tomorrow is going to involve jacking it up, running it with the wheels on, then taking the wheels off, then the drums off, then removing the axle shafts to see if anything changes. If it still vibrates even with no shafts, guess I'll end up pulling the rear end apart.

That or I'll pull the driveshaft and try running it up to speed to see what it'll do. I don't know.

 

[Dave145]

For those following, I'm back again. Still no success.

Jacked the car up, let it idle and watched the wheels. Found both hubs were bent, as the wheels and drums both wobbled as the wheels went around. Both sides were like this.

That being said I chose to replace them. A friend of mine gave me good take off drums with good hubs in them. We popped the hubs out of the drums, put them on the car and drove it. No change. The car feels smoother at speeds up to 69mph, but at 70 it's exactly the same. 100% the same.

Put the turd on stands again and ran it up to speed. Everything looks fuckin hunkey-dorey under there running at speed. No driveshaft wobbly crap, no wiggly wheels, no bouncy castle exhaust or motor or trans. Nothing. Looks like a regular car under there, just all shiny and new.

Shakes the whole damn car apart. Heaven forbid it hits 80! It puts the vibrating chairs at the mall to shame! Repositions both mirrors for me with how bad it shakes. Let off the gas and coast down to 69, and the shaking gets worse!

So as usual, I'm at a loss. I've sunk $1500 and a year into this stupid issue. I've never seen something so God awful retarded. I've got a 3 hour trip coming up Wednesday that I'm taking this car on, and I'm loving the thought of it already.

Rant over but I feel my frustration is justified. Pardon my expletives if this site shows them.

 

[Glenwood]

What hubs, the rear axle hubs? Still sounds like bent axles or bearings in the tubes or differential. Has the center section been removed yet? I think all the rearend parts need to be pulled apart and carefully inspected.

 

[Dave145]

Yes the rear axle hubs.

After replacing them the drums spin true as do the rear wheels. Wouldn't a bent shaft make itself known by not allowing this to happen?

Center section hasn't been removed yet. It doesn't make any noise to indicate a bearing issue, but it is on the list of stuff to pull apart sooner or later.

 

[monaco66coupe]

I had a similar vibration in mine years ago, damn hard to find. Finally a Transmission expert drove it, and said it felt like the bands were trying to put the car in drive and reverse at the same time. He was correct, as shortly after that the trans completely shook itself to death. I know that is a lot of work, and not an easy answer, just something that could have happened.Also, when he took it apart, there was debri from the torque converter in the valve body as well. Maybe drop the transmission oil pan, and look everything over?

 

[Dave145]

I've had the trans pan down. No debris found. Filter replaced but old one looked pretty good. Fluid refilled with regular Dex/Merc trans fluid.